A-lsd

[MANWHORE]

I have an r33 gtst. It has a-lsd (i have the lights on my dash) and it does appear to be working because the light does come on when I lose traction.

I have a bottle of oil in the right hand side of my boot.

I was wondering, how do I change the fluid in this system and what fluid do I use?

The reason why I am wanting to do this, is to hopefully make it more responsive.

Surely someone with an r33 or r34 gtr vspec has done this before?

Cheers

[MANWHORE]

come on guys, 6 views? surely someone must know

[insu]

I also have an A-lsd, and i'm not 100% sure on the process of removing the old fluid and replacing.

One would assume there would be a drain plug somewhere probably around where the lines come down to the diff, and possibly a filter of some description? Maybe not.

I know to replace the fluid you are to use automatic transmittion fluid.

You might be best off pm'ing paulr33, I know he has an A-Lsd and seems to know a bit about them, so i'd give him a go.

[MANWHORE]

I was actually inspecting the unit today, and i seemed to notice a bleed nozel sorta like the brake caliper.

Also, I don't think the fluid is ATF. My jap owner seems to have put atf into the tank on top of the existing fluid. It just floats ontop of the other stuff (which is black). i'm guessing it uses attessa fluid?

I remember looking at a schematic diaqram for it before and it also uses oil pumps and stuff too.

[MANWHORE]

Now, gtrs come with 2 way mech diffs. Vspec comes with these diffs, so surely they must be better? Doesn't feel like it to me though. There are a few more things that I have observed:

My car has got the vspec diff with the finned cover.

I have the fluid tank in the right of the boot

I have the slip/a-lsd lights.

So I guess I could say that it's pretty certain I have A-LSD.

If I drop the clutch, the Slip light comes on and both wheels do spin.

My issue with the diff, is it seems to be quite lazy. I'll elaborate on this further.

I've been in a car with a fresh viscous lsd. I am 100% sure that it was a fresh r33 viscous, because it was on a friend's car (definitely wasn't a mechanical aftermarket). He had it replaced by warranty when his diff died. It was actually quite tight and quite nice. e.g. if you give it a bit more gas when going around a corner, you could feel it go lock lock lock lock lock (sorta like a mech diff, but nowhere near as tight or as brutal).

Now, my A-lsd seems to be quite comfortable, and not what i'd expect of on a vspec, considering it is suppoed to be better than the normal gtr which did come witha mech diff. I seem to have to give it quite a bit when going in a tight circle before the slip light comes on. it deosn't really seem to lock that much either.

Now, I have changed the diff oil to new oil. didn't really do much.

My next thought was that maybe the fluid in the cylinder needed changing. It's strange. My jap owner seems to have tried to top it up with ATF. But the ATF is just sitting on top of the orignal fluid. The ATF looks quite obviously red. The other fluid looks black. So i'm not sure what eh orginal fluid is. Is it attessa fluid?

Do you know how to change the fluid? like do you have anythign on it?

I have the r33 engine manual and the r32gtr full car manual, and neither have it.

[insu]

I'm fairly certain it is ATF you use in there. By saying that the fluid you have placed on top sits on top of your black fluid, says to me that you are most likely in need of a complete flush.

As for the A-lsd being lazy, well it will only lock when it needs to.

A tight new viscous lsd will work when the vanes in the lsd casing are working correctly and are locking both wheels when it is needed.

The A-lsd works in conjunction with your ABS wheel sensors and the A-lsd computer works out when one wheel is spinning more than it should be compared to the other wheel and vehicle speed (as is to my knowledge) and locks the diff where necessary.

You said that you have to give it quite a bit while going in a tight circle before the slip light comes on. Well it seems like its working properly then, as ideally when turning, especially on tight corners, you want your car to behave like it has an open diff (read: a-lsd not locked), and as soon as you give it too much, or one wheel looses traction both wheels should lock, which sounds like what is happening with you?

And again, with you saying it doesn't seem to lock that much, well it all comes down to driving style I guess? And various other factors like weather, suspension and tyres.

If you say its not locking much when you're flogging the car everywhere, then that may be a problem, but as far as everyday driving goes, you should almost probably never see that slip light come on.

Mainly during spirited driving, or maybe if you take a corner too hard and go into some oversteer, or your exiting a round about in the wet and give it too much gas. These are the times you'd expect the diff to lock and it'd be doing its job.

If you're still unhappy with how the a-lsd is performing after a fluid change, i'd get it checked out by someone who specialises in their operating parameters (not easy).

As for information on changing the fluid, i'm sorry I don't have anything, i've only got the engine manual myself which doesn't seem to have the info.

You might want to check out the downloads from these guys, they'll probably have it, but they charge: http://www.jpnz.co.nz/

Goodluck

Edited May 3, 2006 by insu

[paulr33]

I had my ActiveLSD fluid changed this week. My normal mechanic done it and im pretty sure its the same as any other LSD fluid change. He didnt mention anything extra special and knew it was a vspec diff.

The ALSD or Vspec diff isnt a hard locker diff, like a mechanical one.

Once engaged (slip is on) its a much more responsive and snap lock.

It's not like a mech clamp lock and it wont ever do rerp rerp rerp when turning corners like a mech diff does.

If I'm cornering hard and I see slip come on, I usually don't feel any difference in the car. This is the computer sorting out the splitting in real time to prevent that exact, rerp rerp rerp from a mechanical diff.

The Vspec or ALSD is basically a mech lock diff without the nasties associated with a mech lock, such as the rerp rerp repr or crabwalk affect.

I didnt have any problems with my ALSD system or fluid but since Ive applied the PowerFC patch/fix its been working 100% more so Ive sinced organised a fluid change as its on 140 on the ODO so I thought it was time for change of fluid. Other than that it absolutely rawks.

Also I dont believe this was an option for ER34 skylines. I think it was only for R33 GTST known as the GST25TML spec

[paulr33]

my advice would be to drive another ALSD R33 and see how it compares to yours. Maybe your preception of it is wrong or something is wrong with yours. Are you in melbourne? You can drive mine if you wish

[MANWHORE]

Paul, I'm not sure if we're talking about changing the same fluid. I changed the diff fluid, i.e. the drain bolt on the bottom and fill plug on the side.

The old fluid wasn't really dirty. I put in motul lsd oil. this is just used to lubricate the diff.

What i'm unsure about how to change, is the oil in that tank in the boot. This is part of a separate system. this system has an oil pump, which pumps fluid to make the diff lock I bleieve?

The original fluid appears to be black. The jap owner topped it up with some ATF, which is red and just floating on top making me believe the proper stuff is something different.

[MANWHORE]

Unfortunately, i'm not in melbourne, but thanks so much for all the advice.

I guess i was expecting it to be different. Everyone seems to say a tight tight mechanical diff is the goods. I was just thinking that if even my friend's brand new standard viscious does that chirp chirp (crabwalk) thing slightly, i was thinking that this might.

But now i understand. I suppose the best way to think about it is like ABS. Obviously the wheels aren't going to do a full lock like a non abs car.