Front End Shudder - Part II

[admranger]

Originally Posted by Weasel

Could be the front lower control arms... That is the cause of my front end shudder. Check the ball joint at the spindle end of the control arm.

[threadjack] Weasel, I too replaced all of the usual suspects: sway bar links, control arms, tension struts (new, stock arms and bushings) and ball joints, and the tie rod inner and out ends.

Unlike the OP, I don't really have shudder under braking, but rather just driving I have a slight shudder. Ok, so it must be the wheels/tires, right? Bzzzzt, 9lbs out on road force balance. Put on the 2nd set of wheels and I get the same issue.

Checked the strut bearing nuts and the shock nuts. All tight and secure.

It almost feels like the CV joint is iffy, though I just had the outer boot replaced under CPO (slight crack leaked grease on wheels). Could the CV joints or perhaps something else be causing this?

I was beginning to think it was the wheel bearing, but the "grab the tire and jerk back and forth" test only yields a bit of slop in the steering rack (similar to amount in 2002 M3).

I'm kind of stumped here...

FWIW, I haven't done a thing to the brake discs, but they were supposedly ok during the CPO inspection. That's my next thought even though I don't have any pulsation under braking...maybe one threw a balance clip?

[amacman]

cheers weas , I think everything is in good order but of course there will be very slight wear at 62000 miles but not enough to require replacement just now .
things have improved with the tension arm bush / ball joint .
I`ll do the other stuff when I get around to the brake upgrade .

[dpgx5]

Im just throwing a guess either rotors are bad or a caliper is stuck as it heats up when driving. does it happen between 100km to 120?

[admranger]

Originally Posted by dpgx5

Im just throwing a guess either rotors are bad or a caliper is stuck as it heats up when driving. does it happen between 100km to 120?

Happens pretty much as I drive it up to speed on the highway. I hit closer to 130kph at times on the commute. Usually, I'm a bit too busy avoiding people to check the speed that it first occurs (yes, I get passed on my commute...). I'm taking a 450 mile drive tomorrow. I'll try to pay a bit closer attention to the speed.

I am tending towards the front rotors/calipers needing a refresh, but I just hate to do it given the vehicle has the extended maint. plan... I may think different after a long drive tomorrow. Seeing as I have a 2600 mile trip coming up the end of this month, I may just change out the rotors/pads, clean/lube calipers and hope for the best. Hate to have a carpel tunnel due to vibration after 4 days dragging the X5 accross the US.

[Weasel]

If it happens more when on the throttle than cruising it could be the outer axle joints, but it could possibly be a sticking caliper as well... Maybe jack it up and get the front wheels off the ground, then see if one front wheel is noticeably harder to turn by hand than the other one.

[admranger]

Originally Posted by Weasel

If it happens more when on the throttle than cruising it could be the outer axle joints, but it could possibly be a sticking caliper as well... Maybe jack it up and get the front wheels off the ground, then see if one front wheel is noticeably harder to turn by hand than the other one.

I'll do that, but I am pretty sure they both turn freely (I know the LF does as I thought the tire might have a belt slip/flat spot/bent wheel so I turned it last weekend). Vibration feels like it is coming from the LF...

I feel the vibration as I cruise to/from work. I only have 56k miles on the vehicle so the bad CV joint seems remote...

[admranger]

Ok, 1k mile weekend road trip. Averaged 21.3 mpg at less than warp speed, but still moving right along conditions. Vibration felt on steady throttle, acceleration, and sometimes on decel/light braking (just on initial light application of brakes). Gah! Driving me crazy.

I'll put it up on my lift this weekend and check the brakes discs for runout and the calipers for sticking (uneven pad wear). Should be fun as it is supposed to be a cool weekend, only 98 deg F.

[Weasel]

98 degrees is nothing to Vegas, it was 112 when I was there last. It feels MUCH hotter here at 98 then there... 98% humidity vs 8% humidity makes a difference!

If the vibration is felt only under acceleration it likely isn't going to be anything with the brakes. It would have to be in the driveline. It could be a worn center support bearing on the driveshaft, could be the clutch packs in the transfer case acting up, etc.

What frequency does the vibration happen, meaning does it seem to follow wheel speed or is it a slower speed that feels more like the whole vehicle is drunk/wobbly for a second at a time?

[admranger]

Originally Posted by Weasel

98 degrees is nothing to Vegas, it was 112 when I was there last. It feels MUCH hotter here at 98 then there... 98% humidity vs 8% humidity makes a difference!

I was serious when I said 98 deg. F was a cool weekend.

Originally Posted by Weasel

If the vibration is felt only under acceleration it likely isn't going to be anything with the brakes. It would have to be in the driveline. It could be a worn center support bearing on the driveshaft, could be the clutch packs in the transfer case acting up, etc.

What frequency does the vibration happen, meaning does it seem to follow wheel speed or is it a slower speed that feels more like the whole vehicle is drunk/wobbly for a second at a time?

It is wheel speed related and shows up mostly at 45mph on up. 65mph - 75mph it is for sure there. I did have a vibration under deceleration (no brakes, just coasting at about 65 - 45) today. Hadn't really noticed that before. It is clearly felt in the steering wheel, not so much in the butt which keeps me pointed towards the front driveline/suspension, right?

I think I need to closely look at the CPO warranty coverage and make an appointment...

[ncsucarjock]

Admranger -

Just dealt with the same issue. It was actually coming from the rear (new front suspension). Found both lower control arm bushings were toast, the integral links were toast, and there was a bit of play in the drivers side rear axle.

Car is currently in the shop getting all this work (and every other piece of rubber in the rear end replaced). I really believe this will fix the issue.

I agree with Weasel, it's in the driveline somewhere, not the brakes. If you can put it up on a rack and put it under some load while you look for excessive play, that's probably going to be your best bet. Make sure you check those rear bushings - it's really difficult to see - mine were torn in half on the LCA's.