CtrMint Posted January 7 Share Posted January 7 Morning All, I’m starting the process of swapping out my diff on the 620R, I’ve a shiny new Drexler to be fitted. I understand how to remove and fit the diff based on my experience building my 420R, but that’s basically a complete deconstruction of the rear end. Basically all hardware from Dedion, A frame etc gone. I’m wondering if there’s any short cuts to get the diff out, that will save me removing everything? Thanks Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 7 Member Share Posted January 7 Hw much are you replacing? Will you keep the existing carrier? Jonathan Link to comment Share on other sites More sharing options...
CtrMint Posted January 7 Author Share Posted January 7 I need to reuse the carrier, the new diff isn’t in a carrier at present. Link to comment Share on other sites More sharing options...
BigCol Posted January 7 Share Posted January 7 @ScottR400D kindly sent me a summary of the process when I removed my diff last year… I’ll forward it to you by BlatMail (but yes, it is mostly ripping the rear end ifg! 🤷🏻♂️) Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted January 7 Area Representative Share Posted January 7 You can drop the diff without removing the cage from the chassis. Also there is enough room to drop the diff without removing the De dion tube just ! Obviously the hubs & drive shafts will have to come out. Some here have a short cut by removing the whole hub, carriers & drive shafts complete. It has it's merits in that there is less to disassemble but one may miss things that potentially require replacement. Also it is wise to check the torque loading of the hub nut after reassembly. When dropping my diff I went the whole hog as the car at that point in time was eight years old. Glad I did as there was a lot of corroded bolts etc & I could inspect the De dion tube closely. Also I upgraded the rear bearings to the latest spec. It may be wise to manufacture a Diff jig to remove & refit as the BMW diff is more of a problem on the top of a jack than the Type 9. Pictures attached. Link to comment Share on other sites More sharing options...
CtrMint Posted January 7 Author Share Posted January 7 Thanks, this isn’t the BMW diff as it’s on the 620R. Hopefully nothing needs replacing as a Tracsport went in last year, fitted by PGM, so I might try the short cut. If I can avoid releasing the drive nuts that would certainly be handy! Link to comment Share on other sites More sharing options...
BigCol Posted January 7 Share Posted January 7 11 minutes ago, CtrMint said: If I can avoid releasing the drive nuts that would certainly be handy! Shouldn’t need to…. should be able to remove hubs and drive shafts together as a sub-assembly. Link to comment Share on other sites More sharing options...
7 wonders of the world Posted January 7 Share Posted January 7 Why are you taking the Tracsport final drive out....? Link to comment Share on other sites More sharing options...
CtrMint Posted January 7 Author Share Posted January 7 Surprisingly it f’ing noisy, road driving it’s awful. It was the only diff available just before a track day. It’s come it Link to comment Share on other sites More sharing options...
7 wonders of the world Posted January 7 Share Posted January 7 What noises Mark.... I'm guessing final drive noises not LSD noises...? Link to comment Share on other sites More sharing options...
CtrMint Posted January 7 Author Share Posted January 7 Possibly, it was a complete unit. After it went in it was awful. My old final drive is in my original casing mated to a Drexler. Hopefully it will be reliable and back to similar noise levels. Though I can’t get the handbrake to slacken at the moment so it may have to stay for another season! 🤨 Link to comment Share on other sites More sharing options...
7 wonders of the world Posted January 7 Share Posted January 7 Where did you source the donor Sierra final drive from and who built it...? So why swap the LSD the too.. You didn't mention what noises you were getting.. Link to comment Share on other sites More sharing options...
CtrMint Posted January 7 Author Share Posted January 7 I don’t really want to get into naming the history of the current unit, as I’m happy with the servicing etc, and don’t want the thread to look like I’m having a knock at them. I made the decision and bought the replacement diff, so it’s going in. To me it made sense to have a spare being located on the island. Diff rebuilds due to shipping etc are a PITA. Link to comment Share on other sites More sharing options...
ScottR400D Posted January 7 Share Posted January 7 (edited) Any noise is going to be the CWP so a chance that the ‘new’ one might be better. Also you may be able to have the noisy one set up to be less noisy and you have a great spare. Edited January 7 by ScottR400D Link to comment Share on other sites More sharing options...
CtrMint Posted January 7 Author Share Posted January 7 The 'new' one is my original CC housing and CWP, when the Tracsport was fitted the original diff went to Road and Race Transmission for the Drexler. It's been sitting on my worktop since September 2023. I'm properly stuck sadly. I've removed the driveshafts. hubs and brakes, though the brakes are still attached via the handbrake cable. The plastic adjuster is seriously tight and I can't move it, the handbrake has minimal movement too. I figure with the diff out I'll have better access. Getting the diff out has come to halt as I just can't move the prop bolts. I'm working on axle stands so can't get a breaker bar on them. Any tricks for this, I'm at the point where I think I have to take the tunnel cover off to go in through the top, but since the handbrake is so tight I'll struggle getting the handbrake lever up to permit the tunnel cover to be removed. Going at the prop bolts from underneath is still probably the best idea, but I've run out of ideas on how to get them moving. Link to comment Share on other sites More sharing options...
7 wonders of the world Posted January 7 Share Posted January 7 I assume you have the car in gear, ask SWMBO to climb aboard and hold her foot on the brake whilst you crack the prop bolts, ring spanner and a swift clout with a mallet with move them, rotate the prop 90 degrees each time Get yourself a pair of adjustable pliers to hold the main plastic handbrake cable adjuster.... then another pair of pliers or grips the plastic lock nut, once free it will be finger tight. Link to comment Share on other sites More sharing options...
CtrMint Posted January 7 Author Share Posted January 7 Hmm I’ve removed the brakes and drive shafts etc. 😪 Link to comment Share on other sites More sharing options...
ScottR400D Posted January 7 Share Posted January 7 Can you raise the car more so you can get a longer bar on? Neil’s right about method but as you realise that needs to be one of the first jobs. I used to find in gear with handbrake hard on and a quick tap of a 400mm bar would get them loose. Maybe you could try in gear with a bar and a tap if you can raise the car? I guess something through the UJ to lock it might work but not very good practice. Strap wrench round the prop to hold it? Link to comment Share on other sites More sharing options...
Englishmaninwales Posted January 7 Share Posted January 7 (edited) I jam the prop with a hefty screwdriver through the front UJ and lower tunnel chassis tube. Socket with an extension on the prop bolt, with everything correctly lined up. Never done any damage. Edited January 7 by Englishmaninwales Link to comment Share on other sites More sharing options...
7 wonders of the world Posted January 7 Share Posted January 7 carefully you don't snap the grease nipples if you have them though by locking thro the UJ's Link to comment Share on other sites More sharing options...
Englishmaninwales Posted January 7 Share Posted January 7 You need to pick a gap through the UJ without the grease nipple otherwise the screwdriver won’t fit through. Link to comment Share on other sites More sharing options...
DirtBuddha Posted January 8 Share Posted January 8 Ive just removed the diffs from both of my Caterhams as Im swapping them over. I did what others have suggested - used a pry bar (carefully) through the prop UJ to stop it turning while undoing the prop-to-diff bolts. Link to comment Share on other sites More sharing options...
CtrMint Posted January 9 Author Share Posted January 9 I guess they've been gunned up tight or I'm a weakling 😄 I've ordered a new compact impact gun to help, I should be able to get that on an extension into the transmission tunnel and hopefully free them off. Dewalt DCF921P2T-GB 609nm break away, so should be sufficient. Unfortunately Screwfix just called and told me their warehouse cancelled the order, and would I like to reorder. FML 😆. ETA an additional 4 days for that. Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted January 9 Share Posted January 9 2 hours ago, CtrMint said: I guess they've been gunned up tight or I'm a weakling 😄 I've ordered a new compact impact gun to help, I should be able to get that on an extension into the transmission tunnel and hopefully free them off. Dewalt DCF921P2T-GB 609nm break away, so should be sufficient. Unfortunately Screwfix just called and told me their warehouse cancelled the order, and would I like to reorder. FML 😆. ETA an additional 4 days for that. One issue you might have with the impact gun, Mark, is that the head may be too large to get the hex bit squarely into the bolt, risking rounding it off. The break-away torque should be easy to overcome with a breaker bar, but the car will need to be at least 50cm off the ground to get enough access, so needs axle stands that are larger than the standard ones. Link to comment Share on other sites More sharing options...
CtrMint Posted January 9 Author Share Posted January 9 I went back to it this evening for an hour or so. Used an old Sealey 1/2" torque wrench covered in rags, having put my entire body behind them I've 3 out. There's traces of some form of thread locking agent on the threads, so I'm going to replace the bolts. I didn't take the 4th out as I didn't have time for dealing with the prop etc. But at least that's progress. James wrt to the impact gun, I've bought some super long hex sockets, and also impact UJs, but still waiting for those to arrive, island life. 😄 WRT to replace the bolt, I can see they're caphead M10x20, grade 12.9, I assume any bolt with CoC meeting the spec will be acceptable? thanks 1 Link to comment Share on other sites More sharing options...
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