Q Catcher Posted June 27, 2017 Share Posted June 27, 2017 The car's a 2002 K Series with a de Dion and LSD. It's making terminal-sounding clunking/graunching/drumming from the rear and is getting very reluctant to go round corners. (Be in no doubt - this is not trivial.)I have always been given to understand that the diff is from an XR4i. (Is this true?) Does anyone know if it's a straight swap for an ordinary Sierra diff (Chassis mounts, splines, ratio ..?) by any chance, as I don't really need the limited slip feature.Once I've decided whether to replace like-for-like or swap to an open diff, I then need to source a good 'un. Apart from the usual searches on eBay, etc, can anyone recommend a good source that they've used?Many thanks Link to comment Share on other sites More sharing options...
elie boone Posted June 27, 2017 Share Posted June 27, 2017 The diff is Sierra 7" found in most Sierra's except for the Cosworth 3 door that is a 7.5" diff and diff's with factory LSD should be avoided also as mostly they don't work in a 7 but also they normally have a fixed flange for the halfshaft. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 27, 2017 Member Share Posted June 27, 2017 I can't remember the details, but not all Sierra final drives are suitable. (Edited: crossed with elie's.)Have you decided what ratio you want?Jonathan Link to comment Share on other sites More sharing options...
SM25T Posted June 27, 2017 Share Posted June 27, 2017 Can you remove it and send it to someone like Road & Race who can rebuild it or change the spec .... whatever you need Link to comment Share on other sites More sharing options...
Q Catcher Posted June 27, 2017 Author Share Posted June 27, 2017 Thanks. I'll see if I can post some photos. Link to comment Share on other sites More sharing options...
Q Catcher Posted June 27, 2017 Author Share Posted June 27, 2017 I'd like to get the car ready for the 60th celebrations, so will sending it to Road & Race meet that timescale? I was thinking that just buying another and installing it would be quicker.As for ratio, I want the same as at present, surely?Can anyone remind me how to do pictures? (Edited: Found the User Guide - thanks, Jonathan.) Link to comment Share on other sites More sharing options...
Wrightpayne Posted June 27, 2017 Share Posted June 27, 2017 Be aware there was a 6.5" diff fitted to some Sierra's which looks the same in pictures - ask me how I know!!Normally, 5 speed is a 3.9 and 6 speed is a 3.6 ratio. I know Nick Chan had a 3.9 open diff available earlier in the year.Ian Link to comment Share on other sites More sharing options...
Q Catcher Posted June 27, 2017 Author Share Posted June 27, 2017 Thank you. The car has a 5-speed box, so it'll be 3.9 that I need. Link to comment Share on other sites More sharing options...
SM25T Posted June 27, 2017 Share Posted June 27, 2017 Phone Phil Stewart at R&R 01959 525105 and explain your predicament. See what he can offer. Link to comment Share on other sites More sharing options...
Q Catcher Posted June 27, 2017 Author Share Posted June 27, 2017 As seen from the underside, RHS, LHS and the rear plate. Any use in identifying it? Link to comment Share on other sites More sharing options...
Q Catcher Posted June 27, 2017 Author Share Posted June 27, 2017 Phil Stewart's obviously sensible enough to go home on time, so I'll try his number again in the morning. Link to comment Share on other sites More sharing options...
Paul McKenzie Posted June 27, 2017 Share Posted June 27, 2017 Just standard diff, the tab in the last picture might carry the ratio or it'll be on it somewhere - Phil will have hundreds of the standard crownwheel and pinions Link to comment Share on other sites More sharing options...
TomB Posted June 27, 2017 Share Posted June 27, 2017 If your desperate to get it fixed for the 60th, Id be putting out feelers now to borrow one to get you to Donnington. I bet someone somewhere will have a spare. I doubt very much anyone will be able to rebuild it and return for installation with 10 days to go. Link to comment Share on other sites More sharing options...
Roadsport06 Posted June 27, 2017 Share Posted June 27, 2017 SPC would turn it around in that time. No more than a morning's work dropping it back into the car either. Link to comment Share on other sites More sharing options...
Q Catcher Posted June 27, 2017 Author Share Posted June 27, 2017 Who are SPC? Link to comment Share on other sites More sharing options...
Wrightpayne Posted June 27, 2017 Share Posted June 27, 2017 Steve Perks - based in Redditch. One of the few experts on ford and caterham gearboxes and diffs. Designs and engineers improved gear sets and components too.Ian Link to comment Share on other sites More sharing options...
Q Catcher Posted June 28, 2017 Author Share Posted June 28, 2017 Thank you Link to comment Share on other sites More sharing options...
Q Catcher Posted July 1, 2017 Author Share Posted July 1, 2017 So ... looks like we wuz mostly very wrong. Clearly, everything had got very hot (driving in 41 degree heat in Portugal, after all) and the driveshafts were rather stuck in the diff and had to be knocked out, but the main source of the noise was the propshaft. Not your conventional propshaft knocking at all, but a loud rumbling/graunching that was worse on the overrun and worst of all on corners. It turns out the propshaft rear UJ had broken and was only just hanging together.Following the recommendation further above in this thread, I took the diff to Phil Stewart at Road & Race (at Shoreham, near Sevenoaks), who examined it and concluded that it's serviceable. His firm advice is to use a different oil. I'd been using Caterham's own branded oil, which was at the correct level - whereas Phil recommends Castrol 373. Phil clearly knows his stuff, and is a Sevener himself, and says that this particular model of diff is very robust, so the diff is going back in.As for the prop, there was a clear arc of grease all round the transmission tunnel above the rear UJ. And, as mentioned, the UJ itself is utterly cream-crackered. The prop is now with Propshaft Services (part of Bailey Morris, the Caterham prop manufacturers) in Feltham for new UJs and balancing. I should be able to collect it on Monday. When I handed it over, the technician expressed surprise that it was still actually propelling a car (in fact, he used a technical term for it). As for which came first - the grease exiting or the UJ failing - we can but speculate. Link to comment Share on other sites More sharing options...
Wrightpayne Posted July 1, 2017 Share Posted July 1, 2017 Throwing of grease happens when you pump new grease in using a grease gun. It forces the old grease out which is difficult to clean out of the middle of the UJ.Ian Link to comment Share on other sites More sharing options...
Q Catcher Posted July 4, 2017 Author Share Posted July 4, 2017 Aha, but ... having now cleaned the inside of the transmission tunnel, I can say that:- the grease arc above the front UJ was quite narrow and mostly brown.- the grease arc above the rear UJ was rather wider, fuller and mostly charcoal in colour.I notice that the grease nipples on the new UJs are thinner and longer - they look much more useable than the old ones. Link to comment Share on other sites More sharing options...
Tom_Arundel Posted July 5, 2017 Share Posted July 5, 2017 They are prone to breaking off if you are not careful with the grease gon ! Link to comment Share on other sites More sharing options...
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