Problem changing from 3rd to 4th gear

sandford6016 · 10-09-2008, 02:55 PM

Hi,

My 318D M Sport now seems to make a crunch/grind when you change from 3rd to 4th gear (UK manual box) as first I thought it was me, but the clutch is fully pressed in! It only seems to do it for about the 1st 10 minutes of driving when everything is cold I guess?!?!

It's only 7 months old so still under warranty, but I would like to have a faint idea as to what it may be before I speak to the dealer and they try and fob me off with excuses!

roofer · 10-09-2008, 02:58 PM

Sounds like a synchro ring getting worn. If it starts doing it when warm, then its on the way out. Make sure floormat hasn't slipped up behind clutch pedal, longshot, but seen it happen.

sandford6016 · 10-09-2008, 03:03 PM

Thanks, it's definately not the mat, I checked that first! Synchro ring, ok, can I be stupid and ask what that is please?

roofer · 10-09-2008, 07:10 PM

Quote:

Originally Posted by sandford6016

Thanks, it's definately not the mat, I checked that first! Synchro ring, ok, can I be stupid and ask what that is please?

It aligns the gear clusters to enable meshing, when its worn, the teeth don't mesh inline and bounce off each other, this is the graunching noise you hear.

BMW fill their manual boxes with piss oil nowdays due to finer manufacturing tolerances, The old hypoid gear oils used to make cold boxes a bastard, but nowdays, a graunching box is an early indication of trouble, only imo of course, could be totally wrong, but the weakest part of the gear clusters is the synchro rings, so first to go. Notice the brass rings, this is not a BMW box, just for illustration.

sandford6016 · 10-10-2008, 02:55 PM

Cool! Thanks for your help roofer. I may give the dealer a tinkle next week and get them to have a look.

sandford6016 · 03-08-2009, 10:41 AM

Just for info, BMW replaced whole gearbox! No idea what the problem was, they didn't bother looking, just replaced under warranty!

10-09-2008, 02:55 PM	#1
sandford6016 Private 20 Rep 95 Posts Drives: 2014 420D M Sport Join Date: Sep 2008 Location: Berkshire UK iTrader: (0)	Problem changing from 3rd to 4th gear Hi, My 318D M Sport now seems to make a crunch/grind when you change from 3rd to 4th gear (UK manual box) as first I thought it was me, but the clutch is fully pressed in! It only seems to do it for about the 1st 10 minutes of driving when everything is cold I guess?!?! It's only 7 months old so still under warranty, but I would like to have a faint idea as to what it may be before I speak to the dealer and they try and fob me off with excuses!
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10-09-2008, 02:58 PM	#2
roofer Lieutenant 22 Rep 584 Posts Drives: 335D M Saloon Join Date: Apr 2007 Location: Essex iTrader: (0)	Sounds like a synchro ring getting worn. If it starts doing it when warm, then its on the way out. Make sure floormat hasn't slipped up behind clutch pedal, longshot, but seen it happen.
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10-09-2008, 03:03 PM	#3
sandford6016 Private 20 Rep 95 Posts Drives: 2014 420D M Sport Join Date: Sep 2008 Location: Berkshire UK iTrader: (0)	Thanks, it's definately not the mat, I checked that first! Synchro ring, ok, can I be stupid and ask what that is please?
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10-10-2008, 02:55 PM	#5
sandford6016 Private 20 Rep 95 Posts Drives: 2014 420D M Sport Join Date: Sep 2008 Location: Berkshire UK iTrader: (0)	Cool! Thanks for your help roofer. I may give the dealer a tinkle next week and get them to have a look.
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03-08-2009, 10:41 AM	#6
sandford6016 Private 20 Rep 95 Posts Drives: 2014 420D M Sport Join Date: Sep 2008 Location: Berkshire UK iTrader: (0)	Just for info, BMW replaced whole gearbox! No idea what the problem was, they didn't bother looking, just replaced under warranty!
	Appreciate 0 Quote