Ride height demystified
 

I’ve been trying to set up my ‘86 and been getting very confused.

My first mistake was to believe that what is commonly referred to as “Euro ride height” is indeed factory spec for European cars. No matter how hard I tried to set 108mm front and 12mm rear I was always an inch higher than the often quoted 25.5” front and 25” rear at the fenders. I was worried my car was wrong!

So lots of research and reading, lots of listening and changing my car around followed and I now understand - I think.

European ride height, as defined by RoW factory measurements, is in fact 26.5” front and 26” rear if you choose to measure from ground to top of the wheel arch.

The factory defines US ride height 12mm higher at the front and 28mm higher at the rear. Measured to the arches that’s 27” front and back.

The often referred to “Euro ride height” of 25.5” front 25” rear is in fact 1” lower than RoW factory settings front and rear.

RSR height went as low as 143mm +\-5mm front which is down to 25” at the front wheel arch, 1/4 lower if you take the tolerance into consideration, but crucially they leave the rear at 12mm, the same as standard height of 26” measured to the top of the wheel arch.

I presume the logic behind lowering the front and not the rear was to promote another 1 degree of rake (40mm over the wheelbase is 1 degree). What I’m not entirely sure about is rake of the standard 26.5”/26” factory standard, but when my car is set up to factory numbers I’m reading 0.8 degrees at the door sill. This would make the RSR spec a rake of 1.8 degrees.

Hopefully someone far more knowledgable than me can confirm the above is all correct. It certainly is on my car.

Subscribed, I’ll be adjusting my ride height this winter

The 25.5/25 spec originally was the recommendation of Bruce Anderson. I'm sure that others have incorrectly used it as RoW height.

here's a survey of factory specs

http://forums.pelicanparts.com/uploa...1701038212.gif

note that 143+/-5mm(ie down to 148mm) was the spec for street 3.0RS and SC/RS, the RSR's was 160mm.

The lowest main production line car was for the '74 2.7RS @113+/-5mm(ie down to 118mm.)

a well-documented investigation of multiple setups for race use by Danny Kahler settled on 160mm.

Here is a copy of an early factory setup sheet, it goes down to ~160mm front and -38mm rear

http://forums.pelicanparts.com/uploa...1701038661.jpg

Yeah, guilty. I'm one of those calling the 25.5"/25" the Euro ride height. I read that recommendation in Bruce Anderson's book 30 years ago, but so many have referred to it as the Euro ride height that I have been making that mistake for longer than I care to admit.

Thank you Bill, as knowledgable as ever.

Do you know (of course you do!) if the SCRS, RS and RSR had raised spindles to allow them to get that low at the front?

RSR - yes
3.9RS - ?
SC/RS they were optional

At 143 there is some objectionable roll steer but many just live w/ it, ideally, yes, raised spindles would certainly be desirable here.

Thanks for the clarification Bill.