Brockenp Posted February 9, 2020 Share Posted February 9, 2020 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? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 9, 2020 Member Share Posted February 9, 2020 "Which fill hole?"Jonathan Link to comment Share on other sites More sharing options...
Brockenp Posted February 9, 2020 Author Share Posted February 9, 2020 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 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 9, 2020 Member Share Posted February 9, 2020 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 Link to comment Share on other sites More sharing options...
Brockenp Posted February 9, 2020 Author Share Posted February 9, 2020 Thank you. That’s made more access. Do you know the Allen key size by any chance? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 9, 2020 Member Share Posted February 9, 2020 Post #14 says 14 mm.Jonathan Link to comment Share on other sites More sharing options...
Petethediesel Posted February 9, 2020 Share Posted February 9, 2020 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! Link to comment Share on other sites More sharing options...
ChrisC Posted February 9, 2020 Share Posted February 9, 2020 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. Link to comment Share on other sites More sharing options...
Roadsport06 Posted February 9, 2020 Share Posted February 9, 2020 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 Link to comment Share on other sites More sharing options...
SM25T Posted February 9, 2020 Share Posted February 9, 2020 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. Link to comment Share on other sites More sharing options...
Brockenp Posted February 9, 2020 Author Share Posted February 9, 2020 Many thanks for all the info. Great stuff. Link to comment Share on other sites More sharing options...
Brockenp Posted February 10, 2020 Author Share Posted February 10, 2020 Still not done it chaps. I have cut down a 14mm hex and that’s fine but from what I can see my cover plate is a little different with the filling point and hence the nut I am trying to get out pointing downwards towards the dedion tube so the angle of attack is nuts, as it runs close to the tube because of this downwards angle I can not get any real force going, any other thoughts ? Many thanks Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 10, 2020 Member Share Posted February 10, 2020 Have you set the stands as in #4 and #8 above to improve access? And removed the floor as in #7?Jonathan Link to comment Share on other sites More sharing options...
Brockenp Posted February 11, 2020 Author Share Posted February 11, 2020 Yes all done as described. I can see from a picture that some diff covers are different to the one I have and the drain comes out flat on the back, as I mentioned mine is coming out at an angle that even after the tube is Moved the tool used points towards the diff and the tube is in the way of say a breaking bar type tool. Is the cover of my diff standard? Link to comment Share on other sites More sharing options...
Gnockoff Posted February 11, 2020 Share Posted February 11, 2020 Perhaps it's just me, but why are you doing it? Seems a hell of a faff for something which, if it was in a Tintop, wouldn't get touched for years. If there isn't a drain plug, then BMW don't expect it to be drained. Link to comment Share on other sites More sharing options...
ScottR400D Posted February 11, 2020 Share Posted February 11, 2020 I bought a Laser drain plug set, a tenner for 5 different tools. The 14mm goes in the fill plug, ring spanner on other end. Suck out oil and refill. As said above not too critical though done oils are better than others for noise, etc and it can help you check for LSD wear. My fill plug is flat on the back though. Link to comment Share on other sites More sharing options...
ScottR400D Posted February 11, 2020 Share Posted February 11, 2020 I bought a Laser drain plug set, a tenner for 5 different tools. The 14mm goes in the fill plug, ring spanner on other end. Suck out oil and refill. As said above not too critical though done oils are better than others for noise, etc and it can help you check for LSD wear. My fill plug is flat on the back though. Link to comment Share on other sites More sharing options...
ChrisC Posted February 11, 2020 Share Posted February 11, 2020 The back cover and cage has changed design several times, so it's just a different version. Problem is finding the best approch for that version of the BMW diff. If you have an LSD or clutch style diff (Haldex) in a tintop it will have an oil change schedule. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 14, 2020 Member Share Posted February 14, 2020 ... mine is coming out at an angle that even after the tube is Moved the tool used points towards the diff and the tube is in the way of say a breaking bar type tool.What tools are you trying? The most friendly might be a short stub of hex key in a flexible-headed spanner. NB For anyone using a ratchet spanner I strongly recommend the type that reverses when you slide a lever rather than the type that has to be removed and turned over...Jonathan Link to comment Share on other sites More sharing options...
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