Vibration upon Coasting
- Thread starter matreyia
- Start date
I know he has like the ring leader of bastard n54s. I think her single handed pulled down cr reliability rating 1 point lmao . Seriously though I feel your pain every time I touch sonething everything around it breaks.
Ya'll just wait... You be referring to my posts again and again... unless I have a cursed n54. Still... I would not trade it for an n55 after my experience with them.
Yeah, I think so too. The driveline is smooth and no noises or grinding or droning. Shifts are smooth. If you were on top of a hill and the car was in neutral and started to coast down hill, it would make the helicopter sound.
Tires, new
Rotors, new
Calipers new
Wheel bearings new
There was play in rear axles at opposite ends when grabbing and twisting.
There was play on differential when turning wheels to check.
I am in contact now with Synchrotech who sold me the M Factory unit.
Just read the thread again and caught this - sorry for semi-hijack. Is there an Mfactory post somewhere on this?
Filippo
I don't think this is related to the recall. I bought this unit after all their recall and they fixed it. The recall was a year earlier than when I got mine.
I was asking for my diff
I mean I would not rule it out. We will find out next week when I replace both rear axles. Then the only 4 possibilities left would be:
1. LSD unit bad
2. universal joint at center of driveshaft bad (noise does not emit from center),
3. Driveshaft rear connection to LSD bad.
4. Transmission internals are bad...again.
So I just ordered the two rear axles and for good measure, I also ordered the front wheel bearings in case there is a weird acoustical illusion that makes it sound like it's from the rear. These replacement bearings are under FCP lifetime so no expense.
After installing all those things and the sound still arises, then time to replace the LSD.
After replacing the LSD and still sound arises...I will just drive it until the fucking transmission goes to hell and replace it with a normal ZF transmission. No more messing around with this upgraded stuff. And if I replace the transmission with a remanufactured stock unit, then I will keep the car as is and not upgrade the turbos at all...just move onto an actual M Car. Because I am at the "fuck this shit" point right now.
Nah, already know it's not tires. They are new. P li us is it were tires, the sounds would arise based on mph bith during acceleration and deceleration. Here itbis only decelerating.
OK, here is what will be done to attempt to solve this noise.
1. All 4 Wheel bearings replaced.
2. Rear Brakes, Calipers, Rotors replaced.
3. Rear Left and Right Axles replaced.
4. M Factory Rebuild kit (includes seals and axle bearings and ring gear bolts)
5. Rear wheel hubs replaced.
6. Flex Disc replaced.
7. Inspected center support driveshaft - still new.
8. Driveshaft inspection - still new.
I figure why order a new LSD unit and risk downtime when I can do this rebuild kit first to see if the axle bearings are the issue.
After this... the only thing left would be a new LSD install. It just cannot be the transmission...there is no noise in those locations and shifting is smooth. Of course, I will update after work is done.
That was the first thing I checked...and the guibo. The entire driveshaft is less than 2 yrs. old. It was replaced recently. And all the rubber parts are nice and firm with the right amount of give for normal driving.
And there is zero sounds emitting from the center or transmission area and zero vibrations thereto either. All the sounds are coming from the rear, you can really hear it when you sit in the back while someone drives you around and each time he releases the accelerator pedal.
I spoke with M Factory (Synchrotech in cali.) and the guy David said that the rebuild kit address all serviceable parts for the LSD they sell... there is nothing else in the unit that can be serviced. So that makes things a bit final when it comes to other potential shortcomings in rebuilding.
It happens in nuetral but did you every try applying e brake while in nuetral to let the load reverse by using inertial of driveline spinning?
Yep. No change in sound.
Robert at Precision Raceworks suggested I put car on jackstands and use e brake very light to simulate resistance and go to proper speed and let go to see where the noise is emitting from. I will have to use a helper.
Their was a set of bad bolts distributed years back that would back out do you know date of manufacture for your diff?I was asking for my diff
OK... this is weird.. this morning I went to drive to work and there was no more noise at any speed or deceleration or braking... HOWEVER, when I hit traffic, I slowed down and sped up as necessary and only ONCE the car shifted super hard into 2nd gear...as if it were confused and forgot to shift and tried to catch up. Now...the entire car was affected...I was on super smooth highway in traffic yet the car felt like it hit a small pot hole. Then after this, I tried to duplicate it and it never did it again. So...
I have one last suspicion... the Revshift Engine mounts may have been the culprit. This is only a theory, I will have to inspect the mount next week... My theory is that the aftermarket mounts just are not up to task and they began to give out last week. Perhaps that is why it only helicopters when I release the gas pedal...the connection is lost when power is reduced and the point of contact between the engine and mount is loosen under coasting...once you apply power the contact points reconnect and are solid so there is no noise. AGAIN, this is ONLY a theory. It may be completely wrong... But that one single time today when the entire care felt like it hit a pothole is VERY suspicious...as if the mount finally gave up the ghost and broke.
In any case, all those other parts have been ordered and I will go ahead and replace it all just as maintenance items. And this time, I will also check the mounts. I have a good mind to order the damn 335iS passenger mount and be done with it too.
I have one last suspicion... the Revshift Engine mounts may have been the culprit. This is only a theory, I will have to inspect the mount next week... My theory is that the aftermarket mounts just are not up to task and they began to give out last week. Perhaps that is why it only helicopters when I release the gas pedal...the connection is lost when power is reduced and the point of contact between the engine and mount is loosen under coasting...once you apply power the contact points reconnect and are solid so there is no noise. AGAIN, this is ONLY a theory. It may be completely wrong... But that one single time today when the entire care felt like it hit a pothole is VERY suspicious...as if the mount finally gave up the ghost and broke.
In any case, all those other parts have been ordered and I will go ahead and replace it all just as maintenance items. And this time, I will also check the mounts. I have a good mind to order the damn 335iS passenger mount and be done with it too.
