If we really have a glass diff....
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From: Sellersburg
Do these comments suggest that if you supercharge a s2k and rarely if ever launch it that the differential will break?
There is more benefit to a supercharger than coming off the line quick.
-B
There is more benefit to a supercharger than coming off the line quick.
-B
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From: Chicago
I still stand by my opinion that the drivetrain is fine on these cars, and that certain cars (for whatever reason) have some flaws that make them fail. Maybe the Rev's diff case had slighly out of line bearing carriers, so the LSD was held slightly out of line. That would eat a torsen quickly, but not a clutch type.
Ron and Annie (Banannie) ran their car at ProSolo's all year last year - conservatively I would estimate that to be 350-400 launches. Combine that with probably the 200-300 regular autocross runs they did, and you are talking 550-700 autocross runs on STICKY tires. If our diffs were truly glass, theirs would have certainly broken.
There is a certain combination of abuse and defectiveness working in all the diff failures I have read about. The Reverand swears up and down he didn't abuse the car, so that failure should be chalked up to a defect. It also could have been poor installation of the second diff by his dealer that screwed the second one.
However, MikeB talked of a journalist driving when their diff went - I know some journalists and they are not friendly to cars. They almost TRY to break them, and as a rule they are not good drivers at all. It takes a good driver to get the most out of a car without abusing it. This G1S2K character that broke his engine by buzzing it on a downshift, and is now surprised that Honda won't cover his broken diff? I smell abuse all the way.
What I am trying to say is that it's not as bad as it seems. There are going to be three cars running a ProSolos this year - ours (3 drivers) Ron and Annie's (2 drivers) and Joe Goeke/Anna Hedley (2 drivers - Gary Thomason's car). That is allot of data between 7 good drivers autcrossing 3 Stooks, 1 2000 and 2 2001's. It will be a great test of their durability.
I might eat crow and be replacing the diff before too long, we'll see - but for now I think it's too early to cry wolf. As far as supercharging - theoretically if you launch it a bit conservatively the diff should get no more load than stock. The clutch/tranny on the other hand may fail due to the SC.
The biggest killer of Torsen type diffs is axle hop - it doesn't even have to be high RPM, but if you are getting axle hop you are QUICKLY killing your diff. I have started to get it once or twice and I always let off right when I start to feel it. Doing this is the easiest way to save your diff.
Ron and Annie (Banannie) ran their car at ProSolo's all year last year - conservatively I would estimate that to be 350-400 launches. Combine that with probably the 200-300 regular autocross runs they did, and you are talking 550-700 autocross runs on STICKY tires. If our diffs were truly glass, theirs would have certainly broken.
There is a certain combination of abuse and defectiveness working in all the diff failures I have read about. The Reverand swears up and down he didn't abuse the car, so that failure should be chalked up to a defect. It also could have been poor installation of the second diff by his dealer that screwed the second one.
However, MikeB talked of a journalist driving when their diff went - I know some journalists and they are not friendly to cars. They almost TRY to break them, and as a rule they are not good drivers at all. It takes a good driver to get the most out of a car without abusing it. This G1S2K character that broke his engine by buzzing it on a downshift, and is now surprised that Honda won't cover his broken diff? I smell abuse all the way.
What I am trying to say is that it's not as bad as it seems. There are going to be three cars running a ProSolos this year - ours (3 drivers) Ron and Annie's (2 drivers) and Joe Goeke/Anna Hedley (2 drivers - Gary Thomason's car). That is allot of data between 7 good drivers autcrossing 3 Stooks, 1 2000 and 2 2001's. It will be a great test of their durability.
I might eat crow and be replacing the diff before too long, we'll see - but for now I think it's too early to cry wolf. As far as supercharging - theoretically if you launch it a bit conservatively the diff should get no more load than stock. The clutch/tranny on the other hand may fail due to the SC.
The biggest killer of Torsen type diffs is axle hop - it doesn't even have to be high RPM, but if you are getting axle hop you are QUICKLY killing your diff. I have started to get it once or twice and I always let off right when I start to feel it. Doing this is the easiest way to save your diff.
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From: Montreal
[QUOTE]Originally posted by Jason Saini
[B]I still stand by my opinion that the drivetrain is fine on these cars, and that certain cars (for whatever reason) have some flaws that make them fail.
[B]I still stand by my opinion that the drivetrain is fine on these cars, and that certain cars (for whatever reason) have some flaws that make them fail.
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From: Longmont, CO
I'm not much of a techie on how diffs work, but my stook does something the 944 doesn't - when one of the rear wheels is jacked up and the car is in neutral, I can freely spin the airborne wheel. I can't help but wonder if this is normal for the kind of diff we have...?
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Keep in mind that these cars don't have a Ford 9" rear end in them. The effect from doing a 7-8000 rpm launch with a supercharged engine, super wide sticky tires, and a clutch that won't slip(6 puck disc) is about the same as hitting the differential gears with a sledge hammer. You can't expect Honda engineers to be designing the car for that type of abuse.
Elistan, That happens with a Torsen type differential.
Elistan, That happens with a Torsen type differential.
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From: Santa Cruz, CA, US
Originally posted by Mike B at Comptech
Keep in mind that these cars don't have a Ford 9" rear end in them. The effect from doing a 7-8000 rpm launch with a supercharged engine, super wide sticky tires, and a clutch that won't slip(6 puck disc) is about the same as hitting the differential gears with a sledge hammer. You can't expect Honda engineers to be designing the car for that type of abuse.
Elistan, That happens with a Torsen type differential.
Keep in mind that these cars don't have a Ford 9" rear end in them. The effect from doing a 7-8000 rpm launch with a supercharged engine, super wide sticky tires, and a clutch that won't slip(6 puck disc) is about the same as hitting the differential gears with a sledge hammer. You can't expect Honda engineers to be designing the car for that type of abuse.
Elistan, That happens with a Torsen type differential.
Mike, what does Comptech plan to replace theirs with?
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From: You wish
I think Jason and all the other auto-x folks will provide some useful data. They are running on stickier tires and subjecting the cars to repeated abuse. And he's right that wheelhop will hurt you fast. Back in the early days of the RX-7TT some guys were killing diffs with wheel hop. Going to slicks actually stopped that (absorbed the vertical motion) and they stopped hurting diffs.
That said, you really have two options here.
If you want a tougher rear end, not just a diff (the Kaaz won't catastrophically fail on you, so go there to resolve the LSD issue), you're probably going to have to go to bigger gears. Perhaps the Rev can tell us since he took his diff apart, but I'm guessing the ring gear on the S2K is about 7-7.5" in diameter (the housing doesn't look big enough for anything more). Upping that even moderately would help alot. You could also go to thicker teeth. However, that would necessitate a taller rear gear ratio, which would hurt acceleration. However, if you combined with an ATS front gear set you could cancel the two out. Girdling the housing may also be useful if flex is occurring.
The other option is to stop dropping the clutch and start slipping it. On a stock clutch you'll kill the clutch relatively quickly, but on a good aftermarket clutch, preferably a dual disk unit, you can slip away without really causing any problems.
That's the real issue here, as Mike B. pointed out. Dropping the clutch without preloading the driveline is akin to smacking it with a hammer. There is no reason the rear diff couldn't handle a lot more power and torque if we weren't dropping the clutch. There is a reason why the stock Honda clutch slips - its a fuse that protects the rest of your driveline. And its a recoverable link because once it cools back down things are usually fine.
Don't worry about the driveshaft or the axles. And if you're getting the stock diff replaced, ask if the dealer will let you get it coated with a couple mils of Kerontite to harden the teeth. And use the best lubricants you can find to keep the heat down. Most of these failures, with the exception of Comptech's, seem to be gradual in nature and heat/lubrication may be a contributing cause.
UL
That said, you really have two options here.
If you want a tougher rear end, not just a diff (the Kaaz won't catastrophically fail on you, so go there to resolve the LSD issue), you're probably going to have to go to bigger gears. Perhaps the Rev can tell us since he took his diff apart, but I'm guessing the ring gear on the S2K is about 7-7.5" in diameter (the housing doesn't look big enough for anything more). Upping that even moderately would help alot. You could also go to thicker teeth. However, that would necessitate a taller rear gear ratio, which would hurt acceleration. However, if you combined with an ATS front gear set you could cancel the two out. Girdling the housing may also be useful if flex is occurring.
The other option is to stop dropping the clutch and start slipping it. On a stock clutch you'll kill the clutch relatively quickly, but on a good aftermarket clutch, preferably a dual disk unit, you can slip away without really causing any problems.
That's the real issue here, as Mike B. pointed out. Dropping the clutch without preloading the driveline is akin to smacking it with a hammer. There is no reason the rear diff couldn't handle a lot more power and torque if we weren't dropping the clutch. There is a reason why the stock Honda clutch slips - its a fuse that protects the rest of your driveline. And its a recoverable link because once it cools back down things are usually fine.
Don't worry about the driveshaft or the axles. And if you're getting the stock diff replaced, ask if the dealer will let you get it coated with a couple mils of Kerontite to harden the teeth. And use the best lubricants you can find to keep the heat down. Most of these failures, with the exception of Comptech's, seem to be gradual in nature and heat/lubrication may be a contributing cause.
UL