Measuring ride height.

[shaunw]

Since I bought my GT3 I've always thought it had a slight lean to the rear but I wasn't sure if this was because the back was too low or the front was too high.  Curiosity got the better of me today and after consulting the workshop manuaI I measured the ride height. ( as an aside I was surprised to see that the GT3 is set up with a slightly higher ride height than the s4, anyone know why? Is it just a result of reduced weight? ). Anyway it turns out mine is riding about 15mm too low at the back. I then went to measure the front but how on earth do you measure the distance from the front cross member to the floor? Obviously you can't crawl under the front like you can the back. I couldnt find any kind of procedure in the service notes, so how's it done?

Edited August 13, 2023 by shaunw
Grammar

[Escape]

The easy way is on a ramp or over a pit of course. Lacking those, cut a wooden block to the correct height (180mm). You should just be able to get it under the cross member coming in from the side, just in front of the wheel.

[shaunw]

10 minutes ago, Escape said:

The easy way is on a ramp or over a pit of course. Lacking those, cut a wooden block to the correct height (180mm). You should just be able to get it under the cross member coming in from the side, just in front of the wheel.

Thats a good idea, why didn't I think of that? 🙄😄. 

Thanks 👍

 

Shaun

[Chillidoggy]

For a quick check, I use a T-bar, a 170mm length of plastic bar screwed to a wooden handle long enough for me to reach under the car to the crossmember. Doesn’t have to be plastic, knock one up from wood. It’ll tell you whether the car is too high/low, although it won’t give you a millimetre-perfect reading.

[shaunw]

Right, so I've now measured the ride height. ( I ended up using an old metal tape measure cut off at 180mm to measure the front subframe height, very easy to get an accurate measurement ). The front measured about 5mm high but I didn't have two humans available to sit in it so I'd guess its about right when correctly loaded. The back however is running 15mm below spec ( again without anyone sitting in the car! ) The springs and dampers are original standard fit, rear suspension bushes are all newish. Correct size wheels and tyres inflated to spec.  Low mileage car but the springs and shocks are now 25 years old (fronts were replaced a few years ago). I would therefore say they are the most likely candidates for the ride height discrepancy.  Is there anything else I should check / consider?.

[Escape]

Springs can lose some height with age, so replacing those might help. There is also a rubber isolator at the top of the spring, if that has deteriorated (or has been removed) the car will sit lower as well.

[ekwan]

Where would one measure the ride height. Understand it is 180mm all round for an S3, but unlike the later Elise, I cannot find any information in the Workshop Manual.

[Escape]

According to the manual I have (Turbo Esprit and S3), it should be 170mm below the front chassis box (I assume the transverse profile is meant, as on the later ones) and 170mm below rear chassis link brackets (later ones are measured under the hoop). It also states 146mm under the radiator cowling.