stevefoster Posted April 22, 2003 Share Posted April 22, 2003 I had a 2nd hand AP suretrac LSD unit fitted into a Sierra diff carrier (work carried out by a reputable transmission, Caterham knowledgeable place). This is the only thing I have changed. It does what it says on the tin and kicks in as it should or at least as far as I can tell on the road. BUT the car shakes badly at speed, straight line or curves no difference. Most noticeably above 70 mph when it's getting pretty unpleasant to drive. It is def not front wheel balance as the whole car is shaking and through my backside. I have checked rear wheel balance and cannot see any weights missing. No noise to give away any problems either. I am questioning my mounting of the propshaft but assume this is just a bolt up affair. Any ideas? Link to comment Share on other sites More sharing options...
Colin Grundy Posted April 23, 2003 Share Posted April 23, 2003 Steve Are you sure when mounting the diff you mounted it with the correct amount of spacers either side to ensure it is central. If not the drive train will not be inline and could cause vibrations. Would suggest you check the gearbox mounting rubber as well. Link to comment Share on other sites More sharing options...
Graham Perry Posted April 23, 2003 Share Posted April 23, 2003 Also check your propshaft. When fitting the diff, you may have accidentally knocked off the balance weight. Also check that the Universal joints are not about to fail. It sounds unlikely I know but I have heard of this with a tin top. Link to comment Share on other sites More sharing options...
stevefoster Posted April 23, 2003 Author Share Posted April 23, 2003 Thanks guys, The diff is central to within 0.25 mm (checked with my natty digi vernier). All the blue bolts were torqued up to manual rec and are still in place and the shaft / flange run true to each other. Propshaft balance weights. Not seen any on my propshaft ever (I have greased her a few times too). I will check closer. Certainly nothing dropped on my garage floor. I am also currently suspecting tyre balance after a puncture repair. I have never felt anything as bad as this but then never had a tyre out of balance on the 7. You do sit right over the things and it is light so easier to shimmy I guess. My racing pics, 7 DIY, race prep. Updated often here Photo's of the year here Hants (North) and Berkshire Area club site here Edited by - stevefoster on 23 Apr 2003 10:07:47 Link to comment Share on other sites More sharing options...
J.R. Posted April 23, 2003 Share Posted April 23, 2003 Hi steve. So changing the diff was the only thing you did "apart from the puncture repair" then? 😬 😬 😬 Link to comment Share on other sites More sharing options...
stevefoster Posted April 23, 2003 Author Share Posted April 23, 2003 yep Oh and fitted rear aeroquip hoses instead of the copper ones / bled the brakes and charged the battery, refitted the headlights, put the number plates and tax disc back on.. yep that's about it... My racing pics, 7 DIY, race prep. Updated often here Photo's of the year here Hants (North) and Berkshire Area club site here Edited by - stevefoster on 23 Apr 2003 12:15:21 Link to comment Share on other sites More sharing options...
F355GTS Posted April 23, 2003 Share Posted April 23, 2003 It'll be the Headlamps upsetting the sleek lines and causing wind resistance 😬 sorry no help at all... Mark Link to comment Share on other sites More sharing options...
stevefoster Posted April 23, 2003 Author Share Posted April 23, 2003 Not the diff but the puncture repair. To verify this I popped a trusty ZX front on the rear of the 7. 4.25" PCD or whatever that is in French! Polish make of tyre, imPotenzia or something. Took it easy to start with but it actually gripped quite well sparring with a 2mm tread depth 021. No vibe at all even at speed So I hope to be chewing past your tail this time Rob.... New slicks are going on tomorrow. My racing pics, 7 DIY, race prep. Updated often here Photo's of the year here Hants (North) and Berkshire Area club site here Link to comment Share on other sites More sharing options...
F355GTS Posted April 23, 2003 Share Posted April 23, 2003 Steve good to hear you got it sorted and it wasn't my old LSD Mark Link to comment Share on other sites More sharing options...
mav Posted April 23, 2003 Share Posted April 23, 2003 108mm 😬 Link to comment Share on other sites More sharing options...
stevefoster Posted April 23, 2003 Author Share Posted April 23, 2003 F355, It feels quite nice on the road when provoked. Not causing understeer and a nice controlled oversteer. Course, track time will tell. My racing pics, 7 DIY, race prep. Updated often here Photo's of the year here Hants (North) and Berkshire Area club site here Link to comment Share on other sites More sharing options...
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