S3 Ride Height Recommendations

[Elise111]

After a bit of searching, I don't see actual ride heigh details on here, Tech Talk or Piston Heads. I see lots of references to 15mm stagger.  After taking out my Capri sump (luckily it just dripped instead of completely failing) I've put in a new, thicker sump from Redline that looks like the flat bottom Caterham sump.  This is a 1989 S3 with the early style front suspension and deDion rear.  

 

I've put 350lb of sandbags in the seats to represent 2 up street driving.  Lower A arms measure horizontal, and the car is on level ground.  New Spax dampers, and the fronts show about 6mm of shock shaft when loaded.  These came with a 3mm thick plastic C washer between the bump stop and the shock body, so I've sent a note to Spax to understand what that is for and if it is really needed.  Front springs are 250lb/in and new.  Rear springs are 150lb/in and original.  I have adjustable perches on the Spax.  

 

Ride height was measured by the front engine mount region, and at the leading edge of the rear wings. 

Unloaded: F 138mm   R 150mm

Loaded:  F128mm   R 115mm

Sump clearance went from 82mm to 68mm. 

 

If the front is in the right spot, then I think I need to raise the rear to be about 143mm loaded.  6mm of shock travel before touching the bump stops seems small though, but I have no sense of what is typical.  Thanks for any feedback on ride height!

 

I should add that it is on 14" wheels.

Edited June 6, 2021 by Elise111
Added 14in wheels

[sf4018]

You trying to so some aero thing or just avoid hitting stuff underneath?

[Elise111]

Just trying to prevent hitting the sump again.  I got 'lucky' the first time! 

[sf4018]

I have 65mm gap for lowest point to ground (I have dry sump so this is the bell housing). It was lower than that initially but I had issues when running over curbs. Since I raised it to the current position I haven’t had a problem. If you drive pot holed roads you may need to raise.

[Elise111]

Thanks- is that 65mm unloaded?

[sf4018]

Yes

[ashyers]

I have an '03 SV. The drysump and bellhousing are the lowest points (they are on nearly the same plane). With a 23.2" diameter tire I use the long side of a 2x4 as my height gauge under the sump. That  just keeps me off the ground and the roads around here are very poor. Any lower and I'll be clearancing parts or pissing fluids.

 

Of course, this may be useless to you due to different spring rates, bump stops and such, but it's a reference point :).