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    90 BMW 750il, 85k, Transmission/braking problem

    Our transmission wouldn't shift into the higher gears last March/09. There was nothing on the dash and no other problems. We took it to a local BMW expert who said there were no codes given. He thought it was an electronic problem. Apparently not finding an electronic problem he opened up the valve body and told us that the valve body was perfect and super clean, no gunk so he doubted that it was a mechanical problem. Then he changed his mind and said it had to be a mechanical problem with the transmission. He had the car several days so I did some research. A different mechanic told us to replace the switch selector and the EH gearbox switch. We told the BMW expert this but he would not replace the switches. This process took about two weeks and we had to leave the state on business. We decided to take the car home. I returned this August/09 and I had a different mechanic install the new switches. The car ran beautifully. Three weeks later I took it to our regular mechanic because it was running rough right after starting it. He called me after doing a smoke test and asked me if the car ever binded up in reverse. I told him no. He said that when he backed the car out of the shop it went into reverse fine and then after backing five or six feet the car binded up, as if the brake was on. He said it rolled in neutral, so he rolled it out of the shop. I went and picked it up. Drove forward fine. It did the same reverse thing in my driveway. Another mechanic said that it could be a brake issue but the car rolled in neutral. New transmission time? We don't know what happened and we don't know what to do about this. Anyone with similiar experience will you please advise us. Thank you very much.


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    Inner Circle ©156 since: Aug 14, 2003 cheung1 is an unknown quantity at this point cheung1's Avatar
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    Don't recall any similar posts

    I read your post but don't recall reading any past posts in RF or another E32 forum regarding this symptom. The 750's 4HP24 transmission is known to have the A and B clutches worn out because of a pair of stainless steel seals near the front not properly sealing, and hence let pressure through to partially engage these two sets of clutches at >1500RPM in PARK or Neutral positions. I have asked for transmission help from a great guy Kirt Koeller in Michigan seven years ago when he still had time to visit the RF forum. Patrick C 88 750 159K

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    Re: Don't recall any similar posts

    Thank you PatrickC88750, yeah, I couldn't find anything exactly like what we were experiencing in the archives either so I went ahead and called Kirt Koeller today. What an awesome help he was, knows what he's talking about, and really nice. I told him what was going on and he is going to walk our mechanic through disconnecting the transmission computer tomorrow morning. Based on how my car drives without the computer telling the trans what to do, he'll know whether we have a computer problem or a mechanical failure. I will also inform my mechanic of the information you posted. Thanks. Incidently, I was planning to drive the car to the shop this afternoon and I couldn't get it to go reverse at all. Had to have it towed to the shop. I'm dreading the news but at least we will know for sure what's going on. Appreciate your help.

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