X2 ;) Looks high with 225s/245s on 16s but still rubs some with 21/28 T-Bars.

Ahhh... tell you what, I'll measure after my car's back together and let you know.

Ha. Well we know mine is rubbing, and I am probably the last person to help you out, but...My 76 targa is at

With 16X6's and 205/50/16 tires up front, fender to floor is
Drive = 26
Pass = 25 1/2

Rears which we all know rub with 16X7 and 225/50/16 tires is set at
Drive = 25
Pass = 25

I don't have any record showing it nor have I seen any damage to show that mine is tweaked at all. But I'm like you a 31 year old targa has got to have some flex issues.

Some more data after setting up some "level ground" this weekend:

190 lbs in driver's seat [I weigh more than that :shock: :lol:]
3/4 tank of gas [supposed to be 1/2 but WTF :lol:]
32 psi F 34 psi R
215/60/15 all around
sway bars disconnected
All extra sh$t removed from trunk, interior, etc... [spare p-car parts, kid stuff, kid seat, etc...]
Weltmeister rack spacers installed

Leveled 2X12s L to R and F to R.

F wheel center to ground = 303 mm both R and L [~40% of cars weight]
Torsion bar center [cap] to ground = 150 mm L and 145 mm R
Tie-rods about ~1 degrees from horizontal

R wheel center to ground = 300 mm both R and L [~60% of cars weight]
Torsion bar center to ground = 285 mm L and 280 mm R


So ...

FL = 303 - 150 = 153 mm ["euro" is 112 +/- mm] fender to ground 26"
FR = 303 - 145 = 158 mm; fender to ground 25 1/2"
RL = 300 - 285 = 15 mm ["euro" is 12 +/- mm]; fender to ground 25"
RR = 300 - 280 = 20 mm; fender to ground 25 1/2"

Car is a little higher on the left b/c I didn't have enough weight(s) to add ... ;). I also typically have the tank full when car is sitting for periods of time so it gets driven mostly on full. *note the fender height to ground measurements are NOT the standard "F is 1/2" higher than the rear" and that mine are all over the place. IMO, setting ride height via the fenders is bad JU-JU. These cars are tweaked a little here and there and you won't get an accurate ride height setting.

It's nice to have baseline numbers before you corner weight it and screw up the nice measurements and ride height settings [will do soon] again ...

For alignment I used tech articles on pelican [Mike Piera & John Rogers] and experience setting up track cars.

Front toe: [tack in frontmost part of tire; string to ground hanging plumber' bob; X mark the ground and roll car backwards so tack is at rearmost part of tire, mark again; do some math :) ]. I set it at ~1/16" toe in.

Rear toe: Same method but PITA b/c have to set camber first [not hard to do], then loosen things up to use spring plate toe eccentric to pull arms forward a little to get back to desired toe setting]. I set it at 0 toe.

*mark the ecentric bolts for camber and toe with a dot using a paint pen or sharpee to know when eccentric is rotated at max adjust and where relative position is as you turn with 12mm hex.

Set camber with straight edge on wheel [not tire] with bubble level ... [or sawed off bubble level with straight edge] measured distance from edge to top of rim [in 32nds of an inch] when straight edge is level [verticle]. Do some math ...

and ...

... and you get pretty close.

I ended up with [b/c mine is a street car]. ~0.5 F neg camber and ~1.0 R neg camber. Note - to decrease built-in 911 understeer conventional wisdom says to set F and R camber near the same. At the same time ... this is better accomplished with adjustable sway bars rather than setting camber same F and R. :)%

* I also recognize that alignment and corner balancing are typically performed simultaneously [b/c one affects the other] after the initial ride height setting. My weights are prolly off but ... getting height and alignment are more important right now for the ~3-4,000 miles a year I might do on this car :)

FWIW

[edit] Still looking to hear from people with '74 - 89 911s as to what your TB center to ground measurements are on lowered cars ...? :) [/end edit]

I'll take some measurements this week when I put my SC back up on the drive-on lift. It's currently running 205/50/15 and 225/50/15 tires.

Anybody follow up and get these measurements?

It's been six months.

Dohh!

I'll try and get my SC up on the lift this weekend and take measurements.

Timely reminder (6 months!)
I did my home ride height and alignment several months ago.
This was just going to be my 1st step and allow things to settle.
It turned out the car feels good so I planned the final tuning as a winter project.
I guess Winter is here? Anyway I hope to get it up on my homemade rack soon and recheck and tweek everything.
I used a water level to level the setup using the axle centers as opposed to where the wheel is sitting on the platform. This theoretically will eliminate tire variences.

I used recommendations from Bruce Anderson's book on height which I will post later with other info when I get this done!

So.... what are the measurements for ground to TB centers.........?

Jase,

Here are some approximate ride height measurements of my '80 SC with 205/50/15 front tires and 225/50/15 rear tires. In front I measured from the bottom of the front torsion bar cover and in rear I measured from the bottom of the torsion bar cover. The measurements are just about equal on both sides.

Front
115 mm bottom of TB cover to ground
24 1/4" fender lip to ground

Rear
245 mm bottom of TB cover to ground
24 1/2" fender lip to ground

Approx. overall rake 1".