Rear Tire Rubbing on One Side

[ptrmzr]

This one's got me stumped. After doing some rear end work and then on the drive back from Carlisle with a passenger the driver's side rear wheel starting rubbing when hitting a dip in the road.

Car specs: 71FB with tired stock leaf springs, 15x8.5 ARE 200s "Coke-Bottles" w/ 4" offset, new Cooper Cobra 245/60's (in place of an old set of 245/60 Goodyear Eagles)

To replace the center section I slid the axle back on the leafs to clear the stock style mufflers and while putting it all back together I replaced the plastic anti-friction discs and leaf clamps (the old ones were worn paper thin or missing), replaced the rear wheel bearings, swapped out the leaky air shocks for KYB gas.

When arriving home from the drive I found the driver side tire to be a 1/4" further outboard than the pass. side. I put the car back up on the lift and loosened the u-bolts to check if there was clearance between the locating bolt and the hole in the bottom of the perch, but both perches seem to be sitting snuggly on the bolts. I measured the distances from the hub to the brake backplate and from the backplate to the leaf spring on both sides - identical. The shackle bushings are in good shape.

Can it be the leaf springs are "twisted" and biasing to one side? I don't want to go back to air shocks and considering replacing the springs and if that doesn't solve the rubbing problem I'll replace the tires with 235/60s. I think the Coopers may have more sidewall bulge than the Goodyears.

Your thoughts?

Thanks,

Peter

 

[nailpounder]

did you replace one baring ? was it pressed on far enfough ?

 

[ptrmzr]

Both sides replaced a both pressed to correct locations. Confirmed with hub to bake plate measurement.

 

[mjlan]

Maybe your wheels are a little different offset?

Switch sides and check?

 

[ptrmzr]

Hmmm good idea...runs out to garage...

 

[ptrmzr]

OK wheels and tires both have the same dimensions: both 6" from the back mounting surface to the highest point of the outer sidewall bulge, but I found other stuff...Using a plumb bob, the distance from the wheel mounting surface of the brake drum to the driver's side wheel well lip is 5-5/8 the other side 5-3/4. After a closer look at the passenger side tire it was lightly hitting there too. I also measured the distance from the top of the axle to the snubber and compared to see if when the spring were fully compressed where along the side wall it would hit the lip and it will eventually hit the side wall on both sides.

So it looks like a wheel-offset/tire combo that pushes the tire sidewall out more than 5-1/2" from the brake drum is destine to rub unless you have some mechanical means of limiting the spring travel.

My air shocks must have been doing that to some degree. Now even if I go to 235/60s reduces the tread width by 0.39" - not sure how that translates into high point in the sidewall.

I am getting that sinking feeling that I may need to find a different set of rear wheels or swap out the axle housing for a friend's '70 housing and axles (slightly narrower!) in addition to new springs.

 

[mjlan]

5/8 vs. 3/4 doesn't seem that bad for variation, I had to read that twice!

How much arch have your springs lost?

 

[ptrmzr]

I'm not ready to lower the car onto its wheels - I am waiting on pricing and delivery on the springs before I go forward, but the rear was sagging.

How would you measure lost arch?

 

[Qcode351mach]

OK wheels and tires both have the same dimensions: both 6" from the back mounting surface to the highest point of the outer sidewall bulge, but I found other stuff...Using a plumb bob, the distance from the wheel mounting surface of the brake drum to the driver's side wheel well lip is 5-5/8 the other side 5-3/4.

Thats a common issue I've seen quite a lot on cars that have had a quarter panel section or any part of the wheel arch replaced. Very few people check for symmetry the distance of the wheel arch fender lip to the inner wheel house or a good known point on the unibody when replacing panels.

 

[timachone]

OK wheels and tires both have the same dimensions: both 6" from the back mounting surface to the highest point of the outer sidewall bulge, but I found other stuff...Using a plumb bob, the distance from the wheel mounting surface of the brake drum to the driver's side wheel well lip is 5-5/8 the other side 5-3/4.

Thats a common issue I've seen quite a lot on cars that have had a quarter panel section or any part of the wheel arch replaced. Very few people check for symmetry the distance of the wheel arch fender lip to the inner wheel house or a good known point on the unibody when replacing panels.

Good point! But this is even more difficult by the factory asymmetries they built in on the assembly line. What could be read by everyone now on my restauration thread I am replacing my quarters. By cutting off the quarters on the same spot and every part was original sheet metal you could see and measure a slightly difference between left and right distance from outer quarter panel to inner wheel arches.

With that said: it could also be possible that the measurements differ slightly from the factory with all original sheet metal on the car! Back in the days they where not as picky as today by welding parts together...

But that don't protect you from working as accurate as possible. But do not wonder if not all components are perfect aligned from the factory - it was another time...

 

[Jeff73Mach1]

fresh springs and bushings and quality shackles go a long way towards minimizing side to side movement. If that isn't enough, when everything is put together properly, then different wheels would seem to be necessary absent some serious modification (which just takes time money and know how- no biggie)

 

[KT-69]

Something is way wrong I run 15 X 10 rims with 295-15 tires. With 4" offset.

Roll the upper fender lip back-up this gains up to 1/2" and always cut the steel tang off the axle bumper holders.

Grab-a Trak or Scott Drake 4.5-5 leaf springs.

3/4 sway bar

3/8" thick stainless steel 1" extended shackles

And never have any rubbing issues.

15 x 8 wheel 4" offset with 245 X15 tires up front. Cut one coil out of 620 springs and roll upper fender lips in and upward.

1" front sway bar

Good quality shocks up front with bushing perches.

Replace ball joints etc... with Rock-Auto mid cost range components

This combo gives slight raked stance gets rid of the 71-73 *** droop gives the car a much more aggressive look and and I really love dropping the long hood down a tad so I can see over it. Handles way way better to.

Now growing up in the 60's and 70's and driving many of those era Mustangs and Cougars I really miss the quick ratio manual steering. I either swap out the 800 SAG power unit with mid 90's Grand Cherokee internals or send it out to Lee Performance for a 12.7:1 ratio conversion. Add 12" Grant steering wheel. 3.20:1 rearend gears, posi and warm that Cleveland up to around 400 hp with 10:1 compression ....now your driving a fun classic 70's machine.

 

[SR71 BLACKBIRD]

OK wheels and tires both have the same dimensions: both 6" from the back mounting surface to the highest point of the outer sidewall bulge, but I found other stuff...Using a plumb bob, the distance from the wheel mounting surface of the brake drum to the driver's side wheel well lip is 5-5/8 the other side 5-3/4.

Thats a common issue I've seen quite a lot on cars that have had a quarter panel section or any part of the wheel arch replaced. Very few people check for symmetry the distance of the wheel arch fender lip to the inner wheel house or a good known point on the unibody when replacing panels.

I've noticed this situation on every 71-3 Mustang. It's especially noticeable when trying to put the widest rim/tire combo on. I bought a Percy's wheel and tire simulator and would say there's easily a half inch less distance to the outside of the right wheel to the quarter lip than to the left. I'm running a Granada axle housing, which brings the axle flange 1.625 inches inward on each side. Looks like a 18 x 10 rim will fit both sides with 4.25 inch back spacing. Will have to lose the factory style rear sway bar to do this. I was running a 15 x 8 rim, 5.5 back spacing. I experimented with running a .25" spacer on the left side to make it symmetrical to the wheel houses. The car drove weird with it on. Felt unstable, and was too easy to change lanes. I think Ford engineered the car to have the rear offset just a little. I think if a person put a different back space on each side to maximize use of the wheelhouse, the car wouldn't drive right.