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Springs rattle on full droop
MK9R - 5/5/10 at 07:35 AM

Just fitted new dampers and springs to rear of car, now if i set the ride height at the desired level (98mm), when the car is in full droop the springs rattle about, i.e. no compression. I'm guessing the only way around this is to have some graduated springs (not ideal as more expensive and i've only just brand new ones anyway), or maybe some weak helper springs?? How much will springs settle by, as if this happens i maybe able to get the desired ride height without helper springs and get the springs tight. Ideas?

Daddylonglegs - 5/5/10 at 07:38 AM

Me being a tight-a5@e would change the ride height

MK9R - 5/5/10 at 07:40 AM

quote:
Originally posted by Daddylonglegs
Me being a tight-a5@e would change the ride height


LOL! Just looked, helper springs are £13 each @ merlin!!!!!!!!!!!!!!!! i only paid £46 for the pair of proper springs!! And the spacers to hold them in place, another £13!!!!!!!

philw - 5/5/10 at 07:44 AM

Why don't you wind the spring platforms up to take out the slack? won't alter the ride height that much surely, whats the length of the shocks/springs

[Edited on [1273045614R0=073131p: by philw]

MK9R - 5/5/10 at 08:02 AM

With a tiny amount of compression, the ride height is 110mm, which gives far too much rake (front set at 80mm as min ride height in RGB is 75mm). I dropped it 5mm before my last race at the rear (before spring and damper change) and it made a positive difference in the handling at the rear.

Shock are 12.5" open, springs are 7", longer springs won't help as its he amount the springs compress under static load

[Edited on 5/5/10 by MK9R]

Jon Ison - 5/5/10 at 08:13 AM

Shorter springs/make new pick up points/softer springs same length so you can preload ?

edited for speeling

[Edited on 5/5/10 by Jon Ison]

TimC - 5/5/10 at 09:24 AM

What about machining inserts or thicker platforms - how much do you think you need?

MK9R - 5/5/10 at 09:32 AM

quote:
Originally posted by TimC
What about machining inserts or thicker platforms - how much do you think you need?


that won't work as it will raise the ride height, there needs to be more compression of the spring at the required ride height to allow some compression at droop. Its gonna have to be weak helper springs i think

carpmart - 5/5/10 at 09:37 AM

Helper springs are for just this problem. It's your only solution!

MK9R - 5/5/10 at 09:41 AM

quote:
Originally posted by tomgregory2000
the only real answer is to get shorter dampers


nope, that still doesn't affect ride height, anyway, i can't go shorter as will not have enough travel

MK9R - 5/5/10 at 09:42 AM

quote:
Originally posted by carpmart
Helper springs are for just this problem. It's your only solution!


Any suggestions on suppliers that aren't horrifically priced for a bit of wound flat steel??

Jon Ison - 5/5/10 at 10:19 AM

Mike, just my humble opinion but don't go for helper springs, your going to end up with two different spring rates and also introduce some roll during hard cornering, your racing it yea ?

Shorter springs, move the mounts (are the rear shocks upright or angled ?) or go for slightly softer springs that you can pre load, slightly softer springs will help with rear end grip to, without seeing the car and what your trying to achieve this is the advice I would give.

MK9R - 5/5/10 at 10:27 AM

quote:
Originally posted by Jon Ison
Mike, just my humble opinion but don't go for helper springs, your going to end up with two different spring rates and also introduce some roll during hard cornering, your racing it yea ?

Shorter springs, move the mounts (are the rear shocks upright or angled ?) or go for slightly softer springs that you can pre load, slightly softer springs will help with rear end grip to, without seeing the car and what your trying to achieve this is the advice I would give.


Yeah racing. I've just gone for softer springs, and the same length as before and now expiriencing this due to slightly more droop available from the new dampers. I'm hoping they will settle and become tight. The helper springs are only like 4lbs, so not really contributing to anything, just enough to keep tension. I don't want to go softer than i am already, not yet anyway.

Oh and its a live axle, fury, so lots of work to change pick up points, its not a simple change.

P.s. I'm actually called austen, not mike

[Edited on 5/5/10 by MK9R]

ReMan - 5/5/10 at 10:27 AM

Just to clarify...
Are you saying that before you fitted these, the springs were rattling aroung on the shocker body, ie not held between top and bottom spring platform?

MK9R - 5/5/10 at 10:30 AM

quote:
Originally posted by ReMan
Just to clarify...
Are you saying that before you fitted these, the springs were rattling aroung on the shocker body, ie not held between top and bottom spring platform?


No they weren't not with old springs and dampers. All purely down to the fact the new dampers have slightly more travel, although i would have expected the softer springs to compensate for this (dropped from 225 to 180)

rallyingden - 5/5/10 at 10:53 AM

On tarmac set up I had with the rally car I had similar problems but ended up just lockwiring the spring to the bottom seat to stop it moving about ...... worked a treat

RD

MK9R - 5/5/10 at 11:05 AM

quote:
Originally posted by rallyingden
On tarmac set up I had with the rally car I had similar problems but ended up just lockwiring the spring to the bottom seat to stop it moving about ...... worked a treat

RD

Now thats a bloody good (cheap) idea!! LOL! An internal guide would be needed to stop it falling off the seat aswell though

ReMan - 5/5/10 at 11:07 AM

quote:
Originally posted by MK9R
quote:
Originally posted by ReMan
Just to clarify...
Are you saying that before you fitted these, the springs were rattling aroung on the shocker body, ie not held between top and bottom spring platform?


No they weren't not with old springs and dampers. All purely down to the fact the new dampers have slightly more travel, although i would have expected the softer springs to compensate for this (dropped from 225 to 180)


Yes, but surely the spring lenth is set, as is the damper lenght and the 2 should be matched?

Alan M - 5/5/10 at 11:26 AM

can't you use adjustable bump stops?

These were fitted to Toyota sports car suspension in the 80's

TimC - 5/5/10 at 02:42 PM

Ah, I'd misunderstood your problem.

Just get your hand in your pocket Son. Merlin have some good stuff but, by God, does it cost - I went through this with ARB bits.

Then again, think about what your new dampers/springs have cost compaed to those on the SABRE!! (Holy Sh1t!)

Frosty - 5/5/10 at 02:48 PM

I wouldn't cut corners with it. Helper springs and extra platforms are the cheapest proper way to run the target ride height. Do make sure that you have enough travel left in the damper when running short springs though, especially with a soft spring.

Neville Jones - 5/5/10 at 04:37 PM

Do the job properly, once, and fit the right length springs. The suggestions above fix the symptom, not the problem. When softening the springs, you often have to go an inch or so longer.

Faulkners list 7", 8",9", 10",10.5", then 12" and up.

Cheers,
Nev.

Frosty - 5/5/10 at 04:45 PM

quote:
Originally posted by Neville Jones
Do the job properly, once, and fit the right length springs. The suggestions above fix the symptom, not the problem. When softening the springs, you often have to go an inch or so longer.

Faulkners list 7", 8",9", 10",10.5", then 12" and up.

Cheers,
Nev.

So then how does the OP achieve the ride height required with a longer spring?

Presumably the reason the spring is too short at full droop is because a longer spring would not allow the desired ride height at its lowest setting. You have to make the decision to run a shorter spring when the current one is still too high for the desired ride height when adjusted as low as possible. Going shorter will often leave the spring loose at full droop.

There is nothing wrong with a helper spring. They exist for exactly this problem. A longer spring is not the answer.

ReMan - 5/5/10 at 09:06 PM

Surely this is achieved by the corect spring /damper lenth combo?
Am I missing something?

Ahdammit - 5/5/10 at 10:53 PM

Why not make some check straps out of an old seatbelt or similar to stop the shocks extending too far?

Frosty - 5/5/10 at 11:09 PM

quote:
Originally posted by ReMan
Surely this is achieved by the corect spring /damper lenth combo?
Am I missing something?

Eventually it would be, but you wouldn't want to spend around £500 on gear which might not work. If you find at the target ride height you are running out of bump travel then shorter dampers will be the only proper solution.

To begin with though, far better to spend a few quid on helper springs and see if you can make your existing dampers work. If you find the car just doesn't work at the intended ride height then you have lost the cost of the helper springs and a bit of your time

MK9R - 6/5/10 at 06:15 AM

quote:
Originally posted by Frosty
quote:
Originally posted by Neville Jones
Do the job properly, once, and fit the right length springs. The suggestions above fix the symptom, not the problem. When softening the springs, you often have to go an inch or so longer.

Faulkners list 7", 8",9", 10",10.5", then 12" and up.

Cheers,
Nev.

So then how does the OP achieve the ride height required with a longer spring?

Presumably the reason the spring is too short at full droop is because a longer spring would not allow the desired ride height at its lowest setting. You have to make the decision to run a shorter spring when the current one is still too high for the desired ride height when adjusted as low as possible. Going shorter will often leave the spring loose at full droop.

There is nothing wrong with a helper spring. They exist for exactly this problem. A longer spring is not the answer.


I'm so glad you understand this! Spring length has nothing to do with it, its the amount of compression you get from a certain rate of spring.

The only way to aliviate this and still retain the the same amount of droop and ride height (one of the reasons have bought new dampers to increase the damper range so i could drop the ride height 5-8mm and still have enough bump) is helper springs or raise/lower the chassis/trailing arm pick up points, but this is major work on a live axel race chassis fury.

I've been speaking to another guy in RGB and he has exactly the same issue and lockwires his springs in place.

Neville Jones - 6/5/10 at 09:25 AM

For starters, 180lb springs sounds high for that weight of car. Without knowing corner weights and installation angles, then I can only surmise.

A Protech damper, 12.5" between eyes, will have a seat to seat max length of about 7.5". With a corner weight of, say, 170kgs(374lbs), then a 180lb spring @1:1 leverage will crush ~2.1". The overall travel of the damper will be less than 4", so at full extension, an 8" spring installed, will/should never 'rattle'.

The above is dependant on the ride height being correct at damper half travel. Most will have less droop than bump, as is the norm.

But, if lockwire works and fits your operational needs, then do it.

Cheers,
Nev.

MK9R - 6/5/10 at 09:46 AM

quote:
Originally posted by Neville Jones
For starters, 180lb springs sounds high for that weight of car. Without knowing corner weights and installation angles, then I can only surmise.

A Protech damper, 12.5" between eyes, will have a seat to seat max length of about 7.5". With a corner weight of, say, 170kgs(374lbs), then a 180lb spring @1:1 leverage will crush ~2.1". The overall travel of the damper will be less than 4", so at full extension, an 8" spring installed, will/should never 'rattle'.

The above is dependant on the ride height being correct at damper half travel. Most will have less droop than bump, as is the norm.

But, if lockwire works and fits your operational needs, then do it.

Cheers,
Nev.


its a race chassis so sits lower than the usual road car, which allows far less travel on the dampers, something that all Fury lowered cars have to battle with. The old dampers allowed 55mm compression (with bump stops) and 25 droop, the new ones have given me about 5-8mm extra. The springs are 6 or 7" (can't remeber sitting here at work), and the seats are set very near the bottom. The protechs have been specifically made for my car so that they can have maximum travel within the constraints. The basic issue is that the pick ups aren't in the correct place for the ride height as the car was never originally designed to sit that low, so other than making some serious changes, it has to be done with damper and springs.

Rear corner weights are 140-150kg. The springs are upright with no advatage

I have just dropped the rate of the springs to 180, they were 225 (this is how i bought the car) in an effort to increase rear grip as it was very flighty. I have been told i can go as low as 120lbs, but to start with i'm giving the 180's ago. I can't go too soft as i will bottom too easily.

JoelP - 6/5/10 at 08:55 PM

why do you need X amount of droop if its leaving the springs loose when it droops fully?

When messing about with coilovers in the past, ive concluded that, before fitting, you have to have the platform in a position so that the spring is not loose at full extention. If you then fit them and the car is too high, you cannot just wind back the platform as the spring will obviously be loose when the weight is off it. You could either get a shorter spring to lower the car, or remove some droop by getting a shorter body. Or, mess about with tie wraps etc to keep it all in place.

How much droop do you want/need?

MikeRJ - 7/5/10 at 11:47 AM

quote:
Originally posted by JoelP
You could either get a shorter spring to lower the car


No you can't, this gives exactly the same problem. Changing the spring length simply doesn't help in this situation.

quote:
Originally posted by JoelP
, or remove some droop by getting a shorter body.


Then you lose suspension travel, and you don't start with much with a 12.5" damper.

quote:
Originally posted by JoelP
Or, mess about with tie wraps etc to keep it all in place.


Or fit helper springs, since they are designed for exactly this situation!

The only way to fully resolve this issue is to change the suspension mounting points, but in this case it isn't possible without a lot of work on the chassis.

bigfoot4616 - 8/5/10 at 02:53 PM

quote:
Originally posted by MikeRJ

Or fit helper springs, since they are designed for exactly this situation!



which is what i had to do on the front of my striker.
using 12.5" dampers and 7" 200lb springs.
got some 2" 4lb helper springs from demon tweeks