SeanStone
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| posted on 8/11/09 at 03:18 PM |
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7.5" crownwheel and pinion
I'm building a locost with an s2000 engine and gearbox. I want to use the cossie lsd but without spending around £700 on a 4.1 crownwheel and
pinion for it I have decided to go for small wheels (13" and try and find a 3.92 ratio.
I have found a 7.5" diff with the 3.92 ratio, and I am of the belief I have a 7" (a way of checking this would be nice if known) but I
would like to know whether the crownwheel and pinion for the 7.5" is usable in the 7" too.
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RAYLEE29
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| posted on 8/11/09 at 03:38 PM |
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Hi, basically if you measure across the top mount holes its aprox 7.5" on a 7.5" diff and 7" on a 7" diff I dont think you can
interchange the crownwheel and pinion but am happy to be corrected
also do you really need an lsd there has been some debate on this before and the car is so light people say you dont need one unless its for serious
competition
Ray
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SeanStone
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| posted on 8/11/09 at 03:41 PM |
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Well the car is going to be taking a caning when I get it on track. I also have the ability to gain free race tuition so it'll be at the limit a
lot when used in anger
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RAYLEE29
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| posted on 8/11/09 at 03:50 PM |
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ok cool but i dont think theres a cheap way to get an lsd in there talk to rs cosworth breakers about a diff
TEL:02392 379000 or 07968005319
[Edited on 8/11/09 by RAYLEE29]
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SeanStone
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| posted on 8/11/09 at 03:56 PM |
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I've got the diff. But it's the wrong ratio. The standard s2000 final drive is 4.1, hence me going for smaller wheels (than the
s2000's 16" and a 3.9 ratio, if possible
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RAYLEE29
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| posted on 8/11/09 at 06:49 PM |
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maybe fit the diff in the 7.5" housing with the 3.9 cwp?
maybe a case of take both apart and try
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RAYLEE29
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| posted on 8/11/09 at 06:52 PM |
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just a thought but is it for short circuit use then? as id have thought youd want a taller diff with smaller wheels?
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SeanStone
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| posted on 8/11/09 at 07:04 PM |
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It's road and circuit when i can. I want to be as close to the ratio of the final drive of the s2000 as possible. I don't wanna be doing
silly speeds in first
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Liam
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| posted on 9/11/09 at 11:53 AM |
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What's your existing 'cossie' LSD? There's a 3.92 7" LSD available as standard fitted to the 2.0 DOHC XR4x4 so maybe
worth looking for one of those. Or you should be able to source an open 7" 3.92 fairly easily and create one from your existing 3.62 7"
(assuming that's what you have). I dont think you can mix and match bits from 7" and 7.5" diffs.
Liam
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steveyb
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| posted on 9/11/09 at 12:57 PM |
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you'll have to turn the diff upside down to run with the s2000 as it turns the opposite way. you can get a 7" 3:9 lsd diff too if thats
what you need. the 7.5" crown and pinion wont fit in a 7" casing either as its too big.
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Liam
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| posted on 9/11/09 at 01:15 PM |
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quote:
Originally posted by steveyb
you'll have to turn the diff upside down to run with the s2000 as it turns the opposite way.
No it don't
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steveyb
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| posted on 10/11/09 at 05:36 PM |
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quote:
Originally posted by Liam
quote:
Originally posted by steveyb
you'll have to turn the diff upside down to run with the s2000 as it turns the opposite way.
No it don't
are you sure? i thought it did?
and i know a few people who had to flip their axles upside down when using the s2000. is the crown wheel not on the opp side on the honda diff?
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SeanStone
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| posted on 11/11/09 at 05:58 PM |
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You're thinking of the Pre 2005 K20 (civic Type R) and preludes. Thanks for the input though
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MikeRJ
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| posted on 11/11/09 at 07:29 PM |
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The size of the Sierra diff relates to the diameter of the crown wheel, so the parts are not interchangeable between 7" and 7.5" variants.
It's just happy coincidence that the casing is approximately the same measurement.
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Brommers
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| posted on 11/11/09 at 07:46 PM |
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quote:
Originally posted by steveyb
quote:
Originally posted by Liam
quote:
Originally posted by steveyb
you'll have to turn the diff upside down to run with the s2000 as it turns the opposite way.
No it don't
are you sure? i thought it did?
Well, you wrong... the B16A and B18A engines ran the other way round - the F20A runs in the coventional direction, as proved by numerous Westies
and AE86s running them.
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Gary 7
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| posted on 14/11/09 at 11:53 AM |
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Just a thought a ford scorpio 7.5 diff is available in a 4.27 ratio non lsd .
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