G50 LSD
12-17-2002, 03:03 AM
#2
RL Technical Advisor
[quote]Originally posted by Dean:
<strong>I am thinking about putting an LSD in my 88 G50. I was wondering if an LSD from a 993 would fit?
Thanks
Dean</strong><hr></blockquote>
Hi Dean:
OMG, You would NOT want the 993's LSD,...its a real POS. Stay away from those.
LSD's are a great idea, get the one for your G-50 or the Guard Transmission one (ZF-type).
<strong>I am thinking about putting an LSD in my 88 G50. I was wondering if an LSD from a 993 would fit?
Thanks
Dean</strong><hr></blockquote>
Hi Dean:
OMG, You would NOT want the 993's LSD,...its a real POS. Stay away from those.
LSD's are a great idea, get the one for your G-50 or the Guard Transmission one (ZF-type).
12-17-2002, 09:59 PM
#4
RL Technical Advisor
[quote]Originally posted by Dean:
<strong>Hi Steve,
Why are the 993 LSD bad?
Thanks,
Dean</strong><hr></blockquote>
Hi Dean:
Two big reasons:
1) The number of drive & driven plates is 1/2 of the early ones and they are normally all worn out by 25K miles.
2) The 993 LSD cases are cast, not forged, and are prone to break.
We use the Guard LSD's which have 4 plates per side and 4340 chrome moly cases. These never break and maintain their locking factor FAR longer than the ZF 993 ones do. There are other differences in lockup, both under acceleration & braking, as well,.........
<strong>Hi Steve,
Why are the 993 LSD bad?
Thanks,
Dean</strong><hr></blockquote>
Hi Dean:
Two big reasons:
1) The number of drive & driven plates is 1/2 of the early ones and they are normally all worn out by 25K miles.
2) The 993 LSD cases are cast, not forged, and are prone to break.
We use the Guard LSD's which have 4 plates per side and 4340 chrome moly cases. These never break and maintain their locking factor FAR longer than the ZF 993 ones do. There are other differences in lockup, both under acceleration & braking, as well,.........
01-08-2003, 07:16 PM
#7
RL Technical Advisor
</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by RSAErick:
<strong>How about the 40% LSD from the 964? My LSD has 105,000 miles of lickin' and keeps on tickin'.
Erick</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi Erick:
The 964 LSD's are great. Those are FAR better than the 993's where Porsche went el cheapo on the internals.
<strong>How about the 40% LSD from the 964? My LSD has 105,000 miles of lickin' and keeps on tickin'.
Erick</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi Erick:
The 964 LSD's are great. Those are FAR better than the 993's where Porsche went el cheapo on the internals.
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01-09-2003, 08:30 PM
#8
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Hi Steve,
Can you tell me what you would recommend for a LSD in a racing application (never driven on the street) for an '87 911 with a stock 3.2 motor and G50 tranny? Thanks,
steve
Can you tell me what you would recommend for a LSD in a racing application (never driven on the street) for an '87 911 with a stock 3.2 motor and G50 tranny? Thanks,
steve
01-11-2003, 09:34 PM
#9
RL Technical Advisor
</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by stevehay94:
<strong>Hi Steve,
Can you tell me what you would recommend for a LSD in a racing application (never driven on the street) for an '87 911 with a stock 3.2 motor and G50 tranny? Thanks,
steve</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi Steve:
For a race car (or hot street car), the preferred LSD's are the 4340 chrome Moly ones made by Guard Transmission.
Use the ZF-style (clutch pack), not the Torque-sensing kind. The difference in what the clutch pack ones do for handling is night & day over the others.
<strong>Hi Steve,
Can you tell me what you would recommend for a LSD in a racing application (never driven on the street) for an '87 911 with a stock 3.2 motor and G50 tranny? Thanks,
steve</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi Steve:
For a race car (or hot street car), the preferred LSD's are the 4340 chrome Moly ones made by Guard Transmission.
Use the ZF-style (clutch pack), not the Torque-sensing kind. The difference in what the clutch pack ones do for handling is night & day over the others.
02-07-2003, 04:11 PM
#11
RL Technical Advisor
</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by ledyard:
<strong>What about a Quaife LSD for a G50?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi:
The Quaife LSD's are of the torque-sensing kind and are not the preferred item for track use.
Quaife's and the Guard Transmission ones are OK for street use and Autocross.
<strong>What about a Quaife LSD for a G50?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi:
The Quaife LSD's are of the torque-sensing kind and are not the preferred item for track use.
Quaife's and the Guard Transmission ones are OK for street use and Autocross.
02-08-2003, 11:13 AM
#12
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</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Steve Weiner-Rennsport Systems:
<strong> </font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by ledyard:
<strong>What about a Quaife LSD for a G50?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi:
The Quaife LSD's are of the torque-sensing kind and are not the preferred item for track use.
Quaife's and the Guard Transmission ones are OK for street use and Autocross.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Steve, Why? I went from a 915 w/LSD on an 84 Euro 911(heavy mods and 2425 lbs) to a Quaiffe and lowered my track times by at least 2 seconds at most tracks. I pulled through the turns with the TB capability. Most of the guys I raced with on the east coast also swore by these units.
Just curious on your thoughts here.
<strong> </font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by ledyard:
<strong>What about a Quaife LSD for a G50?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi:
The Quaife LSD's are of the torque-sensing kind and are not the preferred item for track use.
Quaife's and the Guard Transmission ones are OK for street use and Autocross.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Steve, Why? I went from a 915 w/LSD on an 84 Euro 911(heavy mods and 2425 lbs) to a Quaiffe and lowered my track times by at least 2 seconds at most tracks. I pulled through the turns with the TB capability. Most of the guys I raced with on the east coast also swore by these units.
Just curious on your thoughts here.
02-08-2003, 05:29 PM
#13
RL Technical Advisor
Hi Bob:
Good question, Sir.
Lets review a few things about the pro's & con's for each type of differential and that will illustrate my point better.
ZF-type LSD's (clutch-pack):
1) These LSD's come in either 40% or 80% locking and are also available with symmetrical or assymetrical ramps. To a point, the pre-load or locking factor is adjustable in each range and gives the owner an opportunity to "tune" these things.
2) These LSD's put the power down quite well and do a fine job of controlling wheelspin. Their chief disadvantage is that they do increase the understeer a little, and they require attention from time to time. Overall, these are quite rugged.
3) These LSD's do something that the Torque-Sensing Diffs cannot do; they keep the rear wheels connected under braking and corner entry. This is VERY important as this plays a big role in stabilizing the rear end of the car at this critical juncture. Given the rear axle antics of the 911 and its propensity for trailing throttle oversteer, this quality is not to be overlooked or discounted.
The vast majority of race cars in the world employ these kinds of LSD's from F1 to Winston Cup, to CART and various venues of sports car racing. These differentials are not recommended for FWD cars unless its for Pro Rally or WRC.
To take advantage of how these LSD's behave, one must adjust the rear swaybar to increase its size to compensate for the inherent understeer, and some driving technique changes will allow you to take full advantge of its capabilities. Without a chassis adjustment, these can make understeer more difficult to deal with. Its not a biggie; one simply must understand the dynamics at work.
Torque-Sensing LSD's (Quaife):
1) These LSD's are mechanically complex but rugged as hell. There is no maintenance to deal with; its a set-and-forget.
2) These LSD's do a decent job of controlling wheelspin but its not the same as the above. A Torque-Sensing LSD sends the most torque to the wheel (singular) that has the most resistance to the ground. Its one or other other, never both, like the ZF-type LSD can do.
3) These LSD's produce negligible understeer and are quite transparent in operation. Since no different driver techniques are needed, these are quite popular as you cannot feel it "do its thing",......its simply "does it",... Generally speaking, no swaybar or other chassis changes are needed.
4) The chief disadvantage here is that the Torque-Sensing LSD's freewheel under trailing throttle like an open differential and provide no handling gains like the ZF-type does.
For street - AutoX - FWD cars, the Torque-sensitive LSD's are a godsend as they control wheelspin without adding the understeer that under these conditions, is difficult to deal with.
Finally, I'll tell you that for a race car with a moderately competant driver (or better), he'll be quicker with the ZF-type LSD provided that some chassis adjustments and driving technique changes are made. There are many other factors here that there is not room to mention, but this ought to give you some idea why I recommended what I did,....
Good question, Sir.
Lets review a few things about the pro's & con's for each type of differential and that will illustrate my point better.
ZF-type LSD's (clutch-pack):
1) These LSD's come in either 40% or 80% locking and are also available with symmetrical or assymetrical ramps. To a point, the pre-load or locking factor is adjustable in each range and gives the owner an opportunity to "tune" these things.
2) These LSD's put the power down quite well and do a fine job of controlling wheelspin. Their chief disadvantage is that they do increase the understeer a little, and they require attention from time to time. Overall, these are quite rugged.
3) These LSD's do something that the Torque-Sensing Diffs cannot do; they keep the rear wheels connected under braking and corner entry. This is VERY important as this plays a big role in stabilizing the rear end of the car at this critical juncture. Given the rear axle antics of the 911 and its propensity for trailing throttle oversteer, this quality is not to be overlooked or discounted.
The vast majority of race cars in the world employ these kinds of LSD's from F1 to Winston Cup, to CART and various venues of sports car racing. These differentials are not recommended for FWD cars unless its for Pro Rally or WRC.
To take advantage of how these LSD's behave, one must adjust the rear swaybar to increase its size to compensate for the inherent understeer, and some driving technique changes will allow you to take full advantge of its capabilities. Without a chassis adjustment, these can make understeer more difficult to deal with. Its not a biggie; one simply must understand the dynamics at work.
Torque-Sensing LSD's (Quaife):
1) These LSD's are mechanically complex but rugged as hell. There is no maintenance to deal with; its a set-and-forget.
2) These LSD's do a decent job of controlling wheelspin but its not the same as the above. A Torque-Sensing LSD sends the most torque to the wheel (singular) that has the most resistance to the ground. Its one or other other, never both, like the ZF-type LSD can do.
3) These LSD's produce negligible understeer and are quite transparent in operation. Since no different driver techniques are needed, these are quite popular as you cannot feel it "do its thing",......its simply "does it",...
Generally speaking, no swaybar or other chassis changes are needed.4) The chief disadvantage here is that the Torque-Sensing LSD's freewheel under trailing throttle like an open differential and provide no handling gains like the ZF-type does.
For street - AutoX - FWD cars, the Torque-sensitive LSD's are a godsend as they control wheelspin without adding the understeer that under these conditions, is difficult to deal with.
Finally, I'll tell you that for a race car with a moderately competant driver (or better), he'll be quicker with the ZF-type LSD provided that some chassis adjustments and driving technique changes are made. There are many other factors here that there is not room to mention, but this ought to give you some idea why I recommended what I did,....
02-09-2003, 07:34 PM
#14
Instructor
Steve:
I really appreciate your information re: Quaife vs Guards/ZF Type LSD's. When I asked my tech to install a LSD into the 915 I'm running and wanted to go with a Quaife because they were so much less expensive than the Guards counterpart. He was absolute in his opinion that I should stay away from the Quaife product. He didn't give me a whole lot of reasons why he felt so strongly about it. Now that I've read your reasoning, I understand the difference and am glad I went with his (and your) advice.
I really appreciate your information re: Quaife vs Guards/ZF Type LSD's. When I asked my tech to install a LSD into the 915 I'm running and wanted to go with a Quaife because they were so much less expensive than the Guards counterpart. He was absolute in his opinion that I should stay away from the Quaife product. He didn't give me a whole lot of reasons why he felt so strongly about it. Now that I've read your reasoning, I understand the difference and am glad I went with his (and your) advice.
02-10-2003, 12:06 AM
#15
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Steve a few more questions,
Your #3 above as to the advantages of the LSD
3) These LSD's do something that the Torque-Sensing Diffs cannot do; they keep the rear wheels connected under braking and corner entry. This is VERY important as this plays a big role in stabilizing the rear end of the car at this critical juncture. Given the rear axle antics of the 911 and its propensity for trailing throttle oversteer, this quality is not to be overlooked or discounted.
I am still unclear. Under braking, how is a LSD helping you brake over a quaiffe? Also, after corner entry as you say later, you can tune the characteristics of the Porsche with other suspensions components. With the said, trailing throttle oversteer with a Quaiffe should be better as power is being sent to the outside of the turn (assuming you have a setup to handle the traction).
The other issue I have trouble with is clutches. Clutches by definition slip to make the wheels turn on the rear with varying radii (sp?) for these wheels in a turn. First, slipping looses power in the drivetrain. Second, slipping looses power by generating heat.
Any insight would be appreciated.
Your #3 above as to the advantages of the LSD
3) These LSD's do something that the Torque-Sensing Diffs cannot do; they keep the rear wheels connected under braking and corner entry. This is VERY important as this plays a big role in stabilizing the rear end of the car at this critical juncture. Given the rear axle antics of the 911 and its propensity for trailing throttle oversteer, this quality is not to be overlooked or discounted.
I am still unclear. Under braking, how is a LSD helping you brake over a quaiffe? Also, after corner entry as you say later, you can tune the characteristics of the Porsche with other suspensions components. With the said, trailing throttle oversteer with a Quaiffe should be better as power is being sent to the outside of the turn (assuming you have a setup to handle the traction).
The other issue I have trouble with is clutches. Clutches by definition slip to make the wheels turn on the rear with varying radii (sp?) for these wheels in a turn. First, slipping looses power in the drivetrain. Second, slipping looses power by generating heat.
Any insight would be appreciated.