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Discussion Starter · #1 ·
from what I read the S4 has a clutch type unit and the S5 has a viscous type. i see these goin for ~$100 locally so im thinkin why not. which is best suited for agressive daily driving and 3300lbs of sedan ?

im looking to source one and swap it into my DOHC car while i replace the sub-frame. on a side note how hard would it be to swap in another sub-frame ?
 

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from what I read the S4 has a clutch type unit and the S5 has a viscous type. i see these goin for ~$100 locally so im thinkin why not. which is best suited for agressive daily driving and 3300lbs of sedan ?

im looking to source one and swap it into my DOHC car while i replace the sub-frame. on a side note how hard would it be to swap in another sub-frame ?[/b]
I can't tell ya about the subframe but I can tell ya that the diff unbolts from the subframe very easily, there's nothing in the way, etc.

Pros for the viscous are that there are no friction parts inside and hence it doesn't wear out like a clutch unit does. It does wear out a little in the sense that the jelly inside goes bad after a while. But Cons for the viscous are that they aren't very "tight" and rely on a certain amount of wheelspin in order to transfer torque to the outside wheel. So when the inside rear spins up, you need to spin it up even more in order to get the torque transfer. So while it's better than nothing, it only tends to feel like a marginal improvement over the stock open diff. For example, viscous diffs generally aren't tight ebough to perform a donut.

Pros for the clutch unit ill be that it'll be a bit tighter and it's rebuildable. They start off from factory being quite soft, but a diff specialist can repack the clutch stack with shims to make it tighter. Downside is that the clutches in any S4 LSD are probably worn out by now...upside is that it gives you an opportunity to repack it tighter :D
 

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Discussion Starter · #3 ·
Thanks for a great explanation Babalouie.
 

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Discussion Starter · #5 ·
yes its been confirmed. something ive suspected for 5 years & was recently solved.
 

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Discussion Starter · #9 ·
same wid our gauges. i recall seeing Denso branded stuff on our HC's.
 

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yup I took it apart and posted pics :)
 

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Hi, just wondering, are all rx7 LSD's limited slip, or do you have to find the right type?
If so, how do you identify if its an LSD or not?
Also, do rx7's have the same diff ratio as us (4:11) or does that vary too?

Thanks for any help. Figure i should upgrade or traction is going to become a huge problem :hmmm:
 

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Hi, just wondering, are all rx7 LSD's limited slip, or do you have to find the right type?
If so, how do you identify if its an LSD or not?
Also, do rx7's have the same diff ratio as us (4:11) or does that vary too?

Thanks for any help. Figure i should upgrade or traction is going to become a huge problem :hmmm:[/b]
no not all came with lsd, if you look on the diff there should be a white tag that says lsd.
 

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Discussion Starter · #13 ·
From the RX7Club.

"Only the following USA model 2nd gen RX-7s had a LSD from the factory:
86-88 GXL
87-91 T2
88 GTU
89-90 GTUs (however not the 89-90 GTU)
It is also rumored that a few rare 91 coupes with both the A (upgraded the interior trim, added a power sunroof, tilt steering wheel, cruise control, and 4 piston front disc brakes and vented single piston rear brakes) and the B package (leather seating, a CD player, and rear cargo cover) came with a LSD, but you should note that Mazda denies that any FC other than the T2 came with a LSD in 91). You can also tell by looking at the differential as there will be a LSD tag on S4 cars with a LSD."
 

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Ok, thanks. Now to find the right ratios and centre type.
 

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I think....not 100% sure that we can't use the RX7 crownwheel and pinion. The pinion's too short IIRC, so you have to re-use your HC diff gears anyway.
 

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damn that sux because i actually wanted to go a lower ratio.
 

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Some ppl say that the crownwheel & pinion that fits HC is the FD RX7 one....I can't confirm this one personally tho, but FD ratios come in 4.1 and 4.3.
 

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yeah id love a 4.3 because the quad cam just loves to rev.. might have to suss this one out.
 

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Well if you could find a 4.3 FD diff, it would have a torsen inside and that would kill 2 birds with the one stone.

So even if you couldn't use the CWP it would still be a good score if you could find one.
 

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Hi, just wondering when buying an after market lsd for the nine, do you buy one for the FD open center diff or lsd diff? Do i need to start with an lsd centre? Whats the story there, what diff should i order for?
Thanks.
 
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