Lower bushings dead at 8000 miles!

[Kern Dog]

What the heck happened?
I rebuilt the suspension in 2003. New everything: Bushings, ball joints, tie rod ends, idler arm....I went with poly uppers and rubber lower contol arm bushings. The ride was decent. A bit of additional firmness but with 1.0 T bars, a 1.25 solid sway bar and KYB shocks, i didn't expect it to ride like an Imperial.
Recently i had a clunk in the front when braking. I got it in the air and noticed rubber shards peeling out of the lower control arm bushings! They were not soaked in oil. The front end had always been aligned. I run a 275-40-18 tire up front though, so I expect that it may have stressed the bushing more than a stock 14 inch Goodyear polyglas stocker.
Pretty surprising though, to have both wear out so early and at the same rate.
Has anyone else had an early failure like this?

 

[68sportsatelliteragtop]

Is it possible your front strut rods are pulling the LCA too far forward and creating a bind on the pivot and bushing? If you are running adjustable struts you may have to readjust to allow the pivot and bushing to work smoothly.

 

[snakeoil24]

Is it possible your front strut rods are pulling the LCA too far forward and creating a bind on the pivot and bushing? If you are running adjustable struts you may have to readjust to allow the pivot and bushing to work smoothly.

68 sport is right on that will do it every time.

 

[Kern Dog]

I can see how that could be a problem, but for that to be the case, my Caster #s would have been Waaaaay extreme!
After seeing the wear, I pulled the entire front end apart. I replaced the upper control arm bushings with the Moog offset units. The LCA bushings were replaced. I even replaced the K member! Last year I modified a spare 1970 B body K member by welding all the seams and adding gussets to the steering box mount. I make a skid plate type deflector for oil pan protection then painted it 3 coats of basecoat black followed by 2 coats of clear.
I told the alignment guy the specs I wanted and he was able to get them: .5 degrees NEG camber, 4 degrees POS caster and 1/8" toe in. It tracks straight and feels spot on.
Looking back, I may have an idea of how my bushings prematurely failed. I may have tightened the LCA pivot bolt nut with the LCA at full droop. I thought I recall hearing that it is supposed to be tightened at the ride height. The belief is that if it is tightened at droop, the bushing distorts instantly as it is lowered down to ride height. This puts a pre-set twist in the bushing material UNLESS it is a poly bushing which rides in a thin bath of lubricant. If the rubber begins in a twisted state, it would probably result in early failure.

 

[benno440]

align it yourself mate I don't trust shops to do my alignments anymore especially with our old cars, SPC make a nice alignment tool, then you can make your own castor turn plates.
should also run poly bushes all round instead of mixing it up. also the 275 would be making huge difference but it would look pretty cool haha.

 

[Mike Z]

Probobly killed them when lower the car after tightening them
Also when adjusting the torsion bar ft. ride hight the LCA should be loosened up when adjusting and tightened once hight is set.
I have seen that kill em too when adjusted when tight.
Mike Z.

 

[67 coronet]

could be that you tightened the lowers before ride hight,but could still be strut rod pulling too hard.caster is a relative # between top and botom arms.if you over tighten an adjustable strut rod then compensate by over adjusting the uppers,your #s would be ok,but the lower bushing would still be crooked.just some food for thought.

 

[RustyRatRod]

Yeah, that'll do it. You gotta torque all the suspension bolts with the weight on the car. PITA as it is.

 

[Kern Dog]

I guess with 10-11 years of sporadic use, I shouldn't complain much. If the front end needs another rebuild in 2023, so be it.
I have been driving the car more in the past few years. When I first built the car, I made some mistakes in terms of driveability. Over the past few years I have been trying to make it more streetable. These cars are no fun if they ride like a brick and cannot clear a Mcdonalds cheeseburger, so I raised the ride height. Road noise wears me out so I added sound deadener. Knocking and pinging isn't any fun so I am trying to come up with a combination of parts and tuning to make it a better driver.
These cars were meant to drive, after all.