Anyone with torque bias (quaife) LSD experience in 951 for autocross?
02-13-2008, 05:46 PM
#1
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Anyone with torque bias (quaife) LSD experience in 951 for autocross?
In trying to decide on an lsd for my '86 951, I'm looking at either the oem unit or dropping in a quaife. My main goal is better autocross performance, but I also want it to be good for track (DE) and street. I'm seeing some conflicting opinions about whether a quaife would be better or worse for autocross. If anyone here has first hand experience with both types in a 951 (or similar car, if there is such a thing 
), please chime in!
Here is a quote from 944online.com about their Torque Bias LSD sold at 944online.com:
), please chime in!Here is a quote from 944online.com about their Torque Bias 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."
Yes, this is a re-post, but noone replied in the other thread and I'm impatient! "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."
02-13-2008, 06:09 PM
#2
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Well from all the info I have gathered I think that the Quaife type is better for street, hwy, autoX however I have the full 80% clutch type and I have to say that I don't notice it on the street being bad at all. I guess if you decide what you want to do the most of, track or AX, then go for the one most suited for that use.
02-13-2008, 06:43 PM
#4
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fyi quaife is a brand not a type of differential. the quaife is a torsen type of diff which is commonly used in center differential applications for awd cars like Audi.
most road racing applications use a locking differential which is similar to clutch type diff available as an option on the 944.
you should check out guard transmission. GT sells both types of diffs and are said to be higher quality then quaife but dont take my word for it, do some research.
I only have a Quaife becuase it came in my car. I would've gone GT clutch type howver for auto x you might be better of with the torsen
most road racing applications use a locking differential which is similar to clutch type diff available as an option on the 944.
you should check out guard transmission. GT sells both types of diffs and are said to be higher quality then quaife but dont take my word for it, do some research.
I only have a Quaife becuase it came in my car. I would've gone GT clutch type howver for auto x you might be better of with the torsen
02-13-2008, 09:32 PM
#5
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Thanks for your help everyone.
Is a torsen type diff any less capable of handling high torque than a clutch type? At some point when I get around to mods under the hood, I think I'll end up in the 300-350 ft-lb range, at the wheels. For now, I basically just want to be able to get out of tight corners quicker without spinning the inside tire.
I guess I'll try to pose this question on the racing forum as well like Michelle suggested.
Is a torsen type diff any less capable of handling high torque than a clutch type? At some point when I get around to mods under the hood, I think I'll end up in the 300-350 ft-lb range, at the wheels. For now, I basically just want to be able to get out of tight corners quicker without spinning the inside tire.
I guess I'll try to pose this question on the racing forum as well like Michelle suggested.
02-15-2008, 12:04 PM
#6
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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?
_
02-15-2008, 03:36 PM
#7
IMO you will not notice a difference between the two on the track. Go with the torque bias, there are no parts that wear like in the LSD. The only advantage is really under braking.
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02-15-2008, 05:42 PM
#8
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Doesn't a torque biasing diff aid steering as the torque is proportioned to the wheel with the most grip i.e. the outside wheel as opposed to an open or LSD where the torque is proportioned to the inside wheel?
My take on it is that you are more likely to loose traction with a conventional LSD but once you loose traction it is more controllable and able to get more power down to the tarmac. I'm probably wrong with this but it is what I seem to get from my understanding of the internal workings.
My take on it is that you are more likely to loose traction with a conventional LSD but once you loose traction it is more controllable and able to get more power down to the tarmac. I'm probably wrong with this but it is what I seem to get from my understanding of the internal workings.
02-15-2008, 08:10 PM
#9
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fyi quaife is a brand not a type of differential. the quaife is a torsen type of diff which is commonly used in center differential applications for awd cars like Audi.
most road racing applications use a locking differential which is similar to clutch type diff available as an option on the 944.
you should check out guard transmission. GT sells both types of diffs and are said to be higher quality then quaife but dont take my word for it, do some research.
I only have a Quaife becuase it came in my car. I would've gone GT clutch type howver for auto x you might be better of with the torsen
most road racing applications use a locking differential which is similar to clutch type diff available as an option on the 944.
you should check out guard transmission. GT sells both types of diffs and are said to be higher quality then quaife but dont take my word for it, do some research.
I only have a Quaife becuase it came in my car. I would've gone GT clutch type howver for auto x you might be better of with the torsen
I think you would notice the difference if you had 2 cars, one with each type, and then went out and did back to back testing. Sounds like for what you want, the Torsen type one is better suited.
02-15-2008, 10:10 PM
#10
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Quaife is NOT a torsen diff! It's a torque biased diff. Very different animals...
How much does it cost to put a lsd into an '86 951? I've found an '86 locally that doesn't have a lsd, thinking about buying it...
How much does it cost to put a lsd into an '86 951? I've found an '86 locally that doesn't have a lsd, thinking about buying it...
02-16-2008, 10:15 AM
#11
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Thread Starter
The range of prices I'm getting are starting at $1250 for a high mileage complete tranny w/ oem lsd. The most expensive option I've seen is one listed on ebay right now with a Buy It Now of $2900: http://cgi.ebay.com/ebaymotors/ws/eB...m=320217092059
You can also just buy an lsd or tbd by itself and install it. Brand new tbd from 944online.com costs $1395. Not sure what it would cost to have it installed.
So, what is the difference between a torsen diff and a torque-bias diff? The wiki page on limited slip differential lists both Torsen and Quaife as "geared torque sensitive differentials": http://en.wikipedia.org/wiki/Limited_slip_differential. Sounds like they are pretty similar animals to me.
You can also just buy an lsd or tbd by itself and install it. Brand new tbd from 944online.com costs $1395. Not sure what it would cost to have it installed.
So, what is the difference between a torsen diff and a torque-bias diff? The wiki page on limited slip differential lists both Torsen and Quaife as "geared torque sensitive differentials": http://en.wikipedia.org/wiki/Limited_slip_differential. Sounds like they are pretty similar animals to me.
02-16-2008, 10:25 AM
#12
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that seller on ebay smokes really good dope, he's high on everything he sells, but hey, it's an auction.
Rule of thumb (others can correct me), but after you buy the differential, you will spend as much having the tranny taken apart and put back together; meaning you would want to replace anything that showed any wear plus the seals.
Rule of thumb (others can correct me), but after you buy the differential, you will spend as much having the tranny taken apart and put back together; meaning you would want to replace anything that showed any wear plus the seals.
02-16-2008, 07:51 PM
#13
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Thread Starter
More of a silent auction... only buy it now or best offer. Wonder if that means he has to sell it to whoever makes the highest offer, or if he can back out if it's too low. Going to have to check the ebay rules, I guess.
02-18-2008, 10:20 AM
#14
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Thread Starter
OK, I am going with a Guard Transmission (GT) torque bias differential with the optional oil cooler gear. 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...
