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Old 02-08-2007, 08:47 PM   #1
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Default damn ... guess its an open :(

Oh well at least it was free, 7", and has more options for the guts. I just dont understand, i thought all miata's 94-97 with manual transmission and non base model recieved the torsen, well I guess i was wrong. Didnt make the car not fun to drive though. So should i go with the rx7 diff guts?

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Old 02-08-2007, 09:52 PM   #2
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yeah buy a rx7 lsd to throw in. it's what im doing. just make sure to buy the right one

i have a few sources once i figure out mine i can throw our way.
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Old 02-08-2007, 10:51 PM   #3
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cool, your awesome man. Im really in no rush right now and im installing it as an open diff for the early autocross season.
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Old 02-09-2007, 03:53 AM   #4
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The Torsen is not very good anyways. You got exactly what you need - the 7" diff housing and gearing. Now go grab the LSD guts from an RX7 and you are good to go. I'd go with the 4.1 since you are only at 4psi... if you plan to up that a bunch the 3.9 may be better.
Great find though! Howd you get it for free??
-Ryan
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Old 02-09-2007, 04:35 AM   #5
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Ya im not too pissed because i figured eventually i would have prefered to have the clutch LSD instead anyway. I am only 4psi now, but my megasquirt is sitting next to the monitor as i type along with 550cc injectors. So hopefully 15psi is not too far off, id go with the 3.9 ... actually i didnt even know that the gearing ratio was dependant on the guts of the diff, thought that the pinion gear and ring made that.
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Old 02-09-2007, 05:36 AM   #6
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i'm sort of in the same boat... i'm in the process of turning a stock open 1.8 diff into something i will like. except mine wasn't free =( at least my stock diff hasn't blown up yet.
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Old 02-09-2007, 09:40 AM   #7
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plus Torsens are running $600-800 for just the LSD. 86-88 RX7 Clutch-type LSDs are in the $150-250 range, and are superior for our applications (Torsen might do better at an autox, however).
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Old 02-09-2007, 10:58 AM   #8
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just this morning my KAAZ saved my *** from gettin stuck on ice. half the alley was covered in ice. right wheel spins, left wheel grabs for traction and I drive to work. I might still be there pushin my **** without that.

interesting sidenote, the KAAZ stacked for 100% locking (all opposing plates) still allows quite a bit of differential action. If I had to guess the power was 66.66/33.33 in favor of the slipping wheel. still enough to move easily though.
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Old 02-09-2007, 10:58 AM   #9
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Quote:
Originally Posted by Braineack View Post
86-88 RX7 Clutch-type LSDs are in the $150-250 range
Plus another ~$200 for rebuilt parts.

Quote:
and are superior for our applications (Torsen might do better at an autox, however).
I feel the stock RX-7 LSD might have a little bit too much lock-up for such a light car. It's fun, though
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Old 02-11-2007, 04:02 AM   #10
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Quote:
Originally Posted by akaryrye View Post
actually i didnt even know that the gearing ratio was dependant on the guts of the diff, thought that the pinion gear and ring made that.
You are correct. I mean that you can choose a different gearing if you want while the diff is out of the car. The RX7 diff will come with a 3.9 so if the open diff you have there is 4.10 you can choose to use one or the other when you swap the guts.

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(Torsen might do better at an autox, however)
A stock clutch type RX7 diff will outperform the Torsen in an autox - I've tried both in different cars... most autocross cars use the Torsen because they are allowed update/backdate between miatas but they can't use stuff from the RX7.
Guys in SM2 with boost however much prefer the Clutch diff...
-Ryan
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Old 02-11-2007, 05:37 AM   #11
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thanks ThePass, thanks for letting me know i have the choice to swap pinion gears as well because i did not know that. In that case, i would almost be tempted to run the 3.9 gear as Im planning on 15psi down the road ... hmm so many options.
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Old 02-11-2007, 05:41 AM   #12
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i just broke off a bolt in my miata ring gear and now hope to use my rx7 ring gear instead it seems to be workable we'll see ill keep you updated on how it sets later today if you like.
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Old 02-11-2007, 06:22 AM   #13
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dude that would be awesome to be able to confirm this. [email protected] 3500rpm would be a dream come true once im putting down 220+rwhp
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Old 02-11-2007, 10:09 PM   #14
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Well my guy gave me relay falckey directions to find him spent about 1 hr looking for his place and no luck so im gonna need to find someone else to do it. ill get back to ya.
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Old 02-11-2007, 10:29 PM   #15
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Quote:
Originally Posted by ThePass View Post
A stock clutch type RX7 diff will outperform the Torsen in an autox - I've tried both in different cars... most autocross cars use the Torsen because they are allowed update/backdate between miatas but they can't use stuff from the RX7.
Guys in SM2 with boost however much prefer the Clutch diff...
-Ryan
From everything I've read it's the opposite. Since the way the clutch engages, responding to driveshaft torque, it is not perfered in low-speed autox corners. It's typically the reason there is such an availibilty of rx7 LSDS, since they all tend to upgrade to a miata/s2000 torsen. Road courses and Drag events on the otherhand....


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Originally Posted by akaryrye View Post
thanks ThePass, thanks for letting me know i have the choice to swap pinion gears as well because i did not know that. In that case, i would almost be tempted to run the 3.9 gear as Im planning on 15psi down the road ... hmm so many options.
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Originally Posted by magnamx-5 View Post
i just broke off a bolt in my miata ring gear and now hope to use my rx7 ring gear instead it seems to be workable we'll see ill keep you updated on how it sets later today if you like.
http://members.aol.com/solomiata/RingandPinion.html

The RX7 "short" pinon, will work, but it needs to be a matched set to the ring-gear as the each have different teeth.
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Old 02-11-2007, 10:42 PM   #16
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im not swapping pinions just the ring gear i believe it had 41 teeth so it should be all good. looks to me like the 3.6 3.9 miatas use the 11 tooth pinion from the rwd 626, and rx3 hmm maybe someone could put a 30 tooth in there and get a 3.6 ratio not bad
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Old 02-11-2007, 11:17 PM   #17
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But your 1.8 miata pinon should have 10 teeth, correct? if you put your RX7 ring gear on there with 49 teeth you'll have a 4.9 end-ratio.

It really as easy as counting the teeth and dividing (ring / pinon = end ratio). Just double-check and make sure. I'm thinking of using the RX7 ring and pinon to achieve a 4.08 end ratio.
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Old 02-11-2007, 11:30 PM   #18
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Quote:
Originally Posted by akaryrye View Post
Didnt make the car not fun to drive though.
Interesting statement.
To be honest, most people who think they need a Torsen wont realize any real benefit over a 1.8 open diff...other then a psychological one.

That is not to say there isnt any performance gain to be had from torsen in a specific circumstance, its just that MOST people rarely drive at a level where they will really benefit from one.
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Old 02-12-2007, 09:55 AM   #19
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Actually looks like:
the 84-85 GSL is a 3.909.
the 84-85 GSL-SE is 4.08.
the 86-88 BASE ,SPORT, SE and GXL is 4.10 w/manual, 3.909 with auto.
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Old 02-12-2007, 10:02 AM   #20
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Quote:
Originally Posted by Braineack View Post
From everything I've read it's the opposite. Since the way the clutch engages, responding to driveshaft torque, it is not perfered in low-speed autox corners. It's typically the reason there is such an availibilty of rx7 LSDS, since they all tend to upgrade to a miata/s2000 torsen. Road courses and Drag events on the otherhand....
All of my friends who have auto-x RX-7 either have, or want the miata LSD...and look at me like I'm crazy when I say I want an RX-7 clutch type.

On this note, I found a guy w/ a complete torsen w/ hubs on the axles locally!
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