indecisive gearbox
Printed From: Bavarian-Board.co.uk - BMW Owners Discussion Forum
Category: Technical & Model Specific Forums
Forum Name: BMW 6 Series
Forum Discription: This forum will deal with any issues on the BMW 6 Series (E24, E63 & E64)
URL: http://www.bavarian-board.co.uk/forum_posts.asp?TID=15287
Printed Date: 14-May-2024 at 10:59
Topic: indecisive gearbox
Posted By: Artley
Subject: indecisive gearbox
Date Posted: 08-March-2005 at 04:48
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A plate 635 CSi Auto
My gearbox is taking a while to 'warm up ' before up shifting when starting from cold. Which makes me look like a right plonker driving at 30 through town with the engine revving to buggery. Now it's started changing down for corners and not going back up after. I had the forward drive clutch re-built 25K miles ago so the actual box is fine. Any ideas? Cheers Art 
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Replies:
Posted By: Brucey
Date Posted: 08-March-2005 at 15:18
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Art, it might help if you say which gearbox you have. Is it the three speed, four speed, or four speed switchable? I'm guessing 4-speed fitted with a kickdown cable (ZF 4-HP22). If you have not changed the fluid and filter since your partial rebuild, it might be a good thing to do. Sadly there are lots of clutches inside these mechanical devils, and although one of them is likely to wear before the others (the 'A' clutch I believe) it doesn't mean to say that the others are not close behind.... What symptoms caused you to have the forward clutch repaired? cheers
------------- ~~~~~~~ Brucey ~~~~~~ |
Posted By: Artley
Date Posted: 09-March-2005 at 04:37
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Brucey
Thanks for your help It's a very early, and it seems very rare version, of the switchable 4 speed. The reason for the rebuild was complete forward drive failure - I looked at the possibility of a straight replacement at the time but couldn't find that exact gearbox anywhere in the country, and was advised by people in the know that it couldn't be guarateed my existing electronics would control a different box. So I opted to repair the original box, which has been fine since. Until the last couple of weeks that is. Once the thing decides on a gear it runs fine and there's no slip on the clutch at all. It only has problems when it's time to think about changing gear. Sometimes it gives up and drops into 'get home' mode. Orange light on the dash and again there's no slip on the clutch. But by switching off the ignition and restarting it always starts again without the orange light This is my first auto car, so my understanding of how the box works is pretty basic at best. Hope this helps - look forward to your reply Cheers Art |
Posted By: Brucey
Date Posted: 09-March-2005 at 17:23
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I wouldn't call myself an expert by any means.... However I am told that the box will go into a 'limp home' mode if its ECU goes bad or there is a dicky connection. On mine I had an intermittent fault with the TPS for a while, and this also altered gearbox performance as I think it reads this signal. Basically the TPS signal needs to go low and stay low in order to allow the gearbox upshift in 'D'. In 's' mode you won't get fourth gear at all, and upshifts are quite delayed. On mine 1st to 2nd is about the same, but 2nd to 3rd needs about 40mph. By contrast in 'e' mode it is in fourth gear by about 47mph on a light throttle. Do double-check the oil level; this needs to be done with the engine running, otherwise the level will be wrong. From your symptoms I might suspect a wiring fault of some kind. Maybe you have a ground fault on the kickdown switch wiring- that would certainly cause a 'no-upshift' condition. Incidentally I looked at the ETK recently and there are at least four different version of the EH box that were fitted to the 6 series and I don't know for sure how many of them are comaptible either. HTH cheers
------------- ~~~~~~~ Brucey ~~~~~~ |