[TonyS]

I read the topic on the shock/tire clearance and have this question.
I have a 67 El Camino with a 69 12 bolt with the following:

After market disc brakes.
15 " x 10" wide, 4-1/2 inch back spaceing, American Torque Thrust Mags.
275/50 BFG.

Here is the problem:
I am cutting the inside of the tires down just at the tire/rim bead. It is not catching the rim, just the tire. I have looked at the shock tower and the shock and see no signs of either touching the tire. With the car on the ground, I have had someone in the bed bouncing the rear up and down, the tower and shock have plenty of room, about two and 1/2 inches of clearance.
I am going to put some white shoe polish on the tire and see if that will help identify the problem.

Other than that, anyone have some ideas?

Merry Christmas and Happy New Year;

Tony

 

[TDW]

Is the cut mark in line with the shock mount?Could the sidewall be flexing that much? I would put the shoe polish on the tire. Drive it in a straight line for a bit. Check the polish. If no marks in the polish, i would try some corners. than check it again. Air pressure correct in the tires? Housing bolted in tight? Rubbing on both sides?

 

[TonyS]

Thanks for the reply. Checked the housing, it's Ok. Seems to be in a straight lin with the shock tower, but again, no rubber on either side. It is rubbing on drivers and psgr. side. Is worse on the drivers side. This happened while driving in a straight line. Tire pressue is correct. Not sure, but I don't think the tire would flex that much right next to the bead.
Shoe polish goes on tomorrow. Can't hurt any more, the tires are runied.
I had a set of ralley wheels on with 295/50 8" X 15" 4" set back, and they would hit the lip of the fender when I would go over a bump or dip in the road. The inside is Ok, no sign of rubbing. I think it's the shock tower, I don't see anythig else around it other than the emergency brake lever off the caliper. And it's not very close.
If it's hitting the shock tower, that's an easy fix.

 

[Clint44]

Your wheels do not have enough backspacing. That's what is causing the problem.
I assume "set back" is referring to backspace.

 

[TonyS]

Yes, backspacing. I thought the increased backspace moved the tire in towards the shock tower? The reason I went from the standard 3-1/2" to
4-1/2" was to move the assembly in and away from the outer lip so it would not hit.

 

[Clint44]

If something is cutting the inside sidewall and yet you have plenty of room between the sidewall and inner fender,you have another problem altogether.

Regardless,trying to run a 15x10 wheel with only 4.5" backspacing just isn't going to work with a stock or 69 width rear end. A 69 rear is even wider and would need even more backspacing.

 

[TonyS]

I guess I am missing something. I put a 15x8 4" backspace and that increased the distance to the shock and shock tower. I installed the 15x10 with the 4-1/2 inch backspacing and that decreased the distance to the shock which indicates that an increase in backspacing will bring the tire surface closer to the shock. At least that's what's happining.

 

[TonyS]

Clint;

I can take a photo of the set up maybe from that you can see where the problem is. I have aftermarket rear disc brakes, the type that take a Cadillac rotor and caliper.
I don't know how to post a photo to the site so if you could send me your email address I will take a photo and send it to you.
My address is [email protected]

Thanks I appreciate the help.

 

[Clint44]

I guess I am missing something. I put a 15x8 4" backspace and that increased the distance to the shock and shock tower. I installed the 15x10 with the 4-1/2 inch backspacing and that decreased the distance to the shock which indicates that an increase in backspacing will bring the tire surface closer to the shock. At least that's what's happining.

Yes,an increase in backspace will decrease the distance to the shock,,all else being equal. But,all else isn't equal. You went from a 15x8 to a 15x10 wheel but only increased the backspace by 1/2". Yes,you decreased the distance to the shock but my guess is the 15x10 wheel is still too far away from it.(it should be within a 1/4" or so,,how much room is there now?) Now,let's look at a bigger problem. By not having enough backspace for that 10" rim,the tire will not fit under the outer fender without raising the ride height dramatically.
The inside edge of the tire being cut is an unrelated problem,IMO.

 

[Clint44]

Clint;
I can take a photo of the set up maybe from that you can see where the problem is. I have aftermarket rear disc brakes, the type that take a Cadillac rotor and caliper.
I don't know how to post a photo to the site so if you could send me your email address I will take a photo and send it to you.
My address is [email protected]
Thanks I appreciate the help.

My email address is available by clicking on my avatar.

 

[TonyS]

Clint;

I agree with what you are saying. Initially I had a 15" X 8" 4" back space ralley wheel with 295 X50 tires, the tire would hit the outer lip once in a while. I put the 15 X 10 4-1/2 set back and do not have a problem with it hitting the outer fender lip, just the inside at the bead. The extra 1/2 inch set back moved the wheel in far enough to eliminate hitting the outer lip. But, as the saying goes, eliminate one problem create a new one. But, I have found out what is cutting the tire. The type of brake caliper, Cadillac with the E brake, combined with the extra 1/2" back space has moved the tire to within a 1/4" of the caliper E brake bracket. I am replacing the calipers with front calipers from an 89 Camaro. I didn't realize how much closer the E brake bracket was to the wheel.
I will send you the photos with the 10" and 8" wheel mounted. It's been raining and snowing here for the past three days, so it will be tomorrow before I can get the photos.
I really do appreciate your help, thank you very much.


Tony

 

[Clint44]

Clint;
I agree with what you are saying. Initially I had a 15" X 8" 4" back space ralley wheel with 295 X50 tires, the tire would hit the outer lip once in a while. I put the 15 X 10 4-1/2 set back and do not have a problem with it hitting the outer fender lip, just the inside at the bead. The extra 1/2 inch set back moved the wheel in far enough to eliminate hitting the outer lip. But, as the saying goes, eliminate one problem create a new one. But, I have found out what is cutting the tire. The type of brake caliper, Cadillac with the E brake, combined with the extra 1/2" back space has moved the tire to within a 1/4" of the caliper E brake bracket. I am replacing the calipers with front calipers from an 89 Camaro. I didn't realize how much closer the E brake bracket was to the wheel.
I will send you the photos with the 10" and 8" wheel mounted. It's been raining and snowing here for the past three days, so it will be tomorrow before I can get the photos.
I really do appreciate your help, thank you very much.
Tony

The numbers don't add up,Tony. It's pretty much a known fact that a 15x10 wheel needs at least 5.5" backspace to fit a 66-72 Chevelle/El Camino with stock width rear. Your rear is wider so even more backspace would be needed. Guess I need to see a photo or two.
It has been between 70 and 80 degrees here,this week. Eat your heart out.

 

[TonyS]

Saw your rides, they are sharp. Hey, it will be 70 to 80 her too, as soon as I turn the heat up.
I like the ZR1. I just sold an 02 z06. Have a new Z06 coming Jan 23rd.
Also doing a fram off on a 71 LS5 4-spd car.
This camino is something I have wanted to do for a long time, build an old farts hot rod. I'm 66 but I have a lot of fun with the classics.

Thanks again for the help. I'll get some photos in the morning.

 

[Clint44]

I'm not as old as you are but I still qualify as an old fart,too.

 

[TonyS]

Clint;

I was incorrect on the cause of tire problem. I thought it was the E brake bracket off the caliper. Not. This morning I put white shoe polish on the tire and found out the shock edge is hitting the tire. Man, when I looked at this on the ground it sure looked liked I had plenty of room. I'll download the photos and send them to you.

Thanks again for the help.

Tony