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Thread: Limited Slip Differential (T2 LSD?)
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sparky
Redlining
Posts: 299
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posted May 19, 2007 09:51 PM |
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Hi Brad,
Are you sure about the all FC's (2nd gen rx7) having LSD and not torsen? I spoke with Dave from Speed Machine in Vista and he said Mazda switched to Torsen on all turbo rx7's '89 and later. Also, do the non turbo FD rx7's have the same Torsen as the turbo models? I'm loooking to get a Torsen soon and may need to visit junkyards.
Thanks.
Scott.
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admin
Administrator
Posts: 446
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posted May 19, 2007 10:37 PM |
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kansei
Redlining
Wankelized
Posts: 423
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posted May 20, 2007 07:48 PM |
 Edited By: kansei on 20 May 2007 19:50 |
LOL
Sparky,
LSDs for FCs:
1986-1988 Turbo, GXL, GTU (I think the GTU for '88 had it, but only for '88), and supposedly a rare few 1988 model year Verts had clutch-type LSD
1989-1991 Turbo only had Viscous-type LSD
1993-1995 US Market cars all had Torsen LSDs, though I have heard a rumor a few years back that someone had an auto equipped FD they swore had an open diff. Not sure if that is true or not.
Isn't Speed Machine and RX-7 tuner shop?? Dave said all 1989 and up turbo equipped cars had Torsen? Not here prior to 1993 model year. Although I have heard some S5 Turbo cars got Torsen for the Japanese market. Maybe he had a RHD JDM car that had Torsen and that's where he got that idea??
Neal.
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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
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posted May 21, 2007 03:00 PM |
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quote:
Hi Brad,
Are you sure about the all FC's (2nd gen rx7) having LSD and not torsen?
That is my understanding and I agree with what Neil says. + all FD's were twin turbo.
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-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge
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Brad
Rotorhead
Posts: 1672
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posted May 21, 2007 03:03 PM |
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Dan
Since it says it'll fit a FD one would assume it would work. But I haven't fitted one, so to guarantee's expressed or implied. Does the snout of that LSD look a little long?
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-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge
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sparky
Redlining
Posts: 299
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posted May 21, 2007 03:56 PM |
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Thanks for all the input. I guess I'll be looking for a torsen from 3rd gen rx7's.
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kansei
Redlining
Wankelized
Posts: 423
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posted May 21, 2007 04:39 PM |
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I forgot...
... the 1990 GTUs had LSD as well, to my knowledge, but since I have never owned one, I do not know for sure. I once heard Mazda brought the clutch type LSD back for the GTUs only (as far as S5 cars go), but once again- I can't confirm that. Remember the GTUs had the highly desired differential ratio as well.
Neal.
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VincenzoL
Revvin Up
Posts: 76
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posted May 21, 2007 05:47 PM |
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Guys, you are all going back on forth on whether or not the FC had a Torsen. The real question is if the FD and FC LSD's are compatible... as in, what are the dimensions of the two? I'd prefer a clutch type anyhow over a Torsen.
As for what LSD the FC chassis came with, I can help shed some light. Series 4 (1986-88) had a clutch type LSD. Series 5 model (89-91) had a viscous LSD. That's it, no other differences other than all TII had a larger rear end for both series so a N/A LSD will not be compatiblle with a TII LSD.
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I'd buy that for a dollar!
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repu510
Hauling
Posts: 141
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posted May 22, 2007 09:50 AM |
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clutch v. torsen?
i'm curious why would one prefer a clutch-type lsd over a torsen? is there a specific (i.e racing) application that a clutch lsd outperforms a torsen?
i'm just curious because i'm still learning about all this stuff, so i'd like to know your view point.
i've read a few articles here and there, and even on this thread, that most prefer torsens over clutch lsds, and that torsens are usually stronger and can handle more abuse than clutch-types. hmmm... very interesting.
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G
Newbie
Posts: 9
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posted May 22, 2007 07:53 PM |
Edited By: G on 22 May 2007 19:55
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quote:
All FD's are turbo, and have torsen. I don't know about the later FC's but the earlier base model FC's didn't come with an LSD.
my only concern about this diff is the lack of windows which would allow more oil to pass thru the housing to cool and lubricate the gear set
here is a little artical about Torsen Diff's
http://www.torsen.com/files/Traction_Control_Article.pdf
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tom93r1
Redlining
Posts: 458
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posted May 23, 2007 09:17 AM |
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quote:
i'm curious why would one prefer a clutch-type lsd over a torsen? is there a specific (i.e racing) application that a clutch lsd outperforms a torsen?
Clutches can be modified in the clutch type LSD. That gives racers more control of how their LSD will perform. I believe it is also more durable for high power applications and situations with high instantaneous load such as drag racing launches.
Generally for street applications a torsen will be smoother and doesnt require periodic rebuilds or specific clutch compatible fluid.
____________
'74 lawn-green
4-port 13b
Weber 48DCO
Racing Beat Header
Magnaflow
resonator/amplifier
really loud!
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Klaus44
Redlining
Posts: 365
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posted May 23, 2007 09:27 AM |
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If it's up to Brad's standards...
...and he's happy with it for the street, as well as autocrossing, then it's on my (longer-term...) "wish list"! ;)
(Of course, I'm not looking to do drag-race launches...)
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Brad
Rotorhead
Posts: 1672
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posted May 23, 2007 03:08 PM |
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Very common for SCCA ITS 2nd gen Rx7's
to switch to a Torsen and not look back. I asked several. They're the hot ticket in EP. So they do very well on the road course too.
Clutch pack LSD's would be better for drag racing as already mentioned, and offroad where you get airborne. Since when a wheel gets air with a Torsen turns it into an open diff and only spins the airborne wheel until that wheel gets back on the ground. Torsen needs resistance on both wheels to drive both wheels.
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-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge
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VincenzoL
Revvin Up
Posts: 76
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posted May 23, 2007 11:03 PM |
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Yes, I know most of you guys would prefer a Torsen but I like the fact that I can rebuild a clutch type LSD and get more longterm usage out of it. Torsen would only be good for me if I drove like an old man.
Okay, with that being said I really want to got the TII LSD route but Brad had these made for the FD Torsen rear ends. DAMN!!! Did some research and... wait for it...
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I'd buy that for a dollar!
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VincenzoL
Revvin Up
Posts: 76
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posted May 23, 2007 11:08 PM |
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... found out the TII rears are interchangeable with the FD rear ends!!!
Now I don't have any hard evidence other than doing some searches on the evil forum but I'm willing to take a gamble and be the guinea pig. I already have a lead on a S4 Turbo II LSD and once I get it I can experiment.
Hope your guy is ready to crank out another set Brad! Willing to help out the guinea pig in order to sell more in the long haul?;)
-Vince
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I'd buy that for a dollar!
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repumax
Redlining
Posts: 427
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posted June 08, 2007 07:07 PM |
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Has anyone tried to put there kit in yet? I'm working on mine and have found a slight problem. I emailed the machinist and am hoping to hear back from him soon.
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1974 Mazda Repu
1986 Yamaha RZ 500
1988 Yamaha YSR 50
1991 Suzuki RGV 250
1992 Yamaha TZR 250 SP
1996 Aprilia RS 250
2003 Ford F-450 6.0 Diesel
2004 Mazda RX8
2006 Yamaha Banshee
2014 18' Eclipse Toy Hauler
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sparky
Redlining
Posts: 299
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posted June 30, 2007 07:40 PM |
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I did it!!! My little truck can do donuts. hahaha. I have a feeling my engine won't last much longer, as the fun factor just doubled. If anyone is planning on upgrading to Torsen on a 77 with .390:1 differential the kit needs some modification. You will need 10 mm bolts instead of 12 mm and the ring gear spacer needs to be .025" thick. I did minimal grinding on the axel housing and on carrier bearing mounts for ring gear bolt clearance. Did not have to machine down bolt heads. I did remove washers on ring gear bolts and used medium strength locktite. I set axel end play at .002" and ring gear lash at .060". Book spec. .002 to .006 on end play and around .075" on lash. I used some prussion blue to check pinion/ring gear contact. I really think the average joe can do this if they can use a dial indicator and don't need to mess with the pinion gear/bearings. BTY. I noticed a big difference in how hard the truck launches on start. I will definitley need more power. Any Q's feel free to contact me.
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repumax
Redlining
Posts: 427
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posted June 30, 2007 08:50 PM |
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Ya I'm putting a 77' ring and pinion in my 74'. Sparky and I have been working on this together. Spacer needs to .250 not .025 as Sparky stated. Rex the machinist is aware of this so please specify to him the year of your repu when ordering. Hope I didn't step on anyones toes here (refering to brad and rex) but I had to rework my spacer to make it work for the 77'. My machinist made me another one for back up at no charge and I ended up giving it to Scott (sparky). Also, Rex is a stand up guy. He was willing to make me another to make it work for the 77' but is was easier to fix mine as my neighbor at work is a machinist. I hope to have mine together this week.
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1974 Mazda Repu
1986 Yamaha RZ 500
1988 Yamaha YSR 50
1991 Suzuki RGV 250
1992 Yamaha TZR 250 SP
1996 Aprilia RS 250
2003 Ford F-450 6.0 Diesel
2004 Mazda RX8
2006 Yamaha Banshee
2014 18' Eclipse Toy Hauler
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sparky
Redlining
Posts: 299
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posted June 30, 2007 09:56 PM |
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Thanks for the correction Max. The spacer needs to be .250".
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Brad
Rotorhead
Posts: 1672
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posted July 09, 2007 10:38 AM |
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glad it worked out guys
Now that I think of it, the four diffs we that have done this before sale were 74's and i think one 75. sounds like mazda changed things back there in 77 but very glad to hear it's figured out and rex can accomodate the taller 77 gears.
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-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge
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