Ok so before I get blasted I have read at least 4 or 5 threads on NAM regarding cupping of the rear tires. My situation might be slightly different so here goes:

-Bought the car with 80K.
-Replaced Control Arm bushings on both rear sides (one was bad but replaced the pair).
-Replaced stock struts with KYB struts since they were wearing and we were back there.
-Performed 4 wheel alignment.
-Previous owner replaced the back tires with Accelera tires just prior to me buying. (these are not good tires)
-Fronts are potenzas (15% tread life left)
-MCS seems to be getting more road noise, especially in the back.
-I have about 100K on the car now.

ok with all the facts out of the way here is what happened today. I was rotating the tires for the first time, after reading some forums I guess I should do that more often. These are directional tires so LR to LF and RR to RF etc.

My right rear tire which has 85% tread remaining has terrible cupping on the inside of the tire, measuring from trough to trough I would estimate 6 inches and this continues around the tire. After moving the tire to the front and visa versa I let the car down from the jack. There was a significant groaning coming from what I would guess to be the spring in the back as the load was increasing.

The left rear was fine and not noticeably cupped. The left rear did not groan as I dropped it from the jack. As a side note the left rear did take almost an hour to remove as the wheel was rusted to the housing.

I have seen some input from folks to place RFT back on as they are better suited for the MCS suspension, I wonder if the non-stock KYB struts take that out of play though. What do you guys think the groaning was?

Now the MCS has a large vibration when slowing down from about 35 down to 20 mph. This is no doubt the POS Accelera's with the front right cupping but anyway, if I replaced the tires I want to make sure that 15-20K miles later I am not right back in this boat because some suspension piece needs to be replaced as well.

Any thoughts on the best course of action?

 

Cupping is usually due to a worn (or bent) suspension part, or a wheel/tire badly out of balance. Given the cupping, the wheel/tire is probably out of balance by now, even if it wasn't before.

Worn shocks are a usual suspect in cupping, but you said that yours are relatively new. Worn shocks may also make a clunk or groan noise when turning onto a sloped driveway entry from the street. The groan might also come from components making contact when the chassis is twisted a bit, as when raising or lowering a corner or entering a driveway. In short, the groan *may* be indicative of a problem.

 

That groan is what I am concerned about. It made a very consistent groan as the jack let the car down. I don't hear it any other time. I guess my question is do the springs in the back (now I am questioning if there are springs in the back) commonly fail and need to be replaced?

Again my concern is replacing the tires with something decent and then doing this all over again because some suspension component is no good.

I replaced the rear struts about 20k ago, what else could make that sound back there?

 

Once the tire starts bouncing, it always will. In other words, the tire was ruined before you did any work. New tires should fix things. Groan is probably lack of grease in the bushings or somewhere else. You can lubricate what you see, but springs should be fine. Get rid of the crap tires.

 

so if I read your post correctly you think the cupping began prior to my CA bushings and strut/4wheel alignment? Sounds logical.

What do you use to lubricate the suspension parts?

 

Was the Pas. side the one with the bad bushings?
If it was I would start by checking to see if something is wrong with the control arm.

Just a thought.

 

hmm, that is an interesting thought. I am pretty sure it was the same side (pass side) and in fact the seller was adamant that I take the car in for an alignment right away because of that side. Dealership said CA-Bushings and I used their service quote to order my parts but not surprised that they missed something.

I have an appointment with a shop I have been recommended who has agreed to put it up on the rack before doing my alignment to let me know if I need to get parts on order like an entire control arm or something else.

Will let you guys know.

 

Did you check to see if the Mini had been in an accident; maybe the repair was not done correctly .........................

 

I wouldn't worry about the noises coming off the lift. There are weird side loads that are unnatural as you let the car down off a jack. I have heard the jack pad itself make noise as the angle changes when lowered. A rear sway bar may have dried up or something that you can grease, but if it is not making noise during normal driving, I would ignore it.