Mark H Posted November 21, 2001 Share Posted November 21, 2001 Does anyone know if it is possible to rebuild a sierra diff, in to LSD spec, if yes who makes the parts ? any idea how much i should expect to spend ? . And is it worth it for a road car ? smile.gif Mark wink.gif Link to comment Share on other sites More sharing options...
Nick M Posted November 21, 2001 Share Posted November 21, 2001 Does anyone know if it is possible to rebuild a sierra diff, in to LSD spec, if yes who makes the parts ? any idea how much i should expect to spend ? . And is it worth it for a road car ? Yes, it certainly is. You have 3 obvious choices that I can think of : 1. Get a Sierra 4x4 LSD - ratio is usually 3.62 unless you're lucky enough to find one from a 2.0 4x4. You could, however, get Road and Race Transmissions to put a 3.9 crown wheel and pinion on the LSD. Cost - £100 for a second hand diff and about £100 for Road and Race to do the CWP swap. 2. Quaife ATB diff - but you may need to check what output flanges you have as the Quaife one isn't directly compatible with the Lobro type joints. This option allows you to stick with your existing diff ratio. Cost - diff is, I think, about £500 but if you need to swap the output flanges it might end up being more. Add fitting to that cost as well. 3. Tran-X plate type diff - more adjustable that the ATB diff in that settings can be changed more easily. No problems with compatibility of the internals with either Lobro or tripod joints. Again it allows you to keep the same diff ratio. Cost - something from about £400-£450 from memory + fitting. I'm not sure which LSD Caterham fit at the moment but that may well be another option. Link to comment Share on other sites More sharing options...
R2D2 Posted November 21, 2001 Share Posted November 21, 2001 I think that the Tran-x operates with a pre-load unlike the Quaife that cannot be pre-loaded. Link to comment Share on other sites More sharing options...
Rob Walker Posted November 21, 2001 Share Posted November 21, 2001 The Seirra 4X4 diff is a viscous type and not very effective in its stock settings, also AFAIK the driveshaft connection to this unit is different to the standard Caterham. Caterham currently fit the ZF plate type diff. This can be fitted to the standard Caterham Seirra diff casing and can be optimised for the Seven by Road& Race transmission. The unit cost is about £600 and fitting £75 Link to comment Share on other sites More sharing options...
murph7355 Posted November 21, 2001 Share Posted November 21, 2001 All in, including softening the preload (35-40lbsft rings bells, and the ramp angles will be 30deg, whatever they are) to suit a 7 the unit is 700+VAT from R&RT. If you give Phil notice (to get the bits in) he can turn it round in a day if you ask nicely. Unless Chris Clark's there with his hammer of course. Link to comment Share on other sites More sharing options...
Graham Perry Posted November 22, 2001 Share Posted November 22, 2001 I concur with what Rob says re the Sierra 4x4 diff, from when I looked at this . The shafts need to be heavily modified, which made it uneconomic compared to the other options Link to comment Share on other sites More sharing options...
WILL FLY Posted November 22, 2001 Share Posted November 22, 2001 Marc Assuming you've got a Caterham and not a n other Se7en, then the sierra option is not very econimical. I know I started down that route. The sierra unit has lobros (bolt on driveshafts) whereas the caterham uses splied slide in ones with tripods. If it is a caterham then the options are Quaife or ZF, I'm leaning towards a Quaife unit for a coupel of reasons. They're more suited for road use in that they're more progressive than a ZF unit which may cause the back end to 'snatch' when it engages. The quaife is cheaper. Unfortunately the bias on a quaife is not adjustable like the zf, but the opinion is with a ZF to set the ramp angle to 30 degrees rather than 45 degrees which I think is the norm for non se7ens. I spoke to Steve at SP Components 01527 894232. Road adn Race Transmissions 01959 525105 (Phil Stewart) was also quite good. If you're interested in a Quaife unit call me on 0207 542 5105, I'll see if they'll give me discount for a bulk order for cash. BTW If I've been talking b*llocks, then anyone in the know, please feel free to chuck in your two penneth. Roy See willfly.net for more info. If you don't spin you ain't trying smile.gif Link to comment Share on other sites More sharing options...
Rob Walker Posted November 22, 2001 Share Posted November 22, 2001 Roy, Don`t let anyone tell you the ZF is hard to live with its not and its action can be tailored to your requirements. Its a super bit of kit I am very pleased with it. Link to comment Share on other sites More sharing options...
WILL FLY Posted November 22, 2001 Share Posted November 22, 2001 Thanks Rob, I'm getting conflicting eports from two supposedly reputable diff 'experts' Steve @ SPC and Phil at Road and Race Transmissions. I've also been told that ZF's can be clonky and noisy especially when they wind up when reversing or turning round in a circle and they they 'slip' ?. I'm looking for something that isn't going to upset the car during road use but stop me spinning the inside wheel on hairpins on trackdays. I don't race or do sprints. See willfly.net for more info. If you don't spin you ain't trying smile.gif Link to comment Share on other sites More sharing options...
EFA Posted November 22, 2001 Share Posted November 22, 2001 ZF's are noisy when they wind up when reversing or turning round in a circle, but this effect is damped by compliance in the drivetrain - something 99% of Sevens have. Only if you run a race clutch do you get all the nasty noises. Out of the box the ZF is snatchy until it beds in. It is like a clutch in that respect, so when its new take it easy on wet roads (especially roundabouts) for a couple of hundred miles. In every other respect the ZF is the diff to go for. Fat Arn The NOW PROVEN R500 Eaterid=red> See the Lotus Seven Club 4 Counties Area Website hereid=green> Link to comment Share on other sites More sharing options...
WILL FLY Posted November 22, 2001 Share Posted November 22, 2001 Arnie What's wrong with the Quaife then ? See willfly.net for more info. If you don't spin you ain't trying smile.gif Link to comment Share on other sites More sharing options...
R2D2 Posted November 22, 2001 Share Posted November 22, 2001 The Quaife doesn't have any preload so when there is no torque on one wheel it behaves as a conventional diff. Link to comment Share on other sites More sharing options...
EFA Posted November 22, 2001 Share Posted November 22, 2001 Thanks Chris.... Fat Arn The NOW PROVEN R500 Eaterid=red> See the Lotus Seven Club 4 Counties Area Website hereid=green> Link to comment Share on other sites More sharing options...
WILL FLY Posted November 22, 2001 Share Posted November 22, 2001 So are you saying that if the inside wheel is in the air then it will spin. I can't see this happening that much on a road car, can you ? If there's anyone near Fleet with a ZF LSD'd car who'd let me have a drive this weekent (salt and rain permitting) please let me know. See willfly.net for more info. If you don't spin you ain't trying smile.gif Link to comment Share on other sites More sharing options...
R2D2 Posted November 22, 2001 Share Posted November 22, 2001 If you lift a rear wheel one will spin and the other won't drive, just like a standard diff.Lifting a wheel is not unlike getting the outside wheel on wet grass I would imagine. Link to comment Share on other sites More sharing options...
Paul Turner Posted November 22, 2001 Share Posted November 22, 2001 I have used both during my time with sevens, I started off with a Quaiffe in my Ital axled car (no option) and it was fine, you simply did not know it was there in normal driving but my times came down in sprints. When I bought the de-dion car it came with a ZF, a bit grumbly but no real problem but after a couple of years I noticed that I was struggling with rear end grip on the slower corners at Harewood. I checked the diff as advised and the torque setting was below new and well below that used by the VX racers. I had it shimmed and there was a great improvement in the dry but when I competed at a wet meeting it was very very twitchy. A couple of years ago I changed back to a quaiffe as a mate wanted another ZF so that he could have 2 diff ratios on identically set up diffs. As before its great, unnoticable on the road and does its job in sprints plus they are friendly in the wet. I was always led to belive that the wheel lifting problems were more concered with rally cars than racers, may be wrong. Paul Link to comment Share on other sites More sharing options...
WILL FLY Posted November 22, 2001 Share Posted November 22, 2001 Thanks paul, that was really helpful. If you get a minute can you ring me on 0207 542 5105 to discuss this further. See willfly.net for more info. If you don't spin you ain't trying smile.gif Link to comment Share on other sites More sharing options...
Mark H Posted November 22, 2001 Author Share Posted November 22, 2001 thanks everybody for the information, it seems my winter rebuild is getting longer and longer,still it can only make my 7 more fun than it already is ! Mark smile.gif Link to comment Share on other sites More sharing options...
Fast Westie Posted November 22, 2001 Share Posted November 22, 2001 I was always led to belive that the wheel lifting problems were more concered with rally cars than racers, may be wrong. It is a problem on race tracks when you bounce off a kerb The car in front is a Westfie1d wink.gif Edited by - Fast Westie on 22 Nov 2001 16:39:48 Link to comment Share on other sites More sharing options...
R2D2 Posted November 22, 2001 Share Posted November 22, 2001 There is another supplier of "Plate type" LSD's for the 7" Sierra Unit. Tran-X in Coventry have a suitable unit and they have several configurations of ramp angle available. http://www.tran-x.com/ I have used their diffs in Escort rally cars and they have always been well made and reliable. They also make a unit suitable for the Ital axle as an alternative to the Quaife. Link to comment Share on other sites More sharing options...
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