Help! Rear end bottoming out destroying fender and tire - Team Camaro Tech
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post #1 of 39 (permalink) Old Aug 7th, 19, 02:05 PM Thread Starter
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David
 
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Help! Rear end bottoming out destroying fender and tire

Need advice please.
1967 restomod, not much original.
When I hit a dip in the road just right, my right rear tire hits the front top of the fender.
This weekend it was so bad it ripped off the wheel well stainless trim, bent out the fender lip and made a deep gouge the tire (ruined it).
I have rear leaf springs and some type of gas shocks. Tires 275/40/17 and have plenty of top and side clearance at rest. It only happens on the one side even though both sides like fairly identical.
How do I fix?
Narrower tire (the current 275 does not seem to stick out too far and has plenty of clearance above)?
Different/better shocks?
Is there some kind of limiting block to prevent bottoming out?
Any help appreciated.
I am unable to upload pictures, not sure if due to my posting status.

Current:
1967 Camaro RS restomod, RamJet 350, 700R4
Past:
1968 and 1969 (3) Firebird Convertibles, 91+94 Alfa Romeo Spiders, 68 Triumph TR250, 64 and 69 Corvette Roadsters, 66 Mustang Convertible, 56 Studebaker Hawk, 58 Cadillac Coupe DeVille
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post #2 of 39 (permalink) Old Aug 7th, 19, 02:26 PM
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Don
 
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Re: Help! Rear end bottoming out destroying fender and tire

Hitting at the 10 and 2 oíclock positions is common when running wide tires, especially on 69ís.

You need wheels with more backspacing, narrower tires, or both. Stiffer shocks might help. You could also raise the ride height if the car is very low.

Post up a couple of pics of the wheel orientation in the wheel opening.

Do you know the width and backspacing of your wheels?

Don

1969 Camaro LSA 6L90E AME subframe and IRS
1969 Camaro vert LS3 4L65E Ridetech level 2 - sold
1959 El Camino project
1969 Mustang Sportsroof project
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post #3 of 39 (permalink) Old Aug 7th, 19, 02:38 PM
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Re: Help! Rear end bottoming out destroying fender and tire

Make sure the 3 bolts holding the the front leaf spring pocket arent loose or broken, it can move around a lot if they're just loose.

Are the shocks "bouncy" or do you think they're blown out ?


I never had an issue with a 275 tire and a 3" drop on my 68.

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post #4 of 39 (permalink) Old Aug 7th, 19, 02:53 PM Thread Starter
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David
 
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Re: Help! Rear end bottoming out destroying fender and tire

Car is not low, if anything rides high, no clearance issues when sitting.
I will check leaf spring bolts.
Wheels are American Racing Torq thrusts, probably 8-8.5 front and 10-10.5 rear, I do not know spacing.
Forum won't let me post pics. Can you see pic of my car if you click on my profile?

Current:
1967 Camaro RS restomod, RamJet 350, 700R4
Past:
1968 and 1969 (3) Firebird Convertibles, 91+94 Alfa Romeo Spiders, 68 Triumph TR250, 64 and 69 Corvette Roadsters, 66 Mustang Convertible, 56 Studebaker Hawk, 58 Cadillac Coupe DeVille
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post #5 of 39 (permalink) Old Aug 7th, 19, 03:03 PM Thread Starter
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David
 
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Re: Help! Rear end bottoming out destroying fender and tire

this is my car when sold by a prior owner, but wheels and tires the same:
https://www.streetsideclassics.com/v...rs-pro-touring

Current:
1967 Camaro RS restomod, RamJet 350, 700R4
Past:
1968 and 1969 (3) Firebird Convertibles, 91+94 Alfa Romeo Spiders, 68 Triumph TR250, 64 and 69 Corvette Roadsters, 66 Mustang Convertible, 56 Studebaker Hawk, 58 Cadillac Coupe DeVille
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post #6 of 39 (permalink) Old Aug 7th, 19, 03:23 PM Thread Starter
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David
 
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Re: Help! Rear end bottoming out destroying fender and tire

shocks not bouncy but they do lose air pressure over time and I never know correct inflation pressure, usually aim for around 26 psi from what I have read

Current:
1967 Camaro RS restomod, RamJet 350, 700R4
Past:
1968 and 1969 (3) Firebird Convertibles, 91+94 Alfa Romeo Spiders, 68 Triumph TR250, 64 and 69 Corvette Roadsters, 66 Mustang Convertible, 56 Studebaker Hawk, 58 Cadillac Coupe DeVille
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post #7 of 39 (permalink) Old Aug 7th, 19, 03:25 PM
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Don
 
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Re: Help! Rear end bottoming out destroying fender and tire

Not enough backspacing imho. Either that or they are just too wide. Measure the clearance between the tire and frame rail. Pull one of the wheels and measure the backspacing.

When you run a 275 tire you have to nail the backspacing. No margin for error.

The wheel is also slightly forward in the opening.

Don
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1969 Camaro LSA 6L90E AME subframe and IRS
1969 Camaro vert LS3 4L65E Ridetech level 2 - sold
1959 El Camino project
1969 Mustang Sportsroof project
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post #8 of 39 (permalink) Old Aug 7th, 19, 03:37 PM Thread Starter
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David
 
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Re: Help! Rear end bottoming out destroying fender and tire

Thank you.
I do not want to spend the $$$ to swap wheels to perfect backspacing. And I suspect the shocks are not the fix. So I guess that leaves me with thinner tires, not sure how much thinner required to fix problem but I suspect 255 not a big enough difference and may need to go down to 225 or 235??? The fronts are 215s.

Current:
1967 Camaro RS restomod, RamJet 350, 700R4
Past:
1968 and 1969 (3) Firebird Convertibles, 91+94 Alfa Romeo Spiders, 68 Triumph TR250, 64 and 69 Corvette Roadsters, 66 Mustang Convertible, 56 Studebaker Hawk, 58 Cadillac Coupe DeVille
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post #9 of 39 (permalink) Old Aug 7th, 19, 03:46 PM
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Don
 
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Re: Help! Rear end bottoming out destroying fender and tire

This pic shows inadequate backspacing imho.

Air shocks were likely added to raise back end to address rubbing.

Don
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1969 Camaro LSA 6L90E AME subframe and IRS
1969 Camaro vert LS3 4L65E Ridetech level 2 - sold
1959 El Camino project
1969 Mustang Sportsroof project
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1956 Cameo project - C5 drivetrain
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post #10 of 39 (permalink) Old Aug 7th, 19, 03:53 PM
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Don
 
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Re: Help! Rear end bottoming out destroying fender and tire

Quote:
Originally Posted by David in NC View Post
Thank you.
I do not want to spend the $$$ to swap wheels to perfect backspacing. And I suspect the shocks are not the fix. So I guess that leaves me with thinner tires, not sure how much thinner required to fix problem but I suspect 255 not a big enough difference and may need to go down to 225 or 235??? The fronts are 215s.
Based on the pic I posted you are most likely not going to fix that with narrower tires. That wheel is too wide for a 225 tire.

Just keep increasing the ride height by adding air until it stops rubbing if you donít want to address the root cause. Jack er up as we used to say back in the day.

Don

1969 Camaro LSA 6L90E AME subframe and IRS
1969 Camaro vert LS3 4L65E Ridetech level 2 - sold
1959 El Camino project
1969 Mustang Sportsroof project
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post #11 of 39 (permalink) Old Aug 7th, 19, 04:24 PM
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That backspacing is all wrong and the rear tire isn’t centered in the wheel well. Fix it sell it or destroy it.

Steve
1968 that started life and a 6 banger with a PG. Now it's a 350 with a TKO600, Moser 12 bolt, Speedtech LCA/UCA, ATS Tall Spindles, Hotchkis Springs, Forgeline ZX3P, C5 (Kore3) brakes with other cool stuff from Ron Davis, Vintage Air and soon to be Terminator EFI.


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post #12 of 39 (permalink) Old Aug 7th, 19, 04:49 PM
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Re: Help! Rear end bottoming out destroying fender and tire

As Don pointed out. Wheels are too wide and most likely not not correct backspacing.

So you can buy wheels that fit correctly or jack it up with the air shocks high enough to stop rubbing.

I would start by measuring the wheel to see exactly how wide they are and what backspace you have.

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post #13 of 39 (permalink) Old Aug 7th, 19, 06:53 PM
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Al
 
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Re: Help! Rear end bottoming out destroying fender and tire

I'm thinking the rear end and possibly the springs may be a transplant. The wheels should be
much closer to centered in the openings and even with the wrong backspace it just looks like
the read end is too wide. Get the code off the axle tube and see what you have.

Al

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post #14 of 39 (permalink) Old Aug 8th, 19, 04:57 AM
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Re: Help! Rear end bottoming out destroying fender and tire

To run a 275 (17 or 18) on a stock width rear in a 67/8 you need a 9" wheel with 5.25" bs. I ran a 275/40-17 (with a 9.5 with 5.5BS) on my 68 but I had to roll the lip and still had some rubbing issues at times. Like others have said, Your backspacing is killing you. Different tires are slightly different width than others that are the same measurement. 69s are a lot more forgiving with the shape of their wheel well.

Chris
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post #15 of 39 (permalink) Old Aug 8th, 19, 05:21 AM Thread Starter
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David
 
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Re: Help! Rear end bottoming out destroying fender and tire

Nothing original on this car, but great parts. All new Moser rear end.
Yes, rear axle and wheels sit slightly forward in wheel well, and yes wheels probably too wide and backspacing wrong.
But, it is an awesome car, which I have put on a couple of thousand trouble-free miles, and only the right rear rubs, not the left despite same set up.
I do not want perfect, only drive-able without destroying tires and fender, and I do not want to start going down the money pit on new rear end or wheels.
So, sounds like maybe rolling the fender lips, narrower tires, keeping air shocks pressurized and I may make it alright.
Fingers crossed.
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