Vibrations on deceleration.

miksebik

Specialist
Feb 27, 2021
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Hi, so here is my E92 335 having a weird issue: the car sometimes vibrates, when off the gas with a gear engaged.
Imagine this:
I put in the third gear, rev it up to 5500rpm, go off the gas and the car is OK (well, I think I feel very small vibrations). Then, I press clutch and go off the clutch (it does not matter whether I change a gear) and the car begins to vibrate a lot. The gear shifter vibrates.. as well as whole car. I can change to whatever gear and it will vibrate at whatever RPMs (the vibrations are still present only when off the gas).

After few seconds of smooth driving I try to decelerate again and... the vibrations are gone.

When I went to have the car inspected the first time, they found nothing else but a damaged pinion nut and "metallic" contamination in the diff oil. After opening the diff, the bearings looked shot, as if they were over-tightened during the first LSD rebuild 6 years ago. So we thought that the issue had been discovered.

I had all the bearings in my mfactory lsd replaced by a shop that repairs transmissions and differentials..

Unfortunately, the problem appeared again. The question is whether it was present immediately or it returned later.
Anyway.. Guys who did the diff bearings job think that it might be the halfshafts. Others tell me it might be the driveshaft. When the car was inspected again all looked OK without any plays.

There must be something worn that moves after an abruption of torque and causes vibrations.. then it "self-repairs", when the torque forces are gone.
 
Last edited:

SlowE93

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Jul 2, 2017
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Hi, so here is my E92 335 having a weird issue: the car sometimes vibrates, when off the gas with a gear engaged.
Imagine this:
I put in the third gear, rev it up to 5500rpm, go off the gas and the car is OK (well, I think I feel very small vibrations). Then, I press clutch and go off the clutch (it does not matter whether I change a gear) and the car begins to vibrate a lot. The gear shifter vibrates.. as well as whole car. I can change to whatever gear and it will vibrate at whatever RPMs (the vibrations are still present only when off the gas).

After few seconds of smooth driving I try to decelerate again and... the vibrations are gone.
I had all the bearings in my mfactory lsd replaced. Guys who did that think that it might be the halfshafts. Others tell me it might be the driveshaft. When the car was inspected all looked OK without any plays.
There must be something worn that moves after an abruption of torque and causes vibrations.. then it "self-repairs", when the torque forces are gone.
Keep driving it till it breaks. Then you will know for sure.
Meanwhile, without me driving it to feel the extent of the vibration, rpms affected, etc....I would look into driveshaft.
 

miksebik

Specialist
Feb 27, 2021
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So it looks like the MFactory Helical is shot. What do you think, does not sound healthy..?

 

SlowE93

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Jul 2, 2017
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Years ago I remember a recall or something. M factory used some bolts that were shearing off or loosening IIRC.
Maybe you fell victim to that ?
 
Last edited:

miksebik

Specialist
Feb 27, 2021
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yes, I do remeber that case.. I thought it did not concern me for some reason.. but I found the warranty cards and the diff is from March 2016. There were no loose bolts inside but this might be a beginning..
 
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miksebik

Specialist
Feb 27, 2021
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fuck...

- Unit failures are not something that just happens all of a sudden. In 100% of cases, those affected have had at least a few days of symptoms before ultimately failing

- Symptoms include unusual rattling and/or grinding noises (not the classic change-gear "thump" that is common with LSD's) coming from inside the Carrier/Pumpkin, unusual vibrations from the rear end that were non-existent previously and hesitations when moving from a standstill or at low speed (i.e like the rear end is locking up and not wanting to turn)

- At higher speeds, a failed LSD is unlikely to lock up the differential due to 2 reasons (1. The weaker material of the bolts compared to the much stronger material of the ring & pinion. 2. Centrifugal forces). Rather, the loose/broken bolts will be forced outwards by the rotating ring gear against the Carrier/Pumpkin housing, and more than likely blow a hole in the weaker aluminium rear cover causing an oil leak

- If you have not already changed your differential oil, now is as good time as any to do so. A full flush is recommended (if possible, preferably with rear cover removed) and replaced with a good 75w90 such as Torco SGO. If any unusual metal particles are visible in the oil (you may need to get your hands dirty
tongue.gif
), or the oil has turned into brown/black slush/goo, please contact us immediately


My oil is dirty after 500km that the differential was assembled (for new bearings)...
 

SlowE93

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Jul 2, 2017
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fuck...

- Unit failures are not something that just happens all of a sudden. In 100% of cases, those affected have had at least a few days of symptoms before ultimately failing

- Symptoms include unusual rattling and/or grinding noises (not the classic change-gear "thump" that is common with LSD's) coming from inside the Carrier/Pumpkin, unusual vibrations from the rear end that were non-existent previously and hesitations when moving from a standstill or at low speed (i.e like the rear end is locking up and not wanting to turn)

- At higher speeds, a failed LSD is unlikely to lock up the differential due to 2 reasons (1. The weaker material of the bolts compared to the much stronger material of the ring & pinion. 2. Centrifugal forces). Rather, the loose/broken bolts will be forced outwards by the rotating ring gear against the Carrier/Pumpkin housing, and more than likely blow a hole in the weaker aluminium rear cover causing an oil leak

- If you have not already changed your differential oil, now is as good time as any to do so. A full flush is recommended (if possible, preferably with rear cover removed) and replaced with a good 75w90 such as Torco SGO. If any unusual metal particles are visible in the oil (you may need to get your hands dirty
tongue.gif
), or the oil has turned into brown/black slush/goo, please contact us immediately


My oil is dirty after 500km that the differential was assembled (for new bearings)...
This is why you need to keep things in one thread.
Was it not on your other thread that you said something about a pinion nut too tight destroying bearings on the same LSD ?
Try and keep all relevant info on one thread so we can all better understand the situation and offer help or guidance.
 
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miksebik

Specialist
Feb 27, 2021
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This is why you need to keep things in one thread.
Was it not on your other thread that you said something about a pinion nut too tight destroying bearings on the same LSD ?
Try and keep all relevant info on one thread so we can all better understand the situation and offer help or guidance.
yes, I will edit the first post.. as there were wild theories as to what is the cause. I do not know it yet.. It all goes from driveshaft, halfshafts, transmission, clutch... but the only thing that seems to have an issue is the differential.
 

miksebik

Specialist
Feb 27, 2021
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Not yet. Tomorrow probably. We just checked the oil and it was contaminated.. after 400km! Also, I am waiting for an answer from MFactory.

My plan for next days is: borrow an open diff.. if there are no vibrations then.. we know for certain that the problem comes from the differential.
Also, I will probably order a new diff, either Helical again but guys told me to buy the metal-plates lsd. I do not want to wait months, I want to drive my car when the summer is behind the door!
 
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miksebik

Specialist
Feb 27, 2021
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So.. after talking to few experienced people, we got hints that it is transmission or flywheel related. Well, unfortunately they were right. There was a broken pin on the flywheel, that normally supports the shaft from transmission.
So much for the PTB flywheel with cca 4000km on.
Now the question is, whether the crank got some damage or not, as it must have been abused a lot. There is a guy who says that the main bearings that hold the crank must be damaged.

As for the mfactory differential, we will definitely open it to check whether there is something wrong.



WhatsApp Image 2022-06-14 at 09.42.51.jpeg
WhatsApp Image 2022-06-14 at 09.42.51 (1).jpeg
 
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miksebik

Specialist
Feb 27, 2021
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Hi guys, let me give you an update. Lucky update. Well, at least partially.

After contacting PTB, the manufacturer of my broken twin clutch kit.. they told me to send them the flywheel for repair. They wanted to reweld it, using a better steel probably. In the meantime I spoke to few engineers who said that welding the pin is a total bullshit as welding heats the material and makes it fragile.
Funny enough that when you check PTB review on google maps, there is a guy with the same problem.. Also I spoke to owner of 55parts.de shop who said that he had had the same issue few years ago. F.ck, did they not take anything from the failures?

Anyway, mine was repaired by a 77y old guy who makes depleted uranium ammunition and if I told you more, I would have to kill you all, lol.

Now... now the car is.. like before. No vibrations at last! Even with the imperfect driveshaft.

We even disassembled the Helical differential to clean it and check it. Unfortunately the bolts snapped after tightening them to 32Nm, as a guy from Mfactory said. Interesting again, the bolts look like unsuitable for this, they may be 14.9 as MFactory claims, but they are not "flexible".

IMG-20220622-WA0019.jpg
 
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Torgus

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F mfactory. Cheap Chinese copies.

But their 1200 coilovers are as good as a 3.5k ohlins according to their posts.

They have had many product issues and do not seem to fix them. Just your general chinese parts imported and bought by Americans.

You can't even deal with mfactory directly you have to use their outsourced US distributor.