CtrMint Posted January 5, 2019 Share Posted January 5, 2019 Guys,This one is really embarrassing but I'd like to check.I'm filling the 420R LSD with oil. I'm unsure which is the fill plug, told you it was embarrassing. I'm sure the larger and lower center plug is the drain, but surely you don't fill by that? Do you use the 8mm hex at the top? It just seem very small.I think it looks like the image from CC's parts website.Thanks Link to comment Share on other sites More sharing options...
Wrightpayne Posted January 5, 2019 Share Posted January 5, 2019 Instinct says the lower one - its a similar way up the casing to the sierra diff.If it was full to the top one I think it would over pressurise and blow the seals. That said I do wonder what it is for?Perhaps google BMW diff oil change - some of the German forums may have information, eg capacity, albeit the cover plate is different.Ian Link to comment Share on other sites More sharing options...
SM25T Posted January 5, 2019 Share Posted January 5, 2019 The fill and oil level hole is around 40% of thr way up from the bottom ... so that big hole in the photo. Anything on tbe top will be for a breather tube. Link to comment Share on other sites More sharing options...
CtrMint Posted January 5, 2019 Author Share Posted January 5, 2019 ahh thanks guys!I must have missed the drain on the bottom face of the diff? Link to comment Share on other sites More sharing options...
Wrightpayne Posted January 5, 2019 Share Posted January 5, 2019 Sierra one doesnt have a drain - fill for life!!You can suck most of the oil out via the filler hole though!Ian Link to comment Share on other sites More sharing options...
CtrMint Posted January 5, 2019 Author Share Posted January 5, 2019 This one is a BMW though, is that the same? Link to comment Share on other sites More sharing options...
ScottR400D Posted January 5, 2019 Share Posted January 5, 2019 BMW one doesn't have a drain, just suck it out. Capacity from memory is 1.2L and you can get just about all of it out pretty easily with a Pela. Link to comment Share on other sites More sharing options...
Grubbster Posted January 5, 2019 Share Posted January 5, 2019 My BMW diff was supplied pre-filled, didn't need to add any oil at all. Link to comment Share on other sites More sharing options...
pugwash Posted January 6, 2019 Share Posted January 6, 2019 IIRC My BMW diff also came with a sachet of some magic solution that needed to be added to look after the LSD. That took a bit of thinking to get it in. The diff oil I squirted in using a Draper oil syringe ( I don’t think it’s called that but thats what it looks like). Link to comment Share on other sites More sharing options...
CtrMint Posted January 6, 2019 Author Share Posted January 6, 2019 The diff arrived with a label saying "No Oil" which I've read to mean its dry. I've also managed to fill an entire 1litre bottle without loss via the lower plug.I am concerned I can't locate any additive yet?? Link to comment Share on other sites More sharing options...
CharlesElliott Posted January 6, 2019 Share Posted January 6, 2019 It's probably a sachet - maybe you have to buy it yourself.....What gearbox oil are you using and where did you get it from? Link to comment Share on other sites More sharing options...
mike150 Posted January 6, 2019 Share Posted January 6, 2019 Just fill oil in the top hole until the oil runs out of the large lower hole. Link to comment Share on other sites More sharing options...
CtrMint Posted January 6, 2019 Author Share Posted January 6, 2019 Charles I've used the Motual shown in the picture,all the fluids came with the kit. Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted January 6, 2019 Area Representative Share Posted January 6, 2019 The fill hole utilises a 14mm hex plug the hole for which is angled upward slightly.About 1.2L will fill to over flowing.If the oil you have used does not state LSD or LS GL5 on the label then yes you will need to add the LSD additive part way through the filling process to ensure it mixes. The LUBGUARD additive should be included with the kit.Is the oil 80w/90 or similar? You will find over time that this oil is not man for the job as far as a BMW LSD is concerned. After five years I have found the oil that keeps the LSD relatively quiet, including knocking & has a good in service life: Castrol Syntrax LSD 75w/140 GL5. Other similar oils are available including Red Line. Motoil 75w/140 is the oil advertised in the CC shop for LSDs.In my build manual CC specified EP90 which to me is a spec just a tad out of date Then a few year down the line one has to wait & see if the out put seals start to leak.......but that is another story. Link to comment Share on other sites More sharing options...
CharlesElliott Posted January 6, 2019 Share Posted January 6, 2019 That Motul doesn't need an LSD additive (but please double check on the label). Link to comment Share on other sites More sharing options...
SM25T Posted January 6, 2019 Share Posted January 6, 2019 I can see the 75W/140 in his photo .... for the diff. Link to comment Share on other sites More sharing options...
CtrMint Posted January 6, 2019 Author Share Posted January 6, 2019 Will grab the bottle out of the bin to double check, but the front defo said LSD. Link to comment Share on other sites More sharing options...
mike150 Posted January 6, 2019 Share Posted January 6, 2019 How often does the BMW LSD oil need changed? Link to comment Share on other sites More sharing options...
CharlesElliott Posted January 6, 2019 Share Posted January 6, 2019 Great, no additive required then. Link to comment Share on other sites More sharing options...
John Vine Posted January 6, 2019 Share Posted January 6, 2019 As Charles says, that Motul oil doesn't require an LSD additive as it already contains a friction modifier (see this Opie Oil info). JV Link to comment Share on other sites More sharing options...
CtrMint Posted January 6, 2019 Author Share Posted January 6, 2019 Thanks all. Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted January 7, 2019 Area Representative Share Posted January 7, 2019 Mike 150 (post # 18) - Not sure as to the period between oil changes for an LSD if at all. The oil does get a fair mashing in use so I would suggest every five years which I do irrespective of mileage. I only do about 4000 a year.I may just drop Castrol a line & see what they say. Link to comment Share on other sites More sharing options...
CtrMint Posted January 7, 2019 Author Share Posted January 7, 2019 Here's my blog on the activity should anyone be interested, and I'm always interested in feedback. https://www.caterham7diaries.com/420r/filling-the-limited-slip-differential-lsd-with-oil Link to comment Share on other sites More sharing options...
ScottR400D Posted January 7, 2019 Share Posted January 7, 2019 In all honesty that seems a long winded way to fill the diff. By all means lift the floor to improve visibility but using a Pela to extract and a Sealey mini pump to refill changing the diff oil is no more than 30/45 minutes. The same pump makes refilling the box a doddle too. How’s the nose/rad fitment going? Link to comment Share on other sites More sharing options...
CtrMint Posted January 7, 2019 Author Share Posted January 7, 2019 Currently waiting for Derek @CC to test fit a replacement 'race' radiator and ship to me. Plan is to provide one which fits under the nose cone. Link to comment Share on other sites More sharing options...
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