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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 490
Registered: 5-2012
Posted on Thursday, 02 October, 2014 - 01:43 pm:   Edit PostDelete PostView Post/Check IP

Hi Folks

I'm in the process of replacing the rear springs on my 1974 SY1, SRX18501. When I contacted Coil Spring Specialties here in the US I was asked various questions: How many coils, 10 or 11. Did I require them 2 inches longer to make up for a missing isolator etc. It was all a bit vague and I did not have the definitive answer to these questions, although my educated guess would have been 11 and no. Fortunately I have been offered 2 springs which were sourced from this company, "on approval". I want to take this opportunity to publish the measurements of these springs and maybe as a group we could define the spec for new rear springs or at least get a list of dimensions for springs from the aftermarket suppliers.

Having removed the first spring I was surprised to see that it only had 9 coils.

spring


This was quite a surprise to me. I took measurements which follow. These are rough averages due to the imperfections in the manufacture of coil springs.

......................... Original Spring ........ New Spring

Length .............. 18 1/8" ................... 21 5/8"
Outside Dia ....... 155mm ....................155mm
X section dia ..... 18.25mm ................ 17.50mm

Quite a difference. I am optimistic the new springs will give me the ride height I require - I guess I will know in a few days time (time permitting)

Does anyone know the dimensions and number of coils for the OEM springs?

Geoff.
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Hubert Kelly
Prolific User
Username: h_kelly

Post Number: 133
Registered: 3-2012
Posted on Thursday, 02 October, 2014 - 06:04 pm:   Edit PostDelete PostView Post/Check IP

Thanks very much for this info Geoff, in 2015 I might get round to purchasing new rear springs... I reckon I'll need the extra height as my springs are quite saggy currently

Hk
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richard george yeaman
Prolific User
Username: richyrich

Post Number: 213
Registered: 4-2012
Posted on Thursday, 02 October, 2014 - 06:57 pm:   Edit PostDelete PostView Post/Check IP

Hi Geoff.

I measured three springs i have, all of them have 10 coils all of them are 155mm outside diameter and the average length was 20 5/8" x section diameter is 17mm approx. I had another spring that I had cut with a grinder that gave me a better chance to measure it all the information above was obtained from four springs taken from a 1970 SS1 and a 1974 SS1 hope this is of some use
to you and others

Richard.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 491
Registered: 5-2012
Posted on Friday, 03 October, 2014 - 01:16 am:   Edit PostDelete PostView Post/Check IP

Richard

Many thanks for that information. It looks as if a previous owner used non-standard springs on my car. 10 coils at the dimensions you specify seem to be the OE standard, with 11 on aftermarket springs to give the rear a bit of extra lift. This gives me confidence the springs I am about to fit will give my car the correct ride height.

Hubert

If you are planning to change the springs only, it is a fairly easy job. Just a case of jacking the car up, disconnecting the height control linkage, half shafts, handbrake cable, rebound straps and damper and lowering the suspension arm to remove the spring. I'll put up a "before/after" pic when I have completed the job.

Geoff
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 890
Registered: 5-2012
Posted on Thursday, 30 July, 2015 - 12:33 pm:   Edit PostDelete PostView Post/Check IP

Just want to push this thread to the top so the search engine might find it in future.

I was responding to an email about rear spring sizes and the only way I could find this thread was to laboriously trawl through the subject headings.
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Chris Miller
Grand Master
Username: cjm51213

Post Number: 379
Registered: 5-2013
Posted on Friday, 31 July, 2015 - 01:11 am:   Edit PostDelete PostView Post/Check IP

Hi Folks,

Is it convenient, or even possible, to measure the lengths of the relaxed springs on the car?

Chris.
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richard george yeaman
Grand Master
Username: richyrich

Post Number: 341
Registered: 4-2012
Posted on Friday, 31 July, 2015 - 02:26 am:   Edit PostDelete PostView Post/Check IP

Chris worn springs don't have a different measurement from good springs, Worn springs have lost their ability to resist twisting the actual length does not change. More coils for a given length = softer ride less coils = stiffer ride.

Richard.

Ps I got this information from my spring maker.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 950
Registered: 9-2004
Posted on Friday, 31 July, 2015 - 04:52 am:   Edit PostDelete PostView Post/Check IP

Hum, well a great deal can be changed to suit the ride with the self leveling and first rate shocks with coil spring helpers.
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 1576
Registered: 6-2009
Posted on Friday, 31 July, 2015 - 06:27 am:   Edit PostDelete PostView Post/Check IP

A great deal can be changed to get rid of the self-leveling and original hydraulic and braking system, if one so desires.

I know of one former member of the RROC-US who used the kind of shocks Mr. Lockeyer mentions when he removed the entire hydraulic system. With specific regard to the height control system: "To compensate for the hydraulic lift in the rear I took the original ones [shocks] out and installed the shocks with the springs right over shocks. The only modification to that is that you have to make the bottom shock holder in the rear shock case a little larger and the set up falls right into place."

He also eliminated the whole accumulator setup for the brakes: "It is really simple to do. On the right hand drive Shadow vehicles you can get a 9-inch dual brake booster under the floor system. On a left hand drive Shadow you can only get a 7-inch booster set up.

You need to remove the entire original system pressure generating system: pumps, accumulators, and accumulator control valves. To use the 9-inch booster you need to do some minor cutting using a grinder. You can stick with a 7-inch if you donít wish to cut anything.

You must use a master cylinder with a 1-1/8 bore. None higher and none lower. It is the perfect size to cover the volume & pressure necessary for the remaining existing brake system components. Install it with 2 residual valves, 2-pound ones not 10-pound. This is to keep the brake fluid from being drawn back being that the master cylinder will be below the calipers.
"

When I last corresponded with him he'd been driving the cars around with these brakes about a year. I've never considered going this route, but it is good to know about should there come a time when replacement parts for the OEM systems actually become "made of unobtainium."

The above is offered only as information regarding what someone has done, and done successfully. It does not constitute either an endorsement from me nor encouragement for anyone to do the same.

Brian
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 353
Registered: 5-2015
Posted on Friday, 31 July, 2015 - 08:33 am:   Edit PostDelete PostView Post/Check IP

If the rams are removed and replaced with simple screw jacks then the ride height ( using new springs) can be accurately set quickly and easily.

The isolators if missing or damaged could be replaced with hard wood ones. Close grain ash ideal. Soak in oil for 2 days before fitting to stop wood rot.

I used hard wood to pack an axle mounting on a trailer. The set up has lasted for 25 years plus with no problems.

I think Richard T has a Bentley T1 on stiffer springs which has greatly improved the car. The ride is still fitted but hardly gets used.

Coil springs can be re set the same as leaf springs. The steel itself doesn't wear out ( rust excluded). What wears out is the temper.

All road springs are made from the same steel. The steel is heated to cherry red then quenched in oil. Dexron 1 is good for this. Then the spring is reheated to a set temp which is about blue for springs, and then agian quenched in oil. If the hardness is left without drawing the temper out the spring will shatter.

To reset they heat to cherry red and slowly cooled this makes the spring soft and pliable. Then the spring is stretched a bit to the required length. Then hardened and tempered. Then shot peened to remove any stress raisers. This is most difinately not a diy job.

I have made small springs from piano wire like this. Sometimes I get it wrong and the spring shatters.

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