7.2 Factory Limited Slip
02-13-2013, 06:08 PM
#18
Rennlist Member
Therefore:
You have some options, none of which I think are illegal, all of which Matt at Guard can do for you.
Keep the stock ramps, but rebuild the entire internals with a new factory clutchpack, however have Matt shim it correctly and put enough pre-load on it so it actually works. Nothing has changed, zero, nada. Just a rebuilt LSD, which IS a wear item, just like brakes, tires, bushings etc. You have replaced it with same exact items, works "mechanically" the exact same.
Or
Keep the stock ramps, but use a Guard clutch pack instead, and rebuild the diff.
Again, you have kept everything mechanically the same, no change in ramps, you have simply replaced a "wear item", which a clutch pack is, with a replacement set. It's not OEM, but mechanically, it works the same. I don't see any issue with this either.
02-13-2013, 06:31 PM
#20
Race Car
02-13-2013, 07:06 PM
#21
Race Director
02-13-2013, 07:08 PM
#22
Race Director
02-13-2013, 07:14 PM
#23
Nordschleife Master
02-13-2013, 07:55 PM
#26
Three Wheelin'
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The reason why I ask about Motorsport parts legality is, technically speaking the parts are available from dealerships as replacement parts. Therefor, if you use a Motorsport diff parts and internals you can gain an advantage, and since it is, by definition from the factory, a wear item, I don't see how they can enforce any kind of non-OE rules violation. But stranger things happen all the time, and interpretation of rules is one of those things...
What rules set are you running? SCCA? I hate their rules definition and weenie protests- what is not explicitly stated in the rule book is illegal, and weenie protests seem to rule the day in autoX.
02-13-2013, 08:03 PM
#27
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02-13-2013, 08:21 PM
#28
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On SCCA ruleset:
"Section 13. Alternate components which are normally expendable and considered
replacement parts (e.g., engine and wheel bearings, seals, gaskets,
filters, belts, bolts, bulbs, batteries, brake rotors, clutch discs, pressure
plates, suspension bushings, drivetrain mounts, fenders, trim pieces,
etc.) may be used provided they are essentially identical to the standard
parts (e.g. have the same type, size, hardness, weight, material etc.),
are used in the same location, and provide no performance benefit. The
allowance for use of such replacements does not include camshafts,
differential covers, or ring-and-pinion sets, nor does it authorize the use
of piston rings having different configurations (e.g. “Total Seal”) from
those of the original."
A limited slip is a wear item, and an aftermarket part is allowed, but there are restrictions. The only way to make the aftermarket LSD legal in a SCCA stock class is by using the same housing as stock, the same number of plates as stock, and the lock/unlock rates of the LSD match the ones in the OEM LSD. The aftermarket part must have no performance benefit.
To prove this, the car owner would need a brand new in-box LSD as equipped in the car, so this can be compared to the one in the car. Get protested (very likely at a Regional or National SCCA autoX event), get suspension disassembled, axle disconnected, LSD removed, and let the SCCA techs or a Porsche dealer compare the two units, and come up with a result that both parts have identical behavior.
By the way, the wording on the above rule is vague and misleading. No aftermarket part will match the same material/weight/size/hardness, not even a bulb. There are tolerances, and even the OEM parts can have different size/material/hardness depending on who supplied Porsche that day of the week.
"Section 13. Alternate components which are normally expendable and considered
replacement parts (e.g., engine and wheel bearings, seals, gaskets,
filters, belts, bolts, bulbs, batteries, brake rotors, clutch discs, pressure
plates, suspension bushings, drivetrain mounts, fenders, trim pieces,
etc.) may be used provided they are essentially identical to the standard
parts (e.g. have the same type, size, hardness, weight, material etc.),
are used in the same location, and provide no performance benefit. The
allowance for use of such replacements does not include camshafts,
differential covers, or ring-and-pinion sets, nor does it authorize the use
of piston rings having different configurations (e.g. “Total Seal”) from
those of the original."
A limited slip is a wear item, and an aftermarket part is allowed, but there are restrictions. The only way to make the aftermarket LSD legal in a SCCA stock class is by using the same housing as stock, the same number of plates as stock, and the lock/unlock rates of the LSD match the ones in the OEM LSD. The aftermarket part must have no performance benefit.
To prove this, the car owner would need a brand new in-box LSD as equipped in the car, so this can be compared to the one in the car. Get protested (very likely at a Regional or National SCCA autoX event), get suspension disassembled, axle disconnected, LSD removed, and let the SCCA techs or a Porsche dealer compare the two units, and come up with a result that both parts have identical behavior.
By the way, the wording on the above rule is vague and misleading. No aftermarket part will match the same material/weight/size/hardness, not even a bulb. There are tolerances, and even the OEM parts can have different size/material/hardness depending on who supplied Porsche that day of the week.
02-13-2013, 08:23 PM
#29
Three Wheelin'
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02-13-2013, 08:48 PM
#30
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On SCCA ruleset:
"Section 13. Alternate components which are normally expendable and considered
replacement parts (e.g., engine and wheel bearings, seals, gaskets,
filters, belts, bolts, bulbs, batteries, brake rotors, clutch discs, pressure
plates, suspension bushings, drivetrain mounts, fenders, trim pieces,
etc.) may be used provided they are essentially identical to the standard
parts (e.g. have the same type, size, hardness, weight, material etc.),
are used in the same location, and provide no performance benefit. The
allowance for use of such replacements does not include camshafts,
differential covers, or ring-and-pinion sets, nor does it authorize the use
of piston rings having different configurations (e.g. “Total Seal”) from
those of the original."
A limited slip is a wear item, and an aftermarket part is allowed, but there are restrictions. The only way to make the aftermarket LSD legal in a SCCA stock class is by using the same housing as stock, the same number of plates as stock, and the lock/unlock rates of the LSD match the ones in the OEM LSD. The aftermarket part must have no performance benefit.
To prove this, the car owner would need a brand new in-box LSD as equipped in the car, so this can be compared to the one in the car. Get protested (very likely at a Regional or National SCCA autoX event), get suspension disassembled, axle disconnected, LSD removed, and let the SCCA techs or a Porsche dealer compare the two units, and come up with a result that both parts have identical behavior.
By the way, the wording on the above rule is vague and misleading. No aftermarket part will match the same material/weight/size/hardness, not even a bulb. There are tolerances, and even the OEM parts can have different size/material/hardness depending on who supplied Porsche that day of the week.
"Section 13. Alternate components which are normally expendable and considered
replacement parts (e.g., engine and wheel bearings, seals, gaskets,
filters, belts, bolts, bulbs, batteries, brake rotors, clutch discs, pressure
plates, suspension bushings, drivetrain mounts, fenders, trim pieces,
etc.) may be used provided they are essentially identical to the standard
parts (e.g. have the same type, size, hardness, weight, material etc.),
are used in the same location, and provide no performance benefit. The
allowance for use of such replacements does not include camshafts,
differential covers, or ring-and-pinion sets, nor does it authorize the use
of piston rings having different configurations (e.g. “Total Seal”) from
those of the original."
A limited slip is a wear item, and an aftermarket part is allowed, but there are restrictions. The only way to make the aftermarket LSD legal in a SCCA stock class is by using the same housing as stock, the same number of plates as stock, and the lock/unlock rates of the LSD match the ones in the OEM LSD. The aftermarket part must have no performance benefit.
To prove this, the car owner would need a brand new in-box LSD as equipped in the car, so this can be compared to the one in the car. Get protested (very likely at a Regional or National SCCA autoX event), get suspension disassembled, axle disconnected, LSD removed, and let the SCCA techs or a Porsche dealer compare the two units, and come up with a result that both parts have identical behavior.
By the way, the wording on the above rule is vague and misleading. No aftermarket part will match the same material/weight/size/hardness, not even a bulb. There are tolerances, and even the OEM parts can have different size/material/hardness depending on who supplied Porsche that day of the week.
The fact that the OEM unit for Porsche varies so greatly is the very reason they couldn't disqualify you, or set up some sort of "standard" other than specifiying that stock ramps, casing, and number of plates must be used. How much pre-load you put on your LSD is your choice, and not somethig to be disqualified for.