Here’s a problem, … anyone?

Driving along I have thud-thud-thud-thud- thud-thud-thud-thud sound and vibration going on. I feel it more then I actually hear it, but it is audible. It increases in speed as the car increases with speed. The longer I dive, it seems to get more obvious. I can ‘feel’ it slightly in the steering wheel and in the seat of the pants. This happens most noticeable from 70mph and higher, but I can feel it as low as 30mph. It dose not change if I hold down the clutch and coast. When I brake, the peddle pulses and the steering wheel vibrates to the exact beat of the thud-thud-thud-thud- thud-thud-thud-thud that I have been hearing and feeling.

Sound obvious? I think so, but I’d like to hear all opinions that may help enlighten me to the possible “not so obvious”.

Read my ** Click Here for info on My MCS ** to see what mods I have as the story seems to start there.

I just hope that this problem will have a happy ending.

Thanks

 

Sounds like an out-of-balance wheel/tire. I hope that's all it is... easy to fix!

:smile:

If you are running aftermarket wheels, you could also be having an issue with centering the wheels on the hubs. Hubcentric rings should take care of that; also a cheap fix.

I know both of those are not exactly secrets, but it's all I could come up with at this hour.

 

Thanks for the reply,
I do have Hubcentric rings installed. I also removed all the wheels, had them all rebalanced and rotated the fronts to the backs and visa-versa.

I've been running these wheels and tires for a while and they have been flawless. This noise/vibration came with later mods.

 

Since you already covered the cheap and easy fixes.....hm.

Your MINI hasn't been executing any manouvers that could flat-spot the tires, has it?

The only other tire-related issue that comes to mind as a possibility is an internal defect in the the belts of one or more of one of the tires. Belts sometimes separate due to manufacturing defects, and/or road hazards, such as potholes...

A tire with such an internal defect can be balanced properly when bolted to balancing equipment, but still vibrate when run on the car. This is because the balancer cannot reproduce the distortion of the tire's structure that is produced by the load of the weight of the car. when the problem area gets "smooshed" as it rolls into and out of the contact patch position, any significant anomaly in the sidewall's flexibilty, or the separation of a belt seam across the tread face, may be felt through the usual driver feedback channels (pedals, steering wheel, seat.)

I had such a tire on one of my cars once. I only got onfiration that this was indeed the problem after the set wore enough that my cheap self was willing to replace them. The only outward indication of the problem area was a larger-than-usual amount of lead clamped to the wheel on the side opposite the defect.

With heavy tires, such as those used on light trucks, it is also common practice when mounting them to sometimes break a tire back off the bead and rotate it relative to the wheel, in order to prevent having to use excessive amounts of lead to balance things out. The idea is to move things around until any existing "heavy" spots in the wheel and the tire are diametrically opposite one another, such that the imbalace forces they produce cancel each other out as much as possible.

Good luck tracking down and eliminating your thump!

 

Is this tire problem something that can develop over a short period of time? I've been using these tires with no problems, and then it seems that one day this problem came about.

Also, I did rotate the tires and I still have the vibration and pulsing in the brake peddle and steering wheel when braking. I did think about 'flat spots' and that's why I rotated.

Just want to clarify that the 'thump-thump-thump' is not as pronounced as I may have made it sound. When it first came about, the passenger had a hard time feeling what I was feeling, but now he can feel and hear it also.

 

I see you have an AM brake set-up. How long after this front stuff was put on, did the pulsation and vibration begin? Could be an out-of-balance rotor?

what about the powerflex bushes? could a bolt be loose somewhere there?

GL. keep us updated on the prob

 

You might have a bad wheel bearing. I had similiar sounds on mine after 123k miles. Replace one front wheel bearing.

 

to find the problem trace back thru your mods. You have elimnated the tires (rebalanced) so focus in on your suspension mods.

 

I would guess bad wheel bearing, or you got a flat spot on your tire.
what tire pressure do you use?


The SP9000DSST's have a problem memorizing the flat spot more than any set of tires ive used. SP8000, Paradas, ES, Pilots, Potenzas, Avids, etc. etc.
I hate those tires just for that noise.

 

Any update?

 

Since the tires have been rotated with no change in brake/steering,tires are ok. Try this, front end on jackstands, wheels removed, start car, go for a slow 1st gear drive.(be nice to your cv-joints they are at fairly sharp angle) Get out & take a look at the spinning rotors. i thing polmear is on the right track. I doubt if the wheel bearing will give steering, braking & thumping feedback.

 

Where do you have the bushings installed?

I would borrow a set of wheels and tires. Change them all to see if it goes away, then swap them back one by one. My guess is you have a tire that has a cord separating or some other defect.

Other area to look at would be the rotors, have they been overheated at anypoint, track stuff?

 

polmear and namwob have it right. I'm surprised that more did not come up with this conclusion. It was my diagnoses also, but I wanted to hear if I might be missing something.

namwob, I did this exact thing and then took them to a machine shop to which they concluded that the rotors were the problem.

 

dingdingdingdingdingdingdingdingding!!!

 

Wohoo........... I mean glad to hear its fixed. Thanks for letting us know what fixed it, many times people don't follow up on the fix, which is frustrating for everyone following a thread. If you said it went "bloop bloop bloop....... thats tires

 

honestly, I didn't read your entire post.

 

Just a follow up here. Problem is still not found.

 

I've experienced similar sounds with my mom's mini which sits for long periods between drives. The run flats take a "flat" spot that dissapates after the tires warms up. But I know this is not your problem.

I'll have to think about this...

 

Randy Webb is heading out next weekend and will check it out with me. We have some ideas, but it is perplexing. Hopefully a new set of track wheels and tires will be here so we can eliminate that my current wheels and tires as the problem or not.

The biggest problem is that the problems are not consistent. All issues lead to the brakes.

I want to be a bit careful here as I don't want to implicate any person/company until I am absolutely sure. All I can say is that some manufacturers out there could sure use a lesson from the wonderful Built-By-Bones guys who did my rollbar. Lack of customer support is a huge issue with me, especially when a good amount of money has been spent.

 

I still say rotors. Did the machine shop machine them or jurt say that was what was causing it?

 

sounds rotor-ish to me OR a brake pad problem (needs a shim or one removed)or the retaining spring might be streched (loose)
wheel bearing issues tend to be decidedly on one side and get louder like a CV joint when loaded.

still think you have a bum rotor (bad warp maybe)

 

I have the same problem!


Had tires rotated and rebalances, still same noise. Taking to MOP soon as possible.

 

Things I'd check

- bent wheel
- flatspotted tire
- wheel out of balance
- bad CV joint

It shouldn't have anything to do with the brakes.

 

So, how long has it been?

Problem was finally solved and it was by chance that it was. In replacing my blown out front and rear struts and replacing them with the new PSS9s, the problem of front wheel shimmy and pedal pulsing under braking is completely gone. It would not have occurred to me that bad struts could cause these problems.

As soon as I installed the PSS9s, the problem disappeared, but I wanted to wait till I tracked the car. After a day on the track and having my TCE Wilwoods work great throughout the day, I feel comfortable saying that the struts were in fact the issue.

Thanks to TCE for their patience and willingness to spend time with me during these problems.

 

LOL> I'm laughing as I read the thread from the top down thinking 'man this sounds familiar...wonder if he has the same strut problem that someone else had?'. Guess that would be a yes. One in the same matter of fact.

We ran into similar strut problems on the SHO years ago when Koni made inserts for the stock parts. The issues were both shaft bottoming at times due to poor or removed bump rubbers (keep them installed) and from improper cut stock housings which allowed the insert to rattle inside the housing. Not bad at first...but over time...thunka-thunka-thunka.