evotell Posted July 4, 2012 Share Posted July 4, 2012 Does anybody know which BMW the diff comes from? When folks talk about noise from the diff what type of noise are we talking about? The BMW diff in one of our cars makes a clanking sound like the pinion is slacl on the crown wheel. Any input would be welcome Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 4, 2012 Share Posted July 4, 2012 1-series I believe. Also understand the parts may be welded, thus not as serviceable as the old school diffs ? Link to comment Share on other sites More sharing options...
evotell Posted July 6, 2012 Author Share Posted July 6, 2012 Not sure what you mean by welded up? Link to comment Share on other sites More sharing options...
rj Posted July 6, 2012 Share Posted July 6, 2012 No bolts in the housing => housing has been welded, hence slightly fussy to disassemble Link to comment Share on other sites More sharing options...
Rattie Posted July 6, 2012 Share Posted July 6, 2012 Welded up? Are you 100%? The casing is bolted certainly. As for "gears welded to shafts" which was SM25T's original assertion, quoting the famous "I. Heard" 😬, I'm not sure I can think of which gears would be welded to which shafts to make it unservicable. That's not to say it's not true, just that looking at the unit I'm a touch sceptical. I'd be interested to know the source on that one. I suspect it may just be that as a BMW OEM part they are set up so as to not need a change of oil, but the Caterham rear cover plate has a fill/drain port and it's been used, to added oil and LSD additive at CC Mids. Oh and yes, it comes from a 1 series, specifically I. Heard says it's a Coupe. Who am I to argue Superb unit, far better than the late pattern Sierra, even with Quaife CW&P. Martyn Link to comment Share on other sites More sharing options...
evotell Posted July 6, 2012 Author Share Posted July 6, 2012 Thanks for your reply. My original question related to the noise, any suggestions? Terry Link to comment Share on other sites More sharing options...
CB Posted July 7, 2012 Share Posted July 7, 2012 It might be worth checking that the noise isn't actually the mounting bolts or the carrier coming apart - a number of this year's Academy cars have had "issues" and we are all being very careful to do a lot of checking whilst CC work out what to do about it... Link to comment Share on other sites More sharing options...
evotell Posted July 7, 2012 Author Share Posted July 7, 2012 It's most defiantly the pinion, one does have to wonder when Caterham are going to sort this issue for good Link to comment Share on other sites More sharing options...
Rattie Posted July 7, 2012 Share Posted July 7, 2012 Odd, a slack mesh on the pinion to crown wheel with usually make awful whining noises before it makes clonking noises. The biggest source of clonking noises is the tripod UJs on the drive shafts. They're often poor and only get worse with wear. Is there evidence you haven't mentioned that leads you to the conclusion that is defo the pinion? Link to comment Share on other sites More sharing options...
DJ. Posted July 8, 2012 Share Posted July 8, 2012 When I had my Sierra diff sorted at Road and Race, I was chatting with Phil, and he showed me some bearings that were about to be used to rebuild the same BMW diff as now fitted by Caterham. He definitely said they can be serviced, but the parts were twice the price of a Sierra diff. He didn't mention anything about them being welded up, and I got the impression that Caterham are disassembling the BMW diffs to fit LSDs. If that is the case they will have to reset the crownwheel/pinion mesh on those units themselves. Duncan Link to comment Share on other sites More sharing options...
evotell Posted July 8, 2012 Author Share Posted July 8, 2012 What puzzles me is why Caterham can't seem to sort this out Link to comment Share on other sites More sharing options...
pugwash Posted July 9, 2012 Share Posted July 9, 2012 Mine makes a sort of clunk when pulling away and similar when lifting off. Having never had a car where I could listen to the LSD before I just assumed TADT. PBC at CC was less than a month ago and will be back for the 1000 mile first service in a few weeks. I will ask them to confirm if this is a normal thing or not. Dont really know how the LSD works but have seen a stripped down drive shaft so I get the point about that could be the reason for the clunk. Link to comment Share on other sites More sharing options...
evotell Posted July 10, 2012 Author Share Posted July 10, 2012 It's not the LSD that makes the diff noisy it's the pinion bearing and the pinion not being correctly setup with the crown wheel. BMW would never alow one of their cars to go out the door with a houling and clonking diff. Link to comment Share on other sites More sharing options...
AJC Posted July 10, 2012 Share Posted July 10, 2012 Its probably one that BM threw out and flogged it Caterham. Link to comment Share on other sites More sharing options...
mic Posted July 10, 2012 Share Posted July 10, 2012 There is nothing welded inside the diff, unless BMW did it during manufacture . Link to comment Share on other sites More sharing options...
evotell Posted July 11, 2012 Author Share Posted July 11, 2012 Quoting mic: There is nothing welded inside the diff, unless BMW did it during manufacture . Do you know that for sure? Have you had one apart? Link to comment Share on other sites More sharing options...
mic Posted July 11, 2012 Share Posted July 11, 2012 Yes, and yes Link to comment Share on other sites More sharing options...
Rattie Posted July 17, 2012 Share Posted July 17, 2012 clonking on transition between power on and power off is slack in the drive shaft UJs. Tripod UJs are like that. Grinding and whining noises are from the crown wheel to pinion mesh quality/alignment/gap. LSD noises, like snapping and a particular type of grumbling/grinding only show up when cornering. When going straight the LSD or open diff is almost a paperweight 😬 Link to comment Share on other sites More sharing options...
andyseven Posted July 18, 2012 Share Posted July 18, 2012 How do you know if its a BMW or Sierra diff on the car? what should I look for to differentiate? Link to comment Share on other sites More sharing options...
CB Posted July 18, 2012 Share Posted July 18, 2012 The Sierra diff casing bolts directly to the chassis. The BMW is physically smaller (and black - the Sierra one is plain alloy I think) and has a frame around it (that bolts to the diff at the front sides and the back). That frame is then bolted to to the chassis. Link to comment Share on other sites More sharing options...
andyseven Posted July 18, 2012 Share Posted July 18, 2012 mine is alloy not black, car is brand new so thought would be BMW? Link to comment Share on other sites More sharing options...
DJ. Posted July 18, 2012 Share Posted July 18, 2012 If it works well and you are happy with the car, don't worry. The Ford diff is well engineered. Duncan Link to comment Share on other sites More sharing options...
CB Posted July 18, 2012 Share Posted July 18, 2012 From one of this year's Academy build diaries - a BMW diff here (though you wouldn't have the circular flange - it gets removed later in the build and the drive shaft inserts directly) Edited by - CB on 18 Jul 2012 16:57:13 Link to comment Share on other sites More sharing options...
Rattie Posted July 18, 2012 Share Posted July 18, 2012 If you just look from the rear, the back plate is silver on both diffs, though the BMW one has a (7) logo engraved on it. You'll have to look through the spokes of one of the rear wheels to get a good look at the body of the diff. The BMW one is black as mentioned and even has "BMW" cast into the side just in front of the right hand drive shaft. (You can just barely make it out in that photo) Martyn Link to comment Share on other sites More sharing options...
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