Unofficialbmw.com

swamit · Joined: 22 Jan 2002 Posts: 1

Hey guys,
My 1990 735i is behaving a little funny over the last few days. At high-speeds this car runs like new. A low speeds (around 40 and below) it has started making a weird vibration - like something is pulling on it - a periodic 'grrrr" at regular intervals.
Hmmmm...so i think it could be the transmission - well, but even at low speed, if I STEP on the gas hard, it runs without any vibration at all...its only if i gradually accelerate and when i brake down slow that i feel that stupid vibration...and i just HATE it...i dont where to check or where to start...I changed front brake rotors, checked the drive shaft, put new engine and trani mounts....NOW WHAT DO I DO ?....I have run out of my resources and cannot think what else to try...any suggestions ???....

PJK

My son in law (former tire man) says check for cupped tires.

Phil

quote:
Originally posted by swamit:
Hey guys,
My 1990 735i is behaving a little funny over the last few days. At high-speeds this car runs like new. A low speeds (around 40 and below) it has started making a weird vibration - like something is pulling on it - a periodic 'grrrr" at regular intervals.
Hmmmm...so i think it could be the transmission - well, but even at low speed, if I STEP on the gas hard, it runs without any vibration at all...its only if i gradually accelerate and when i brake down slow that i feel that stupid vibration...and i just HATE it...i dont where to check or where to start...I changed front brake rotors, checked the drive shaft, put new engine and trani mounts....NOW WHAT DO I DO ?....I have run out of my resources and cannot think what else to try...any suggestions ???....

dale · Joined: 22 Aug 1999 Posts: 3087 Location: Seattle, WA USA

I'd say check your guibo (rubber flex disk in drivetrain on back of transmission) for cracks and wear also.
If it hasn't been replaced, that's likely the problem. My '80 528i's guibo is shot and I only get vibrations around 35mph.

Dale

Gil T

Hello I have been looking at the message boards for a few hours now. I have been having the groaning or grrrr noise and it sounds that is may be the same thing that has been going on with my 86 535i. I know that it is the power steering pump or something to do with it. The power steering seems to work as it should, with ease but the the Grrr sound is mostprevelent a low speed or idling. When I removed the pump's fan belt the problem went away.
I picked up the rebuild kit for the PS pump and when I took it apart, everything appeared to look well inside. No observable damage to parts or to seals or gaskets. I put every back together with the parts from the kit and started it up. The Grrr sound was still there. I attempted to bleed the system as explained in the Bentley manual with no luck. I checked further for the vibration and found that the solid metal high pressure tube had the vibration on it and it continues all the way to the pressure regulator or maybe the other way down. Now I'm thinking it could be the pressure regulator and/or the pressure accumulator. For the record, I replaced the accumulator also known as the brake bomb sometime last year. I really don't know how long the brake bomb usually last but it maybe the culprit. I hope. The symptoms of the brake bomb going south is a stiffer brake petal and the red brake light going on for a brief second while depressing the brake pedal. I also noticed that the lower ps hose (cloth cover hose) was partially collasped. I hope this helped you get started but if by chance you had the problem corrected, I would like to hear about the outcome in your situation.
Many Thanks Gil
giln1oiw@hotmail.com

quote:
Originally posted by swamit:
Hey guys,
My 1990 735i is behaving a little funny over the last few days. At high-speeds this car runs like new. A low speeds (around 40 and below) it has started making a weird vibration - like something is pulling on it - a periodic 'grrrr" at regular intervals.
Hmmmm...so i think it could be the transmission - well, but even at low speed, if I STEP on the gas hard, it runs without any vibration at all...its only if i gradually accelerate and when i brake down slow that i feel that stupid vibration...and i just HATE it...i dont where to check or where to start...I changed front brake rotors, checked the drive shaft, put new engine and trani mounts....NOW WHAT DO I DO ?....I have run out of my resources and cannot think what else to try...any suggestions ???....