So I've been steadily restoring this 88 duke 5-speed for the past 10 months and have successfully rebuilt the top end, completely restored the interior, and tons of other fixes. It's starting to look and run really good. The one big thing that remains appears to be a rear suspension issue. When I bought the car, all four tires were badly worn on the inside, right down to the belts while the outside tread was still good. It is clear this car was driven for a long time with a bad suspension issue. Looking at the car from the rear, both rear tires appear to have a significant negative camber (top tipped inward). I assume the PO wore out the rears and rotated the fronts onto the back until they were shot too. At this point I think the problem is the rear.
I know nothing about suspensions. I have not replaced the shocks, but the car rides really well (at least compared to my old 87). There is no play in the wheels either top-to-top or side-to-side when jacked up. The tires are newand are mounted to the stock 14" snowflake wheels.
Should I just take it in for a 4-wheel alignment, or should I replace the shocks first? Any other possible causes for this issue that I should check out before persuing an alignment? Another thing is that I am considering changing to the staggered 15" wheels off an 88 Formula or GT. I assume that if I go that route that I should do that before dropping big $$$ on an alignment. Thoughts?
another thing to check is the long bolt that goes through the rear knuckle at the bottom and connects to the lateral links. It could be worn or the hole elongated. I think Rodney has a fix for that though.
Replace all the parts you plan on replacing, then take it in for an alignment. Toe out of adjustment will wear tires faster than the negative camber and I would suspect the front vs. the rear.
Reason being is most places forget to jounce the suspension while aligning to restore it back to the ride height (this is specifically called for on the 88's). So after they lift the front suspension once to make an adjustment, it sits a couple inches higher for the balance of the alignment. They set the toe to this higher ride height and as soon as you drive it off the lot you have a toe out condition that wears the inside of the tires. This toe out condition also makes the front of the car jump side to side in the rain.
The lack of jouncing is less of an issue in the rear of the 88's as the toe adjustment doesn't change as much and there is more weight to help it settle to ride height. But the rear could have worn/shifted bushings and the long lateral link bolt could be loose. The long bolt being loose normally causes the car to pull to one side while under throttle, then to the other side when you brake.