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Benoit Leus
Prolific User
Username: benoitleus

Post Number: 255
Registered: 6-2009
Posted on Sunday, 22 May, 2016 - 01:37 am:   Edit PostDelete PostView Post/Check IP

Over the winter I rebuild the transmission on my '79 Shadow as it was leaking and the shift from 1-2 was a bit rough. It all went well and the leaks have completely dissapeared.

With the engine/gearbox cold the 1-2 shift is very smooth. However, once the whole assembly is thoroughly warmed up, the shift from 1-2 is rough again, unless I accelerate hard.
The shift from 2-3 is perfect as it can not be felt at all.

I'm not 100% sure about fluid levels. Am I correct in assuming that the following procedure is correct :
- start the car (engine/gearbox cold), put it in Drive & Reverse, then in Park again and the fluid level should be +/- 16mm under the min. level on the dipstick.

Any ideas are appreciated.

Benoit
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1534
Registered: 6-2006
Posted on Sunday, 22 May, 2016 - 06:57 am:   Edit PostDelete PostView Post/Check IP

Take the car for a 16 minute drive until the fluid is hot.

Check the level on park with the engine running. It should be around maximum.

Cheers. . Paul.
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David Gore
Moderator
Username: david_gore

Post Number: 2050
Registered: 4-2003
Posted on Sunday, 22 May, 2016 - 07:27 am:   Edit PostDelete PostView Post/Check IP

Benoit,

Did you replace the O-ring on the top of the fluid pick-up tube from the sump?

If not sealing properly or displaced, this allows the transmission oil pump to suck air into the valve body and some of this air may end up in the clutch cylinders causing the problem you describe.
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Patrick Ryan
Prolific User
Username: patrick_r

Post Number: 194
Registered: 4-2016
Posted on Sunday, 22 May, 2016 - 08:29 am:   Edit PostDelete PostView Post/Check IP

Gents,
We had a similar problem a few years ago with our Holden autos, in a new updated car.
The problem was to much pressure from the factory.
The factory fix was to remove the valve body and insert a flow restrictor into one of the galleries.
This fixed the gear hammer perfectly.

I have been wondering if there was a mod like this for the TH400.

What mine does while the car is cold and under choke with higher idle revs, it's slides into gear beautifully.
Once the choke is off (I move it out of the garage to warm up to stop the rich fumes entering the house) you select drive or reverse and wham!!
Quite a hard selection.
When very hot this almost goes away.
When driving under part throttle or hard acceleration the 1-2 shift is very buttery. But under mid to lively acceleration, it get a slight hammer between 1-2.
Temperature does not effect this shifting when driving.
When I have people in the car I just accelerate slowly so there is no feel of the 1-2 shift.
However if we have taken people out then get back in the car, the park to drive hammer is quite embarrassing.
I feel your pain Benoit.
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Hubert Kelly
Prolific User
Username: h_kelly

Post Number: 196
Registered: 3-2012
Posted on Sunday, 22 May, 2016 - 05:39 pm:   Edit PostDelete PostView Post/Check IP

"rolls royce silver shadow gearbox repair", type this into Google, Ronnie from California has a 5 part step by step video on the Gm 400 transmission repair on youtube.
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Jean-christophe Jost
Experienced User
Username: jc_jost

Post Number: 15
Registered: 3-2016
Posted on Sunday, 22 May, 2016 - 07:35 pm:   Edit PostDelete PostView Post/Check IP

I have no precise exprience on this issue but in the workshop manual troubleshooting section they mention up to 6 possible causes for "rough 1-2 up-change". (sorry if you've already been there).
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Patrick Ryan
Prolific User
Username: patrick_r

Post Number: 195
Registered: 4-2016
Posted on Sunday, 22 May, 2016 - 07:54 pm:   Edit PostDelete PostView Post/Check IP

Haven't been there Jean.
I'll need to check that out.
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Benoit Leus
Prolific User
Username: benoitleus

Post Number: 256
Registered: 6-2009
Posted on Sunday, 22 May, 2016 - 08:06 pm:   Edit PostDelete PostView Post/Check IP

Thank you everyone for your help.

Paul,
I did as you said and the oil level is slightly under max so I guess this is OK.

David,
I did replace the O-ring so I assume this shouldn't be an issue

Patrick,
it indeed seems you have the same issues when shifting from 1-2. I also try to drive around it.

Hubert,
I know the video and it has been a great help. Also the book "How to rebuild and modify GM Turbo 400 Transmissions" has proven invaluable.

Jean-Christophe,
Thanks for pointing it out. I had already consulted the workshop manual. But as it only happens with the transmission thoroughly warmed up, I can't really pinpoint the cause.


I now have an adjustable vacuum modulator installed. I have noticed that it's upshifting quite late and kick-down comes too soon, so I will adjust it, so that it upshifts sooner. I hope this might help a bit with the rough 1-2 upshift.

I am considering installing a Transgo Shift Kit.
They're inexpensive, easy to install and I know Jean-Pierre Hilbert has a good experience with it, claiming that shifts are unnoticeable.
Has anybody else installed one ?

Benoit
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Omar M. Shams
Grand Master
Username: omar

Post Number: 646
Registered: 4-2009
Posted on Monday, 23 May, 2016 - 03:14 am:   Edit PostDelete PostView Post/Check IP

Dear Benoit,
I am going to recommend a whacky idea.
Change the oil!!!
This time try a different brand of oil and then see. It is a rough and ready cheap thing to do before you start to tear into it.

Take care
Omar
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Benoit Leus
Prolific User
Username: benoitleus

Post Number: 257
Registered: 6-2009
Posted on Monday, 23 May, 2016 - 04:12 am:   Edit PostDelete PostView Post/Check IP

Hi Omar,

the oil is fresh Q8 Dexron 3.
I'm no oil specialist but would it be possible that a different brand to the same spec will improve the upshift ?

Benoit

ps. I'm still on the hunt for the Moon leopard brochure.
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Omar M. Shams
Grand Master
Username: omar

Post Number: 647
Registered: 4-2009
Posted on Monday, 23 May, 2016 - 04:26 am:   Edit PostDelete PostView Post/Check IP

Dear Benoit,
It is a very very slim chance.
But one that I would take given the relatively low cost. But I would use an oil that is a different make to ensure the formulation is not the same as the oil used this time.
If you get the same result you will know its not the oil.

Oil companies can make oils that are at one end of the specification limits - people always assume that oil is always perfect....... not always.......

The oil change will also allow you to inspect the old oil for any debris that may have gathered after the overhaul to give you any clues about what to look for later (if any).

I am most touched about your comment regarding the brochure Benoit.
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Jean-Pierre 'JP' Hilbert
Prolific User
Username: jphilbert

Post Number: 138
Registered: 9-2013
Posted on Monday, 23 May, 2016 - 09:36 am:   Edit PostDelete PostView Post/Check IP

(please read the .pdf attached below, the formatting of the text was lost by pasting into the thread box).

Benoit,
I believe your gearbox internals are fine because you DO GET a smooth change when cold and also when warm but only under full throttle.
Hence I think that your rough change when warm and under partial throttle comes from how the power flow happens during a 1-2 shift. The wordings below is a copy/paste from the workshop manual and I made the relevant words bold. One really needs to read this slowly, and many times, and read it as you would read some philosophy essay from the 18th century.

In essence, 1-2 shift happens when the intermediate clutch is applied.

Now, there is a clever, build-in mechanism to control the apply pressure of the intermediate clutch. This all happens in the rear servo: the piston is pushed by the

From the workshop manual, page T1-6:
First gear Second gear
Forward clutch applied applied
Direct clutch released released
Intermediate clutch released applied
Roller clutch effective ineffective
Front band released released
Intermediate sprag clutch ineffective effective
Rear band released released

From T12-1:
To initiate the change from first to second, governor pressure is directed to the end of the 1-2 shift valve. As the car speed increases, governor pressure moves the valve to allow drive oil to apply the intermediate clutch. This makes the intermediate clutch effective and the transmission changes into second gear.
Now here it comes (still on T12-1):
Clutch application control
: To introduce gearchange feel, and to ensure long clutch plate life, the clutch apply pressure is regulated to suit throttle application (see fig. T12-2)
The intermediate clutch is controlled according to the throttle opening as follows: Line pressure is varied by the modulator.
A 1-2 accumulator valve train provides a variable accumulator pressure to cushion the clutch application. The 1-2 accumulator valve train is supplied with drive oil and is controlled by modulator pressure. During light throttle application, drive oil is reduced to a low accumulator pressure. During heavy throttle applications, accumulator pressure approaches full main pressure. Accumulator pressure is made to act on one side of the rear accumulator piston in the rear servo (see Section T13). In first gear, the accumulator piston is stroked to its lower position to prepare it for the change to second gear.
When the 1-2 shift valve opens, intermediate clutch apply oil is also directed to the rear servo accumulator piston, stroking the piston against the 1-2 accumulator oil and the accumulator spring (see fig. T12-3). This action absorbs a small amount of the intermediate clutch apply oil and permits the clutch apply time and pressure to be controlled for the correct gear change feel.

Now, because your 1-2 shift is good when cold, and good when warm but only when under full throttle, I believe to think that there is some issue within the valve body and my main suspect would be the rear servo. Either this action of '' intermediate clutch apply oil is also directed to the rear servo accumulator piston''
is not happening, or the rear servo simply does not respond well to it.
What I would do in your place is to remove the valve body again (fluid drained of course and transmission still installed) - well, the checkballs will fall into your face - and verify all fluid passages free of debris and lint, and re-open the rear servo to verify proper action of the piston.
My belief is that some foreign matter has impeded the proper functioning of the gearchange feel which happens on both sides on that rear servo piston.
Below the .pdf version of above text, it contains formatting which was lost by pasting the text into the thread.
application/pdfGearbox 1-2 shift
Gearbox 1-2 shift.pdf (48.3 k)
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Jean-Pierre 'JP' Hilbert
Prolific User
Username: jphilbert

Post Number: 139
Registered: 9-2013
Posted on Monday, 23 May, 2016 - 10:10 am:   Edit PostDelete PostView Post/Check IP

The TransGo kit provides you with different springs to install in the governor, and the front & great servos. In your particular case, you may select a softer spring inside the rear servo to manipulate and hence ''adjust'' the mechanism of the shift feel. I believe that this kit will NOT allow you to mask the issue with your 1-2 shift.
No matter what, the TransGo kit is simply installed with the gearbox remaining in the car, so you can do that easily while replacing the fluid as Omar suggested.
In your place, and in line with the contamination which Omar suspects, I'd remove, dismantle, clean and then re-assemble the whole valve body. I have one or two spare paper gaskets which I can mail you (you should install a fresh gasket).

Jean-Christophe pointed in the right direction, the manual actually mentions 8 issues (nr. 4 is my favourite, but I suggest you concentrate on nr. 7).

1. Incorrect fluid level in transmission: Top up as necessary.
2. Vacuum modulator: (a) Check for loose fittings, restrictions in line, or the modulator assembly inoperative. (b) Check that the modulator valve is not sticking.
3. Oil pressure: (a) Check that the oil pump regulator or boost valve has not jammed. (b) Check for the pump to case gasket being incorrectly fitted or damaged.
4. Check condition of engine: Tune the engine.
5. Control valve assembly (valve body): (a) Check that the 1-2 accumulator valve train is not sticking. (b) Check that the valve body to case bolts are not loose. (c) Check that the valve body spacer plate gaskets are not damaged, incorrectly fitted, or the wrong gasket fitted.
6. Case: (a) Check the intermediate clutch ball (missing or not sealing). (b) Check for porosity between channels.
7. Rear servo accumulator assembly: (a) Check the oil seal rings for damage. (b) Check that the piston has not jammed. (c) Check that the spring is not broken or missing.(d) Check that the servo bore is not damaged.
8. Intermediate clutch: (a) Check that only one waved plate has been fitted (not applicable to Turbocharged cars). (b) Check that the clutch plates are not burnt.
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Mark Aldridge
Grand Master
Username: mark_aldridge

Post Number: 304
Registered: 10-2008
Posted on Monday, 23 May, 2016 - 07:18 pm:   Edit PostDelete PostView Post/Check IP

Gentlemen, I have a change problem on the recon box fitted to my 1983 Mulsanne. This is the opposite to Benoit's. The box changes 1-2 and 2-3 with a jerk when the box is cold, and ambient temp is below 6 centigrade and the change points are only at max speed for each gear. As soon as the box warms up, changes are perfect. Now ambient temp is about 12 degrees overnight, the changes are perfect from cold. Are the faults in any way related, and is the Vacuum modulator valve the culprit ? The oil is dexron 3
Mark
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Jean-Pierre 'JP' Hilbert
Prolific User
Username: jphilbert

Post Number: 140
Registered: 9-2013
Posted on Monday, 23 May, 2016 - 08:55 pm:   Edit PostDelete PostView Post/Check IP

Mark,
You are right, if the gears don't change before max rpm then start your troubleshooting by changing the vacuum modulator. They are cheap, buy an adjustable one, NO need to buy the OEM RR/B! Also verify the integrity of the vacuum line and compare the vacuum at the end of the hose with what you have at the source (wet-finger test). Do that test with engine cold and then when warm. Do you feel a difference? You may need to drive to Snowdonia now to replicate the cold-weather.
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Benoit Leus
Prolific User
Username: benoitleus

Post Number: 258
Registered: 6-2009
Posted on Tuesday, 24 May, 2016 - 07:24 am:   Edit PostDelete PostView Post/Check IP

Jean-Pierre,

thank you so much for all your help and effort.
Over the next few weeks I should have time to dismantle the valve body and check everything as needed.
Hopefully, this will prove succesfull.

Benoit
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Jean-Pierre 'JP' Hilbert
Prolific User
Username: jphilbert

Post Number: 141
Registered: 9-2013
Posted on Tuesday, 24 May, 2016 - 08:22 am:   Edit PostDelete PostView Post/Check IP

Benoit, It'll take you 2 hours once you find those 2 hours;)
During the overhaul, you replaced the seals, o-rings and the like on the valve body and the 2 accumulator pistols, right?
Maybe really an opportunity to install the TransGo shift kit!
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Patrick Ryan
Prolific User
Username: patrick_r

Post Number: 200
Registered: 4-2016
Posted on Tuesday, 24 May, 2016 - 08:35 am:   Edit PostDelete PostView Post/Check IP

Gents,
Would a trans go kit help with the hammer into drive from park I described earlier?
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Alan Dibley
New User
Username: alsdibley

Post Number: 4
Registered: 10-2009
Posted on Tuesday, 24 May, 2016 - 09:05 am:   Edit PostDelete PostView Post/Check IP

In the Citroen world it has been claimed that Dexron 3 is not an exact substitute for Dexron 2, hence the ZF box on CX 25Gtis behave better on Dexron 2 than on 3, in spite of what it says on the tin. I use Dexron 2 in both Cxs and Bentley T and have never had problems (so far). That goes for about a dozen similar Cxs over the last umpteen years.

Just a thought.
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Jean-Pierre 'JP' Hilbert
Prolific User
Username: jphilbert

Post Number: 144
Registered: 9-2013
Posted on Tuesday, 24 May, 2016 - 09:27 am:   Edit PostDelete PostView Post/Check IP

Patrick, hammer into drive? Is your engine idling too high?
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Patrick Ryan
Prolific User
Username: patrick_r

Post Number: 201
Registered: 4-2016
Posted on Tuesday, 24 May, 2016 - 10:19 am:   Edit PostDelete PostView Post/Check IP

Hi Jean,
No mate, its quite slow, but not sure of the exact RPM.
When its hot, its great.
First thing on start up on choke and high RPM it slides in real nice.
Just when it's warm BANG from park to drive.
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Hubert Kelly
Prolific User
Username: h_kelly

Post Number: 199
Registered: 3-2012
Posted on Wednesday, 20 July, 2016 - 08:13 pm:   Edit PostDelete PostView Post/Check IP

Hi, would anyone know what a 1968 4 speed gearbox might weigh.
Thanks in advance
Hk
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richard george yeaman
Grand Master
Username: richyrich

Post Number: 566
Registered: 4-2012
Posted on Wednesday, 20 July, 2016 - 08:35 pm:   Edit PostDelete PostView Post/Check IP

Hi Hubert I don't Know but my guess would be around 55kg to 65kg, I wonder why you nee to know, Just being nosey!!!

Richard.
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Hubert Kelly
Prolific User
Username: h_kelly

Post Number: 200
Registered: 3-2012
Posted on Wednesday, 20 July, 2016 - 09:31 pm:   Edit PostDelete PostView Post/Check IP

Hi Richard, thanks for that, I hope to buy one in England, just trying to figure out how much it might cost to have delivered to Ireland.
Thanks again.

Hk
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Alan Dibley
Experienced User
Username: alsdibley

Post Number: 21
Registered: 10-2009
Posted on Thursday, 21 July, 2016 - 12:09 am:   Edit PostDelete PostView Post/Check IP

Nobody has picked up on my earlier post about the difference between Dexron 2 and Dexron 3. When these cars were made Dexron (as specified in the handbook) meant Dexron 2 because Dexron 3 didn't exist and Dexron 1) was history. What do other folk use, 2 or 3? As I said before, the Citroen world thinks that 2 and 3 are sufficiently different to change the behaviour of the ZF boxes fitted to CXs (for which Dexron 2 is specified by the manufacturer). Maybe GMs too? What is the GM spec for the 400?

Alan D.
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Mark Aldridge
Grand Master
Username: mark_aldridge

Post Number: 328
Registered: 10-2008
Posted on Thursday, 21 July, 2016 - 04:01 am:   Edit PostDelete PostView Post/Check IP

Alan, from my own experience D3 tends to give a slightly smoother change , particularly on cold mornings on THM 400 boxes.
On my S1, the gear change is much smoother with D3, the "jerkomtic" nickname totally disappears.
Mark}
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1036
Registered: 5-2015
Posted on Thursday, 21 July, 2016 - 04:03 am:   Edit PostDelete PostView Post/Check IP

No kits are necessary, because the TH400 slush box is known to be a smooth operator normally.

I suspect it's something to do with the vacuum module.

The pipe from the module to the inlet manifold has a restrictor.
Check it's still there.
When the pipe is replaced the restrictor gets left off because it's not obvious.
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Alan Dibley
Experienced User
Username: alsdibley

Post Number: 22
Registered: 10-2009
Posted on Thursday, 21 July, 2016 - 04:13 am:   Edit PostDelete PostView Post/Check IP

Mark, thanks for that news - it saves me the trouble of hunting for D2 if D3 will do the job OK. I suppose the Citroen CX ZF box is a different kettle of fish.

Alan D.
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David Gore
Moderator
Username: david_gore

Post Number: 2122
Registered: 4-2003
Posted on Thursday, 21 July, 2016 - 08:58 am:   Edit PostDelete PostView Post/Check IP

Patrick,

Your rough engagement when idling may be either of the following:

1. Problems with the pawl that locks/unlocks the transmission when Park is selected/released not disengaging smoothly when the selector is moved from the "Park" position.

2. The engine hot idle may be too slow and the fluid pump is not delivering enough pressure to the transmission valve body for the control valve responsible for engaging the "Drive" function to open smoothly.

First thing I would do is check the hot idle with a tachometer - I used a hot idle speed around 700rpm for DRH14434 as I found this together with a static timing setting of 6 degrees BTDC gave a smooth idle and best acceleration from rest. The 1-2 shift was noticeable under hard acceleration as I had modified the valve body to allow instantaneous clutch engagement by eliminating the in-built clutch plate slip for imperceptible gear changes in the R-R version of the T400. This modification is detailed in the B&M T400 overhaul kit instructions [pages 18 to 22] which can be downloaded from the link below:

https://drive.google.com/file/d/0Bz2EYc0pOpXkamxQVW0wR095YVk/view?usp=sharing

The following thread is also relevant:

http://au.rrforums.net/forum/messages/17001/17442.html

The first thing I would do is check your hot idle speed and adjust it to 650/700rpm and see if this reduces/eliminates the rough engagement when selecting drive. If there is no change and you are concerned with possible damage to the transmission, it may be appropriate to have it checked by a GM auto transmission specialist - I suggest fellow Club member Neville Vassallo who had [and may still have] an automatic transmission service centre Neville's Automatic Transmissions at 143 Canterbury Rd, Bankstown NSW [we held one of our Self-Help Days here in November 2002 and Neville gave an excellent presentation on the 4 speed Hydramatic transmission].
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 1589
Registered: 6-2006
Posted on Thursday, 21 July, 2016 - 09:05 am:   Edit PostDelete PostView Post/Check IP

DVI now. As in Roman 6.

My Transmission builder swears by it. So that's all I've been using for quite a few years now and is all I use in the GM boxes these days. It seems to suit them well.

It's supposed to last twice as long but I will still do 4 years max. It's not worth the risk IMHO.

I still have D3 for PAS. D2 is old hat and is often more expensive in a lot of places in any case.

"
From a GM tech bulletin:

Although DEXRON-VI (fig. 1) was introduced into production starting with 2006 model year vehicles (see bulletin 04-07-30-037D), there are still some misunderstandings about it. Here are some facts to help clear up these misunderstandings.
Since GM introduced the first service-fill specification for automatic transmission fluid (ATF) in 1949, it has been necessary periodically to upgrade the specification as part of a continuous improvement strategy. The upgrading process ensures that available service fill fluids are of an appropriate quality for use in transmissions that have been designed around the improved factory fill fluid performance.

IMPORTANT: As with previous upgrades, DEXRON-VI fluids are designed to be backward compatible with earlier transmission hardware. But more important, earlier type fluids are NOT FORWARD COMPATIBLE with transmissions that were designed to use DEXRON-VI.
DEXRON-VI can be used in any proportion in past model vehicles equipped with an automatic transmission, in place of DEXRON-III (for instance, topping off the fluid in the event of a repair or fluid change). DEXRON-VI is also compatible with any former version of DEXRON for use in automatic transmissions.

TIP: Simply topping off the fluid is adequate, but a full drain and replacement is preferred, to obtain the full benefit.

IMPORTANT: DEXRON-VI Automatic Transmission Fluid (ATF) is the only approved fluid for warranty repairs for GM transmissions requiring DEXRON-III or prior DEXRON transmission fluids.

TIP: Any vehicle that previously used DEXRON-III for a manual transmission or transfer case should now use p/n 88861800 (88861801 in Canada) Manual Transmission and Transfer Case Fluid. And power steering systems should now use p/n 89020661 (89021183 in Canada) Power Steering Fluid.

TIP: Since some early bulletins were issued, further validation has taken place and certain transfer cases and manual transmissions now DO use DEXRON-VI, so it's important to refer to the owner manual for appropriate recommendations.
All licenses for DEXRON-III expired at the end of 2006 and will not be renewed. Fluids sold in the market after that date bearing claims such as "suitable for use in DEXRON-III applications" or similar wording should be avoided, because 'DEXRON-III' fluids are no longer checked and policed by GM and therefore may not be the originally tested and approved formulation.

ADVANTAGES OF DEXRON-VI

GM uses an ATF for factory fill that provides significantly improved performance in terms of friction durability, viscosity stability, aeration and foam control, and oxidation resistance. In addition, the fluid has the potential to enable improved fuel economy and extended drain intervals. The service fill specification for a fluid meeting these standards is designated as DEXRON-VI.

When compared with earlier automatic transmission fluids, DEXRON-VI offers these improvements and benefits:

- enhanced performance of both new and older transmissions
- longer ATF life (160,000 km/100,000 miles normal, or 80,000 km/50,000 miles severe). It is important to refer to the owner manual because certain vehicles recommend a normal service drain interval of 150,000 miles (240,000 km).
- consistent shift quality throughout the life of the transmission
- extended transmission life.

To achieve these benefits, DEXRON-VI offers significant improvements in these operating characteristics:

Friction Stability (improved 100%) -- Friction describes how the fluid behaves when transmission clutches or bands are engaged. A fluid with poor friction characteristics leads to grabbing, chattering and slipping (fig. 2).





DEXRON-VI also offers a 120% improvement in clutch durability (fig. 3).




A DEXRON-III
B DEXRON-VI

A Clutch operated with DEXRON-III
B Clutch operated with DEXRON-VI

Viscosity Stability (greatly improved) -- Viscosity is a description of how thick or thin a fluid is at various temperatures. In a hydraulic system, components can function sluggishly or improperly when viscosity is wrong. As determined by comparison testing (fig. 4),



DEXRON-VI maintains an almost constant viscosity over time, while the viscosity of DEXRON-III degrades considerably.

A DEXRON-III
B DEXRON-VI

Foaming Resistance (improved 150%) -- Automatic transmission fluid may contain air in three forms -- dissolved, entrained (aeration) and foam. Oil containing air doesn't do anything very well -- lubrication is affected, heat transfer in affected and pressures are unstable. Anti-foam additives are used to control and limit the effects of air in the fluid (fig. 5).



A DEXRON-III foam test
B DEXRON-VI foam test

Oxidation Resistance (improved 100%) -- Oxidation describes the length of time it takes for a fluid to reach the end of its useful life. Oxidation generally occurs more quickly at higher temperatures (fig. 6).




And oxidation has an effect on how long a fluid can be used before replacement is necessary.

A Aftermarket fluid oxidation test
B DEXRON-VI oxidation test

TIP: Just because another auto maker does not require use of DEXRON-VI, this does not imply that their required fluid is in any way inferior to or better than DEXRON-VI. It simply means that the other auto maker has established its own, unique fluid requirements. Their transmissions may be built with different materials, and may be designed to perform in different ways, neither of which is necessarily inferior to or better than GM's transmissions, just different. Variables include the material used for friction surfaces, the material used for reaction surfaces, the types of control mechanisms and the characteristics of the factory fill fluid. This means that each manufacturer must tailor their transmission fluid requirements to meet the needs of their own transmissions. And a fluid may cause entirely different performance when installed into transmissions of different designs.

COUNTERFEIT PRODUCTS

Beware products that claim to be DEXRON-VI but are not; for instance, some products claim to be multi-purpose. And beware the products which claim to provide DEXRON-VI characteristics when added to other ATFs. Unlicensed products have not been tested by GM to determine whether they meet GM's specifications.

ADDITIVES

DEXRON-VI is formulated to meet and exceed GM's specifications and requirements. Additives are not needed and are not recommended.
The best thing that can happen when using an additive is that it will do nothing. At worst, an additive can ruin the transmission.

DEALING WITH CONTAMINATION


Anything but DEXRON-VI in the automatic transmission is considered a contaminant. Typically, a customer or other service facility may add fluids other than DEXRON-VI. This includes aftermarket additives -- they are not needed and should not be used. In case like this:

- drain the transmission fluid
- flush the system with DEXRON-VI (NOT solvent)
- fill the system with the correct amount of DEXRON-VI.

FLUSHING

Many aftermarket flushing systems rely on solvents, which essentially may be considered contaminants. The effects of these contaminants may lead to transmission failure.
Refer to bulletin 02-07-30-052E and also document 1601517 for the complete story on using the Automatic Transmission Oil Cooler Flush And Flow Test Essential Tool J 45096 TransFlow. Here are some highlights.
Two significant features of the J 45096 are (1) that it uses DEXRON-VI, not solvent, as a flushing agent, and (2) that it injects high pressure air into the fluid stream to agitate the ATF oil to enhance removal of contaminated ATF and debris.

TIP: It is important to flush the system in both directions (back-flush and forward-flush). There are instructions in SI to explain how to make the proper hookups for both directions.
There are also instructions in SI explaining which adapters to use for various transmissions.

TIP: It is necessary to fabricate adapters for Vibe, Wave and Aveo, using instructions in SI. Also, although these vehicles have a slightly different transmission oil requirement, the small amount of DEXRON-VI remaining in the system after flushing is compatible.

In addition to the flushing capability, the J 45096 also has a digital flow meter to check and indicate the flow capability of the ATF oil cooling system.
Oil temperature has a direct bearing on flow rate, so SI explains several ways to ensure that the DEXRON-VI in the storage reservoir is suitably warm for an accurate test. And there is a table showing the minimum flow rate at various temperatures and for both steel and aluminum coolers."
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 328
Registered: 4-2016
Posted on Thursday, 21 July, 2016 - 11:08 am:   Edit PostDelete PostView Post/Check IP

Thanks David,
I had better go out and buy an electronic tacho & timing light.
I have not needed one for years!!
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1311
Registered: 5-2012
Posted on Thursday, 21 July, 2016 - 12:54 pm:   Edit PostDelete PostView Post/Check IP

Paul - Thanks for that info. It's really useful.

Patrick - My advice on the tacho and timing light is to buy a quality one. I'm talking in relative terms here. I'm sure professional workshops pay $$$$s for theirs. I settled for an Innova Pro at $110. Don't be tempted by the cheap $25 ones. You get what you pay for. I'm really pleased with the one I bought. Remember, The quality will remain long after the price is forgotten.

Geoff
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 331
Registered: 4-2016
Posted on Thursday, 21 July, 2016 - 02:14 pm:   Edit PostDelete PostView Post/Check IP

Hi Geoff.
Agreed, sick of buying poor quality anything based on price.
In this day and age in Australia it's almost impossible to buy things of non Asian manufacture.
I will be sure to look this brand up.
I was having a quick look at work before heading to the airport (here now killing time) and noticed some lights with in built tacho's. Have you seen these?
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1313
Registered: 5-2012
Posted on Thursday, 21 July, 2016 - 04:13 pm:   Edit PostDelete PostView Post/Check IP

Hi Patrick

Yes - the better ones have the inbuilt tachos. The one I bought also measures dwell angle. I suspect all of the pro versions have this functionality, plus a brighter and more precise tube.

Geoff
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 333
Registered: 4-2016
Posted on Thursday, 21 July, 2016 - 09:26 pm:   Edit PostDelete PostView Post/Check IP

Thanks Geoff,

Im currently traveling with work.

I will probably need to wait until the weekend to check these out.
Thanks again for the advice.
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David Gore
Moderator
Username: david_gore

Post Number: 2123
Registered: 4-2003
Posted on Friday, 22 July, 2016 - 07:56 am:   Edit PostDelete PostView Post/Check IP

Patrick,

I purchased my tach/dwell meter from Repco so long ago I cannot recall when. I also bought a timing light at the same time.

They are trade quality units and not the cheap DIY units.
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 335
Registered: 4-2016
Posted on Friday, 22 July, 2016 - 02:00 pm:   Edit PostDelete PostView Post/Check IP

Hi David
I do quite a lot of work at home and only use Repco parts exclusively. Never had a problem, the parts are high quality and the guy behind the counter really knows his stuff.

Just did brakes on a Mazda Premacy last week, and the parts were spot on, the job went like a breeze.
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John Beech
Frequent User
Username: jbeech

Post Number: 51
Registered: 10-2016
Posted on Sunday, 27 November, 2016 - 03:24 pm:   Edit PostDelete PostView Post/Check IP

So I should tell my tranny guy to use Dextron VI in Tootsie when I take her in for a flush and service next week, eh? I'm glad I've been poking through previous threads. Really good stuff here, especially the tech document Paul Yorke posted vis-a-vis the fluids and their differences. He'll ask if I want a shift kit - I always say yes because of how well they respond once he installs it (that, and the cost is peanuts for the benefit). Unlike our European friends, the TH400 is common as dirt here in America and every shop knows them very well. I'm doubly fortunate in that my local guy is also whom the local racer-crowd use. On my step van he swapped in a 700R4 in exchange for the perfectly functioning TH350, plus $800. Switching to an OD transmission in that truck is the best thing I ever did. And it shifts perfect by just 'thinking' at it - don't laugh, it's really slight pressure with my foot - but it's very very good at matching shift points to my mood.

Meanwhile, Tootsie shifts perfectly but I have no proof the transmission fluid and filter have been changed in 47 years. She's only got almost 16,000 miles on her and spent a total of 39 years in air conditioned storage so she may as well have been in a time capsule. Maybe there's a receipt missing but letting him look her over is cheap insurance. Thus, refreshing her fluids is next on the agenda.

Oh and yesterday she fulfilled her first mission. A friend gave me a bottle of coconut flavored rum so I mixed up pina coladas in the blender, grabbed plastic cups, jumped in Tootsie and visited friends a few miles away to share. My pal is into really old Indian motorcycles and has an MG TD, which he drives regularly - I met him when it was broken down on the side of the road, stopped to see if he needed help and ended up towing him home. Anyway, after draining the pitcher (between four of us so I was not anywhere near the limit), and with the mosquitoes just beginning to swarm aggressively, we hurried home. Tootsie ran perfectly!
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Luis San Juan Bueno
New User
Username: guillesanjuan

Post Number: 6
Registered: 10-2018
Posted on Thursday, 25 October, 2018 - 05:17 pm:   Edit PostDelete PostView Post/Check IP

Hello Al,

My new Rolls Royce Silver Shadow 2 (1979) does not like going into D. Every time it is cold I have to first go into I and when it engages it allows me then to go into D.

In addition, the transition from P to I is quite harsh meaning that you can feel how the gear engages. Once it is running, the transmission works perfectly.

Not sure if this is normal or not. The guy I bought it from, told me that he got the transmission recently worked on.

Thanks in adavance,
Luis
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h_kelly
Prolific User
Username: h_kelly

Post Number: 264
Registered: 3-2012
Posted on Thursday, 25 October, 2018 - 06:15 pm:   Edit PostDelete PostView Post/Check IP

Hi, take a look at the linkages between the actuator and gearbox ,possibility linkage may gave been strained etc?.
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Luis San Juan Bueno
New User
Username: guillesanjuan

Post Number: 7
Registered: 10-2018
Posted on Thursday, 25 October, 2018 - 08:10 pm:   Edit PostDelete PostView Post/Check IP

Thank you h_kelly for your help.

I am kind of new so could you help to know where to find those linkages between the actuator and the gearbox. I have attached a driagram which I hope it helps to precisely identify the part I need to replace.

Thanks,
luis
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Luis San Juan Bueno
New User
Username: guillesanjuan

Post Number: 8
Registered: 10-2018
Posted on Thursday, 25 October, 2018 - 08:13 pm:   Edit PostDelete PostView Post/Check IP

application/pdf
Gearbox_Actuator.pdf (287.0 k)
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h_kelly
Prolific User
Username: h_kelly

Post Number: 265
Registered: 3-2012
Posted on Thursday, 25 October, 2018 - 10:20 pm:   Edit PostDelete PostView Post/Check IP

Luis, see the long screw at the bottom right of your diagram, it's attached to the actuator and then other end goes to the gearbox. If you have some way to record it's movement as you shift gear, it may identify a problem?. Equally if you disconnect this rod it may give you a scene of what's happening with same,ie actuator not functioning correctly or indeed the actual gearbox shift is stiff or difficult to move.
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Luis San Juan Bueno
New User
Username: guillesanjuan

Post Number: 9
Registered: 10-2018
Posted on Thursday, 25 October, 2018 - 10:54 pm:   Edit PostDelete PostView Post/Check IP

Thank you again h_kelly,

Just to make sure, i have highlighted in red the rod on the attached document.

I will try to identify it and record a video when shifting this weekend.

Thank you gaain,
Luis
application/pdf
gearbox.pdf (273.7 k)
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h_kelly
Prolific User
Username: h_kelly

Post Number: 266
Registered: 3-2012
Posted on Thursday, 25 October, 2018 - 11:31 pm:   Edit PostDelete PostView Post/Check IP

Luis, that's the one, the reason I think it's related to this part or gearbox is from your diagnosis of problem,keep I'm mind I could be totally wrong,but in saying that it appears you have current/voltage to same, plus the gears change, though not sequencially as described. My theory is fouling to rod you highlighted, tight linkage ie at pin joint or the lever at gearbox and or actuator need oil grease etc.
Others may offer more suggestions. Good luck with it
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gordon le feuvre
Prolific User
Username: triumph

Post Number: 274
Registered: 7-2012
Posted on Monday, 29 October, 2018 - 12:07 am:   Edit PostDelete PostView Post/Check IP

If kick down switch sticks, box will only upchange on full throttle. Easy diagnosis when switch on carbs(early cars), not so much fun when under floor with access by taking all screws out of rat trap(aluminum cover over brakes / throttle linkage
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Mark Aldridge
Grand Master
Username: mark_aldridge

Post Number: 572
Registered: 10-2008
Posted on Monday, 29 October, 2018 - 09:39 am:   Edit PostDelete PostView Post/Check IP

Gordon, this may well have been the cause of the problem I posted earlier on this thread. The car is now sold ( problem un resolved), but I have noted your advice in case the symptoms arise in any of my other cars.
Mark
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Alan Dibley
Prolific User
Username: alsdibley

Post Number: 171
Registered: 10-2009
Posted on Monday, 29 October, 2018 - 10:14 pm:   Edit PostDelete PostView Post/Check IP

I disconnected the kick-down switch sixteen years ago out of respect for a forty-year-old engine (still original, I think). I haven't felt a need for it since, and the engine is still good-ish after warm-up.

Alan D.

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