Quote:
Originally Posted by 1stgenbird
No heavy added equipment nor "overloaded" driver or passenger. Lol! Bump stops are all there.
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Funny I know, but I've seen it. Cars bottoming out or vehicle performance isn't what the owner thinks it should be. Meanwhile there's 600 lbs between the husband and wife sitting in the car.
Anyhow, onward.
I ran your wheel and tire setup for the rear into a calculator. I assumed based on your statements a 100% factory original suspension and axle length as a result. I used the 6Jx14et8 wheel that should be on the car from the factory with the optional wide tire, that equates to a current 205/75/14. Wheel 1 would be the factory fitment, wheel 2 would be your current fitment. I'm assuming you have something like a Coker rally II wheel that has a standard 0 offset, 4.5" backspace.
What jumps out to me is the change in tire location towards the outside wheel lip. Your tire sits almost an inch and a half further out than the factory wheel would have. On a 67-68 car with the rounded fenders, you can get away with poking the tire outside of the sheet metal, or even directly under the wheel lip, but you do run the risk of slamming the sheet metal onto the tire itself.
As a 69 owner, we have to be much more careful and sensitive to this situation.
Is there a chance that your car is coming down on top of the tire? Look for witness marks on the underside of the wheel lip and possible marring/scraping on top of the tire tread.
If that's the situation, either pulling the wheel inward towards the suspension, or sourcing a wheel with a proper backspace would resolve the issue. You could also go to a stiffer spring and shock setup which would not allow the car to travel as much in bump.
If the bumpstops are in place, bottoming out the car should not result in a loud bang. You should feel the car stop moving, but noise should actually be minimal. The bump stops in the rear are several inches thick if in good condition.
It may not be the tires, but if there's a loud bang, you're definitely hitting something.