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Gear ratios and LSD recommendations


Sabbot

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It's that time of year.......the caterham is looking neglected on ramps for the winter and not much to do apart from move snow around the yard and browse websites for caterham upgrades.

 

I would appreciate any thoughts on the solutions to the following:

 

Issue 1: 1st and 2nd gear ratio's in the T9 5 speed are wrong for the caterham: Proposed solution buy a CR HD 5 speed gearkit from Quaife, BGH, redline or other - any recomendations on supplier / ratios? (current budget doesn't stretch to a 6 speed)

 

Issue 2: The car currently runs an open diff: any preferences or thoughts on Quaife ATB LSD?

 

For context the motor will also get some modiications and should be about 180-190bhp (flywheel) with a ~8000rpm redline by the time I get around to changing diff and gears etc. and the car is a summer road and track day toy.

Thanks,

Stewart

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Issue 1: 1st and 2nd gear ratio's in the T9 5 speed are wrong for the caterham: Proposed solution buy a CR HD 5 speed gearkit from Quaife, BGH, redline or other - any recomendations on supplier / ratios? (current budget doesn't stretch to a 6 speed)

 

Stewart,

 

If interested (worth a shot?), you might try contacting Dick Brink at http://www.texasmotorworks7.com/ While Dick deals in Birkins, he may have a close ratio five speed in stock that you could possibly use.

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Stewart - General sentiment on Blatchat seems to be that the Quaife is not as suited for track. It's a "viscous" LSD, rather than "plate type", and apparently isn't happy going over curbs. Of course, you'll find Quaife LSD owners on Blatchat who say that's rubbish.

 

I have a Tran-X plate type, but believe they got out of the LSD business, at least for the Sierra diff. I think Titan may now be the plate LSD of choice.

 

Steve

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I put together a gear comparison chart a while ago that might be helpful. It shows speeds in gear, rpm after an upshift, and the rpm when cruising at 70 mph for the Caterham 6-speed, the BGH long 1st gear (E2) and two versions of the BGH Sporting close (E7): one with the shortest 1st and tallest 5th, and the other with tightest 1st and 5th combo. The speed in gear and revs at 70mph data assume a 7500rpm redline and 205/60-13 rear tires.

 

I ended up keeping my 3.62 LSD diff and going with the BGH long 1st gearbox. My engine (210hp 2.0L Duratec) has such a broad torque curve that the 6-speed was pointless, and although I would prefer the E7 for the tighter gap from 3rd-4th, those ratios are really optimized for a 3.92. No complaints.

http://www.throttle-steer.com/uploads/1/1/0/8/11083275/7645517_orig.jpg

 

-John

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I have used Quaife LSDs on quite a few cars over the years including my current Caterham and always found them perfectly acceptable. Once had a Tran-X plate diff on an Escort Mk 1 rally car that would lock and throw you off the road which was very entertaining. Plate diffs need careful setting up especially in a light Seven otherwise they can be harsh whereas the Quaife is much more friendly and progressive.

 

My 2c

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See, didn't even have to go to Blatchat for a Quaife owner to offer their (totally valid) viewpoint. :)

 

Agree, from what I've read, that the ramp setup on a plate type is crucial, particularly for a Seven. My Tran-X had ramp angles specifically setup for a Caterham, and I haven't experienced any nasty behavior. But I've also read (again, on Blatchat) of semi-nightmarish handling due to not having a plate type correctly setup. And again, lots of happy Quaife owners on Blatchat.

 

Steve

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Stewart - General sentiment on Blatchat seems to be that the Quaife is not as suited for track. It's a "viscous" LSD, rather than "plate type", and apparently isn't happy going over curbs. Of course, you'll find Quaife LSD owners on Blatchat who say that's rubbish.

 

I have a Tran-X plate type, but believe they got out of the LSD business, at least for the Sierra diff. I think Titan may now be the plate LSD of choice.

 

Steve

 

This is right on......the Titan is preferred for actual competition use. It is a clutch type. Torsens like the Quaife are quiet and trouble free and a great limited slip until they aren't....as in when you run over a curb and that wheel goes light. At a point (Taylor says 20%) when a wheel is unloaded it acts like an open dif. It's probably a great choice for combination track/street usage. I know at one time Taylor Race Engineering was working on somthing to put in the Formula SAE Quaife units to overcome this tendency.

 

There is no special setup on a Titan. You order it from Redline and install and set up the diff like any other. Or I believe they will sell you a complete dif.

Edited by dallasdude
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  • 2 weeks later...

Thanks to everybody for the sugegstions. I contacted Texas mtor works and BGH and they were both vertyy helpful and seem to be able to supply the apprpriate parts. BGH recommended their E8 box and the consensus seems to be that the realtively new LSD from Titan is the way to go, given the rest of the set up on my car (it's a bit prone to lifting it's inside rear wheel).

Thanks again,

Stewart

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Give Dan Taylor a call, at Taylor Driveline Services, he supports a number of race teams and has rebuilt and installed LSDs in our Sierra diffs. Dan can be reached at 972-838-7054.

Oh, a lot of shops will not work on the Sierra diffs as the the screw on side covers tend to gall and destroy themselves on disassembly.

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  • 4 months later...

I'm bringing this back to life in case there are any new opinions. Has anyone used the Quaife for considerable track time? Has anyone failed one?

 

Has anyone here driven a CSR with open diff and Quaife?

 

Daniel

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My Caterham SV came with an open Sierra diff. I put in a Quaife LSD during assembly. It now has 25k hard miles on it with about 1,500 on the track. It has handled my heavy right foot and 300 RWHP and 265 torque with no problems.

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