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Discussion Starter · #1 ·
Hello All,

I have 05 e46 330xi with 83,000 miles on it. I get a knocking noise underneath the car, when i brake 30-40 miles/H. I took it to a independant mechanic and after analaysis, they seem to hear it from the front drive shaft, and would like to replace it. Also they suspect the center flange in the housing the shaft connects to as they a play around that sections as well.
Any ideas or suggestions is appreciated. I am still not sure if that could be the problem. Estimate to replace drive shaft is $1200 :( Thanks in advance.
 

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Have you checked the front lower control arm ball joints? If they are worn out, putting the brakes on will cause them to move around and make noise. Fairly easy to check the ball joints; Jack each side up one at a time, with the tire 1 to 2 inches off the ground, using a longer screw driver or some lever, pry up on the wheel/tire and feel and look for excessive ply/movement and or the noise. At the same time you can take the tire/wheel at 3 and 9 o'clock and move side to side to check for worn tie rod ends. The outer lower control arm ball joints seem to wear out quicker than the inner ball joints. You will also wan to jack the car up higher then, support with jack stands (NEVER WORK UNDER A CAR SUPPORTED BY A JACK ALONE, ALWAYS USE JACK STANDS) and check to see if the rubber in the lower control arm bushings is cracked/torn/broken. $1200 for a new front axle is way too high!! At 83k miles, unless the boots are cracked, the axle should still be good (have an 03 e46 325 with 100k an the original front axles, no cracked boots and no issues with the axles).
 

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Discussion Starter · #4 ·
Guys,

Firstly - Appreciate your responses. I am not a big DIY guy, as I don't have a place to work. I really love my E46 and would like to keep it longer. Let me checkout your suggestions in another place. Knocking happens between 30~40 miles/h and not all the time. Its a metal on metal hitting sound that comes from underneath and it appears like it comes from front side.

Thanks
 

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Discussion Starter · #6 ·
Guys, I dropped it off at the dealership yesterday for a second opinion. Sadly they could not reproduce this noise while braking, but they checked front drive shat area and they think its ok. Also they found some groove in the front brake rotor area which they think could possibly contribute to the noise. Also i brought to their attention that i get a clunk when i go from Park to Drive and then to reverse, that they think could be transfer case not sure yet ,if its wearing due to age of the car :(. I am going today to pick up car today. Nexts steps go back to German auto shop.

Cool Breeze - Drive shaft replacement was recommended by German auto specialist shop, but dealer thinks its not drive shaft but coming from brake assembly.

Will keep posted - thx guys.
 

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So it's a repeating knock like something under rotation where the sound varies with speed? You are rolling along at 30+, apply the brake and cyclic, bop, bop, bop sound occurs? Metal to metal has a distinctive, metallic chirp to it not a dull thud. Sounds in the chirp or click range can be brake related. A thump or pad bucking would be felt in the pedal if your brake was grabbing or something. I'm thinking brakes can be ruled out as they tend to be fussy at all speeds when there's a problem.

The issue may be when the body suspension loads from the squatting affect (when braking). Some rotating mass goes out of balance setting off the sound. That would be consistent with worn axles, transmission or transfer case mounts or other drive-train components allowed to flex. Basically, all the heavy, spinning things that could run off-center. It is tricky identifying the culprit when they can't duplicate it on the lift.

Try driving in an enclosed garage structure with your windows down. Take slow, tight turns applying brakes on and off. You'll hear sounds reflecting from your car you may not hear outside. Listen for clicks and pops. Sometimes, having an assistant walk the corners outside of the car can spot a trouble zone. Any more info. you can provide may help the shop.
 

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Discussion Starter · #8 ·
White Knuckles - I think you are right on. Yes its a repeating knock and its mostly happening at 30~40 miles as far i have heard it. To me from your note looks like body suspension loads from squatting effect.
German shop thinks front drive shat is gone bad and may be some issue with transfer case as well. I took it to the dealer and they could not reproduce the noise. I have another appt on tomorrow where i am going to drive around with the foreman to see if can duplicate it. Transfer case and Drive shat [ Quote $1200 and Transfer case is $1400]could be a big bill, I hope its something else.

Thanks -
 

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Remember, mounts for the trans, or transfer case can fail. A loose or broken mount can cause flex and scary sounds. This hopefully is simple (at your mileage) but the car needs proper inspection to be sure. Always good to get a second opinion with questionable estimates. Those are blue-sky quotes at best.

Don't jump at a work-order sign-off without a clear agreement that the problem has been absolutely identified and the parts/labor/warranty is a fixed amount. As in - "not to exceed" the agreed, written amount without customer approval. In my state, a "not to exceed" written agreement is a contract. I request them to write it on the work order, sign and date it. Sometimes they have to ask the boss, but most agree to it. The guarantees you unforeseen charges will not creep in. They still could call you with the "we found something else" story but your contract prevents them from adding anything without approval.
 

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Discussion Starter · #10 ·
Dealer could not reproduce the problem and I drove around with a foreman too. It still keeps happening and also found out that I have a bad water pump too, I was like that's great its all starting to add up now. Taking it to Independant mechanic next week to take the transfer case and Drive shaft out to see if there are any issues, this is only investigation and no replacement.
 

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Dealer could not reproduce the problem and I drove around with a foreman too. It still keeps happening and also found out that I have a bad water pump too, I was like that's great its all starting to add up now. Taking it to Independant mechanic next week to take the transfer case and Drive shaft out to see if there are any issues, this is only investigation and no replacement.
Why are you taking all these things out? If you have a knocking noise that comes under braking, it's nothing to do with the transfer case. If it was, believe me, you'd know it. Taking the drive shaft out is expensive and not worth it unless you are sure that's the issue.

Are you experiencing vibration under acceleration? If no, then your axles are probably fine. Also turn wheen to full lock in one direction and drive slowly with windown down. Listen for clicking noises. If no noises, axle is good.

My bet is still on the front control arm bushings.

83k miles is about time for a new water pump, expansion tank, and thermostat. DIY this and it'll be much cheaper. I highly recommend investing in a basic set of metric sockets and ratchets and having at it. It's really not as hard as it may seem to be.
 

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I also think its a FCAB or brake related issue. I thought I had bad FCABs because I had clunks/bumps and darting while braking. It turned out to be a combination of bad sway bar end links and a warped/damaged driver's side front rotor. After I replaced the end links, the clunks went a way. Replacing the rotor made the darting and shuddering steering wheel go away.

The transfer case and diff's will make a slight click/clunk when you turn a wheel/tire by hand with the car jacked up off the ground. If its a loud clunk or there is a lot of play in the drivetrain, THEN I would start looking at TC or front diff. Otherwise, a slight click/clunk and less than 1" of play is normal. Start by changing all fluids if you have concerns after checking for free play and noises in the drivetrain.
 

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So you are paying a shop to remove the TC and the drive shaft? For what? I don't see how a TC or a solid shaft would make a loud clunk. This is stupidity. the shop should be ashamed.
Sounds like a lack of maintenance to me. Start by replacing the front bushings and the sway bar links. The "groove" in the rotor could be a possibility for the clunk.
Why not start with the small and obvious things?
 

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Discussion Starter · #14 ·
Samdoe1,Bobby330xi and e36alfonso - Thx for your inputs. I am Not really very technical as you guys are and not a DIY person either as i don't have a place to do it. I trust German shop on these to fix the problem. Dealer is pretty convinced that Drive shat is fine and they replaced my rear diff two years ago when it was under warranty. Independent German tells me that its front Drive shaft and they also see some play in the center flange area in TC. They asked to me bring it in next week just to take DS out to see if there are any issues. Control arms checked ok by dealer. I am definitely going to ask them to check front bushing, Sway bar and check brake rotor before touching anything with DS or TC. Appreciate it guys!! Thanks.
 

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I have some play around that area as well, i think its normal. I dump the clutch at 4k rpm all the time and i have no issues, just saying.
The stock bushings only last two years, you should just replace them. GL
 

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Discussion Starter · #16 ·
Guys,

I got it checked today with a independant mechanic and started with the smaller things all front side suspension parts then Drive shaft and Transfer case as a final step. Unfortunatley all suspension components looks okay and issue seem to come from the flange in the transfer case. Mechanic has asked me to drive around with it and ignore the noise, if not replacement would be a expensive repair, I looked up, just for the part itself could be $2000 plus labor :(. Any thoughts?
 

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Guys,

I got it checked today with a independant mechanic and started with the smaller things all front side suspension parts then Drive shaft and Transfer case as a final step. Unfortunatley all suspension components looks okay and issue seem to come from the flange in the transfer case. Mechanic has asked me to drive around with it and ignore the noise, if not replacement would be a expensive repair, I looked up, just for the part itself could be $2000 plus labor :(. Any thoughts?
If you are 100% positive that it's the TC (FWIW, I'm still not convinced it is), you can get a used TC from a junkyard or a part out for a lot less than $2k.

Also, I don't see how the TC would make a clunking sound when braking from 30-40mph. The gears in the TC are constantly meshed, there's nothing that moves other than in a spinning motion. If there truely was an issue with the TC (ie broken gear tooth or bad bearing), you'd notice it in both acceleration and decelleration not just one. What you have described, and again this is just an internet diagnosis, is classic textbook FCAB failure or front control arm ball joint failure.

I suggest you go back to the mechanic and have him show you what's broken before you pay to have it fixed. If the flange is broken to the point where it's making the noise then it'll be obvious what's going on.

This is where learning to DIY comes in handy. :)
 

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Discussion Starter · #18 ·
I did drive around today and to me it also seem to happen when acclerating as well and not just braking, I didn't mean to create any confusion but it is not really as obvious as it is while braking and its that weird metal in metal chirp. I have to work on my next steps and decide. Thx for your reply - Samdoe1.
 

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It still can be bad axles or FCABs, but it is starting to sound like a TC to me too. The Transfer Case provides the AWD/4WD operation for our cars. If it is starting to fail and has lots of free play, IT WILL make a loud clunk when a load is placed on the TC (accelerating OR decelerating). This is also a common sound that you hear with a worn transmission with the diff inside (FWD cars and '80 and earlier VW's/Porsche's).....Makes for a loud clunk and free play between accelerating and decelerating.

With the car up on on a jack with load off the wheel, you should be able to reproduce the clunk easily by rotating the wheel by hand back and forth. You can also jiggle the axles and flanges up and down to check for play. Have the mechanic show you this first before you decide to replace the TC..... It only takes 5 minutes to demonstrate this to the customer once its on a lift/jack. The important part is being able to rotate the tire by hand to feel and listen for clunks.
 

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Discussion Starter · #20 ·
Bobby 330xi - Thanks for writing. You are correct, its loud especially when you have the load coming from the rear to the front while braking and not too loud while acclerating. The place I got it checked has been lot of experience and has been handling German cars for over 40 yrs, I only hope they are right on with this diagnosis :). All front suspenison parts were checked out today to make sure its not something in the front suspension.
 
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