Front ride height math

[steely]

I am in the process of checking my ride height all around since I recently did the rear suspension bushings - but there is something I don't understand about the front- hoping someone will set me straight.

The Front Ride Height US spec is 99 mm, or 3.9 inches.

Using the equation A-B = C, where A is the wheel cap ctr hgt from ground (or 12.25), and B is the TB cap ctr from ground, this means that my TB caps should be closer to 8 inches than the 6.25 I measured - in order to reach the goal C of 3.9 inches. (12.25-3.9 = 8.35)

I had lowered the one side and the fender is now lower, but the TB cap lowered too. (it didn't go up as the math would suggest and is counter-intuitive)
By the equation above, shouldn't the TB cap have gotten higher?
My ride height value went from ~140 to 150 mm. I thought it would go down towards 99mm.

I want to get away from measuring at the fender, and I don't want to lower the car anymore. I read a lot of posts, maybe my comprehension is going.
Overall tho', the front stance looks ok now.

I have to re-index the rears and then get an alignment, or maybe that will have a big affect on the front? I would like to make sure I got it close or at least understood wth was going on - anyone?


thanks

[Arne2]

By '87, there shouldn't be a "US-spec". My information shows all 3.2 cars world-wide for '84-on at 108 ± 5 mm. So a car in good condition should sit between 103-113mm.

But for what it's worth, my car is sitting at about 135mm up front (significantly below the "official" euro/RoW spec). With stock size tires, my fenders measure around 25.5-25.75" depending on how full the fuel tank is. Seems plenty low enough to me.

Also, FWIW - make certain you are adjusting the TB's the correct direction. Tighten the adjuster should raise the car, loosen to lower.

[turborat]

Subtract 12.25 - 6.25 = 6. Front is probably too low by 1" - 1.5". Looking for a delta of 4" - 5"....5" being aggressive for street.

[steely]

Originally Posted by Arne2

By '87, there shouldn't be a "US-spec". My information shows all 3.2 cars world-wide for '84-on at 108 ± 5 mm.

Well that would be key - I didn't realize there was no Euro spec for '84 on.

Originally Posted by Arne2

So a car in good condition should sit between 103-113mm.

But for what it's worth, my car is sitting at about 135mm up front (significantly below the "official" euro/RoW spec). With stock size tires, my fenders measure around 25.5-25.75" depending on how full the fuel tank is. Seems plenty low enough to me.

More re-assuring info - I went from 140 to 150 and wound up with 25.75 on the fenders down from 26.25 - full tank, refreshed suspension. Maybe she was ok to begin with. Maybe it is an aesthetic question. To get 108, I might wind up with inches of air between the wheel top and the fender.

[steely]

Originally Posted by turborat

Subtract 12.25 - 6.25 = 6. Front is probably too low by 1" - 1.5". Looking for a delta of 4" - 5"....5" being aggressive for street.

So, with 5, the TB ctr would wind up around 8 off the ground, right? (Sounds like a dumb question - but humor me?)

[Arne2]

Originally Posted by steely

More re-assuring info - I went from 140 to 150 and wound up with 25.75 on the fenders down from 26.25 - full tank, refreshed suspension. Maybe she was ok to begin with. Maybe it is an aesthetic question. To get 108, I might wind up with inches of air between the wheel top and the fender.

Yes, I believe you would have significant fender gap at 108. With stock size tires, I estimate the fender measurement would be pushing 27". And while that may be RoW factory spec, it does look a bit tall visually. The 25.5" number that is frequently thrown about as being "euro height" is actually 1" to 1.25" lower than true RoW factory spec.

Again FWIW - my measurements on the rear are similar. The popular and oft-quoted 25" "euro" height is actually an inch lower than true RoW spec when measured correctly.

[Arne2]

Originally Posted by steely

so, with 5, the tb ctr would wind up around 8 off the ground, right? (sounds like a dumb question - but humor me?)

7 1/4"

[steely]

I'll throw up a pic after work tomorrow of her stance.
I am looking for street / stock setup w/o a baja look.

[steely]

Originally Posted by Arne2

7 1/4"

You are correct of course - thanks

[Arne2]

Here's a recent pic of mine. Not too low, but not jacked either. I consider this totally streetable. My numbers are approx 135 front, -15 rear.

[steely]

Originally Posted by Arne2

Yes, I believe you would have significant fender gap at 108. With stock size tires, I estimate the fender measurement would be pushing 27". And while that may be RoW factory spec, it does look a bit tall visually. The 25.5" number that is frequently thrown about as being "euro height" is actually 1" to 1.25" lower than true RoW factory spec.

Again FWIW - my measurements on the rear are similar. The popular and oft-quoted 25" "euro" height is actually an inch lower than true RoW spec when measured correctly.

Well if that is the stock setup, I will strive for that first.
I will use the (Bentley) 16mm for the rear.
In stead of lowering the allegedly offending wheel in each case (F&R), it sounds like I should be raising the opposite wheel.
on edit: guess what I will be doing on my July 4th wknd.

Thanks

[steely]

Originally Posted by Arne2

Here's a recent pic of mine. Not too low, but not jacked either. I consider this totally streetable. My numbers are approx 135 front, -15 rear.

She's beautiful - I must have lost earlier in my battle not to be biased by fender height.