Quaife vs. oem LSD for autocross in 951
02-14-2008, 12:01 PM
#1
Rennlist Member
Thread Starter
Quaife vs. oem LSD for autocross in 951
In trying to decide on an LSD for my '86 944 Turbo, I'm looking at either the oem unit or dropping in a Quaife or Guard torsen type. My main goal is better autocross performance (ability to burst out of tight corners without spinning the inside rear tire), but I also want it to be good for track (DE) and street. I'm seeing some conflicting opinions about whether a torsen type LSD would be better or worse for autocross. If anyone here has first hand experience with both types in a 951, please chime in! Or, general knowledge of the pros/cons of both types would be useful as well.
Here is a quote from 944online.com about their Torque Bias (same as torsen type?) LSD sold at 944online.com:
Here is a quote from 944online.com about their Torque Bias (same as torsen type?) LSD sold at 944online.com:
Link: New Torque Bias Limited Slip Differential
"Torque-biasing differentials provide lock-up on acceleration only. The amount of lock-up (5-80%) increases as the amount of torque increases. On deceleration, lock-up is negligible, making the TBD the ideal diff for the slower speed turns of autocross. (In the same slower-speed turns, an 80% LSD would most certainly cause understeer.)
A torque-biasing differential performs like an open diff whenever one of the two drive wheels lifts off the ground.
Lock-up and traction are lost untill both drive wheels are again planted firmly on the ground."
"Torque-biasing differentials provide lock-up on acceleration only. The amount of lock-up (5-80%) increases as the amount of torque increases. On deceleration, lock-up is negligible, making the TBD the ideal diff for the slower speed turns of autocross. (In the same slower-speed turns, an 80% LSD would most certainly cause understeer.)
A torque-biasing differential performs like an open diff whenever one of the two drive wheels lifts off the ground.
Lock-up and traction are lost untill both drive wheels are again planted firmly on the ground."
02-15-2008, 10:03 AM
#3
Rennlist Member
Thread Starter
Looks like Guard makes some very nice diffs. Here's what their site has to say on the subject:
Link: http://www.guardtransmission.com/lsd_info.htm
Also, they provide a link to an article from Velocity magazine which describes the construction, operation, and pros/cons of various types of differentials: http://www.guardtransmission.com/velocity.htm
So, with all this information, it sounds liike the torque bias differential fits my immediate goals better. However, I'm still considering the oem lsd due to it's advantages on the track. Has anyone out there used a TBD (Guard or Quaife) for DE or racing on a track? Is it really noticeably inferior to an lsd for track use?
_
Link: http://www.guardtransmission.com/lsd_info.htm
Differential Recommendation
Generally speaking, this is what most customers opt for:
(a) Street / autocross - Torque-biasing
(b) Street / track - Torque-biasing if light-duty track use, with stock suspension. 40% limited-slip if car has stiff suspension or power upgrades.
(c) Track only - 80% limited-slip differential or spool.
Limited-slip differentials provide lock-up on both acceleration and deceleration. The amount of lock-up on accel and decel can be adjusted by selection of the internal plate sequence. Lock-up on deceleration allows aggressive entry into a turn and late braking, reasons why all Pro race teams (that we are aware of) utilize LSDs, rather than TBDs.
Torque-biasing differentials provide lock-up on acceleration only. The amount of lock-up (5-80%) increases as the amount of torque increases. On deceleration, lock-up is negligible, making the TBD the ideal diff for the slower speed turns of autocross. (In the same slower-speed turns, an 80% LSD would most certainly cause understeer.)
A torque-biasing differential performs like an open diff whenever one of the two drive wheels lifts off the ground. Lock-up and traction are lost until both drive wheels are again planted firmly on the ground.
There seem to be two very distinct groups, one favoring the use of LSD, and the other favoring the use of TBDs. We at Guard Transmission try to avoid making the decision for the customer. We would rather our customer confer with the race shop or transmission builder performing the installation, in order to make an informed choice.
Our primary role is simply to provide the marketplace with the highest quality examples of each and every differential type, all backed with a full 100% money-back guarantee.
Generally speaking, this is what most customers opt for:
(a) Street / autocross - Torque-biasing
(b) Street / track - Torque-biasing if light-duty track use, with stock suspension. 40% limited-slip if car has stiff suspension or power upgrades.
(c) Track only - 80% limited-slip differential or spool.
Limited-slip differentials provide lock-up on both acceleration and deceleration. The amount of lock-up on accel and decel can be adjusted by selection of the internal plate sequence. Lock-up on deceleration allows aggressive entry into a turn and late braking, reasons why all Pro race teams (that we are aware of) utilize LSDs, rather than TBDs.
Torque-biasing differentials provide lock-up on acceleration only. The amount of lock-up (5-80%) increases as the amount of torque increases. On deceleration, lock-up is negligible, making the TBD the ideal diff for the slower speed turns of autocross. (In the same slower-speed turns, an 80% LSD would most certainly cause understeer.)
A torque-biasing differential performs like an open diff whenever one of the two drive wheels lifts off the ground. Lock-up and traction are lost until both drive wheels are again planted firmly on the ground.
There seem to be two very distinct groups, one favoring the use of LSD, and the other favoring the use of TBDs. We at Guard Transmission try to avoid making the decision for the customer. We would rather our customer confer with the race shop or transmission builder performing the installation, in order to make an informed choice.
Our primary role is simply to provide the marketplace with the highest quality examples of each and every differential type, all backed with a full 100% money-back guarantee.
Also, they provide a link to an article from Velocity magazine which describes the construction, operation, and pros/cons of various types of differentials: http://www.guardtransmission.com/velocity.htm
So, with all this information, it sounds liike the torque bias differential fits my immediate goals better. However, I'm still considering the oem lsd due to it's advantages on the track. Has anyone out there used a TBD (Guard or Quaife) for DE or racing on a track? Is it really noticeably inferior to an lsd for track use?
_
02-18-2008, 05:19 PM
#5
Rennlist Member
Thread Starter
OK, I am going with a Guard Transmission (GT) torque bias differential with the optional oil cooler gear. I lucked out getting the oil cooler gear, as Zuba951 on the list is selling the package to me (it's the only one he has).
I might try to get an S2 ring and pinion set to put in as well while I'm in there. I think that would be the ultimate autocross setup for a 951... Let me know if you have an S2 r&p to sell.
I might try to get an S2 ring and pinion set to put in as well while I'm in there. I think that would be the ultimate autocross setup for a 951... Let me know if you have an S2 r&p to sell.
02-28-2008, 10:10 AM
#6
Rennlist Member
Thread Starter
I bought the GT diff, and now I'm second guessing myself. I have an opportunity to buy an oem S2 lsd trans, and I think that might be better overall for auto-x in a 951, due to the shorter gearing (ring and pinion is 3.875:1 in the S2 vs. 3.375:1 in the 951).
My question is: what SCCA auto-x class would I be in if I swapped in the oem s2 transmission? As it is, I'm in ASP right now. Would that trans swap put me in SM2 or A-Prepared or something, or could I legally stay in ASP?
My question is: what SCCA auto-x class would I be in if I swapped in the oem s2 transmission? As it is, I'm in ASP right now. Would that trans swap put me in SM2 or A-Prepared or something, or could I legally stay in ASP?
02-28-2008, 02:22 PM
#7
Burning Brakes
I bought the GT diff, and now I'm second guessing myself. I have an opportunity to buy an oem S2 lsd trans, and I think that might be better overall for auto-x in a 951, due to the shorter gearing (ring and pinion is 3.875:1 in the S2 vs. 3.375:1 in the 951).
My question is: what SCCA auto-x class would I be in if I swapped in the oem s2 transmission? As it is, I'm in ASP right now. Would that trans swap put me in SM2 or A-Prepared or something, or could I legally stay in ASP?
My question is: what SCCA auto-x class would I be in if I swapped in the oem s2 transmission? As it is, I'm in ASP right now. Would that trans swap put me in SM2 or A-Prepared or something, or could I legally stay in ASP?
