Joel Posted May 23, 2023 Report Share Posted May 23, 2023 Hello all. The mounting plate on the diff on my mark 2 has cracked and the spring and bolts have detatched themselves. I've removed the diff and have found one on Ebay from a Mk4 Spit. Will this fit? "Marked FH so 3.89 from a MK4 but also suitable for some other models" Link to comment Share on other sites More sharing options...
JumpingFrog Posted May 23, 2023 Report Share Posted May 23, 2023 Spitfire Mk. IV is equivalent, but one caveat, usually the Spitfire Mk. IV casings had 2 of the spring stud holes blanked off (actually something like a crude cut-off bolt/stud). You'll need to either remove these plugs or drill and tap the holes if you want to have all 6 spring mounting studs. 1 Link to comment Share on other sites More sharing options...
Josef Posted May 23, 2023 Report Share Posted May 23, 2023 Looks like the ratio should be the same https://www.teglerizer.com/triumphstuff/spit_and_gt6_specs.htm I’m not well up enough on diffs to say anything for certain though. Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 23, 2023 Report Share Posted May 23, 2023 to add the extra holes drill 8.3mm tap 3/8x24 Unf use the top plate as a jig drilled mine with a battery drill easy drill down about 25mm you wont break through . Pete 1 Link to comment Share on other sites More sharing options...
johny Posted May 23, 2023 Report Share Posted May 23, 2023 Yes nobody knows if 4 holes is enough but a non swing spring probably puts more stress on fixing than the original set up... Link to comment Share on other sites More sharing options...
Joel Posted May 23, 2023 Author Report Share Posted May 23, 2023 Again, thanks to you all for helping me along with this! The old one is REALLY done! I'm going to have a chat with the Ebay seller and discuss the wear/age issues on the one he's selling but otherwise, it looks like a recon from Rimmers. A grand is a bit steep so if I can drill the 2 extra stud holes, this would be prefereable. Thanks to Johny, Pete (as always) Josef and Jumping Frog for the advice and hand holding!! Link to comment Share on other sites More sharing options...
johny Posted May 23, 2023 Report Share Posted May 23, 2023 Wow that is an advert for having all six fixings. However it looks as if its only the rear casing thats damaged and theres nothing important in that part. So if theres nothing wrong with the gears and bearings they can be very easily transferred to another case.... Link to comment Share on other sites More sharing options...
Josef Posted May 23, 2023 Report Share Posted May 23, 2023 Shoot Mike Papworth an email (details should be in the courier ad or I can send over his email address) before going to Rimmers. He will be able to give you advice, almost certainly supply you with a replacement case, or sell you a recon if that’s what you end up needing. He’s probably rebuilt more TSSC gearboxes and diffs than the whole of this forum membership put together! Link to comment Share on other sites More sharing options...
ahebron Posted May 24, 2023 Report Share Posted May 24, 2023 To me that damage looks like bolts or studs bottoming out in the holes then being gorilla-ed a little bit more tight. Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 24, 2023 Report Share Posted May 24, 2023 i cant see anything in normal life that would wreck the case apart from some serious demolition process i mean thats pretty unbelievable damage Pete Link to comment Share on other sites More sharing options...
johny Posted May 24, 2023 Report Share Posted May 24, 2023 Could be but must have been some gorrilla to do it repeatedly😂 Link to comment Share on other sites More sharing options...
ahebron Posted May 26, 2023 Report Share Posted May 26, 2023 A gorilla with a rattle gun is a very dangerous beast. Link to comment Share on other sites More sharing options...
Joel Posted May 31, 2023 Author Report Share Posted May 31, 2023 It would appear that the studs were re-threaded (or at least two of them were) at some point and a new top plate fitted. I decided to avoid a rebuild as the crown wheel is pretty worn (perhaps the source of a whine over 50 mph?) so contacted Fitechet's who were able to supply a recon. Don't think I'll get anything back from them for the old one though!! Anyone want it? Link to comment Share on other sites More sharing options...
johny Posted May 31, 2023 Report Share Posted May 31, 2023 Think whine is much more likely to be a bearing. In fact Ive never seen an obviously worn gear set and I think the recon units are just used gears rebuilt with new bearings👍 Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 31, 2023 Report Share Posted May 31, 2023 agree bearing whine , mesh howls Pete Link to comment Share on other sites More sharing options...
johny Posted May 31, 2023 Report Share Posted May 31, 2023 And I take it Pete howl can be reduced with the correct shim adjustment? Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 31, 2023 Report Share Posted May 31, 2023 theres a few things the pinion brgs are shimmed /collapsible to get pre load on the pinion brgs mesh involves setting the mounting distance and backlash to set the pinion aligned with the crownwheel with shims under the head of the pinion the small backlash/tooth clearance is shim the carrier brgs unless you have some decent measuring equipment its hopeless and easy to make a howler Pete 1 Link to comment Share on other sites More sharing options...
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