Lowering my 1971 - Wayne's #'s dont seem to work - Help!

Sam1905 · Sam1905's Garage

Hi,
Got the new shocks on Jezibel today and went to go about lowering the front.
According to Waynes 101 Projects the difference between Torsion bar height and road wheel center should be 99mm for US cars and 108mm for EU cars.

I measured my heights and found:

Center of road wheel - 292mm (L) and 290mm (R)
Torsion bar height - 135mm (L) and 132mm (R)

This gives a difference of 157/158mm suggesting my ride height should be RAISED 50mm to get to EU????

The car is on 205 55R15's and I enclosed a picture that seems to I would have thought suggested the car is currently around US height.

What am I missing?
Thanks
Sam
P.S. I know - front bumper needs rehanging.....

Arne2 · Arne2's Garage

First, the US spec of 99mm only applies to impact bumper cars, '74-83. All long hoods (as well as '84-up short hoods) used the 108mm spec.

Second, it is my experience that no one these days truly remembers just how freaking tall these cars sat from the factory.

Your 205/55-15 tires are just over an inch shorter than stock. That means that your fender gap will be larger too.

I'm currently running my car at about 130-135mm in front. Still far lower than factory spec, although you'd never know it to look at it.

RSTarga · 11-29-2013, 04:01 PM

I'm at 300 and 160, feels and kooks good. 205/50/16

Sam1905 · Sam1905's Garage

Just found out stock tire was a 185 70/R15 with a radius of 320mm..
Need to do some math.
Any guidance on another way to assess a good streetable height?

RSTarga · 11-29-2013, 04:51 PM

I'd drive it a little to see if the shocks settle some then shoot for about the 140mm difference

Arne2 · Arne2's Garage

My car was at 140+ when I bought it, and was low enough that I felt it was hitting the bump stops a lot, ride was harsh and jittery. Much better around 130.

RSTarga · 11-29-2013, 05:14 PM

Quote:

Originally Posted by Arne2

My car was at 140+ when I bought it, and was low enough that I felt it was hitting the bump stops a lot, ride was harsh and jittery. Much better around 130.

What size tires?

Arne2 · Arne2's Garage

Quote:

Originally Posted by RSTarga

What size tires?

Stock 205/55-16. But measuring in the factory manner makes tire size irrelevant. You are truly measuring the suspension ride height.

Bob Harriman · Bob Harriman's Garage

Set your ride height where you like it. Too low in the front compared to the rear will stand out like a sore thumb. If you lower the front to close that gap so your wheels fill the wheel well with 55 series tires you'll also have to lower the rear stance as well. That will require re-indexing you TB unless you have an adjustable spring plate.
This is my front with 55 series tires.

No speed bumps for me. My rear sway bar is about 3" off the ground!

Bob Harriman · Bob Harriman's Garage

The rear must come down also with 55 series

javadog · 11-30-2013, 03:20 AM

If you are more interested in how it drives, raise it. If you want it to drive like it did when it was new, put taller tires on it. Wanna run low profile tires? Swap the 15's for 16's... If looks are more important, use your own judgement and put up with the driveability issues.

How much fuel is in the tank, as pictured? That changes the height a fair bit, as well.

JR