Spring free length ??
Discussion
With regard to the Suspension Wiki...
IMHO there is one crucial detail missing !
That's is the spring free length.
For example....
Picking on Gaz Gold Pro shock absorbers on the rear.
Most of the wiki listred ratings are 350-375lb rating, from various owners.
But at what free length of spring ????
I have some new 9" springs, at both 350 & 375, obviously the 350 will compress slightly more than the 375 (under static applied weight conditions), but both make the ride height too high. Yes, even when the spring seat is wound down to it lowest position.
So, now stating the obvious.....
I need a shorter spring, but why isn't that info readily available in the wiki... Grrr.
My next choices are 7" or 8", and in theory, if I say used either 350 or 375, they will compress the same as the 9" spring did,,so the ride height should go down 1" or 2" respectively.
Please please don't reply with all of the formulae that are readily available, as that will just confuse the matter... To me at least, if not others too.
In simple terms, the info must be out there already. Its just that its not recorded here on the wiki.
TerryB.
IMHO there is one crucial detail missing !
That's is the spring free length.
For example....
Picking on Gaz Gold Pro shock absorbers on the rear.
Most of the wiki listred ratings are 350-375lb rating, from various owners.
But at what free length of spring ????
I have some new 9" springs, at both 350 & 375, obviously the 350 will compress slightly more than the 375 (under static applied weight conditions), but both make the ride height too high. Yes, even when the spring seat is wound down to it lowest position.
So, now stating the obvious.....
I need a shorter spring, but why isn't that info readily available in the wiki... Grrr.
My next choices are 7" or 8", and in theory, if I say used either 350 or 375, they will compress the same as the 9" spring did,,so the ride height should go down 1" or 2" respectively.
Please please don't reply with all of the formulae that are readily available, as that will just confuse the matter... To me at least, if not others too.
In simple terms, the info must be out there already. Its just that its not recorded here on the wiki.
TerryB.
It depends entirely on the position of the spring seats on the specific dampers you are using, which is highly variable between brands/types. The only useful information that can be provided is the overall damper length fully open / fully closed. You would need to calculate the required spring length from that based on the spring seat position and expected spring deflection at rest.
The original trailing arm design was 'acquired' from Reliant and as TVR wanted to try and use off the shelf Koni's, they moved the shock pick up on the trailing arm (as so the leverage points) from the rear of the arm further forward ...the fact that there are then 4 different pick up points across the era range of the S Series leaves the whole suspension rather variable, depending on yor car being a S1/1.5/2/3. Eventually, TVR put the pick up near as the same as the Reliant to stop the arms from failing. A@
Edited by Adrian@ on Tuesday 2nd July 14:53
Guys...
With the greatest respect to the replies so far, I think you could be missing the point..
I'll try to simplify...
On line 2 of the wiki. GGP shocks/Rear300/S3
On line 17 of the wiki. GGP shocks/R300/S3
Two different people on the same model car, using the same shocks, at the same rating. Therefore logic says, these most likely will be the same free length.
And if they're not (of which I accept they could be different lengths), then one car must ride higher than the other !
Also...
On line 7, GGP, Rear350, S3c
On line 16, GGP, Rear325, S3c
Once again, logic says, these most likely will be the same free length.
So, is there anyone out there that knows their free length of their rear Gaz Gold Pro shocks, rear springs.
Regards..
TerryB
With the greatest respect to the replies so far, I think you could be missing the point..
I'll try to simplify...
On line 2 of the wiki. GGP shocks/Rear300/S3
On line 17 of the wiki. GGP shocks/R300/S3
Two different people on the same model car, using the same shocks, at the same rating. Therefore logic says, these most likely will be the same free length.
And if they're not (of which I accept they could be different lengths), then one car must ride higher than the other !
Also...
On line 7, GGP, Rear350, S3c
On line 16, GGP, Rear325, S3c
Once again, logic says, these most likely will be the same free length.
So, is there anyone out there that knows their free length of their rear Gaz Gold Pro shocks, rear springs.
Regards..
TerryB
Blue 30 said:
I need a shorter spring, but why isn't that info readily available in the wiki... Grrr.
I suspect that's because nearly everyone buys the shocks & springs as an assembled package and have no real reason to ever measure the spring free length?My car runs on Protech's, which have 9" springs. You may be surprised how much the car will "settle" once you can drive it?
To my simple logic, if car is sitting two inches too high buy a two inch shorter springs or even shorter if it's two inches too high with adjuster wound right down?
Hi Mike..
Thanks for your input, I suspect you are right says that most owners buy a 'shock & spring' package as an off the shelf item.
In truth, I had already done my own scribbles in my garage.
IE.
Using a 9" free length 350lb spring on Gas Gold Pro shocks on the rear of my S3.
Under standing body weight, the spring compresses to 7 1/4". (25% compression being the ideal)
And with the adjuster seat at its lowest the body sits around 1" too high, with no adjustment to lower it further.
So in theory (and as you said) using a 2" shorter spring of the same rating, the adjuster can be wound up to suit a better body position, and still have some both way adjustment to do any fine adjusting.
One of my concerns in using a 7" 350lb spring was that it will compress to 5 1/4", and as coil binding will take place at around 3". Will 2 1/4" of downward shock absorber travel be enough.
So all I wanted the free length spring info from others was, was to give me the confidence & confirmation in my spring purchase.
I do agree & understand the points made about S model variations, but there must be a fair few standard S3's running around with Gas Gold Pros on the rear.
Note.. I have factory reconn AVO's on the front using 9" free length springs (where the seat adjuster sits mid point). But as I have the lighter AJ30 Jag engine in situ, there's no point in recording the spring rating.
Cheers.
TerryB.
Thanks for your input, I suspect you are right says that most owners buy a 'shock & spring' package as an off the shelf item.
In truth, I had already done my own scribbles in my garage.
IE.
Using a 9" free length 350lb spring on Gas Gold Pro shocks on the rear of my S3.
Under standing body weight, the spring compresses to 7 1/4". (25% compression being the ideal)
And with the adjuster seat at its lowest the body sits around 1" too high, with no adjustment to lower it further.
So in theory (and as you said) using a 2" shorter spring of the same rating, the adjuster can be wound up to suit a better body position, and still have some both way adjustment to do any fine adjusting.
One of my concerns in using a 7" 350lb spring was that it will compress to 5 1/4", and as coil binding will take place at around 3". Will 2 1/4" of downward shock absorber travel be enough.
So all I wanted the free length spring info from others was, was to give me the confidence & confirmation in my spring purchase.
I do agree & understand the points made about S model variations, but there must be a fair few standard S3's running around with Gas Gold Pros on the rear.
Note.. I have factory reconn AVO's on the front using 9" free length springs (where the seat adjuster sits mid point). But as I have the lighter AJ30 Jag engine in situ, there's no point in recording the spring rating.
Cheers.
TerryB.
Are they the correct shocks? Something just doesn't sound right to me? I'd put money on springs supplied by Gaz being around 9 not 7"?
I'm sure you've seen enough pictures and real cars to know the S does look a bit like the wheels and wheelarch have had a row, they're never going to be a nice huggy fit!
That's worth a thought.
Okay then.... New question.
Does anyone know the open/closed length of an S3 Gaz Gold Pro shock absorber ?
But thinking on my feet, so to speak.
Even if the shock absorber was wrong, as long as its somewhere away from its full open or closed length, then its the spring that is holding the car off the ground.
With the 9" 350lb spring fitted, the body is to high. The bottom seat is wound fully down, the top seat is fixed if course, and is a standard Gaz fitting.
I could drop to say 300lb 9" springs, but surely that would be heading towards being over 30% spring compression under its standing weight, plus getting dangerously close to coil binding.
So, as per the wiki lines I mentioned previously.
That takes me back full circle, into wanting to know what others springs free length is....
T.
Okay then.... New question.
Does anyone know the open/closed length of an S3 Gaz Gold Pro shock absorber ?
But thinking on my feet, so to speak.
Even if the shock absorber was wrong, as long as its somewhere away from its full open or closed length, then its the spring that is holding the car off the ground.
With the 9" 350lb spring fitted, the body is to high. The bottom seat is wound fully down, the top seat is fixed if course, and is a standard Gaz fitting.
I could drop to say 300lb 9" springs, but surely that would be heading towards being over 30% spring compression under its standing weight, plus getting dangerously close to coil binding.
So, as per the wiki lines I mentioned previously.
That takes me back full circle, into wanting to know what others springs free length is....
T.
Hi Damian...
Thanks for joining in.
Being as I had my used Gaz rear shocks from you, I know they are correct.
I also agree with you in that I am finding that 9" are too long.
I think that if I down size to 8", plus down rate to 300lb, then at least I'll have up/down adjustment, even if I'm a bit light on rating.
Here are my shocks and 9" spring fitted with the trailing arm hanging.
Here are glenrobbos rear Gaz shocks with springs fitted. Unless they are longer shocks, which they don't appear to be. Just look at how the lower seat adjuster is wound up. Surely indicating a shorter spring ?
This photo was lifted from another suspension thread.
TerryB.
Thanks for joining in.
Being as I had my used Gaz rear shocks from you, I know they are correct.
I also agree with you in that I am finding that 9" are too long.
I think that if I down size to 8", plus down rate to 300lb, then at least I'll have up/down adjustment, even if I'm a bit light on rating.
Here are my shocks and 9" spring fitted with the trailing arm hanging.
Here are glenrobbos rear Gaz shocks with springs fitted. Unless they are longer shocks, which they don't appear to be. Just look at how the lower seat adjuster is wound up. Surely indicating a shorter spring ?
This photo was lifted from another suspension thread.
TerryB.
Protech 600 dampers here so not Gaz but for info.
450lb front 8" free length. Small amount of preload, maybe 10/15mm compression.
375lb rear 8" free length. No preload, seats just wound up so springs are not loose at full droop.
I did have 425lb 7" on the front previously but they needed a bit more preload to lift the nose up, changed to what I have now after one spring fractured.
HTH,
Carl.
450lb front 8" free length. Small amount of preload, maybe 10/15mm compression.
375lb rear 8" free length. No preload, seats just wound up so springs are not loose at full droop.
I did have 425lb 7" on the front previously but they needed a bit more preload to lift the nose up, changed to what I have now after one spring fractured.
HTH,
Carl.
With your spring seat fully down is there any pre-load on the spring or is it already loose?
If it's already loose you need a shorter damper open length AND shorter springs
If there's some pre-load then you can use a shorter spring and lower the seat some more.
The springs in the pic above look to be 8 coils, the industry standard is one coil per inch, making them 8 inch springs.
If it's already loose you need a shorter damper open length AND shorter springs
If there's some pre-load then you can use a shorter spring and lower the seat some more.
The springs in the pic above look to be 8 coils, the industry standard is one coil per inch, making them 8 inch springs.
Edited by spitfire4v8 on Wednesday 3rd July 08:17
Haha... Now we (the collective) seem to be getting somewhere 
On my rear GGP shocks, when I fitted the 9" springs, there is some pre load even with the lower seat adjuster sitting in its lowest (longest) position.
Therefore, following my own gut feeling, plus the info directly above. I can use a shorter spring.
Plus other offered info above seems to clearly indicate that 8" springs on at least 2 different branded shocks (GGP included) are already being fitted.
All I have got to do now is choose the rating !!
I originally fitted 350lb 9". The 'bounce' felt okay, and body weight compression of the 9" spring, measured at around 7" which is just a bit less than the 25-30% ideal.
So, my purchase (pockets being checked) will most likely be 325lb/8" in blue
I'll let you know after a brief holiday break....
Many thanks for all current offered, & any future replies.
Don't forget..... Get your (if known) full shock & spring info added onto the suspension wiki.
TerryB.
On my rear GGP shocks, when I fitted the 9" springs, there is some pre load even with the lower seat adjuster sitting in its lowest (longest) position.
Therefore, following my own gut feeling, plus the info directly above. I can use a shorter spring.
Plus other offered info above seems to clearly indicate that 8" springs on at least 2 different branded shocks (GGP included) are already being fitted.
All I have got to do now is choose the rating !!
I originally fitted 350lb 9". The 'bounce' felt okay, and body weight compression of the 9" spring, measured at around 7" which is just a bit less than the 25-30% ideal.
So, my purchase (pockets being checked) will most likely be 325lb/8" in blue
I'll let you know after a brief holiday break....
Many thanks for all current offered, & any future replies.
Don't forget..... Get your (if known) full shock & spring info added onto the suspension wiki.
TerryB.
Gassing Station | S Series | Top of Page | What's New | My Stuff