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Index > Engine/Drivetrain > Thread: Limited Slip Differential (T2 LSD?)
Thread: Limited Slip Differential (T2 LSD?) [' This thread is 7 pages long: (1) 2 3 4 5 6 7 ']
admin


Administrator
Posts: 446
posted October 12, 2004 02:04 PM

Limited Slip Differential (T2 LSD?)

I had an interesting conversation with the guy who runs Checkpoint Engineering (they have changed their name) and he says the rear diff of the REPU can be swapped out for one out of a Turbo2 RX-7.

Can anyone explain (or point to a website) how the differential is constructed in the REPU: as in:

What are all the different parts?

What can/may be swapped out?

How do you change ratios?



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kansei


Redlining
Wankelized
Posts: 423
posted October 18, 2004 09:11 AM
Edited By: kansei on 18 Oct 2004 09:16

No website, but...

I would surmise that they mean you can swap out the differential only (basically the spider gears and clutch pack from the T2- not too sure about the feasibility of the viscous unit from the S5s). I would be very surprised if the pinion and drive gear can take the place of the REPUs, though I honestly have never compared them. The spline count on the REPUs drive axles and the diameter would need to be the same as those on the T2's corolla shafts, which may be where the swap becomes feasible. I have never seen the two diffs side by side, but if the whole diff including the pinion and drive gear can be swapped in/rigged somehow, remember you will lose low end speed because you're dropping down to a 4.100:1 rear end ratio from the T2. Of course, if you retain the REPU pinion and drive gear, you maintain that final drive ratio.

Sorry if I stated a bunch of stuff you already knew.
____________
Neal A.E. Swigert
Greenville, Michigan
1974 REPU Resto Project
1976 808 Wagon
1977 Cosmo
1978 Savanna RX-7 GT
1980 Leather Sport RX-7
1980 Petty Targa RX-7 #11
1985 GSL-SE RX-7
1988 RX-7 10th Ann
1993 RX-7 VR Touring




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brad


Rotorhead
Posts: 1672
posted October 18, 2004 02:07 PM
Edited By: brad on 18 Oct 2004 14:08

I had an interesting conversation with the guy who runs Checkpoint Engineering (they have changed their name) and he says the rear diff of the REPU can be swapped out for one out of a Turbo2 RX-7.

wouldn't be suprised. mazda has been pretty good at compatability within and some times across product lines. i thought it was a 3rd gen LSD that required minimal machinework to fit in REPU

Can anyone explain (or point to a website) how the differential is constructed in the REPU: as in:

What are all the different parts?
ring and pinion, LSD clutch pack, pinion bearing, side bearings, pinion crush tube

What can/may be swapped out?
all of the above are removable. Getting parts from car A to work with truck B is another story. Requires measurements and more measurements

How do you change ratios?
the ring and pinion gears as a set determine rear end ratio.

for your reading pleasure:
http://members.aol.com/solomiata/Drivetrain.html
http://members.ij.net/mrmazda/interchange.html#DIFFERENTIAL



____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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Brad


Rotorhead
Posts: 1672
posted January 04, 2005 08:12 PM
Edited By: Brad on 4 Jan 2005 23:13

So has

anyone done further research on this? I autocrossed my REPU at Cal Speedway JGTC mid December and had a general lack of traction all around, but especially when getting on the power exiting a corner. Desperately need LSD and wider tires back there.

The rear end fishtailed real good with pleanty of tire squeal.

Anyone have good suspension setup for REPU autocrossing? I want to race in the TRUCK class this year; first race on 1/23, my B-DAY!!!!!!!!
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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Brad


Rotorhead
Posts: 1672
posted January 07, 2005 07:51 PM

bump

For anyone who has a LSD in their repu, has more info on it, or even a good hypothesis!
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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mother1ship


1st Gear
Posts: 13
posted January 23, 2005 08:50 AM

me, too!

Brad -- I would also like any information available about this subject -- am going to RALLY my 74 REPU -- and we will be addressing this very subject within the next two weeks (soon as we get the truck out of the shop, getting the cage and seats finalized). Any info from someone who may have added LSD to a repu??

____________
Fling Pu rotary racing team
79 RX7, #229
74 RX3, #452
74 RePu, #498
the Fling Pu REPU

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klaus42


Rotorhead
Posts: 1877
posted January 25, 2005 12:45 PM

Ask Rob

...at Pineapple Racing about this; 'back when' I recall he had some ideas. Might know more by now?

(Belated) Happy Birthday, Brad!

       
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Tom93R1


Redlining
Posts: 458
posted January 25, 2005 10:44 PM

Does the ford 9" have an LSD option? I believe my friend who knows Paul Yaw said has a ford 9" on his REPU. I need to get down to Yaw's shop one day and see what all he has done to it, get some ideas and maybe some Weber tuning advice.
____________


'74 lawn-green
4-port 13b
Weber 48DCO
Racing Beat Header
Magnaflow
resonator/amplifier
really loud!

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Brad


Rotorhead
Posts: 1672
posted February 08, 2005 02:15 PM

quote:
Brad -- I would also like any information available about this subject -- am going to RALLY my 74 REPU -- and we will be addressing this very subject within the next two weeks (soon as we get the truck out of the shop, getting the cage and seats finalized). Any info from someone who may have added LSD to a repu??



Any progress mother1ship? I am trying to get my hands on a used repu diff so I can take it apart and do measurements.

Yes Tom, Ford 9 has had many LSD's. If you go to summitracing.com and search on limited slip or LSD, you'll see several aftermarket options. Including some for late model mazda trucks..... got the creative juices flowing.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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mother1ship


1st Gear
Posts: 13
posted February 08, 2005 04:35 PM



Far as I can tell, it has to be an LSD from an RX7 -- so we're proceeding along those lines. Don't think there ever was an LSD for the REPU, but I haven't received much response so not real sure....


____________
Fling Pu rotary racing team
79 RX7, #229
74 RX3, #452
74 RePu, #498
the Fling Pu REPU

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Brad


Rotorhead
Posts: 1672
posted February 09, 2005 09:37 AM
Edited By: Brad on 9 Feb 2005 12:55

quote:


Far as I can tell, it has to be an LSD from an RX7 -- so we're proceeding along those lines. Don't think there ever was an LSD for the REPU, but I haven't received much response so not real sure....




REPU never got LSD, nor did courier or b1600/1800/2000/2200.
From the research I've done, Mazda didn't put a LSD in a truck until late 80's 4x4 version.

Rumor mill is a 3rd gen or 2nd gen T][ LSD can fit in REPU with minimal machine work.

____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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klaus42


Rotorhead
Posts: 1877
posted February 10, 2005 07:04 PM

Cheapest? Best?

Sounds like taking a used Mazda 4x4 rearend and adapting might be least expensive... would an adapted rx-7 unit be any better than a specific custom-adapted Ford 9" ?

       
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Brad


Rotorhead
Posts: 1672
posted February 11, 2005 10:21 AM

quote:
Sounds like taking a used Mazda 4x4 rearend and adapting might be least expensive... would an adapted rx-7 unit be any better than a specific custom-adapted Ford 9" ?


Mazdaspeed Motorsports sells oversized discs for rx7 trannies. So I can tighten up the LSD as tight as needed.

Stock new factory 1st gen rear LSD breaks loose @ 90psi which is pretty good. PRO7 racers oversize disc it up to 120psi.

*and* there are aftermarket diffs for rx7's ala Kaaz if you wanna drop some coin.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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Brad


Rotorhead
Posts: 1672
posted February 21, 2005 08:33 AM

any update on the LSD

for the Fling Pu?
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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mother1ship


1st Gear
Posts: 13
posted February 21, 2005 09:29 AM
Edited By: mother1ship on 21 Feb 2005 12:31

the Fling Pu REPU

Brad - thanks for asking!

Since rally season is nearly upon us (first race is March 4!) and we had lots of 'stuff' to do -- custom cage, replace rear window (cage had to go thru there) racing seats, a rally computer & intercom, etc. etc. etc. -- we decided to give it a try as is for now, and address LSD maybe in March, (depending on how the first race goes) or maybe wait til later in the season.

still on the list, but moved down a bit! I'll post as soon as we get it done, and should have some pictures soon, too! She be lookin' FABULOUS!!!


____________
Fling Pu rotary racing team
79 RX7, #229
74 RX3, #452
74 RePu, #498
the Fling Pu REPU

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Brad


Rotorhead
Posts: 1672
posted March 15, 2005 07:37 PM

how'd the race go?

How did it finish in class and overall?

Any traction problems?

What size ring gear is on the REPU? It looks like it could be a 7.5 using my tape measure, but B2000/B2200 were a 7.2" so it's tough to tell.

Any pictures?

Any LSD progress?

Brad

____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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Mazdafun


1st Gear
Posts: 22
posted May 11, 2005 01:12 AM

B2000 LSD in REPU

Hi all.

I have a B2000 partscar sitting here. In the nordic countries (I am from Norway), they all got LSD. Now, the REPU has none, and I would really like to swap it in.

Doeas anyone has the axle spline dia (-in mm. please) on the REPU? And the number of splines on it?

Also it would be nice if someone had the propeller flange bolts diameter/pattern.

Thank you


       
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Brad


Rotorhead
Posts: 1672
posted May 11, 2005 12:03 PM

I have this info at home

and will look it up tonite.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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Mazdafun


1st Gear
Posts: 22
posted May 25, 2005 06:36 AM

Tonight came and went....what 's up?!

Hi.

Any news?


       
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Brad


Rotorhead
Posts: 1672
posted May 25, 2005 07:46 AM

sorry, been real busy

i know it's 30 spline, i'll look up the rest of the info i have written down at home.

       
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