hallmark Posted December 2, 2023 Share Posted December 2, 2023 Hi everyone, I've bought myself a new diff for Christmas but I've got a problem with the passenger side lower diff mount - I just cant get it to align properly with the chassis mount, it's approx a millimetre or two out. Everything else aligns perfectly and I've tried installing the carrier first without the diff just in case that was applying any 'influence' on the shape of the carrier but it's still the same. I've also tried installing the bolts to the lower mounts first, but then I cant get the top carrier (with the long bolt) to align. My previous diff carrier aligned without any issues at all, but that unfortunately doesn't fit the new diff. Is there a secret to aligning these, or has anyone got a work around? Thanks 🙂 Mark Link to comment Share on other sites More sharing options...
Phil G Posted December 2, 2023 Share Posted December 2, 2023 The SOP appears to be brute force Mark. Assuming you're replacing like for like........ Mount diff onto carrier first > grind a slight taper on the long bolt > install lower mount hand tight with appropriate spacer washers > offer up long bolt and belt the s**t out of it > swear a lot when the spacer washers drop out > apply band-aid to grazed knuckles! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted December 2, 2023 Member Share Posted December 2, 2023 You've already tried with and without the carrier. There's one story in the archives where a bit of jacking made the difference. Jonathan PS: Do you have John Vine's diagram with the correct positioning of the Schnorr washers? PPS: Full search of the archives. Link to comment Share on other sites More sharing options...
hallmark Posted December 2, 2023 Author Share Posted December 2, 2023 Thanks both for the replies, I've got to say I did laugh out load at your suggestion Phil - I think that approach could also be quite therapeutic! I'll read through more of the archive links Joanthan sent through first, just in case but I've got a feeling I'm going to need to get the BandAid's out ready! Link to comment Share on other sites More sharing options...
John Vine Posted December 2, 2023 Share Posted December 2, 2023 When I built my R400D, I couldn't line up the lower (Ford) diff mounts: I asked CC, and their advice was pretty much what Phil G said above. That's what they do in the factory, they assured me, and reckoned the only variable was the size of the mallet. Oh, and jacking helps a lot: JV Link to comment Share on other sites More sharing options...
Phil G Posted December 2, 2023 Share Posted December 2, 2023 (edited) Whist said with tongue firmly in cheek there was an element of truth in what I suggested......as John will attest. Edited December 3, 2023 by Phil G Link to comment Share on other sites More sharing options...
hallmark Posted December 2, 2023 Author Share Posted December 2, 2023 Thanks John - that's pretty much exactly what I'm seeing so I think I'll crack on as suggested. Hope I can save the skin on my knuckles! 1 Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted December 4, 2023 Area Representative Share Posted December 4, 2023 When fitting my BMW diff I made a a long bullet from rod similar to the dia of the top bolt. Lots of grease & a carefully utilised lump hammer to assist the way through. ⚒️ Upward pressure from a jack accompanied by much swearing & cursing does help. When dropping the diff for the TITAN change I left the carrier in. Expecting problems on refit the unexpected pleasure was that all the diff fixings glided in. Obviously on original build hole realignment had been carried out ! Link to comment Share on other sites More sharing options...
Old Caterhamian Posted December 4, 2023 Share Posted December 4, 2023 Very similar solution. After wasting a day as you described, CC advised me to use a thin long screwdriver (found cheap one on amazon) to hold the top of bmw diff, gives more movement whilst sorting bottom bolts. Then once bottom bolts are finger tight, use the persuader knock the top bolt in (and screwdriver out). The top bolt is held in bushes that flex as you knock the top bolt in, so with bit of force it lines up. Link to comment Share on other sites More sharing options...
Phil G Posted December 5, 2023 Share Posted December 5, 2023 (edited) How do I delete a duplicate comment????? Edited December 5, 2023 by Phil G Link to comment Share on other sites More sharing options...
Phil G Posted December 5, 2023 Share Posted December 5, 2023 On 04/12/2023 at 15:58, Old Caterhamian said: Very similar solution. After wasting a day as you described, CC advised me to use a thin long screwdriver (found cheap one on amazon) to hold the top of bmw diff, gives more movement whilst sorting bottom bolts. Then once bottom bolts are finger tight, use the persuader knock the top bolt in (and screwdriver out). The top bolt is held in bushes that flex as you knock the top bolt in, so with bit of force it lines up. K Series cylinder bolts are just the ticket! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted December 5, 2023 Member Share Posted December 5, 2023 11 minutes ago, Phil G said: How do I delete a duplicate comment????? I don't know a way. You can remove the contents using the ... button and then Edit. Jonathan Link to comment Share on other sites More sharing options...
Tom_Arundel Posted December 6, 2023 Share Posted December 6, 2023 I fitted the front bolts then sat it on a jack.....lined up the top holes as best they would and ran a half inch drill through the top bushes and diff casing......All fine for 50K miles. Maybe if you force the bolt through then you will preload the bushes and transmit more noise....just a thought Link to comment Share on other sites More sharing options...
hallmark Posted December 14, 2023 Author Share Posted December 14, 2023 Hi everyone, Well, the lower bolts went in, aligned the top ones as best I could, used the grinder to create a 45 degree 'slope' on the long bolt, covered it in copper grease and gave it a tap - didn't work. Tapped it again (slightly harder) - no effect. Thought "**** it, give it a hell of whack" and it went in perfectly 🙂 Torqued everything up and tried the new diff yesterday - wouldn't know its there sound wise so I'm happy! Thanks again to you all for helping out, it's appreciated 🙂 Mark 2 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted December 14, 2023 Member Share Posted December 14, 2023 Well done. Thanks for adding the outcome. Jonathan Link to comment Share on other sites More sharing options...
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