jeyjey

Back in 1987 I was enthralled by pictures & reviews of the BMW M6 but decided I should give the competition a try too, so I test drove the M6, a 560SL, and a 911. I have a couple of memories: the M6 had horrible axle tramp, the 911's sunroof motor sounded like it was made out of legos, and the 560SL was glorious from head to toe (I ended up buying it instead of the M6).

I was reminded of this when I used the electric boot switch on my new-to-me 944. Refined it is not.

Has anyone tried any mitigation? Maybe isolation dampening between the motor and the chassis? Or wrapping the motor in Dynamat?

Presumably there are reduction gears inside the motor can? (I don't think the motor itself would be noisy -- but that would probably suggest Dynamat over isolation.) I don't think re-greasing the gears would help, as the 911 I drove back in the day was brand new. But maybe they weren't greased from the factory and some lithium grease would help?

maybeillbuyit

Your post is a little timely for me. Yesterday I was taking my 87 BMW 635 for its first drive of the spring and needed to to do a little outside rear view mirror adjustment and was actually shocked at how loud and unrefined the sound they both made. Little grinding motors / linkages etc sound terrible. Everything is working fine and I assume this was how they came from the factory. Not sure theres a fix to it and I don't have any plans to to try, just an observation.
As for the M6 axle tramp , since all M6s came with an LSD I assume thats what caused what you are referring to. Although I've driven a few LSDs and wouldn't describe it as tramp. More of a chirping around corners. I'll be putting an LSD into the 635 soon so hopefully it won't be too intrusive.
Not sure what causes these 80s motors to be so noisy/crappy sounding but car makers must have figured it out as the new cars sure don't do it.
Dave

harveyf

My impression is that the 944 sunroof retraction design does not represent Porsche's finest hour of design. I tend to, once I get it closed, I leave it closed. That will also solve your motor noise

If you insist on having it functional, I would consider getting a new actuator cable from the motor to the roof. The one you have is probablly full of 35 year old grease. As I recall, they don't look like they could be regreased but others may have had some luck with this. Your poor motor may be working against a higher torque load than it likes and doth protest mightily.

jeyjey

Hi Dave, no I'd call the LSD-caused effect "wheel scrub". I only find it objectionable at higher speeds when I've forgotten to take my Land Rover out of 4-wheel-drive.

Axle tramp is when the rear suspension repeatedly loads up and unloads during straight-line hard acceleration. My guess is the fault is caused by the extra torque of the M6 motor and your 635 is probably free from it.