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YOUR RESEARCHLSD rebuild & upgrade
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Reported cause
This is due to the fact that the plate type is more adjustable and a true LSD but they wear and need adjustment and the torque bias gear type fit and forget.
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Suggestion · Original poster
I have been checking into the options to get the diff rebuilt and considered the following.
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Suggestion · Original poster
I completely agree with your point about an early oil change after the discs are bedded in a bit.
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Suggestion
Best to run in carefully for at least 500 miles, change oil then run again for 2,000 miles(change oil) then your back to the the normal oil change periods.
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Suggestion
Best to run in carefully for at least 500 miles, change oil then run again for 2,000 miles(change oil) then your back to the the normal oil change periods.
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Suggestion
Best to run in carefully for at least 500 miles, change oil then run again for 2,000 miles(change oil) then your back to the the normal oil change periods.
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Suggestion
Best to run in carefully for at least 500 miles, change oil then run again for 2,000 miles(change oil) then your back to the the normal oil change periods.
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Suggestion
Best to run in carefully for at least 500 miles, change oil then run again for 2,000 miles(change oil) then your back to the the normal oil change periods.
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Reported cause
This is due to the fact that the plate type is more adjustable and a true LSD but they wear and need adjustment and the torque bias gear type fit and forget.
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I thought I might post some pics before these parts go into my LSD.
My car being a 99 C2 has the Option 220 LSD fitted and no PSM. That's a good start but these diffs have a pretty low locking rate of 22%/40% and they are pretty well known for the OEM friction discs to become non effective pretty quickly. When I have the car on the lift the rear wheels offer very little turning resistance (pre-load) and the other wheel does not turn at all.
I have been checking into the options to get the diff rebuilt and considered the following.
New OEM clutch kit
New motorsports clutch kit
New motorsports clutch kit and GT3 ramps (40/65)
GT Gears clutch kit
GT Gears Clutch kit & billet ramps (40/60 & 50/80)
In the end I went with the GT (Guard Transmission) clutch kit & ramps - with the goal being to get friction discs that work (& keep working) and a lockup rate that is going to make a worthwhile improvement on track. These parts are the same parts that go in a GT-3/motorsports LSD if you were rebuilding it.
So next is to pull the diff out and get to work!
Some 996's already have 40/60 ramps fitted(exc bite on exit). 997's have a lower lock-up and 28/40 ramps. I believe they are not as good as the 996's, so best sticking with 40/60(or close enough)...as you have done :thumb:
What you also have to be aware of is that diff cracking can occur on upgraded 996 carrera cases if the car is being raced/tracked hard. Best to run in carefully for at least 500 miles, change oil then run again for 2,000 miles(change oil) then your back to the the normal oil change periods. Try and avoid lap-after-lap /long track sessions to minimise the risk of case fracture.
Stick the motorsport plates into it and you'll be all set :thumb:
Pre-load is VITAL... best get it done by someone who has the gauges/tools(if you don't).
From my discussions with Matt (at GT) it seems that the 996 LSD is basically the same strength wise as the other 996/GT3 LSDs Porsche (actually GKN) produced in the same era and it has the cut gears vice the cast gears of the later 997s so I'm not overly concerned about stressing the LSD housing, especially with my meagre 300hp and relatively short sessions on track. I completely agree with your point about an early oil change after the discs are bedded in a bit.
The GT carbon discs are equivalent to the motorsport discs and the discs and plates that Matt has provided me with, in conjunction with the GT ramps more or less form a matched set to deliver the appropriate pre-load in my LSD (that's from Matt and I'm more than happy to trust his judgement on LSD issues). As you can imagine we have discussed that issue. I did talk to Steve McHale at JZM about my LSD options and he was pretty helpful and if I get into difficulty I can always head down there and have them re-assemble it, but to be honest, whilst I've rebuilt engines and transaxles before, I've never done an LSD so I'm kind of keen to have a go.
That said I'll still be taking measurements along the way and consulting with Matt when I assemble the LSD. I brought my micrometers and calipers with me so I can get accurate measurements while I'm doing it.
I know I'm bring up an old tread. However I'm looking into have my 220 factor fit diff rebuilt. I've been in touch with some Porsche indi's who recommend replacing the plate diff with a Quaife ATB LSD. I'm not keen on doing this so wondered what other people have done to re build or upgrade there plate diffs? Also who they recommend to carry out the work?
Have a chat with Mike. They rebuild a lot of Porsche gearboxes. Mike runs a modified 996 GT3 so can probably advise the best for what you require
https://sportsandclassic.com/
I've always believed a plate type LSD was preferred for track and a Quaife or torsen torque bias diff for road. This is due to the fact that the plate type is more adjustable and a true LSD but they wear and need adjustment and the torque bias gear type fit and forget.
The disadvantage for the gear type is if one wheel does leave the ground they do loose drive to the non loaded wheel. Not normally an issue on road may be in a race riding the kerbs.
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