Vintage Mustang Forums banner

1 - 3 of 3 Posts

·
Registered
Joined
·
329 Posts
Discussion Starter #1
I originally bought 17x8 Torq Thrust IIs in a 4.75" backspace a few years ago. A few years later, I went with the 70 disc brake spindles so that I could add the Baer 13" rotors up front (at the time baer didn't have a kit for the 68, I think).

I believe the 70 spindles increased the front track width by 1/2" on either side for a total of 1". I'm not sure on this, so confirmation if anyone knows might help.

I also ended up going with the TCP front coilovers, which allows me to adjust my ride height. I've got the front as low as it will go without rubbing the fenders, but would like to go further. I'm pretty sure that before the 70 spindle swap, I could get the front wheels to tuck under more. Ultimately I'd like to lower the front just a bit more before taking it to a shop to have the tie rod height set properly to account for bump steer (believe you need to first set ride height...then set the rest of the alignment specs).

So, would I need to switch to a 5.25" backspace on the front wheels? (running 234/45/17 tires). I've looked at dodgestang's wheel guide and the only thing I see close is where someone is running a 17x7 up front w/ 4.5" backspace. Any thoughts on how it would look with front and rear wheels having a different backspace?
 

·
Registered
Joined
·
2,392 Posts
The '68 and '70 spindles are "supposed" to have the same geometry, so that change by itself shouldn't have affected the needed backspace. There could be some difference due to allowable production tolerances at the time, but I really doubt that would account for as much change as you noted. What I suspect is the cause is the amount of lowering you've done. Without modifying the UCA in any other way (such as lowering the mounting holes when doing the Shelby/Arning mod), cutting the springs or installing lowering springs will cause the UCA to move the top of the tire outward towards the fender. If you haven't done it yet, I'd suggest lowering the UCA 1" before deciding to get different rims. There really isn't any down side to doing that mod, you get better handling and the revised camber curve gives a little more fender/tire clearence as the suspension is compressed.

I just re-read your post and realized you have TCP UCA's which adjust the camber setting by altering the length of the UCA. Check those arms to see if the adjustment has a lot of thread showing, that would account for moving the tire closer to the fender.
 

·
Registered
Joined
·
329 Posts
Discussion Starter #3
I guess I forgot to mention that I did the shelby drop too. Other than that, the only lowering I have done is via the adjustable spring seat collar on the shock body.

Thanks for the input, but, I doubt the combination of a shelby drop and installation of the TCP coilover setup (with the tubular upper and lower control arms) is what caused my apparent track width increase. Camber surely isn't causing my problem...if I camber was the problem, then you'd think that the camber would have to be off such that it is visible to the naked eye to be causing it to no longer tuck under the fender. The car has been aligned, just haven't tried to align it to correct for bumpsteer yet since I thought I had it dialed in close enough that a standard alignment would be sufficient.

At one point in time, these wheels tucked under the fenders nicely. The rears at the same backspace fit under the fenders nicely. Since the fronts don't...it just doesn't look right.

I just thought I remember hearing at one point (can't remember the source)that yes, the 70 spindles are the same geometry in terms of angles and tie rod, upper and lower ball joint locations...but they have a wider track width on the car (and the spindle portion itself is thicker). I can't remember where I heard that from or where/how to confirm it.
 
1 - 3 of 3 Posts
Top