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Graeme Söderlund
Prolific User
Username: graemeaus

Post Number: 32
Registered: 6-2003
Posted on Wednesday, 02 June, 2004 - 03:19 pm:   Edit PostDelete PostView Post/Check IP

G'day Technical People.

Gearbox in Shadow leaking - told rear seal gone. Ready to replace but would like any hints, suggestions or technical advice.

Current symtoms are continual dripping of red oil onto garage floor!
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David Gore
Moderator
Username: david_gore

Post Number: 257
Registered: 4-2003
Posted on Wednesday, 02 June, 2004 - 07:01 pm:   Edit PostDelete PostView Post/Check IP

Hi Graham,

Before proceeding further, grab a hose and give the transmission case a good wash from end-to-end to remove all traces of fluid and take the car for a 10/15 minute drive before checking for evidence of fluid leaks. This should indicate if the rear seal or the oil pan joint is the source of the fluid [assuming you have the 3 speed torque convertor transmission].

The rear seal on the 3 speed transmission can be relaced as follows:
1. Remove the gear change actuator
2. Remove the drive shaft and remove the coupling flange by pulling it back from the casing.
3. Remove the 6 setscrews attaching the rear housing to the transmission case and slide it carefully backwards and down until it clears the output shaft.
4. Push out the old oil seal, check bore for damage and the drainage port is not blocked.
5. Fit new oil seal.
6. Fit new "O" ring seal on extension housing.
7. Carefully slide housing over output shaft taking particular care to avoid damaging the lip seal with the shaft splines.
8. Fit setscrews and torque to 23 ft/lbs
9. Replace coupling flange, propellor shaft and actuator.
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Richard Treacy
Grand Master
Username: richard_treacy

Post Number: 201
Registered: 4-2003
Posted on Wednesday, 02 June, 2004 - 08:53 pm:   Edit PostDelete PostView Post/Check IP

David,

I have replaced the rear seals a few times without removing the extension housing. This also saves messy transmission fluid going everywhere, although a new filter and Castrol Transmax Z fluid are probably due anyhow (Dexron III is very good, but synthetic Transmax Z is unbeatable).

It was a rather short job. I disconnected the prop shaft, pushed it upwards and sideways, and pulled out the drive flange. After removing the funny spring clip retainer over the end of the housing, the old seal came out with a heavy-duty screwdriver.

Using some slide-show plastic to protect the new seal (wrapped around the splined shaft, or a bit of thin plastic tube over the splines would be better I admit) and an old bearing outer shell of the same size as the seal as a drift, they go in fine.

Rear transmission leaks in these transmissions are rare. You are quite correct that the source needs confirmation. As you imply, transmission sump leaks are far more common, and I have never seen a sump with tight bolts: they need retightening a few thousand km after the sump has been refitted after an overhaul or filter service, and then a year or so later.
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Graeme Söderlund
Prolific User
Username: graemeaus

Post Number: 33
Registered: 6-2003
Posted on Thursday, 03 June, 2004 - 09:33 am:   Edit PostDelete PostView Post/Check IP

Thanks David & Richard,

Will take note of all your advice - we will clean and check for sump leak first and go from there.

Will advise what we find and what course of action taken.

Regards,

Graeme.
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Graeme Söderlund
Prolific User
Username: graemeaus

Post Number: 34
Registered: 6-2003
Posted on Thursday, 03 June, 2004 - 11:04 am:   Edit PostDelete PostView Post/Check IP

Forgot to ask,

in the event of seals etc being replaced, can I use generic parts or do I use specific RR parts? I know there is a list of items available that can be used instead of the RR parts, but don't remember if seals like this were part of it.
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Richard Treacy
Grand Master
Username: richard_treacy

Post Number: 203
Registered: 4-2003
Posted on Thursday, 03 June, 2004 - 05:24 pm:   Edit PostDelete PostView Post/Check IP

Transmission parts, including seals, are of the few sections of your car where non-Crewe spares are safe. Use Delco-GM spares.

The cost savings are minor, but at least your local GM or transmission outlet can usually supply spares over the counter. However, oil seals like the rear transmission seal are much cheaper than the oil they leak, so I would not bother shopping around too much. Even a sump gasket costs more, but that is definitely a standard GM 400 Turbohydramatic item.

The disadvantage in bargain-hunting here is that you may need to immobilise the car to remove the old seal first, and then find a pattern replacement. This time, a rear seal ordered from the UK may alleviate some risks: GM probably had more than one type of rear extension housing on the many tens of millions of 400 THM transmissions they produced.
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Robert Chapman
Prolific User
Username: shadow

Post Number: 50
Registered: 5-2003
Posted on Thursday, 03 June, 2004 - 09:22 pm:   Edit PostDelete PostView Post/Check IP

Graeme,
Don't be taken in by the ridiculous hype when purchasing parts for your Rolls-Royce, buy your seals from the original supplier GM.
If you buy from Crewe you will pay probably two or three times the price (for exactly the same part) for another party to put it in their plastic bag. The vast majority of "genuine" parts are made by other manufactures (but of cause they are made especially to R-R and B exacting standards and individualy tested!)yeah right.Most "genuine" parts can be sourced from the original supplier at very great savings and they must be "safe" to use.

(Message edited by admin on June 04, 2004)
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Graeme Söderlund
Prolific User
Username: graemeaus

Post Number: 35
Registered: 6-2003
Posted on Friday, 04 June, 2004 - 09:49 am:   Edit PostDelete PostView Post/Check IP

Thanks Richard, Robert.

Being A Supply Manager, I really object to "Original" parts when there is the generic one available!Hence my question.

I will discuss with the local GM person over the weekend.

It is not a problem for the car to be immobilised
as I really only use it at weekends, and then just to make sure everything is running properly. It genuinely is a car "that was used on Sundays, and always home before dark".

Once again, thanks for your information, will advise all the results after the job is done.

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John Dare
Unregistered guest
Posted From: 144.138.194.252
Posted on Friday, 04 June, 2004 - 08:40 pm:   Edit PostDelete PostView Post/Check IP

Thats right! Many so-called "genuine" (and of course, superlative quality!) R-R parts are simply outside mnfrs.parts retailed in genuine R-R/Crewe packaging. For example, few would (or should) buy "genuine" oil filters/spark plugs/wheel bearings etc., from R-R/Crewe etc. Having said that, one must be aware of low cost, SAFETY related parts (NOT sold through authorised R-R dealers) such as suspension pins/bushes and ball joints often being of ASIAN (low cost) origin and greedily priced (by some unscrupulous repairers) at, or proximal to, genuine R-R/Crewe prices!. Not suprisingly, these and other parts have spectacularly FAILED R-Rs stringent quality control/destruction tests. Legal opinion suggests that if your car happens to be involved in an accident, your insurer may deny liablity for any material loss/damage etc. In the event of a fatality, there could be suggestions of culpability if the accident was found (in any way) to be attributed to the failure of NON-genuine, SAFETY related suspension componentry. You have been warned.
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William H. Trovinger II
Grand Master
Username: bill_trovinger

Post Number: 112
Registered: 8-2003
Posted on Saturday, 05 June, 2004 - 02:25 am:   Edit PostDelete PostView Post/Check IP

Graeme;

On the 400 transmissions GM is no longer making at least the sump seal and GM dealers here do not even show them in their parts manuals anymore. Explanation given to me is that as so many aftermarket companies like NAPA and Advanced Auto are producing and selling the seals too much competition for GM to make a profit.

I will also tell you that when I ordered my last set for Albers a few years ago they came in GM packaging not RR or Crewe.

Best regards,
Bill
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Graeme Söderlund
Prolific User
Username: graemeaus

Post Number: 36
Registered: 6-2003
Posted on Monday, 07 June, 2004 - 02:29 pm:   Edit PostDelete PostView Post/Check IP

Thanks to all for the information and advice.

I did buy the seals and will keep them for another day. Thanks for your advice Bill, they were all marked GM and not Rolls Royce.

I spent Saturday morning under the car checking out all the hints given me - found the nuts on the sump cover had worked loose - so loose that several were about to drop out! I spent the rest of the afternoon under the car checking every nut/bolt/screw that I could see.

As per David's original advice, I had washed everything down, and drove around the streets for about 15 minutes and then checked the oil leaks again - nothing!

Will check again this evening when I get home, but it seems to have overcome the problem. Does go to show that one should set aside a weekend here and there to check everything is tight and in place.

Regards and thanks to all,

Graeme.