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Brockenp
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BMW LSD diff

Hi all. New to a BMW diff so a little confused as to how to drain it and refill it, it would appear that if there is a drain it’s on the rear plate , pointing, what would seem at a  downwards angle with the dedion tube running close ish to it, I cannot see a drain on the bottom of the diff. Any suggestions, am I in the correct area?

Jonathan Kay
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Brockenp
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Hi. I can see it but how are you meant to get it out with the dedion tube in the way, theres not a lot of room to get anything in there, is it a case of cutting down and Allen key, do you suck out the old oil as I have read others saying there is a drain but I can not see anything. I’m sure I’m being a bit thick on this. Thanks

P Williams

Jonathan Kay
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Post #7 says that there isn't a drain hole, so you 'd need to suck with or without a pump. Much easier with warm oil.

With the Sierra diff you can improve access by jacking the suspension around. I'd guess something similar would work. This and other great hints from Alcester Racing Sevens.

Jonathan

Brockenp
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Thank you. That’s made more access. Do you know the Allen key size by any chance?

P Williams

Jonathan Kay
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Post #14 says 14 mm.

Jonathan

Petethediesel
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I recently changed the oil on my BMW diff and made a tool by welding a short section (8mm) of 14 mm hex bar to a length of thin section plate. If you try to cut down a 14mm allen key to make such a tool be aware that many are chrome vanadium and very hard to cut. Yes a suction pump is required, and you will find it easier to gain access for filling again by removing the floor or even better, making an access plate in the floor as has been described on the forum earlier. Yes, with a tad more effort it could have been made nigh on impossible!

Pete C

ChrisC
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14mm hex socket and a breaker bar will loosen it,  There is plenty of clearance if your car isn't supported by the De Dion tube but by the chassis on axle stands. 

Maybe this helps with pictures of the tools and how to access the fill plug.  My 14mm hex socket is from a Laser set. 

https://caterham420detailedbuildblog.co.uk/2020/02/06/fill-the-diff/

To drain the diff I used a large Sealy oil suction syringe.

Roadsport06
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Lidl have an electric suction pump on sale from Thursday. I've got one and used it to drain gearbox oil on a tintop. Worked very well. Ultimate Speed Oil Pump https://www.lidl.co.uk/p/p29572?productId=29572&countryCode=GB
SM25T
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If it is anything like the fill/level plug on my Ford diff ... a long breaker bar is a must. It takes a lot of force ... then it goes with a bang. Seems to tighten in service.
Brockenp
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Many thanks for all the info. Great stuff.

P Williams