Hi all,
i have a 2006 g35 coupe and it's automatic , all of the aftermarket LSDs say they're for MT, (manual transmission)
I really want to make this work, does anyone have any recommendations or info to help me out!
I don't want a VLSD, i heard they go out,
Not sure what to do here !!

 

I would recommend calling Z1 Motorsports and they will help you find the best diff setup for your intended uses. I personally like the tomei 1.5 way for track type driving. If you want to drift it’s the wrong choice though.

the VLSD is good in a similar way, but it is not consistent and at 20+ years old it’s probably worn out.

are you going to change the ring gear too while doing the upgrade?

 

The VLSD is great, sure it's not going to hold up in ACTUAL RACING conditions on a track (and it's terrible for drifting) but unless you're pushing the car 100% and doing a bunch of hot laps it's perfectly fine.

I autoX track my car with the VLSD, granted I'm not gutted out and actually going for time (if I was I would not be in a G35 anyways...) and even after like 6-7 laps it's still transferring a lot to the other tire. I have never gotten mine hot enough to cook it but it can definitely happen.

If you are in the market for a mechanical LSD then the big question is will you EVER drive this car in the rain. If the answer is YES then your best option will be a torsen/helical diff. It's really hard to get enough grip on a clutch diff for it to engage in the rain for city driving so you basically just end up driving an open diff which sucks. When it does engage it shakes the tires and makes it very unpredictable on wet roads.

If it's a dry weather track only then it doesn't matter which clutched diff you get really. track cars are noisy so it doesn't matter if you have a noisy diff. Some LSD like the Cusco are adjustable from 1, 1.5, or 2 way with a replaceable insert which is cool. Personally I like about an 60-80% bias 1.5 way for dedicated track use. At 80% It will push you out of a corner but not TOO bad, just really have to work on your corner exit timing because once the car hits it's exit line you can't really change it unless you lift off the throttle. 60% is much more forgiving. Obviously you will set bias based on your specific track usage, corner heavy slow tracks use less bias than faster tracks.

If it's dry weather street car you want to be REALLY particular about which clutch diff you get because they can be super obnoxious after a while, trying to quiet them down can be tricky and it takes a little experimentation with how many clutch plates you actually want. So you'll have that diff torn apart a few times before you get it just the way you want. Too tight and it understeers BAD when it engages (great for drifting to run them tight though), too lose and you're getting all the noise of a clutch LSD with little of the benefit and you would be better off with a torsen probably. I personally don't like a clutched diff biased more than about 50% for street use. Trying to accelerate out of a corner and having it engage too much makes the car less predictable and a LOT less fun.

Your suspension will make a HUGE difference as well, if your car is really tight you want a less bias like 40-50% or you're going to shake the tires badly. If you're running pretty soft you might be up to 80%.

Basically, if it's a track-only car or you just want adjustability and max performance get a clutched LSD, if it's a street car and driven in the rain but will still see some aggressive track use get a nice quiet Quaife torsen/helical, if you don't mind a 20% bias but want something that's extremely CHEAP ($200 or so) then get a stock VLSD and drive it until it dies. My 2006 VLSD feels exactly the same as it did when the diff was new, 130k miles on the car, I bought it like 7-8 years ago and it's been in about 20 autoX events and down the 1/4 mile for fun probably 50 times or so. Plus a lot of street driving, but it's mostly stock, no forced induction so slipping is minimal anyways on good rubber.

If you're using some kind of forced induction that will also factor in to how aggressive you need to be to put the power to the road.

 

[QUOTE=cleric670;7216666]The VLSD is great, sure it's not going to hold up in ACTUAL RACING conditions on a track (and it's terrible for drifting) but unless you're pushing the car 100% and doing a bunch of hot laps it's perfectly fine.

I autoX track my car with the VLSD, granted I'm not gutted out and actually going for time (if I was I would not be in a G35 anyways...) and even after like 6-7 laps it's still transferring a lot to the other tire. I have never gotten mine hot enough to cook it but it can definitely happen.

If you are in the market for a mechanical LSD then the big question is will you EVER drive this car in the rain. If the answer is YES then your best option will be a torsen/helical diff. It's really hard to get enough grip on a clutch diff for it to engage in the rain for city driving so you basically just end up driving an open diff which sucks. When it does engage it shakes the tires and makes it very unpredictable on wet roads.


What is a good torsen/helical limited slip differential that i can throw in my automatic then ?
Yes it'll be for driving in the rain and daily driving fun.

 

5AT or 6MT doesn't make any difference, it's all the same R200 or R200V differential (V means viscous coupling). They've been using R200 differentials for a long time and for the most part the internals are all interchangeable depending on a bunch of little factors. The external housing could have different mounting holes and stuff though. They were used on the Z32, Z33, Z34, V35, and V36 platforms. Just get one that works for a G35/350Z so it will have the correct spline counts and such.

The biggest thing to verify is your stub shafts, there are two different length stub shafts for one side, a long and a short one. I can't remember which is which (pretty sure it's the right side stub that can be longer) but the long shaft was used on viscous units and you need the short shaft for aftermarket clutch or helicals. You can use a portaband and cut down the long shaft to make a short shaft, just trim 1 inch off of it and file the sharp edge. On the open differentials both shafts were the same part number. If you have an open diff then you already have the correct shafts.