[firefish]

Decided to check the function of the LSD this morning. I remember the PO saying something about the springs being bad (which I assume means that is is slipping). Jacked up on one side and, indeed, the wheel is spinning freely without any friction at all. And without any noise too which I guess is a good thing.

Now to the questions. Can the stock LSD be rebuilt? Or should I get better one (assuming that there better ones available)? I do not have any leaks from the tranny, nor do I have any of the dreadful R&P noises. Should I replace the P&P bearing now for safe measure or leave it until it becomes a problem? Can the LSD be removed/installed with the tranny in the car? What other things, except maybe for the R&P bearing, should be adressed if I take the transaxle down?

I wanna do it right but I do not want to replace a lot of working parts just for the sake of replacing them (limited finacial resources) so point me in the right direction please [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]

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[Big Dave]

It all depends which type of diff you have fitted.
If its a plate LSD then yes its rebuildable. If its the Torsen type [torque biased] then as far as i know its not rebuildable...
Usually the early cars were fitted with "plate" diffs + later cars Torsen diffs...
Yes you can remove + replace the diff whilst the box is in the car. BUT if your doing other seals etc then its better out of the car...
Have you considered the fact that you might not have a LSD .?? I know of a few cars that had the diffs removed [because of costly rebuilding ] + fitted with a standard "open" diff,,even though it had a 220 code on the options list...Just a thought...

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[968gene]

just a simple question...was the car in gear?

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[firefish]

I sure hope that they have not removed the LSD...

About the gear. I jacked the left rear tire up with the right tire on the ground and trans in neutral. The LSD did not brake as I assumed it would. Should I have done it differentely?

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[968gene]

I always thought that you place the car in gear, jack up both rear tires and spin one. The other tire will turn in the same direction if you have an LSD, and in the opposite if non-LSD. If the car has LSD and passes the first test, it should be difficult to turn one tire off the ground if the car is in gear. You may been turning only a neutral transmission. (or I may be completely wrong, anyone else?)

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[firefish]

<!--quoteo(post=71465:date=May 6 2009, 12:52 PM:name=968gene)-->QUOTE (968gene @ May 6 2009, 12:52 PM) <{POST_SNAPBACK}><!--quotec-->I always thought that you place the car in gear, jack up both rear tires and spin one. The other tire will turn in the same direction if you have an LSD, and in the opposite if non-LSD. If the car has LSD and passes the first test, it should be difficult to turn one tire off the ground if the car is in gear. You may been turning only a neutral transmission. (or I may be completely wrong, anyone else?)<!--QuoteEnd--><!--QuoteEEnd-->

I usually do that too. But in this case, from what I have read, the idea is to measure the "health" of the LSD by measuring the torque needed to turn one wheel when the other one sits firm on the ground with the engine in neutral. With an open diff the necessary torque is about zero until the prop shaft starts to turn. With a LSD you first have to overcome the limited slip that connects the two wheels. I read somewhere that a fresh LSD takes about a 100 Nm before it slips. In my case it took zero torque so A; it is completely shot or B; it has been removed (worst case I might add).

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[p65356sc]

I just drop a patch of rubber on the driveway.................If I get two marks I'm fine

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[firefish]

<!--quoteo(post=71475:date=May 6 2009, 03:28 PM:name=p92968)-->QUOTE (p92968 @ May 6 2009, 03:28 PM) <{POST_SNAPBACK}><!--quotec-->I just drop a patch of rubber on the driveway.................If I get two marks I'm fine<!--QuoteEnd--><!--QuoteEEnd-->

Talked to a reputable shop today (works mostly in 997 GT3 Cup though...). Appearantely the stock LSD has very little "pre tension" so you can not determine the condition of the diff by measuring the torque needed to turn the wheel. You can tell wether it has a LSD or not the classic way. Jack the rear up and if the wheels are spinning the same direction OR if the other wheel is standing still = LSD. If it turns the opposite direction = open. The shop also said that it is almost unheard of that the stock style LSD simply breaks and stops doing its job (unless it goes boom and you have a major failure). It is however common that they over time and mileage get weaker and will eventually require a rebuild. It is supposedly hard to measure the status of the LSD without taking it apart and you'll have to push the car in order to find out, ie two black = ok, one black = no ok. Or if the inner tire spins in the turns on the track.

So, since my opposite tire is standing still when turning the wheel it leads me to assume that the 220 option LSD is still in place. I'm way to cheap to simply burn up rubber so that I can count the stripes so I guess I have to find a track instead [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]

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[fla968]

<!--quoteo(post=71492:date=May 6 2009, 01:30 PM:name=firefish)-->QUOTE (firefish @ May 6 2009, 01:30 PM) <{POST_SNAPBACK}><!--quotec-->Talked to a reputable shop today (works mostly in 997 GT3 Cup though...). Appearantely the stock LSD has very little "pre tension" so you can not determine the condition of the diff by measuring the torque needed to turn the wheel. You can tell wether it has a LSD or not the classic way. Jack the rear up and if the wheels are spinning the same direction OR if the other wheel is standing still = LSD. If it turns the opposite direction = open. The shop also said that it is almost unheard of that the stock style LSD simply breaks and stops doing its job (unless it goes boom and you have a major failure). It is however common that they over time and mileage get weaker and will eventually require a rebuild. It is supposedly hard to measure the status of the LSD without taking it apart and you'll have to push the car in order to find out, ie two black = ok, one black = no ok. Or if the inner tire spins in the turns on the track.

So, since my opposite tire is standing still when turning the wheel it leads me to assume that the 220 option LSD is still in place. I'm way to cheap to simply burn up rubber so that I can count the stripes so I guess I have to find a track instead [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]<!--QuoteEnd--><!--QuoteEEnd-->

In gear or out?

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[rustech]

The diff functions independent, unless you want to turn the motor with it, keep it in neutral. (BTW, TBD's behave like open diffs and turn opposite directions.)

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[RS Barn]

OK,
Unless you have an early 92 with clutch style LSD you will not get any drag on second wheel with car elevated.
You most likely have Torsen style LSD which is Torque sensing and takes a significant load to start working.
The only way I've found to tell if TS style is working is to find an open parking lot and race in 3rd gear to 5k and threshold brake and heel tow to second with high revs and then hammer on throttle while turning at 90 degrees.
You will then experience wild wheelspin and then the LSD locking which will snap the car back. Then you know!!!
otherwise pull LSD from car and visually confirm
Ask me how I know!!!!
Pete

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[Mark]

Hey Pete can you check my LSD out while you have the car? [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]

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[RS Barn]

Mark,
Is yours an LSD?
I'll have to do my extreme 968 teste
Pete

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[Mark]

That one supposedly has a 220 or 221 option code. [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]

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[fla968]

<!--quoteo(post=74135:date=Jun 17 2009, 05:42 PM:name=rustech)-->QUOTE (rustech @ Jun 17 2009, 05:42 PM) <{POST_SNAPBACK}><!--quotec-->The diff functions independent, unless you want to turn the motor with it, keep it in neutral. (BTW, TBD's behave like open diffs and turn opposite directions.)<!--QuoteEnd--><!--QuoteEEnd-->
TBD's? I jacked my (95 Cab) rear up and spun right wheel. The left one was still. I do notice that when I spin the rears in a tight turn, it seems to slide a bit then "grab".

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