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ross kowalski
Prolific User
Username: cdfpw

Post Number: 1285
Registered: 11-2015
Posted on Monday, 02 December, 2019 - 01:02:   Edit PostDelete PostView Post/Check IP

I need to get some rear springs for SRH 8844.

My rear rams are at 100% to keep it level.

Here's what I will be researching.

coil diameter = ?
wire diameter = ?
uncompressed height = ?
number of coils = ?
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Larry Kavanagh
Frequent User
Username: shadow_11

Post Number: 528
Registered: 05-2016
Posted on Monday, 02 December, 2019 - 02:20:   Edit PostDelete PostView Post/Check IP

Hi Ross, Another thig to bear in mind with rear springs is that on some models each side has a slightly different length, this is to compensate for the weight of the fuel in the tank and the weight of the driver. I don't know if this applies to your model but probably worth checking.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 2164
Registered: 05-2012
Posted on Monday, 02 December, 2019 - 03:08:   Edit PostDelete PostView Post/Check IP

Hi Ross

I'm currently running with the following spring dimensions:

coil diameter = 155mm OD
wire diameter = 17.5mm
uncompressed height = 21 5/8"
number of coils = 11

There is more info in the following thread:

http://au.rrforums.net/forum/messages/17001/16457.html?1438295588
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 2165
Registered: 05-2012
Posted on Monday, 02 December, 2019 - 03:17:   Edit PostDelete PostView Post/Check IP

I think next time I would go for 10 coils at 20 5/8" length, as specified by Richard in the thread I pointed to previously.

The ones I fitted did seem slightly high at first but have settled down to the correct ride height.
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 1287
Registered: 11-2015
Posted on Monday, 02 December, 2019 - 06:34:   Edit PostDelete PostView Post/Check IP

Geoff,

Thanks, Just out of curiousity, how's the ride with those springs?
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Robert J. Sprauer
Frequent User
Username: wraithman

Post Number: 565
Registered: 11-2017
Posted on Monday, 02 December, 2019 - 07:12:   Edit PostDelete PostView Post/Check IP

I would use the Bentley Heritage Parts website to research numbers. There was also a Bulletin regarding springs. There are different part numbers for L vs R. In my situation, I was reproducing the spring part number tags during restoration. The spring rates were calculated by the factory for comfort, IE ride quality.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 2166
Registered: 05-2012
Posted on Monday, 02 December, 2019 - 07:47:   Edit PostDelete PostView Post/Check IP

Hi Ross

It's the boulevard ride - love it. Very soft but not too bouncy.
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 1288
Registered: 11-2015
Posted on Monday, 02 December, 2019 - 10:47:   Edit PostDelete PostView Post/Check IP

Geoff,

Here's a spring rate calculator I wrote up from the information at bluecoilsprings.


I processed the information and got the following numbers.

And got the following numbers for compressed height.

13.4 for the oem spring

14.7 for the replacement spring

Now we just need someone with good springs to measure the height with the wheels down.

I'm going to guess the loaded height with wheels down should be 14ish

I'll start looking for a match.

--------------------------------
Here's the numbers I used

org new
length 18.125 21.625
od 6.1 6.1
bar dia 0.71 0.69
active coils 9.5 11.5
comp height 13.4 14.7
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 1289
Registered: 11-2015
Posted on Monday, 02 December, 2019 - 11:06:   Edit PostDelete PostView Post/Check IP

Geoff,

It looks like the OEM springs had a 324 spring rate and the replacements have 172 so they should be plusher than the OEMs which sounds good to me.
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 1290
Registered: 11-2015
Posted on Monday, 02 December, 2019 - 11:39:   Edit PostDelete PostView Post/Check IP

OK,

I did the numbers again and looks like

A compressed heights of 14.4 at rate of 324 for the OEM.

A compressed height of 14.7 at a rate of 172 for the replacements.

so 14.5 is probably the compressed height we are looking for with a spring rate anywhere from 172 to 324
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 1291
Registered: 11-2015
Posted on Monday, 02 December, 2019 - 12:41:   Edit PostDelete PostView Post/Check IP

Larry,

I am RHD and I have the gas tank on the drivers side so I am sure I have those springs.

Robert,

Any idea where I find that bulletin? I would like to read it.

Glen,

To be clear, you are running a SS1 and we are talking about rear springs correct.

Thanks,
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 2167
Registered: 05-2012
Posted on Monday, 02 December, 2019 - 13:59:   Edit PostDelete PostView Post/Check IP

Ross

Yes, an SS1 and rear springs.
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Robert J. Sprauer
Frequent User
Username: wraithman

Post Number: 566
Registered: 11-2017
Posted on Monday, 02 December, 2019 - 23:13:   Edit PostDelete PostView Post/Check IP

Ross The Bentley Heritage site will show you what parts are in your car by chassis number

In the technical section there are workshop manuals and technical bulletins that were sent to dealers.
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 1293
Registered: 11-2015
Posted on Tuesday, 03 December, 2019 - 06:01:   Edit PostDelete PostView Post/Check IP

Robert,

I'll check it out.

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