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Discussion Starter · #1 ·
ok its made that sound since i bought the car in February but it wasn't this bad it happens when I accelerate from a stop and when high rpm shifts are made. at first i thought it was the normal m3 diff clunk but eventually it got to the point where when i made high rpm shifts or accelerated fast it felt light someone was hitting the underbody of my car with a hammer ( a big hammer) now im just afraid of driving hard or even gong any higher than S1 on my SMG its been like this for a while and this morning i decided to check if it was the rear diff bushings so i lifted the back end and tried ti see if the diff had any movement and it turns out they are still good there wasn't any movement with the diff also the subframe bushings are good as well and so is the Guibi or whatever u call it the rubber spacer between the driveshaft and the Diff. so i guess my question is:

1. Where else is the sound coming from it feels like mid to rear clunk.

2. Could it be the Driveshaft center support? :dunno:

3. i need to fix this please help :(
 

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ok its made that sound since i bought the car in February but it wasn't this bad it happens when I accelerate from a stop and when high rpm shifts are made. at first i thought it was the normal m3 diff clunk but eventually it got to the point where when i made high rpm shifts or accelerated fast it felt light someone was hitting the underbody of my car with a hammer ( a big hammer) now im just afraid of driving hard or even gong any higher than S1 on my SMG its been like this for a while and this morning i decided to check if it was the rear diff bushings so i lifted the back end and tried ti see if the diff had any movement and it turns out they are still good there wasn't any movement with the diff also the subframe bushings are good as well and so is the Guibi or whatever u call it the rubber spacer between the driveshaft and the Diff. so i guess my question is:

1. Where else is the sound coming from it feels like mid to rear clunk.

2. Could it be the Driveshaft center support? :dunno:

3. i need to fix this please help :(
I get the exact thing on mine under hard acceleration. If I lift my foot off the pedal when it shifts, it doesn't do it.

I had my car looked at in a dealership and they found that the shafts were loose in the diff. Everything else is still very solid. (bushings in front and behind the diff, tower mounts, subframe, etc.) My problem is the diff and shafts. That, at the dealership is a $5000 repair.
 

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I haven't done anything yet. It is in storage for the winter. I will try and find a used diff over the course of winter because $5000 is way too much. Or I might have this one rebuilt. There is a shop that specializes in diff reconstruction not too far from where I live. I will have them look at it before I do anything.

I don't know about your diff, but mine is leaking slightly too.



EDIT: I just noticed where you are from. I bought my car in Scottsdale. North Scottsdale BMW did the inspection and completely missed that.
 

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Discussion Starter · #5 ·
yea here in scottsdale there a chappman bmw thats where i buy my oil and all but im afraid to take it to get it inspected and have it come out with something else that didnt fix the problem and cost me an eye. i mean my diff feels good the car is really fast doesnt feel like something is wrong with it other than that loud bang i guess the best thing i could do is take it and see what they come up with
 

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Yes, mine does the same thing. My diff is leaking a little too. Again, if I lift a little when shifting it doesn't do it. I would also like to know what the cause of this is. Maybe a mileage thing. I have 70k. Does anyone have the same issue with low mileage leads than 20k?
 

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yea here in scottsdale there a chappman bmw thats where i buy my oil and all but im afraid to take it to get it inspected and have it come out with something else that didnt fix the problem and cost me an eye. i mean my diff feels good the car is really fast doesnt feel like something is wrong with it other than that loud bang i guess the best thing i could do is take it and see what they come up with
My diff feels fine as well. There's no loose feeling when I turn corners. There's no wandering on the highway. The car is as fast as can be. It can spin the tires up and into 3rd gear. But when I give it a go, like you said it thumps so loud that it feels like the rear end will shear off.

Yes, mine does the same thing. My diff is leaking a little too. Again, if I lift a little when shifting it doesn't do it. I would also like to know what the cause of this is. Maybe a mileage thing. I have 70k. Does anyone have the same issue with low mileage leads than 20k?
I have 97k on mine now. I don't know the previous owners driving habits either. Are all these cars from southern states where it is hot year round? I did notice that in Arizona, it was practically impossible to to make the rear tires spin on the hot pavement. Maybe the extra grip causes (premature?) wear on the diff and drivetrain?
 

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Discussion Starter · #8 ·
i didn't notice any oil leaking and yea mine pretty much burns out up to 3rd gear as well and i have 9+ inches of rear tire with my IForge rims, i dont think its the extra grip that does it, but thats the thing i just dont know what it can be that makes such a loud thump or bang sound i mean you feel it hit pretty hard in the underbody or somewhere and when i lifted the car the Diff looked and felt really solid no play at all i even tried moving it with a crowbar and some leverage but nope no play at all. my other option or thought was that it could be the shaft center support that might be worn so it could have some kind of play in the shaft and when you give it power or shift it could bump but idk since it was covered up by the heat shield
 

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2009 BMW X5 Xdrive3.0
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I am buying a 2004 M3 with 99,000 miles. The owner said he replaced the diff fluid with Royal Purple fluid which does not have a friction modifier. He said he had it for a few months like that and before I purchased the car he would drain it and put in the OEM fluid?

Do you think this would have any negative effect or have destroyed anything?
 

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Discussion Starter · #11 ·
I am buying a 2004 M3 with 99,000 miles. The owner said he replaced the diff fluid with Royal Purple fluid which does not have a friction modifier. He said he had it for a few months like that and before I purchased the car he would drain it and put in the OEM fluid?

Do you think this would have any negative effect or have destroyed anything?
Its like they say the M devision spent tons and tons of money labor and science making these cars. I wouldn't put any other fluid other than what it is suppose to have. other ppl say royal purple works for them but i would just feel safer with the OEM fluid. just sayin...
 

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2019 440i xDrive Coupe
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I've dealt with this complaint on three occasions on E46s that I can remember. Two ended up needing the diff bushing replaced, and one had a cracked rear subframe. The diff bushing cars were both automatics and clunked whenever you shifted between park, reverse or drive. The cracked rear subframe vehicle was a manual and was terrifying to drive. It made loud noises every time you shifted gears, sounded like the rear end of the car was going to fall off.

A damaged subframe should be fairly easy to spot if the vehicle's up on a lift.
 

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Discussion Starter · #13 ·
I've dealt with this complaint on three occasions on E46s that I can remember. Two ended up needing the diff bushing replaced, and one had a cracked rear subframe. The diff bushing cars were both automatics and clunked whenever you shifted between park, reverse or drive. The cracked rear subframe vehicle was a manual and was terrifying to drive. It made loud noises every time you shifted gears, sounded like the rear end of the car was going to fall off.

A damaged subframe should be fairly easy to spot if the vehicle's up on a lift.
when i checked mine the bushings looked good

i have to check if its the subframe but how do you repair that?
 

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Turner Motorsport has a kit to fix/prevent the subframe mount issues.

But it is a weld in kit and requires some skill to install.
 

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2019 440i xDrive Coupe
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when i checked mine the bushings looked good

i have to check if its the subframe but how do you repair that?
The one we did had to have the whole subframe replaced. However, it was pretty badly damaged; it had two very large cracks on both sides.
 

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wow thanks guys. I was just about to post a question but I think I found the answer. I hear a "thud" after shifting into gear and releasing clutch. I think its the differential but I dont hear anything though as been described. What does "wandering " mean?
 

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I recently spoke to one of my technical advisors from a high performance shop I usually bring my other cars to and he said the thump we hear would be "normal". He said the system as it is will feel like the whole rear end wants to rip right off the back. Also said that the car may feel like it wants to break itself in half. We'll see, I have plans on getting that thoroughly checked out in the spring. Possibly even change the diff.
 

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I recently spoke to one of my technical advisors from a high performance shop I usually bring my other cars to and he said the thump we hear would be "normal". He said the system as it is will feel like the whole rear end wants to rip right off the back. Also said that the car may feel like it wants to break itself in half. We'll see, I have plans on getting that thoroughly checked out in the spring. Possibly even change the diff.
Uh, NO.
 

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Discussion Starter · #19 ·
Any new News??? i wanna see if we can bring this thread back to life im still having the problem and im just getting more and more scared one day ill look in the rearview and see my diff on the ground :yikes::eek: and now i hear that the vanos bolts are crap and they sheer off potentially killing your engine wtf? i swear i have nightmares :bawling: why are e46 full of problems all of a sudden thi has always been one of my dream cars now i kind of regret having it :mad::cry:
 

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Discussion Starter · #20 ·
also before i forget since i live in arizona its always hot here but recently its been pretty cold well to us arizonians 57 degrees is cold. and when i start my car in the morning and switch to auto on the SMG on S1 it will not shift from 1st gear to 2nd till like 5k rpm or unless i switch to paddles but after a few gear changes i go back to auto and its fine. dont tell me my trans is gone now too ill shoot my self. any comments??
 
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