How much to repair/replace GT2 LSD?
#1
05-09-2009, 07:53 PM
Join Date: Nov 2006
Location: Texas
Posts: 8,083
Rep Power: 671 
How much to repair/replace GT2 LSD?
I may have a problem w/ my LSD. Not sure yet but want to start preparing psychologically/financially.
What are the costs involved in repairing a GT2 LSD? If I have to replace it, how much will that cost and what are the aftermarket options?
I always prefer to get the best stuff I can afford and hopefully not have to replace it again.
What are the costs involved in repairing a GT2 LSD? If I have to replace it, how much will that cost and what are the aftermarket options?
I always prefer to get the best stuff I can afford and hopefully not have to replace it again.
#2
05-09-2009, 08:08 PM
Sorry OT but does the GT2 LSD work in a TT? Anyone tried it? Is it a clutch type?
From what I've heard the GT2 LSD's are pretty weak. There are some other alternatives out there that aren't that expensive (less than 2k). By the time you buy one and strengthen it to being strong enough you may have been better off buying a new aftermarket one.
From what I've heard the GT2 LSD's are pretty weak. There are some other alternatives out there that aren't that expensive (less than 2k). By the time you buy one and strengthen it to being strong enough you may have been better off buying a new aftermarket one.
#3
05-09-2009, 08:21 PM
Join Date: Nov 2006
Location: Texas
Posts: 8,083
Rep Power: 671
The TT has AWD so no LSD. According to what I have read over on Rennlist, the Porsche LSD is not all that great. I see that the Quaife is 1.4K. Is that a good unit? What will the labor run?
#4
05-09-2009, 08:29 PM
Yeah I know the TT doesn't come with one, but you can still add one. I'm wondering if the GT2 one will work like the Gaurds one that everyone seems to get. The Guards LSD seems to be the most expensive though.
What I do know is that you have lots of power, make sure you research the torque limits on any LSD you buy or you'll be in for a lot of headache. That is why I say the GT2 rebuild to make it durable may make it more expensive than a good one.
I would search the Quaife LSD too, seems like I read some negatives about that one too, but i can't remember for sure because it was a long time ago.
Good luck.
What I do know is that you have lots of power, make sure you research the torque limits on any LSD you buy or you'll be in for a lot of headache. That is why I say the GT2 rebuild to make it durable may make it more expensive than a good one.
I would search the Quaife LSD too, seems like I read some negatives about that one too, but i can't remember for sure because it was a long time ago.
Good luck.
#5
05-09-2009, 08:36 PM
Join Date: Nov 2006
Location: Texas
Posts: 8,083
Rep Power: 671
I have started my research....it seems the Guard is better. It is 3K and of course both require close to a K in labor.
Man I really was hoping to have an expense free summer...silly me!
Man I really was hoping to have an expense free summer...silly me!
#6
05-09-2009, 08:39 PM
Here is some more information I found on the LSD types. Quaife is a TBD, not really an LSD. But for what you are doing, it may actually be a good fit:
TBD - Torque Biased Differential
A TBD provides limited torque differential between the two wheels only during acceleration. The more torque that's being applied, the more resistance to different speeds a TBD will provide. When the car is being driven on the street under light acceleration, the TBD remains loose like an open differential. This makes the TBD a good choice for someone that uses their car on the street most of the time, but does some auto crossing. It goes well with the Jekyll/Hyde nature of the typical Cayman.
For serious auto crossing, some form of limited slip differential is almost a must. During tight turns, applyin torque to both drive wheels helps rotate the car and accelerate away from the turn.
The biggest weakness of the TBD is the fact that if you lift a wheel, all torque will go to that wheel making all benefits go out the window. This is more likely to happen on a high speed track event when the car is experiencing high G's for longer periods of time through sweeping turns. When a TBD lifts a wheel, and that wheel slips, the TBD itself takes a real beating. Repeated and prolonged incidents of wheel lift will wear and/or destroy a TBD over time.
The biggest strength of a TBD is the fact that if it is applied properly (not on a high horsepower car that experiences a lot of wheel lift), it will last virtually forever without any service or maintenance.
LSD - Limited Slip Differential (aka "clutch type")
The other type of limited slip differential is the clutch type, usually referred to as the LSD. This type of LSD applies a constant amount limited slip between the drive wheels through friction clutches. Modern designs have made it possible to apply a different amount of torque during acceleration than during braking. In Robins first post you see two LSDs, a 60/40 and an 80/50. These numbers communicate the amount of torque transmitted between the drive wheels during acceleration and decelleration.
60/40 means 60% on acceleration, 40% during braking. Likewise, 80/50 supplies 80% during acceleration, 50% during braking.
A TBD provides no benefit during braking. Limited slip during braking can be very helpful on the track. Limiting the slip during braking will push the front wheels, keep the car going straight and help it resist spinning making late braking more stable. Trail braking into a turn with an LSD will help a good driver walk the tail out a little before the apex and set up for a nice tail out exit after the apex. This is not for the faint of heart. A novice drivers will likely lift when they feel this, spin and lose it.
During wheel lift, and LSD still provides torque to the planted wheel. It's better when used on a high horsepower car that sees aggressive tracking. But because and LSD provides limited slip all the time, you will experience binding when driving through tight turns on the street, you will see more rear tire wear, and you will experience more tail out power sliding in slippery conditions.
LSDs need to be rebuilt periodically as the clutches wear. Usually suggested every 2 years or so. So there is a maintenance cost.
Click here for more info from Guard Transmission.
LSD - Limited Slip Differential 
A limited slip differential (LSD) is a modified or derived type of differential gear arrangement that allows for some difference in rotational velocity of the output shafts, but does not allow the difference in speed to increase beyond a preset amount. In an automobile, such limited slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.
The main advantage of a limited slip differential is found by considering the case of a standard (or "open") differential where one wheel has no contact with the ground at all. In such a case, the contacting wheel will remain stationary, and the non-contacting wheel will rotate freely– the torque transmitted will be equal at both wheels, but will not exceed the threshold of torque needed to move the vehicle, thus the vehicle will remain stationary. In everyday use on typical roads, such a situation is very unlikely, and so a normal differential suffices. For more demanding use however, such as driving off-road, or for high performance vehicles, such a state of affairs is undesirable, and the LSD can be employed to deal with it. By limiting the velocity difference between a pair of driven wheels, useful torque can be transmitted as long as there is some friction available on at least one of the wheels.
To see the installation of a LSD style unit Click Here -> Article Forthcoming Stay Tuned
TBD - Torque Biased Differential
A TBD provides limited torque differential between the two wheels only during acceleration. The more torque that's being applied, the more resistance to different speeds a TBD will provide. When the car is being driven on the street under light acceleration, the TBD remains loose like an open differential. This makes the TBD a good choice for someone that uses their car on the street most of the time, but does some auto crossing. It goes well with the Jekyll/Hyde nature of the typical Cayman.
For serious auto crossing, some form of limited slip differential is almost a must. During tight turns, applyin torque to both drive wheels helps rotate the car and accelerate away from the turn.
The biggest weakness of the TBD is the fact that if you lift a wheel, all torque will go to that wheel making all benefits go out the window. This is more likely to happen on a high speed track event when the car is experiencing high G's for longer periods of time through sweeping turns. When a TBD lifts a wheel, and that wheel slips, the TBD itself takes a real beating. Repeated and prolonged incidents of wheel lift will wear and/or destroy a TBD over time.
The biggest strength of a TBD is the fact that if it is applied properly (not on a high horsepower car that experiences a lot of wheel lift), it will last virtually forever without any service or maintenance.
LSD - Limited Slip Differential (aka "clutch type")
The other type of limited slip differential is the clutch type, usually referred to as the LSD. This type of LSD applies a constant amount limited slip between the drive wheels through friction clutches. Modern designs have made it possible to apply a different amount of torque during acceleration than during braking. In Robins first post you see two LSDs, a 60/40 and an 80/50. These numbers communicate the amount of torque transmitted between the drive wheels during acceleration and decelleration.
60/40 means 60% on acceleration, 40% during braking. Likewise, 80/50 supplies 80% during acceleration, 50% during braking.
A TBD provides no benefit during braking. Limited slip during braking can be very helpful on the track. Limiting the slip during braking will push the front wheels, keep the car going straight and help it resist spinning making late braking more stable. Trail braking into a turn with an LSD will help a good driver walk the tail out a little before the apex and set up for a nice tail out exit after the apex. This is not for the faint of heart. A novice drivers will likely lift when they feel this, spin and lose it.
During wheel lift, and LSD still provides torque to the planted wheel. It's better when used on a high horsepower car that sees aggressive tracking. But because and LSD provides limited slip all the time, you will experience binding when driving through tight turns on the street, you will see more rear tire wear, and you will experience more tail out power sliding in slippery conditions.
LSDs need to be rebuilt periodically as the clutches wear. Usually suggested every 2 years or so. So there is a maintenance cost.
Click here for more info from Guard Transmission.
LSD - Limited Slip Differential A limited slip differential (LSD) is a modified or derived type of differential gear arrangement that allows for some difference in rotational velocity of the output shafts, but does not allow the difference in speed to increase beyond a preset amount. In an automobile, such limited slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.The main advantage of a limited slip differential is found by considering the case of a standard (or "open") differential where one wheel has no contact with the ground at all. In such a case, the contacting wheel will remain stationary, and the non-contacting wheel will rotate freely– the torque transmitted will be equal at both wheels, but will not exceed the threshold of torque needed to move the vehicle, thus the vehicle will remain stationary. In everyday use on typical roads, such a situation is very unlikely, and so a normal differential suffices. For more demanding use however, such as driving off-road, or for high performance vehicles, such a state of affairs is undesirable, and the LSD can be employed to deal with it. By limiting the velocity difference between a pair of driven wheels, useful torque can be transmitted as long as there is some friction available on at least one of the wheels.
To see the installation of a LSD style unit Click Here -> Article Forthcoming Stay Tuned
#7
05-09-2009, 08:41 PM
I'd look into the OS Giken one as well. I have been on their site and they do have around a 600 ft lb limit on their diffs so you may be over the power level.
You might as well go big or go home in this case because you do not want to have to keep rebuilding the LSD.
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#10
05-09-2009, 08:58 PM
I have a full monty coming in this month.... akram is about to do my transmission... you know I had the blow out two days before the supra nats and wrecked my car?? So all those people I was racing was only racing a shell of a car... I was only making about 85% of what I could be making....
Robert
Oh to answer your question I purchased everything from a group that builds porsche racing transmissions in colorado... call akram for the details
robert
Robert
Oh to answer your question I purchased everything from a group that builds porsche racing transmissions in colorado... call akram for the details
robert
#11
05-09-2009, 09:12 PM
Go with the Guard, you're looking at about 3k + 1k in labor, be careful as other things may come up while you're in there that could add another 1-2k to the cost. I'm quite impressed with the results, since adding it to our car it hooked much beter AWD that we where convinced to conver the car to RWD. Guard also offers a few different variations to their differentials in both material and ratio.
The person RobMD is speaking off in Colorado is GBox. They are very knowledgeable when it comes to the G50s, as are the nice folks at Guard. I learned more than I ever could need to know about the 996 transmission in the week I had ours rebuild (just days before TX as well).
The person RobMD is speaking off in Colorado is GBox. They are very knowledgeable when it comes to the G50s, as are the nice folks at Guard. I learned more than I ever could need to know about the 996 transmission in the week I had ours rebuild (just days before TX as well).
#12
05-10-2009, 02:01 AM
Sean, I am running the Quaife... TBH my friend is a good friend of Phil Quaife and I got a pretty good deal on one... the only downside with the Quaife is that if one wheel is off the ground the other will not operate (I looked at this as a positive) it's extremely difficult to get a rear wheel on our rear engined cars off the ground in the first place and if your doing so IMO it's giving you a warning 
... the Quaife unit is bullet proof and comes with a lifetime guarantee and they do them for some pretty high HP/Torque motors. I'm off to SPA in 3/4 weeks and will be giving it some beans as usual so I can give you good honest feedback, if you can wait!... I have no doubt that the Guards unit is the best out there but as I say I got a cracking deal and thought I would at least give it a try.
... the Quaife unit is bullet proof and comes with a lifetime guarantee and they do them for some pretty high HP/Torque motors. I'm off to SPA in 3/4 weeks and will be giving it some beans as usual so I can give you good honest feedback, if you can wait!... I have no doubt that the Guards unit is the best out there but as I say I got a cracking deal and thought I would at least give it a try.
#13
05-10-2009, 02:35 AM
Registered User
Join Date: Feb 2004
Location: In a Canyon - Really :)
Posts: 4,880
Rep Power: 288
My understanding is that the TT and GT2 have the same tranny. I have read here that some euro spec TT cars came with an optional LSD.
If upgrading or repairing, I think you should go with the Quaife or Guard.
Stevo: what do you mean by "won't operate with one wheel off the ground'? I'm puzzled at how that works mechanically.
If upgrading or repairing, I think you should go with the Quaife or Guard.
Stevo: what do you mean by "won't operate with one wheel off the ground'? I'm puzzled at how that works mechanically.
Last edited by Turbo Fanatic; 05-10-2009 at 11:42 AM.
#14
05-10-2009, 05:09 AM
Some interesting info on diffs => http://faq.ford77.ru/trans/differential.htm
Supra came with Torsen diffs which I believe are the "torque biased" spoken about here. One thing that could supposedly happen on track in a straight quarter was the rear could "steer" the car. It seems power isn't applied quite evenly when you had traction! I may have experienced this but am not sure, it was pretty spooky! Certainly a question to ask as high torque is likely what did it. Anyway, worth considering. The lack of maintenance on the gear type is nice IMO, no special additives either.
Wes, will you be offering tranny rebuild services and modification work now? I hope to never need it but....
Supra came with Torsen diffs which I believe are the "torque biased" spoken about here. One thing that could supposedly happen on track in a straight quarter was the rear could "steer" the car. It seems power isn't applied quite evenly when you had traction! I may have experienced this but am not sure, it was pretty spooky! Certainly a question to ask as high torque is likely what did it. Anyway, worth considering. The lack of maintenance on the gear type is nice IMO, no special additives either.
Wes, will you be offering tranny rebuild services and modification work now? I hope to never need it but....
#15
05-10-2009, 05:33 AM
Gaurd LSD
Sean, I am running the Gaurds' for 2 years now. Love it! I was told by several race
shops most are running it. I spoke with Tom Kerr's shop before going RWD and he
said they run the Gaurd's exclusively. There is a previous thread discussion on LSD
with RWD conversion. GL
shops most are running it. I spoke with Tom Kerr's shop before going RWD and he
said they run the Gaurd's exclusively. There is a previous thread discussion on LSD
with RWD conversion. GL