Torsen vs. RX7 LSD
#1
Junior Member
Thread Starter
iTrader: (1)
Join Date: Jan 2009
Location: Bradenton, FL
Posts: 290
Total Cats: 5
Torsen vs. RX7 LSD
I've had a Torsen in the car since I originally built it back 3 years ago. The car was primarily used for auto-x and street driving. I've now turned the car to primarily being a track car and have read that the clutch-type RX7 GXL LSD is superior in tracking situations. But that's all I can find. No one says why, or if it will be lightyears faster.
I have access to said diff and a 1.8 open to make a usable diff if I trade my Torsen. I may ask for cash on top, but I'm unsure of the value of a RX7 LSD. My car will be down for a few months yet anyway and was wondering if its worth it to make the trade.
If I go this route is there anything you all recommend to replace/rebuild while I have it apart to swap carrier assemblies? Are there better clutch pack available and such?
Obligatory picture of car in its current state to show you I mean business.
I have access to said diff and a 1.8 open to make a usable diff if I trade my Torsen. I may ask for cash on top, but I'm unsure of the value of a RX7 LSD. My car will be down for a few months yet anyway and was wondering if its worth it to make the trade.
If I go this route is there anything you all recommend to replace/rebuild while I have it apart to swap carrier assemblies? Are there better clutch pack available and such?
Obligatory picture of car in its current state to show you I mean business.
#2
Not sure on the rx7, but I like the feel of the torsen, its amazing in basically any situation where you dont have an inside rear wheel off the ground. Its predictable, natural feeling, all around good. To me there are 3 performance characteristics of a diff that are important, power handling capability (ie wont break with the power you're making), feel, and being able to apply power in all situations. The torsen hits the first tow points amazingly and only fails on the 3rd one when lifting a wheel. And on that scale the only thing I see as an upgrade is the geiken. Since its predictable if setup correctly, feels good different from the torsen though, and if setup up right will put power down if you lift the inside rear. The rx7? It should hold the power and it should not spin up the inside rear if you lift it, but how does it feel?
#3
Moderator
iTrader: (12)
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 20,652
Total Cats: 3,011
I believe the torque sensing diff is the most commonly used unit in track Miatas, but that might be due to abundance and relative low price rather than superiority. As I recall, the TorSen is more likely to allow one drive wheel to briefly spin faster than another but less likely to allow on-throttle oversteer. A tight clutch type LSD can be more prone to on-throttle oversteer, especially in the wet. A TorSen will allow some initial overspin of one wheel relative the other before locking in.
#4
Senior Member
iTrader: (4)
Join Date: Jan 2008
Location: Falls Church, VA
Posts: 1,361
Total Cats: 17
I paid $100 for an open 3.909 just because I wanted the R&P gears. The LSDs don't go for a whole lot more because most people assume if you're buying a used one that it will need to be rebuilt, and the discs & shims cost a little dough. On rx7club, complete 3rds out of the carrier go in the $150 ballpark IIRC. Don't hold me to that though; it's been a couple years since I looked. I would assume you could get more if you had dated receipts to prove it was serviced recently.
A clutch type diff will be better than a Torsen at the drag strip but for a road car I'm keeping the Torsen until such time as I ever have the need for a Giken.
A clutch type diff will be better than a Torsen at the drag strip but for a road car I'm keeping the Torsen until such time as I ever have the need for a Giken.
#7
Junior Member
Thread Starter
iTrader: (1)
Join Date: Jan 2009
Location: Bradenton, FL
Posts: 290
Total Cats: 5
Everyone seems to be steering towards keeping the Torsen. Just because clutch-type is more prone to oversteer doesn't necessarily mean it's not faster on the track. Looking to see who has possibly used both and their thoughts on both.
Like sixshooter said, is the reason everyone uses Torsen because of availability and price or are they faster then any other available option?
Like sixshooter said, is the reason everyone uses Torsen because of availability and price or are they faster then any other available option?
#8
Either diff will be fast at the track. The issue is, what one do you like the feel of, and does one induce effects that are detrimental. The torsen spinning the inside wheel if it lifts only makes you a hair slower coming out of the corner. The clutch pack locking up and spinning both wheels can make you a lot slower. But the big thing is feel. If the clutch pack was 1 second a lap faster but felt like garbage I wouldnt run it because I know that with me driving it I'd be slower due to lower confidence. Just because the car is faster from an engineering perspective doesnt mean that its possible to drive it that fast. See Lotus 79.
#10
I have both in different cars. Both have their merits but my preference is the RX-7 diff. I did not adjust the preload of the diff when I installed it (found ALL the plates to be within brand new spec) and enjoy the smoothness of it.
I have also heard stories of people grenading torsens on bumpy tracks. Going at a high rate of speed , bump a curb or whatnot, puts one tire in the air while under WOT and when it comes back down, the shock on the drivetrain cause the diff to let go. Have no actual experience with this, just hearsay.
I have also heard stories of people grenading torsens on bumpy tracks. Going at a high rate of speed , bump a curb or whatnot, puts one tire in the air while under WOT and when it comes back down, the shock on the drivetrain cause the diff to let go. Have no actual experience with this, just hearsay.
Last edited by karter74; 07-05-2012 at 03:09 PM.
#12
I've never used the RX7
In theory a TorSen is better at distributing torque to the wheel with more grip than a clutch type (probably why people feel it doesn't break the rear end free as easily) however, it also saps a relatively large amount of power, and in doing so creates a lot of heat.
Of course, just because it theoretically transfers torque better, doesn't mean its actually faster or better. Sav has reported dropping significant time by switching from a TorSen to an OS Giken, so obviously a well setup clutch type can be superior depending on your driving style and situation.
Also, if you're driving the wheels off the thing and bouncing off curbs all day, the lack of power with a wheel in the air might be an issue.
In theory a TorSen is better at distributing torque to the wheel with more grip than a clutch type (probably why people feel it doesn't break the rear end free as easily) however, it also saps a relatively large amount of power, and in doing so creates a lot of heat.
Of course, just because it theoretically transfers torque better, doesn't mean its actually faster or better. Sav has reported dropping significant time by switching from a TorSen to an OS Giken, so obviously a well setup clutch type can be superior depending on your driving style and situation.
Also, if you're driving the wheels off the thing and bouncing off curbs all day, the lack of power with a wheel in the air might be an issue.
Last edited by Handy Man; 07-06-2012 at 08:25 AM.
#13
Former Vendor
iTrader: (31)
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 15,442
Total Cats: 2,099
Everyone seems to be steering towards keeping the Torsen. Just because clutch-type is more prone to oversteer doesn't necessarily mean it's not faster on the track. Looking to see who has possibly used both and their thoughts on both.
Like sixshooter said, is the reason everyone uses Torsen because of availability and price or are they faster then any other available option?
Like sixshooter said, is the reason everyone uses Torsen because of availability and price or are they faster then any other available option?
I ran mine for a year and traded it for a Torsen. They are awful differentials and they have no place anywhere but a dragstrip.
#17
Tour de Franzia
iTrader: (6)
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,085
Total Cats: 375
I have used both. The Rx7 LSDs are total garbage. You can preload them, but the turn-in gets worse and worse, and they will never adequately lock in low-grip situations. You end up with all of the downsides of a 2-way diff and none of the upsides.
I ran mine for a year and traded it for a Torsen. They are awful differentials and they have no place anywhere but a dragstrip.
I ran mine for a year and traded it for a Torsen. They are awful differentials and they have no place anywhere but a dragstrip.
#18
Boost Czar
iTrader: (62)
Join Date: May 2005
Location: Chantilly, VA
Posts: 79,494
Total Cats: 4,080
Ie. On a drag strip. Not clutch kicking around a corner. Big difference in the load the hexigears see and how manly you are.
Last edited by Braineack; 07-09-2012 at 09:00 AM.
#20
Senior Member
iTrader: (2)
Join Date: May 2005
Location: Edmonton Ab, Canada
Posts: 1,202
Total Cats: 21
I have used both. The Rx7 LSDs are total garbage. You can preload them, but the turn-in gets worse and worse, and they will never adequately lock in low-grip situations. You end up with all of the downsides of a 2-way diff and none of the upsides.
I ran mine for a year and traded it for a Torsen. They are awful differentials and they have no place anywhere but a dragstrip.
I ran mine for a year and traded it for a Torsen. They are awful differentials and they have no place anywhere but a dragstrip.
I have no complaints with mine (only took 3 rebuilds to get it to the way I liked it though). After a few months of driving with a torsen in my s2000 I can't wait to get rid of it, miatas rearend feels much more predictable.