SMG Gearboxes

[Thorney]

Getting back to your question, do you run a gearbox cooler? I cant remember with all the other stuff we've looked at as we do on my car and we've not any any such problems on a stcok flywheel, gb and clutch thats been in the car for the last race season and previous 35k road miles.

Originally Posted by Thorney

Getting back to your question, do you run a gearbox cooler? I cant remember with all the other stuff we've looked at as we do on my car and we've not any any such problems on a stcok flywheel, gb and clutch thats been in the car for the last race season and previous 35k road miles.

Didn't know you ran a gearbox cooler John! The more I've looked into this, the more I think its gearbox oil temperature related. Do you run the OEM gearbox oil, or do you run something else?

Can you supply details of what you've done to install the gearbox oil cooler?

[The Gorilla]

Hi,

I have Gearbox Oil and Diff oil temp in my car
as well pumps/coolers.

You would be surprised the temps in the gearbox
on a warm 32c plus day can reach when your pushing
the Car on a Track.

I have said before, this is due to the 'Thermal store'
created by the Alloy of the gearbox housing.

Once the gearbox oil has reached temp, its the
thermal store that will continue to raise its temp.

By re-circulating the oil away and back again you
not only reduce oil temp, but you ensure that the
Thermal Store does not continue to absorb heat,
as its primary heat source is now being cooled.

Regards,

The Gorilla.

[Hypnotic]

Had same problem with mine, it was as if the box tried to change gear without dippin the clutch ,BMW replaced the box and then clutch and flywheel ,with previous to that ,the rear axle/diff. All been fine since.
Good luck.

[mil]

Hello everyone,

Google guided me to this thread and as here seem to be many people with knowledge I decided to register. I hope it's ok to return this "old" thread.

Anyway my car has this very same problem and surprisingly the history sounds very similar to what Steve has been experiencing. The issue has not been solved but I want share my experiences if someone finally manages to find the root cause for this problem.

Everything started when the clutch was replaced. There was nothing "broken" with it as far as I know, but it was suspected to be quite used after 110000 km and plenty of track use and it was slipping a bit. I never had any problems what so ever with original components and that mileage. With new OEM clutch I had the first failures to shift to 4th gear pretty much immediately with this famous grinding noise. After that SMG adapation program was done again and it might have helped for some time. This problem never appears in the ECU logs, no error codes what so ever.

I did quite a lot of searching in the net and many people had reported that similar problems were fixed with new gearbox. So that was done. Ridiculously expensive work regardless of some compensation by BMW. So I was not too pleased when the problem came back on the second day after gearbox replacement. This happened in completely normal driving on street. This is why I suspect that this has nothing to do with gearbox itself and it should not be replaced. I got complete remanufactured gearbox, all new fluids, with all new SMG sensors. At least this is what they tell me.

After that SMG software was updated to the latest and SMG adaptation was redone. The software was the first thing that had a small impact. Car was running ok for maybe one month. At this point I was at Nurburgring and I ran into Schirmer Motorsport, which is BTW absolutely great place. According to Mr. Schirmer it should work with new clutch and gearbox. As my car had so high mileage, we decided to replace all suspension rubber bushings including rear differential mountings, with uniballs and Schirmer's aluminium bushings, as any clearance in the transmission could have an impact. Great modification BTW, but it had no help with SMG issue.

Now everyone seem to be pretty much out of ideas.

Hypnotic, you mention that you have replaced also rear axle/diff + everything else. Is it still working and what was the component that fixed it?

My car is standard E46 M3, but as these parts are more or less identical, I don't think it matters. Now I'm thinking going back to the clutch / flywheel section. Maybe it's all there where it started..

Any help or ideas are more than welcome.

//mil

[shimmy]

£5 spring

I'll find the tech details when I am back on the PC

[NZ_M3]

Originally Posted by shimmy

£5 spring

I'll find the tech details when I am back on the PC

I mentioned it on page 1

http://www.cslregister.com/forum/sho...31&postcount=7

[mil]

shimmy,

I'm aware that this small spring is important, however I'm under impression that it fixes cases where it is slow to change to 4th gear but there is no mechanical noise. Maybe that's different problem...

I did specifically ask that new gearbox also includes this spring and the answer was yes. So the spring should be ok. Would be worth of checking anyway when opened next time.

[shimmy]

Originally Posted by mil

This is why I suspect that this has nothing to do with gearbox itself and it should not be replaced. I got complete remanufactured gearbox, all new fluids, with all new SMG sensors. At least this is what they tell me.

i read this to mean that the gearbox was reconditioned and not NEW. If new it shouldnt be the spring i agree

have you seen this

http://www.m3forum.net/m3forum/showthread.php?t=231113

Originally Posted by shimmy

i read this to mean that the gearbox was reconditioned and not NEW. If new it shouldnt be the spring i agree

have you seen this

http://www.m3forum.net/m3forum/showthread.php?t=231113

Shimmy all BMW supplied gearboxes are classed as reconditioned - I'm told that the whole internals are brand new but the case is reconditioned. When I bought a new gearbox from BMW that was all I could order - there wasn't a choice of new or reconditioned.

It did look shiny though if that helps