[rismo]

Hi Guys,

After two weeks of a very paipnfull M3 suspension parts and Drexler LSD installation I finally have my car back from the shop.... Cornering is NICE.... :-)

BUT:

I have a crazy drivetrain vibration upon acceleration from 1000rpm up to 3000 rpm....

I'm done with the shop and will bring my car monday to my dealer... but in the meanwhile I was wondering if you somebody could guess what it could be and if it would be harmfull.... on full speed no vibration, only on acceleration... could it be the driveline? it looks like that when torque kicks in, the vibration starts and goed away on higher speeds....

Pretty sh#t.....

[The HACK]

The bolts on the input to the diff and output to the diff needs to be torqued and torqued in the RIGHT ORDER. One or more of the bolts may not be torqued to spec.

[rismo]

Fast response....


Ok, if that is the case, could it damage the car? Or can I drive with it till I bring it into the dealer on monday?

[The HACK]

Whether or not it'll damage the drivetrain depends on how bad the vibration is.

[scottp999]

I know when I talked to former boosted IS before my LSD install he suggested I replace the 12 half shaft bolts (#3 in the picture) because he believed they were one time use (flex bolts). I ordered them from Tischer and the shop replaced them. I have been vibration free. BMW recommends a ton of bolts on the car are one time use only, but I only did the half shaft bolts on the LSD swap and no issues.

You should ask your shop where they got the torque specs, and what they were. Then check them against the bentley manual.

[rismo]

Great, I ordered my bentley manual, should be there in the next days... will order the bolts anyway on monday and have them review the installation...

Very frustating this all together.... but your responses are great!

[marcel b]

sorry to hear this! annoying especially after it took already that long... Not sure where you are living in Europe. But I can recommend Raeder motorsport close to the Nürburgring in Germany.

[marcel b]

any news? hope everything was sorted out!

[rismo]

You do not wanna know ;-)

Ok here it goes:

The driveline was wrongly installed after the LSD installation, they corrected this but:

They reused the fasteners which is incorrect, they should be replaced.
They told me nothing was damaged, but my dealer showed me wear on some of the driveline parts
There is still noise upon acceleration from 60-100 mph

I had a appointment with my dealer scheduled for august. In the meanwhile:

my watherpump started to die, so I had a appointment today to have it replaced but:

My car died completly over the weekend, last week it already had some ecu reset codes, but I think the ecu died over the weekend. The car is completly down and cannot be started. Idrive, dashboard are going completly nuts when I try to start the car.

Bottom line, dropped the car at my dealer and told them to return it when all is fixed.
The ECU/DME is a new one from only 2-3 months old, the last one was replaced because of cold start issues (After they replaced the complete fuel system)

I don't know, I think the car needs some bleshing ;-)

Very frustrating especialy as i'm always very precise with the car, very frequent oil changes, no racing upon complete warm up etc....

Thanks for asking! How are you doing?

[Former_Boosted_IS]

How did they damage the driveline? Can you be more specific? There are only some simple bolts that need to be replaced. I would be shocked if you could damage any part by not replacing a flex bolt?

[rismo]

They installed the driveline out of balance and under pressure.

The "Wheel" that keeps the driveline in balance was worn and they did not use the correct torque specs

[Former_Boosted_IS]

Originally Posted by rismo123

They installed the driveline out of balance and under pressure.

The "Wheel" that keeps the driveline in balance was worn and they did not use the correct torque specs

That doesn't make sense? I have removed the driveshaft and re-installed it. I am not sure what "pressure" they could have used? Out of balance? Did they knock a balance weight off the driveshaft?

The "wheel" for the driveline is simply center mount with a bearing.



How could they mis-torque this? It is two tiny bolts with simply torque specs (number 9 in the picture).

[shifterboy45]

from what he is describing as the "wheel" is most likely the flex coupling at the front of the driveshaft assy.. (PN#1) aka "Guibo" coupling..

since the driveshaft is two pieces there is a normal pre-load that is required to keep the shaft assy from damaging the center support.. if the entire assy is installed "wrong" the deflection angle of the shaft is incorrect, at times causing damage to the guibo and the center support.

this is pretty common occurance with those who dont work with multi-piece shafts that require pre-loading -- lot of smart guys out here should look that up *before* you remove the shaft assy...

in most cases ppl get away without following the repair procedures but once in a while someone gets bit..

sorry to hear OP

[shifterboy45]

normally a vibration on acceleration is attributed to either the flex coupling or the center support... or both in cases of excessive wear ..

very common on early E30, E36

[rismo]

It was the center support and flex, both will be replaced.

Initialy there was sound on low revs, affter the reinstall of the driveline, the noise popped up under higher speed when accelerating.

As they did not have the tools to unbolt the driveline from the diffhouse, they took it completle off, there it started to go wrong...

[shifterboy45]

Definitely not good ... that was a recipe for disaster...

again, sorry to hear...

hope everything else is good for you

[shifterboy45]

Originally Posted by rismo123

It was the center support and flex, both will be replaced.

Initialy there was sound on low revs, affter the reinstall of the driveline, the noise popped up under higher speed when accelerating.

As they did not have the tools to unbolt the driveline from the diffhouse, they took it completle off, there it started to go wrong...

like a cyclic knocking noise under your seat during accel?

[Former_Boosted_IS]

Originally Posted by shifterboy45

from what he is describing as the "wheel" is most likely the flex coupling at the front of the driveshaft assy.. (PN#1) aka "Guibo" coupling..

since the driveshaft is two pieces there is a normal pre-load that is required to keep the shaft assy from damaging the center support.. if the entire assy is installed "wrong" the deflection angle of the shaft is incorrect, at times causing damage to the guibo and the center support.

this is pretty common occurance with those who dont work with multi-piece shafts that require pre-loading -- lot of smart guys out here should look that up *before* you remove the shaft assy...

in most cases ppl get away without following the repair procedures but once in a while someone gets bit..

sorry to hear OP

I do understand what you are saying and how the flex disc works, but I cannot imagine you could damage this if you simply follow the normal procedures. As for the installed at the incorrect angle, how is that even possible?

I am interested in the pre-loading procedure for the driveshaft. I following the Bentley service manual and reinstalling the driveshaft didn't seem like rocket science.

[Former_Boosted_IS]

Originally Posted by rismo123

It was the center support and flex, both will be replaced.

Initialy there was sound on low revs, affter the reinstall of the driveline, the noise popped up under higher speed when accelerating.

As they did not have the tools to unbolt the driveline from the diffhouse, they took it completle off, there it started to go wrong...

AHHHH, that makes a lot more sense. You have to drop that driveshaft according to procedure to protect the center supporting joint.