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Old 12-06-2008, 12:21 PM   #1
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Default Open vs Torsen

I had picked up a 96 rearend. It was the base model car with a/c, and mabe cruise, with steelies.

Anyway, I know the torsen locks both wheels when one slips.

Is the open one of those rearends where you go all the way down the track with one wheel spinning? Or do both lock up?

When my girl gets out of school, I'll probably hit the track. But for now $14 for all day fun at the strip, and $5.00 nacho's with the guys will work. And if the open is good for dragging, I'm good.

Thanks.

And yes I seached through the 1,000,000,000 pages.
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Old 12-06-2008, 12:31 PM   #2
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Torsen all the way
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Old 12-06-2008, 12:33 PM   #3
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the open diff wont be spinning 1 wheel the whole time. it will lock up sometimes and not other times. most of the time it wont lock up though (at least in my case)...torsen will lock up every time, and there is no comparison. the car does get ridiculously tail happy with the torsen though. If you're using it primarily for drag racing, I would keep the open simply because it is so much cheaper if you break it.
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Old 12-06-2008, 12:45 PM   #4
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Thanks guys,

I hope mine is a torsen. I read some about the RX-7 guts swap in. But it was some what unclear. Will I still be able to use my half shafts?

Then I read where you bolt the front onto the rx7 rearend.

If I can put the guts into the 1.8l rearend and keep my half shafts, that sounds like the easiest approach.

I would apreciate some clearification, if someonw knows.
Thanks
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Old 12-06-2008, 01:33 PM   #5
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Open's don't break because you can't load them. You do a hard launch and it just wheel spins. You put a torsen and do a hard launch, and you get ~twice as much power sent through the diff/ring and pinion/etc. Open diffs suck for drag racing. So does IRS though.

Braineack has the RX7 diff swap outlined in this big faq IIRC. It's outlined on this site somewhere. All the info in the world.
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Old 12-06-2008, 01:35 PM   #6
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I asked the same question before and got pwnd lol.. its all in the "garage" section of m.net

but afaik you can swap the rx7 guts into a 1.8 housing and use the 1.8 half-shafts/driveshaft.....
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Old 12-06-2008, 01:52 PM   #7
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Quote:
Originally Posted by patsmx5 View Post
Open's don't break because you can't load them. You do a hard launch and it just wheel spins. You put a torsen and do a hard launch, and you get ~twice as much power sent through the diff/ring and pinion/etc. Open diffs suck for drag racing. So does IRS though.

Braineack has the RX7 diff swap outlined in this big faq IIRC. It's outlined on this site somewhere. All the info in the world.
I his all in one big post thing. But I was unclear as to if I have to use the rx7 half shafts.

If he has anther post I'll check it out. And m.net again.
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Old 12-06-2008, 02:30 PM   #8
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Quote:
Originally Posted by 18psi View Post
I asked the same question before and got pwnd lol.. its all in the "garage" section of m.net

but afaik you can swap the rx7 guts into a 1.8 housing and use the 1.8 half-shafts/driveshaft.....
You are the man, Thanks. I'll have positive traction then right? And it will just about be bullet proof right?

Will the half shafts be crap then?
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Old 12-07-2008, 12:08 AM   #9
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You use everything except the circlips. Rx7 LSD, Rx7 circlips, Miata housing, Miata R&P, Miata stub/halfshafts. This is for an FC diff swap; the earlier FB diffs are different and harder to do.
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Old 12-07-2008, 12:20 AM   #10
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Quote:
Originally Posted by 18psi View Post
the open diff wont be spinning 1 wheel the whole time. it will lock up sometimes and not other times. most of the time it wont lock up though (at least in my case)...torsen will lock up every time, and there is no comparison. the car does get ridiculously tail happy with the torsen though. If you're using it primarily for drag racing, I would keep the open simply because it is so much cheaper if you break it.
There is nothing in an open diff to "lock". An open diff will spin the wheel that has the least amount of traction...and that would be the one spinning tire down the track. An open diff for drag racing is total waste of time.

Tony
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Old 12-07-2008, 08:22 AM   #11
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Todd, the RX-8 diff I bought is already in NJ (at keinayo's). Wait a few days and I'll be able to provide additional info on it (and BTW, it cost me $90).
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Old 12-07-2008, 08:58 AM   #12
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Quote:
Originally Posted by mrtonyg View Post
There is nothing in an open diff to "lock". An open diff will spin the wheel that has the least amount of traction...and that would be the one spinning tire down the track. An open diff for drag racing is total waste of time.

Tony
ok that part I was incorrect about. I guess what I was trying to say is that sometimes it will spin the one tire sometimes it wont. it doesnt ALWAYS spin one tire throughout a whole quarter mile pass.

and if the open is a waste for drag racing, then the torsen will be an even more waste since its not much (if any) stronger than an open and costs more than double to replace.

for drag racing I have heard/read the rx7 clutch type diff holds up pretty well.
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Old 12-07-2008, 11:22 AM   #13
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The open then is basically the limited slip on a old chevy, one tire spins, sometimes you can get 2 to spin. And you go out to tape off the 2 tire spin marks when it happens. Lol

Thanks guys.

Quote:
Originally Posted by Savington View Post
You use everything except the circlips. Rx7 LSD, Rx7 circlips, Miata housing, Miata R&P, Miata stub/halfshafts. This is for an FC diff swap; the earlier FB diffs are different and harder to do.
So would you do it? Or just leave it alone?

Quote:
Originally Posted by Rafa View Post
Todd, the RX-8 diff I bought is already in NJ (at keinayo's). Wait a few days and I'll be able to provide additional info on it (and BTW, it cost me $90).
Sweet deal,
I would appreciate the info. So will the internals swap out, or are you swapping the entire rearend?

The rx8 has positive traction doesn't it?

Thanks again, Good Luck!
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Old 12-07-2008, 11:31 AM   #14
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Quote:
Originally Posted by 18psi View Post
ok that part I was incorrect about. I guess what I was trying to say is that sometimes it will spin the one tire sometimes it wont. it doesnt ALWAYS spin one tire throughout a whole quarter mile pass.

and if the open is a waste for drag racing, then the torsen will be an even more waste since its not much (if any) stronger than an open and costs more than double to replace.

for drag racing I have heard/read the rx7 clutch type diff holds up pretty well.

torque spins tires, not diffs. but with an open diff, you get only one tire's worth of torque before you spin.

we all love the clutch type diffs. they are somewhat more forgiving and rebuildable than a torsen. cheaper too.
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Old 12-07-2008, 11:34 AM   #15
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Quote:
Originally Posted by Toddcod View Post
The open then is basically the limited slip on a old chevy....

An open diff is simply a basic non-locking differential. A differential allows one wheel to turn at a different rate as the other around a corner so the inside wheel doesn't skip, hop, and slide. the end.

this video is an oldie but goodie:





With that said, I do not recommend a torsen for drag racing. The hexicoil gears seem to be a weak point under load.
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Old 12-07-2008, 11:53 AM   #16
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Quote:
Originally Posted by Toddcod View Post



Sweet deal,
I would appreciate the info. So will the internals swap out, or are you swapping the entire rearend?

The rx8 has positive traction doesn't it?

Thanks again, Good Luck!

Give me a few days to get it and test it. I promise to pm you all the info. I can provide you which ebay vendor I bought it from. Let's see how it works first

I'm only swapping the diff. Nothing else.
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Old 12-07-2008, 03:32 PM   #17
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I just got into a set of 3.9 gears with the speedo sensor and a Torsen 1 for right at $350 shipped. Pretty stoked to set it all up.
Beats the hell out of the 4.30 Open i'm running now.
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Old 12-07-2008, 04:03 PM   #18
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Quote:
Originally Posted by Braineack View Post
7MIN 40SEC is the best. Image of drive shaft next to someones leg.
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Old 12-08-2008, 06:45 PM   #19
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I'm about to do the RX7 swap and my mechanic told me that there are 3 adjustment to make. Bearing adjustment, Tooth Flank and the Backlash. In all the swap faq I read everyone talk only of the backlash. Why?
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