Ride height difference left-right

[taylormj4]

Hi there,
Recently replaced the rear shocks and springs on the Chimaera with the original spec parts (Bilstein and Eibach). I measured the ride height at the rear before removing the old units and noticed that the OS was around 5mm lower than the NS. Thought this was due to tired springs on the OS.

However, having replaced both units, the ride height has dropped by around 5mm but is still 5mm out left to right, with the OS being 5mm lower than the NS.

No change to tyres between measurements.

Assuming the new springs are not at fault, what else can cause a ride height difference like this?

I am measuring under the rear pivot point/chassis mount of the lower wishbone on each side.

[DaveWesty]

A couple of questions that may help us answer you

1. Do the new shocks have adjustable spring platforms?
If so, did you check the height and set the new shocks the same?

2. What's the ride height like at the front?
Is it similar on both sides?

Dave

[taylormj4]

DaveWesty said:

A couple of questions that may help us answer you

1. Do the new shocks have adjustable spring platforms?
If so, did you check the height and set the new shocks the same?

2. What's the ride height like at the front?
Is it similar on both sides?

Dave

Hi Dave,
Good questions ! The new Bilsteins are height adjustable. They were both on the top notch from te factory and I left them there as I was informed this would give standard height. The pic below shows the old and new dampers side by side. As you can see the top notch on the new dampers, would appear to be lower than the old ones.

The measurements before and after changing the shocks is as follows:

Corner Height before (mm) Height after (mm)
N/S rear 162 156
O/S rear 158 153

So as you can see there has been a drop of around 3-4mm with the new shocks, even though it looked as if they would go up and the O/S is consistently around 4-5mm lower than the N/S (before and after).

I haven't checked the height under the fronts. Can you explain how that would help solve the problem ?

Edited by taylormj4 on Tuesday 3rd March 14:48

[bluezeeland]

I do think your are rightly concerned with the ride height, altho for reasons different...

If having installed new shocks and springs on a TVR (or any sportscar for that matter) it makes sense to 'corner-weight' the car, improving high speed stability, handling and general drivability.
They will probably find that there will be some mm difference in the 'corners', obviously to make up for chassis inconsistencies and so on.
Whilst at it, they will prior to the corner weight, give it a laser geo, basically having pointing everything in the 'same' direction again...

Frank

[blitzracing]

I would not regard this as a problem, more an opportunity to tweak things to get it spot on. Ride height is a very subjective, as in an ideal world you want all 4 wheels to have the same downward force on them to keep the grip the same on each tyre. You adjust this with the ride height on each corner, so by say lifting the car on any one spring, you increase the downward force on that corner. This opens up a can of worms, as the car is unlikely to be perfectly balanced to allow all the corner weights to be matched, plus the balance of the car will completely change depending on how many occupants its has. So this gives you two options- 1) Try and set front / rear corner weights with something about the same weight as you in the driver seat. You need specialist scales for this, so you would need to go need to find someone with the correct equipment, and its pretty time consuming, or 2) Simply find the ride heights the car left the factory with, and simply replicate these by winding the spring platforms up or down. You will need a level garage floor to make sure the car sits evenly. This means at least that the wishbones will be in the correct point to make sure the camber is correct to start with- (assuming the camber changes as the suspension moves up and down on the TVR).

[taylormj4]

Pic of the two shocks (old and new) that I forgot to add to my earlier post - ooops.

You can see the bottom of the spring on the new one is further up the shock from the bottom mount on the old one. So I was expecting ride to be higher.



I was told the top notch would give standard road height, so not sure if that was incorrect or if my old ones were incorrect. The new bilsteins were for Griff 500, which I was told was the later TVR spec fitted to Chimaeras.
Still doesn't explain the left/right height issue anyhow.

You can actually see the car is leaning to one side. It would be better if it were leaning the other way really as at least it might level up when I got in.

Edited by taylormj4 on Tuesday 3rd March 14:50

[blitzracing]

I would not worry, just set the platform height until you are happy with the cars stance and heights. If you are worried that camber may be out if the ride height is now changed, simply take the car for a lively run on dry road. Then run you hand across the tyre tread from inner to outer on each wheel and feel the temperature. It should be even across the tyre width, showing even tyre contact. The finger tips is quite sensitive enough to feel subtle differences. If you do feel a difference it would be worth a full geometry check on a laser set up.

[taylormj4]

blitzracing said:

I would not worry, just set the platform height until you are happy with the cars stance and heights. If you are worried that camber may be out if the ride height is now changed, simply take the car for a lively run on dry road. Then run you hand across the tyre tread from inner to outer on each wheel and feel the temperature. It should be even across the tyre width, showing even tyre contact. The finger tips is quite sensitive enough to feel subtle differences. If you do feel a difference it would be worth a full geometry check on a laser set up.

Not heard of that technique before Mark, interesting one. I'll try that.

[DaveWesty]

If the front is out it can skew the rear. For example, if the front left is high it can lower the right rear.
I'd suggest you get the car corner weighted as already suggested.
That way you can get the stance right and make sure that all 4 wheels are bearing a similar weight.

[taylormj4]

Thanks guys, I'm going to change the front springs and shocks so not getting geo done until after that's done, yes good advice.

I feel like I am nose-high when driving now, which is a bit weird. Amazing that you can detect the difference, it is only 4mm or so lower at the rear but then I have been driving it daily for 14 years I guess !

Does anyone know what the original ride heights were from the factory ?