Cold BMW gearbox.

[Colin Barratt]

Hi,

When the gearbox on my 325i based Sportster is cold gearchanges are rather "notchy". It smooths out after a few miles but I would have thought that a gearbox which uses ATF as a lubricant would be smooth at any temperature. Has anyone else had this problem ?

Colin.

[copperleaves11]

Re: Cold BMW gearbox.

Hi Colin. I find that the first selection of third is reluctant. Fortunately I live on a level straight bit of road and solve the problem by starting in second and changing right into fourth. After a few hundred yards the oil seems to have reached the vital bits and the gear selection/change is fine. David

[Colin Barratt]

Re: Cold BMW gearbox.

Thanks David. I have been doing a net trawl and there are a lot of opinions expressed about the type of lubricant to use - ATF vs MTL, Lighter vs Heavier etc etc. When my '91 gearbox was built the recommendation was for Dexron II ATF but there are many more modern lubes now up to and beyond D4. The two favourites seem to be Redline D4 and Motul Multi ATF. Even though BMW recommend ATF some go for Redline MT90 which is manual transmission specific. I don't know whether the fluid was changed before I bought the car so it may just be knackered. In the winter I could do with good low temperature performance - which I don't have at the moment - so I think I shall try the Motul Multi ATF.

Does anyone have advice on how to do the refill without spilling any - they sell it in 1L packs and it needs 1L so I don't want to lose any!!!
Colin.

[copperleaves11]

Re: Cold BMW gearbox.

Hi Colin. When I had the Rover V8 & LT77 fitted the same discussions arose over which oil to use. The LT77 was reluctant to go into second when cold. I used Castrol SMX S and found that solved the problem, again the popular choice was ATF.David

[dogoncrazy]

Re: Cold BMW gearbox.

Hi Colin
I purchased a Sealey siphon pump a while back for topping up /refilling gearboxes/diffs. it came with a short length of plastic pipe which I extended to suit my purpose. Still a mite messy but you can draw off the oil from the container and 'inject' into box/diff.

[Colin Barratt]

Re: Cold BMW gearbox.

Hi David,
I have bought a litre of Motul Multi ATF and have found a way of filling through the stupidly positioned fill hole. The guy at Opie Oils suggested transferring the fluid to an empty 1 litre washing up liquid bottle then fitting a piece of plastic tube onto the spout so that the oil can be squeezed into the gearbox. It will work but I couldn't see how the last drops would get into the box. Then I realised that if the tube was long enough you could squirt the fluid in from above the engine and leave it there until the last vestiges drain in. One other hint from the web is to undo the fill nut before you drain the old fluid. If it is stuck and you have emptied the box you'll never be able to refill it!! I'll let you know how the new fluid performs.
Colin.

[Colin Barratt]

Re: Cold BMW gearbox.

In case you are about to change your gearbox fluid I will offer a nugget of advice.

Although the manual says it takes 1.0 litre of ATF this will not be enough. If you follow the "fill it until it runs out of the fill hole and then leave it until it stops dripping" advice you will/may need about 1.2 litres.

I bought 1.0 litre of Motul Multi ATF from Opie Oils and it wasn't enough to run out of the fill hole. I had made sure that the engine was completely level by holding a spirit level along the top edge of the sump. Rather than wait until another order went through I topped it up with some Dexron III Power Steering Fluid. The man at Opie had already said that if it wasn't enough then put some of the old fluid back in but my old stuff was very dirty so I thought that another clean Dexron III fluid would be better.

My advice is "buy 2.0 litres" next time then you will only need to buy 1.0 litre for each of the following four changes. (100,000 miles worth!!)

Colin.

[Colin Barratt]

Re: Cold BMW gearbox.

The gearbox fluid volume required for an M50B25 engined 2.5i IS 1.2L. I was working on the 1.0L figure in the Haynes manual but when I found the BMW owners manual which came with the donor car is said 1.2L. I hope there aren't any 2.5i gearboxes running around with 16% too little fluid because of this.

My gearchange is now perceptibly, but not earthshatteringly, smoother. Reverse is still a hard push from cold and it sometimes graunches but overall things have improved.

Colin.