E9X Help diagnosing terrible front end vibration

langsbr

Captain
Apr 5, 2017
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Need some help with a front end vibration. Car was perfectly fine, no issues - smooth, all the way to 130+.

Got some new front tires (cheapo Achilles) and then had a terrible front end vibration - so bad you felt like the dash was gonna shake off. Had the tires indexed, and it improved slightly - was only bad at 80+ instead of awful at 50+. I pretty much didn't drive the car with these tires on it - maybe 100 miles total. It was just no fun.

Decided to get some better tires - Got Michelin Pilot Super Sports. Car STILL has a vibration above 80. Better than it was, but still not something you'd want to drive fast at all.

The vibration occurs at speed - in gear, out of gear, clutch in, clutch out, coasting, or wtih brake applied. Clears up below 60mph now.

Guibo looks fine. Haven't had it algined, but it tracks perfectly straight.

Never hit anything that I know of - I barely even drive the car - ~4000 miles a year.

I'm at a loss and don't want to just start swapping parts randomly, but diaging this seems very difficult.
 

Rcboosted2007

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Jan 28, 2018
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Hey, by any chance did your wheel lose a balancing weight?or perhaps the balancing process didnt go too well. Next i would look into the the brakes/rotors.
 

langsbr

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Apr 5, 2017
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I had the Achilles tires balanced by my buddy on his chickety China balancer so that was indeed my first thought. I took them to a shop with a hunter road force balancer and had them indexed. They were at 40lbs of road force before indexing and 12 after, so better but still not very good. Don't that helped a bit, but it just tried the speed where the vibration became unbearable.

The new michelins balanced very well with under 7lbs of road force.

I have an appointment racing bbk, and my only real option is to swap back the stock brakes which is like to avoid right now. The issue is present only at speeds over 60. Below that is fine, under Accel, cruise, or braking. The vibration occurs under each condition as well, so I figured less odds for a braking part issue.

The car does have 140k, so I'm thinking it could use new thrust arms anyways, so that will be my likely next step.

I'm tempted to get an alignment first, just to see if that can help. If I can find a coupon for Firestone's lifetime, I'll do that and then do thrust arms if it doesn't improve with the alignment alone.

I'm just stumped as to how it basically went from perfect to awful overnight.
 

fmorelli

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Aug 11, 2017
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The more experiences I get, the more ardent I become about having people touch my stuff that are great at what they do. I don't even have cheap places do oil changes any more. There is just too much to screw up. My alignment guy runs about $250 and takes his time to do it right. When it is done, it's right. It's not just the equipment but the technician. I've just gotten burned too many times :-(.

Back to helping out (the above comment was more an encouragement to go with talent), given your tire change and balance equipment change - this could be a double whammy: that is, suspension was getting tired but working, shit tires and balance beat the hell out of suspension, better tires and balance diminished their contribution, but at that point something got pretty spanked by the experience.

BTW us old guys call them "thrust" arms, but the newer suspensions use a tension strut. The difference is the thrust arm comes from behind the spindle (ala most BMWs prior to E90 time frame) whereas the tension strut mounts forward of the spindle. BTW I think @[email protected] is doing sealed BMW OE monoball versions of that tension strut. They are about to go on my Z4, he's got them on the 335i mule ... no idea where he is on having them available.

Good luck. This kind of stuff is annoying!

Filippo
 

langsbr

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Apr 5, 2017
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I think Turner and ECS offer a monoball version of the M3 tension struts but they are very proud of it. It's hard for me to justify them at double the cost of regular M3s.

I'm hoping you're right on the combination of wear, plus poor tires just making it worse. I know at 140K I'm due for a lot of suspension components and I have that planned, I just can't bring myself to be a typical consumer that replaces a bunch of parts with an expectation of an improvement without context. Nothing is more irritating than having someone bring a car in and say they want new shocks for example. The shop replaces the shocks (let's say they were worn and needed anyways). The customer gets the car back and then complains about an issue still being present. But they didn't bring it to the shop and say "I have an issue, please diag it", they did their own 'diagnosing' and figured that's what it needed. I also hate just parts swapping to try and find the root cause of an issue. My IT background also won't let me change more than one thing at a time so I have a single variable and can pinpoint the issue. Such fun!
 
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[email protected]

Corporal
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Jun 4, 2018
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Need some help with a front end vibration. Car was perfectly fine, no issues - smooth, all the way to 130+.

Got some new front tires (cheapo Achilles) and then had a terrible front end vibration - so bad you felt like the dash was gonna shake off. Had the tires indexed, and it improved slightly - was only bad at 80+ instead of awful at 50+. I pretty much didn't drive the car with these tires on it - maybe 100 miles total. It was just no fun.

Decided to get some better tires - Got Michelin Pilot Super Sports. Car STILL has a vibration above 80. Better than it was, but still not something you'd want to drive fast at all.

The vibration occurs at speed - in gear, out of gear, clutch in, clutch out, coasting, or wtih brake applied. Clears up below 60mph now.

Guibo looks fine. Haven't had it algined, but it tracks perfectly straight.

Never hit anything that I know of - I barely even drive the car - ~4000 miles a year.

I'm at a loss and don't want to just start swapping parts randomly, but diaging this seems very difficult.

Saw this last night and was thinking about it. Lets narrow this down...

Car was perfectly fine, no shake then replaced with Achilles tires, and immediate shake? I ask because if it started shaking 50 to 100 miles AFTER the achilles tires maybe it could be coincidentally something else, like engine mounts (unlikely) or something. But if it happened literally right after the Achilles tires I'd say the massive shake then destroyed something else in the process which is why new tires still shake. Basically what @fmorelli was getting at.

What control arm bushings do you have for the tension arm and lateral arm? Aftermarket or OEM shocks and how many miles? What top shock mount as well? Just curious if a blown shock all of a sudden.
 

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Corporal
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I think Turner and ECS offer a monoball version of the M3 tension struts but they are very proud of it. It's hard for me to justify them at double the cost of regular M3s.

I'm hoping you're right on the combination of wear, plus poor tires just making it worse. I know at 140K I'm due for a lot of suspension components and I have that planned, I just can't bring myself to be a typical consumer that replaces a bunch of parts with an expectation of an improvement without context. Nothing is more irritating than having someone bring a car in and say they want new shocks for example. The shop replaces the shocks (let's say they were worn and needed anyways). The customer gets the car back and then complains about an issue still being present. But they didn't bring it to the shop and say "I have an issue, please diag it", they did their own 'diagnosing' and figured that's what it needed. I also hate just parts swapping to try and find the root cause of an issue. My IT background also won't let me change more than one thing at a time so I have a single variable and can pinpoint the issue. Such fun!


Know exactly what you mean... I took my truck in to have a coolant leak fixed. They claimed to have fixed it because of a leaky thermostat. Brought it back home and next day woke up to dripping coolant leak the exact same as before I took it in, grrrr.
 

langsbr

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Apr 5, 2017
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Saw this last night and was thinking about it. Lets narrow this down...

Car was perfectly fine, no shake then replaced with Achilles tires, and immediate shake? I ask because if it started shaking 50 to 100 miles AFTER the achilles tires maybe it could be coincidentally something else, like engine mounts (unlikely) or something. But if it happened literally right after the Achilles tires I'd say the massive shake then destroyed something else in the process which is why new tires still shake. Basically what @fmorelli was getting at.

What control arm bushings do you have for the tension arm and lateral arm? Aftermarket or OEM shocks and how many miles? What top shock mount as well? Just curious if a blown shock all of a sudden.

Yes, it was immediately after the achilles tires were installed. This is a pleasure car only, and I barely put 5000 miles a year on it. I should say - my old tires had some very strange wear on them, which I've never seen when not under inflated. There were cords showing on the inside and outside edge, but the center was fine. The car drove beautifully though, tracked straight, was smooth as glass.

I figured, cheapo tires are fine since I don't put many miles on it, and don't track it - why spend a ton? Right after installing the Achilles - the drive home from the shop with the china balancer - terrible vibration. So bad I just didn't drive the car, except maybe 20 miles total. I then got the road force balance done, and it moved the speed up where the vibration occured, but was still present. I pretty much parked the car and maybe only put another 30 miles total on it and never over 50mph.

Finally bought the Michelin PSS and vibration is still there.

I am still running stock suspension - pretty much everything due for replacement at 140K. New shocks are on my list as well very soon. There is a drag event coming up in a couple weeks and I was hoping to have the vibration resolved instead of having to throw a bunch of money at it immediately and still not be guaranteed a solution. :(

Would you think starting with tension struts (which I understand wear faster than the rest) would be ok, or would i be risking damaging them with old shocks?
 

NoQuarter

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Nov 24, 2017
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Brian - you said the shaking happens without brakes and when braking. But... Does it change when braking? What is going on with the steering wheel when this is happening? Does the wheel shake when braking? Does it shake when not braking?
 

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Corporal
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There is a chance you "finished off" the 140k mile original shocks with the shake. A quick diagnose would be to pop the front wheels off and check to see if you see any oil residue down the side of the shock indicating its blown. You would want to look right where the piston shaft enters the body (IE top of the shock housing right near the bottom of the spring). The stock shock is a twin tube low gas pressure shock. Even if it were "blown" it would be hard to feel. It would literally have to have lost almost all of the oil for you to feel a major difference. Unlikely your problem.

My bet is on a bad bushing or ball joint.

Another thing to do is jack up the car (put on jack stand of course) and grab the wheel and try to move it around. Tug on it pretty hard and see if it moves easily. Try the following scenarios...

Try to pull the whole wheel towards the front or rear of the car. This will help check the tension arm bushing or ball joint.

Put one side of the car on the ground and the other in the air, this will allow the opposite tire to hold the steering rack from moving. Then try to grab the wheel that's in the air at "9 o'clock" and "3 o'clock". Push on one side and pull on the other. This will help diagnose a tie rod ball joint.

Grab the wheel at "12 o'clock" and "6 o'clock" and push on one and pull on the other. This will help diagnose the lateral control arm bushing or ball joint.


Hope this helps!
Barry
 

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Corporal
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Sorry, didn't answer all your questions...

If you were to replace the tension arms and retained the old shocks you would not wear them out any quicker really. Tension arms are loaded the most from braking.
 

langsbr

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Apr 5, 2017
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Brian - you said the shaking happens without brakes and when braking. But... Does it change when braking? What is going on with the steering wheel when this is happening? Does the wheel shake when braking? Does it shake when not braking?

The shaking isn't really coming thru the steering wheel except as a byproduct of the entire front end vibrating. There's no 'warped rotor' wheel shake, and once the speed is reduced to below 60, all vibrations cease, regardless of braking, coasting, or accel.

I drove the car yesterday after getting the new tires on, and it was the first I've driven it in the dark, and even the headlights vibrate - it's amazingly irritating. The whole front end - dash - everything just shakes.
 

langsbr

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Apr 5, 2017
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Another thing to do is jack up the car (put on jack stand of course) and grab the wheel and try to move it around. Tug on it pretty hard and see if it moves easily. Try the following scenarios...

Try to pull the whole wheel towards the front or rear of the car. This will help check the tension arm bushing or ball joint.

Put one side of the car on the ground and the other in the air, this will allow the opposite tire to hold the steering rack from moving. Then try to grab the wheel that's in the air at "9 o'clock" and "3 o'clock". Push on one side and pull on the other. This will help diagnose a tie rod ball joint.

Grab the wheel at "12 o'clock" and "6 o'clock" and push on one and pull on the other. This will help diagnose the lateral control arm bushing or ball joint.

We did all of this on the lift at my buddy's shop - everything appeared tight. The only thing we noticed - with the car on the ground, turning the wheel full lock you can hear a click or pop sound. Both directions, but only once its at full lock. No loose bolts, all bushings looked ok visually, no abnormal play.
 

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Corporal
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Jun 4, 2018
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hmmm...

Turning all the way one way or the other tweaks the ARB linkages. They seem OK? I've seen ARB linkages cause vibrations.

Maybe a shock is toast then. It may just have zero damping at small displacements causing the spring to never recover from oscilating. Still seems unlikely since its a twin tube damper.

My gut still says bushing and likely the front tension arm bushing.
 

langsbr

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Apr 5, 2017
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To give an update on this, I've done the following:

New shocks and struts
M3 upper and lower control arms
new guibo/flex disc

The vibration STILL exists. I believe that it's not a front end vibration, but rather a driveline vibration. I see the passenger seat vibrate tremendously. I guess I thought it was a front end vibration as it comes thru the steering wheel as well, and at night you can see the headlights vibrate.

I've also been trying to quantify when/how it is most present. It is fairly non-existent below 75mph. Over 75, and if accelerating heavy it is much worse. It's slightly present at cruising speeds of 80 or higher, and seems to clear up a bit over 120. It's more pronounced on acceleration and decel. On steady state cruise or with very very light accel, it's not as bad.

The only other 2 things I can possibly think of is the center support bearing (has no play or slop by inspection though) or possibly rear axles. My friend is leaning towards axles, but I'm just tired of playing parts swap monkey.

It's quite frustrating that this can't be properly diagnosed, or I can't find a shop that knows how. Everyone just drives it, then says "oh it's probably this". Thanks, but I am not interested in letting them experiment and then say, we'll try this next. Granted, so far, everything I've replaced has been in need of replacement - the shocks and struts were completely blown at 140K miles, and the M3 arms/bushing did give a nice improvement in handling, even if mild. The guibo was a waste, as mine was in great condition, but it was only $60.

I am hesitant to replace the axles with stock ones, as new axles are fairly pricey, and if I'm going to do the work, I'll just go full M3 LSD setup.

Anyone have any other suggestions (I prefer diagnosis methods to simply trying different parts) before I do the M3 LSD/axles/driveshaft? If I swap to the M3 stuff and the vibration is still there, I'm gonna push this thing off a cliff.

I guess I should be happy I haven't experienced the myriad of typical N54 issues. Even with the vibration, I took the car to the track back in March and it took a beating. At least 20 back to back 1/4 mile passes, and roll races and the car never missed a beat. Drove it an hour and a half there, raced, and drove back. No misfires, no issues - ran 128 in the 1/4 (can't hook so stuck with 12.0s lol) but DAMN that vibration.
 

fmorelli

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Do you have a spare set of wheels and tires? Or a friend you can do a swap? Typically with wheel/tire presentss at a slightly lower MPH (50-70, for instance), but would be nice to rule that out.

Filippo
 
Last edited:

birrcrin

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Jul 26, 2018
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Have you tried replacing the front wheel bearings? Easy job and not very expensive. I was getting a lot of front end vibration and shaking past 140. Replaced the front wheel bearings and shaking is gone. Car has 125k miles.
 
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langsbr

Captain
Apr 5, 2017
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07 335i 6MT e90
Do you have a spare set of wheels and tires? Or a friend you can do a swap? Typically with wheel/tire presentss at a slightly lower MPH (50-70, for instance), but would be nice to rule that out.

Filippo
Sadly I don't know anyone in my area with a BMW or a spare set of wheels. It's all ls based or fox body stuff here.

There was a guy selling a set of stock e90 wheels about and hour and a half away that I was tempted to buy, I just hate buying them for potentially no gain.
 

fmorelli

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Used aluminum wheels, almost by default, are never straight. It's the nature of the wheels. A good shop can tell you if the wheel is bent. In my younger years at the shop, I would spin the wheels on the balancer and hold a tool on the inner lip, then outer lip (top of wheel when facing the wheel from its side - imagine the wheel as it hit a pothole and pushed the wheel inward toward the center). Then I would check the lip face spinning the wheel with a hard tool on the lip face, looking for "center bent" wheel, that is that the wheel is bent from the hub to outer rim (versus just the outer rim being bent).

Who is doing your wheel balancing? The other possible suspect issue is a bad tire. Sorry not trying to pile on ... but hope something I said is helpful.

Filippo
 

langsbr

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Apr 5, 2017
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For the wheels, I have Apex EC7s with 18x9.5 rear and 18x8.5 in the front. The rear tires are fairly decent tread Federal 595 RS-RRs, I've had them installed well before the issue began. The fronts were running 235/40/18 MPSS. They were worn and I bought some cheap Achilles. I thought that was the issue, so I chucked them and bought new MPSS. I had them installed by a local shop that has a Hunter road force balancer and I even had them indexed. The Achilles were indexed and were still in the 19lb road force range. The Michelins came in under 6. I'm using only stick on inside wheel weights as well.

There was no runout when the wheels were checked on the hunter machine, but I guess they could still be slightly bent?