Value of 220 limited slip diff on G50 3.2? Diff type?

[r-mm]

Can anyone tell me what type of locking diff option code 220 would indicate on a G50 carrera? Meaning is it a viscous type and do they typically wear out with high miles? I'm looking at a car with over 100k that has this option code and trying to figure out if its an asset. Don't think it's a liability - i my experience when most locking diff's wear out they just rever to being open - is that the case with this one?

[spuggy]

G50 uses a plate-type ZF LSD just like the other factory ones (but they won't interchange).

Matt said (in another thread) that they're worth about $1000 more in a used G50. His sell new for more than twice that - and good luck finding one of his used, think I may have seen one or two...

Factory ones (at least on 3.2s with 915s) typically don't grip as hard as aftermarket/motorsport ones, and the later ones are referred to as "snow-only" diffs. Quick check to check if it's still fitted is to jack up the rear and rotate one wheel, watch the other one - with an open diff, it rotates the other way, LSD will rotate the same way. No idea at all what a completely worn-out LSD would do - I suspect either rotate the same way and break away easily, or do nothing if it's complete toast...

Think you can hold the other wheel fixed and check the breakaway torque with a torque wrench.

I had a 40/65 fitted to a car which previously had an open diff. It was eye-opening - makes a tremendous difference.

[r-mm]

Thanks this is very useful. I've searched on this site and found a few references to people rebuilding their own diffs. For a street only car (which will be driven in rain etc) If one were to sublet this work to a shop would it make economic sense to have the factory unit rebuilt or would you only ever replace it with an aftermarket unit? The car I'm looking at is high mile and I'm nearly positive the LSD will be more or less open by now so I'm trying to figure out if it actually ads to the value of the car or not and what I should plan for.

Originally Posted by spuggy

G50 uses a plate-type ZF LSD just like the other factory ones (but they won't interchange).

Matt said (in another thread) that they're worth about $1000 more in a used G50. His sell new for more than twice that - and good luck finding one of his used, think I may have seen one or two...

Factory ones (at least on 3.2s with 915s) typically don't grip as hard as aftermarket/motorsport ones, and the later ones are referred to as "snow-only" diffs. Quick check to check if it's still fitted is to jack up the rear and rotate one wheel, watch the other one - with an open diff, it rotates the other way, LSD will rotate the same way. No idea at all what a completely worn-out LSD would do - I suspect either rotate the same way and break away easily, or do nothing if it's complete toast...

Think you can hold the other wheel fixed and check the breakaway torque with a torque wrench.

I had a 40/65 fitted to a car which previously had an open diff. It was eye-opening - makes a tremendous difference.

[spuggy]

Originally Posted by r-mm

Thanks this is very useful. I've searched on this site and found a few references to people rebuilding their own diffs. For a street only car (which will be driven in rain etc) If one were to sublet this work to a shop would it make economic sense to have the factory unit rebuilt or would you only ever replace it with an aftermarket unit? The car I'm looking at is high mile and I'm nearly positive the LSD will be more or less open by now so I'm trying to figure out if it actually ads to the value of the car or not and what I should plan for.

You may be surprised; it's not hard to refurb one and it could already have been done. LSDs set to high breakway values need attention more often - so, conversely, "softer" diffs probably don't Fairly sure my old 944 had never had the transmission opened - and the LSD still hooked up on that with 150,000 miles on the clock...

How desirable an aftermarket diff is depends on your projected usage and the power of the car, I feel. Extensive track use or high powered car both might mean you'd be better served by an aftermarket/motorsport unit - but my vote is that any LSD is better than open.

For a stock N/A car almost 100% street driven, factory LSD in good shape might be all you need - and dirt cheap to refurb, in comparison to buying one and fitting it... Plus putting the original back in could avoid a bunch of time-consuming measurements/setup that would be necessary if you changed it (or added one to a transmission without one)...

Personally, I'd just talk to Matt Monson of Guards Transmissions; pretty sure they service LSDs as well as building new ones. May even be able to offer upgraded parts for the factory unit to perform better.

[r-mm]

Interesting. I will also ask the mechanic who knows the car and will be doing a PPI for me this week. Thanks for the tips. In practical terms as far as street driving is concerned, how does an LSD feel different than an open diff on a rear engined car like the 911, with lots of on-throttle traction?

Originally Posted by spuggy

You may be surprised; it's not hard to refurb one and it could already have been done. LSDs set to high breakway values need attention more often - so, conversely, "softer" diffs probably don't Fairly sure my old 944 had never had the transmission opened - and the LSD still hooked up on that with 150,000 miles on the clock...

How desirable an aftermarket diff is depends on your projected usage and the power of the car, I feel. Extensive track use or high powered car both might mean you'd be better served by an aftermarket/motorsport unit - but my vote is that any LSD is better than open.

For a stock N/A car almost 100% street driven, factory LSD in good shape might be all you need - and dirt cheap to refurb, in comparison to buying one and fitting it... Plus putting the original back in could avoid a bunch of time-consuming measurements/setup that would be necessary if you changed it (or added one to a transmission without one)...

Personally, I'd just talk to Matt Monson of Guards Transmissions; pretty sure they service LSDs as well as building new ones. May even be able to offer upgraded parts for the factory unit to perform better.

[spuggy]

Originally Posted by r-mm

Interesting. I will also ask the mechanic who knows the car and will be doing a PPI for me this week. Thanks for the tips. In practical terms as far as street driving is concerned, how does an LSD feel different than an open diff on a rear engined car like the 911, with lots of on-throttle traction?

If you drive the car in low-grip conditions, or drive hard in the summer, a LSD is a no-brainer, I think.


An LSD feels different to an open diff to drive quite often, especially when traction is low.

What you tend to notice most often is a satisfying "scrunch" from BOTH rear tires pulling away on loose surfaces like gravel

Where any LSD shines is on over-application of throttle (poor tire choice or bad conditions can make even a sedate pull away on a slimy road surface - raining, fuel/oil dropped at a stop light - an "over-application") where the rears break traction.

The car keeps going more-or-less straight in the direction of travel, can be steered via throttle/opposite lock, throttle modulated or simply shift up - very little drama.

Without an LSD, things can be more exciting and they can happen very quickly. Not necessarily as much fun as it sounds.

A torque-biasing diff mostly behaves like a plate-style LSD when power is on (although I believe they go open if a wheel leaves the ground).

However, deceleration lockup comes into play with a plate-style LSD when you shut the throttle. Like when WOT suddenly isn't appropriate any more.

With an open diff, the car then feels loose and floaty until things settle down. With an LSD, you lift and it tries to pull the car straight and keeps the rear nailed down; it's just planted.

This is why AX'ers can prefer torque-bias units over plate-style LSD's; those guys WANT the car to rotate - in comparison, if I want to hang the rear out on a skid-pan, I have to bang the throttle shut to get the rear light turn in and re-apply power to start it sliding. Otherwise, under power, the front just ploughs and the rear just.. won't... unstick...

Folks get better lap times with an LSD, because they can keep the power on later, get more on the road through the corner (because they don't just spin the light wheel) and get it in earlier on the apex.

Going from open diff to a factory LSD won't be as dramatic a difference as going to a motorsport unit - but almost every time you notice it's there, you'll thank yourself...