Shimming an R200 or J30 vlsd

[Mtndrifter14]

By: Hunter Rodziczak

I could not find a comprehensive guide to doing this, So I thought I would make one for the good of the S chassis community.

Benefits: Get clutch type lsd action for a 1/4 of the price.

Well post j30 VLSD installation I found myself quite unsatisfied with the performance. As with Many VLSd's after becoming heated up they simply refuse to work properly and your VLSD becomes a one tire fire and thats no good. So after looking for upgrades I stumbled across a few options. Since I have a J30 vlsd with 5 bolt output shafts I would have to switch back to the standard 240sx R200 differential housing in order to run a clutch type lsd. I sold my old diff and a clutch type lsd wasn't in my budget. Somehow I stumbled across Shimming. Shimming involves adding an extra shim(s) to the original preload shim and causes the vlsd to lock similarly to a clutch type lsd. This preload shim costs $10 from you local Nissan dealer so this is definitely worth the money.


-Add one shim and vlsd will act similarly to a 1.5 way lsd

-Add two shims it will act like a 2 way/welded diff.

Here is a picture of the Shim with part no: ( this fits both j30 and R200 diffs)

Here's your standard diff, Start By removing the diff from the car and unbolting the 8 bolts holding the diff cover on.

Once that is completed, separate the cover like so and before you put the new sealant on remember to scrap off all old sealant and I recommend using brakecleen to clean surfaces before applying sealant back on.

This is what you'll see:

Next before anything else knock out the output shafts. This takes quite a bit of effort but don't be scared they will eventually come out. I recommend hitting them from behind with a hammer:

Next you can take off the cap bolts like so:

IMPORTANT: Remember which side the shafts and caps cam from as to not mix them up

And this is what you're left with:

Next, it's time to pry out the differential. Unless you have superhuman strength you have to get it out using a bar that give leverage:

And end result:

Unless you have a very good impact gun the next part is almost impossible. Take these bolts out to separate the ring gear from the diff.

Next take off these two Phillips head screws.

Pry apart:

The Almighty shim:

Now take this and put it over the existing shim:

And now put the diff back together the same way you took it apart.


Impressions: Awesome locking compared to the stock vlsd can't complain.

[UNISA JECS]

Here goes another link also:

http://www.d1nz.com/forum/viewtopic....561d68f2602e75

[derek_s13]

i think this is one of those things that makes perfectly clear forehead-slapping sense once explained to you..

..but for some reason just did not even cross your mind ever before.


shimming a stock diff ACTUALLY works. duh.




so yeah, i feel stupid, but i'm glad you're intelligent. just wanted to say how cool i thought this write-up was.

[Mtndrifter14]

Thanks man,

archive fact worthy?

[motegineon]

sweetness, now do you have to measure/do the backlash?

if so anyone got a link lol

[awesomenick]

I was under the impression that our gear lash was set with washers? Do you have to change their configuration?

[Mtndrifter14]

nope no changes need to be made

[Sileighty_85]

This works good, I had two friends do this 3 weeks ago

[Def]

Aren't you just causing the gear engagement between the spider gears in the diff to be more heel/root heavy and therefore bind up?

I don't see how this is an "awesome mod." You're just incorrectly adjusting spider gears. Once you get a gear incorrectly adjusted like that, there will be relatively movement between gears as they mesh, which will wear them down in short order. Wear in a diff means metal shavings, which will cause accelerated wear in other components and potentially massive failure.

[SoSideways]

Originally Posted by Def

Aren't you just causing the gear engagement between the spider gears in the diff to be more heel/root heavy and therefore bind up?

I don't see how this is an "awesome mod." You're just incorrectly adjusting spider gears. Once you get a gear incorrectly adjusted like that, there will be relatively movement between gears as they mesh, which will wear them down in short order. Wear in a diff means metal shavings, which will cause accelerated wear in other components and potentially massive failure.

I thought the viscous diffs just had viscous fluid engaging the plates inside the housing, thus transferring torque between the 2 wheels?

If so, there shouldn't be spider gears turning and being meshed and destroyed, no?

[Black R]

Originally Posted by SoSideways

I thought the viscous diffs just had viscous fluid engaging the plates inside the housing, thus transferring torque between the 2 wheels?

If so, there shouldn't be spider gears turning and being meshed and destroyed, no?

From nrr:

Originally Posted by djsilver

OK, I'm ready to stir the pot

Here's the diagram for the VLSD diff on page PD12;
http://www.240edge.com/manuals/91-94_240sx/pd.pdf

The VLSD does still have spider gears. The viscous coupling forms one side of the spider gear. One axle stub is fixed to the outer case of the VLSD coupling and the other stub is fixed to the inner case of the VLSD coupling. The "SHIM" selection guide is on page PD25 and gives a range of backlash, not pre-load. If you pre-load the spider gears, any change in LSD action you get is from grinding the spider gears against each other, not any change in the function of the VLSD coupling.

The VLSD coupling is filled from the factory with a viscous fluid. The function has already been explained. I have actually, really, for sure, experimented with one of these! When the units are filled from the factory, they drill two counter-bored holes to fill it, then they insert ball-bearings into the counter-bores and stake them in place. I removed the balls and tapped the two holes. I then flushed the old fluid out and replaced it with newer, thicker fluid. The VLSD was installed into a Z31 300zx running about 400WHP! It would work much better than a stock VLSD until it got hot. When it got hot it would lock solid and act like a spool. I did some research on this phenomena and the general theory is that when the interposing discs get hot enough, they expand, distort, and bind against each other. Our conclusion was that we couldn't make the VLSD any more effective.

Ultimately, if you're using a VLSD/HLSD/open diff, you need articulation/droop in the rear suspension and roll-stiffness in the front suspension, to keep the rear tires on the ground. If you're running a clutch/spool diff you can ignore this to some extent and drive on one wheel, at least until your power output overloads your outside rear wheel. Then you're back to the same place My buddy with the Z31 went around the world with LSD's, but came back to his shocks/swaybars/camber/toe/tire pressure settings to maximize corner exit.

This really helped my understanding of the vlsd

[motegineon]

well in that case dont drift or drive your car hard because your wearing it faster, inevitably causing your vehicle to fail..

btw im one of the people that shimmed my diff about a month ago and it is still fully locked and feels amazing

[quach]

how is a shimmed vlsd for daily driving? I'm getting sick of my welded diff since i only daily drive the car now, is it anything like a welded? Also, what are the long term ill effects of doing this to the diff?

[motegineon]

mine is exactly the same as a welded, but i have a lot thicker shims in mine than a lot of the people who just add a small on to tighten it up a tad, in that case it would feel just like a normal vlsd that just locks easier

[breakneckspeeds]

I added 1 shim a couple weeks and its pretty tight, mine had a ratcheting sound on slow tight turns, but after breaking it in and a lsd additive the ratcheting has almost gone but there is a ton more lock than i thought there would be. if i knew how much there would be i might have only replaced the shim other than adding 1. how was breakin for everyone else??? any noise or just some tire chirping??

[lazysk8er2]

can anyone list the part number cuz the pics arent working for me if its on there gonan do this asap very much hating on my vlsd right now

[motegineon]

-Shims go up in 0.3mm increments from 0.8 to 1.49mm

38424-40F60 =0.80mm(same as in the picture)
38424-40F67 =1.01mm
38424-40F75 =1.25mm
38424-40F83 =1.49mm (the biggest)

[racepar1]

Originally Posted by motegineon

-Shims go up in 0.3mm increments from 0.8 to 1.49mm

38424-40F60 =0.80mm(same as in the picture)
38424-40F67 =1.01mm
38424-40F75 =1.25mm
38424-40F83 =1.49mm (the biggest)

What shim originally comes in the diff? I am thinking about doing this, but I only want to make a small difference. I figure if I replace the stock shim with one that is one or two sizes thicker it should do just what I want. Since my car is a trackday/autocross car I really don't want the diff to lock in an aggressive manner.

[SoSideways]

Originally Posted by racepar1

What shim originally comes in the diff? I am thinking about doing this, but I only want to make a small difference. I figure if I replace the stock shim with one that is one or two sizes thicker it should do just what I want. Since my car is a trackday/autocross car I really don't want the diff to lock in an aggressive manner.

You might have no choice but to open up your diff, then use a mic to see how thick it is, as I think the diffs can come from the factory with a few different thicknesses, which is why you can buy so many different thickness washers to begin with...

[motegineon]

Originally Posted by SoSideways

You might have no choice but to open up your diff, then use a mic to see how thick it is, as I think the diffs can come from the factory with a few different thicknesses, which is why you can buy so many different thickness washers to begin with...

Yea what he said

Heres what I suggest:

Being that they are only a couple dollars, order 1.01 and 1.25. Open your diff and compare the shim that is in there to the 2 you bought, and base that off which one you choose for your application, then just go return the one you didn't use.

[MunsonAuto]

Will this work with a stock open diff. too?

[motegineon]

no

msg length

[kouness]

wow this is awesome.. i have a vlsd lying around.. i need to do this before i throw it into my pumpkin.. nice...

[Chrischeezer]

bumping a good old thread..

just took my lsd apart, had a 1.25mm shim in there from the factory (odd) and I could only get a .80mm and a 1.01mm from nissan, i installed both of them... think its gonig to fully lock?

edit: Update...

here is a very easy trick that will save you a headake when installing the diff back into the pumpkin.

-lift the whole pumpkin up with all the bearings and spacers aligned. and drop it on the drive shaft end. ( a nice 1 foot drop)
-use a phone book or somthing to drop it on.
-the impact(s) will pull the lsd bearings and spacers all into place effortlessly.

(took me about 4 drops and i couldn't believe it was that easy. lol

first impressions.. (awesome) It was fully locked but i did a few figure eights and it loosened up a bit. feels perfect.... super tight.

[SoSideways]

Originally Posted by Chrischeezer

-lift the whole pumpkin up with all the bearings and spacers aligned. and drop it on the drive shaft end. ( a nice 1 foot drop)

So I guess you can get buff while doing this too huh?

lol

The diff is like 100 pounds hahaha

[aziankingz]

^ you wanna help me do mine lol?

[Chrischeezer]

Originally Posted by aziankingz

^ you wanna help me do mine lol?

sure, pm me

[smelly240]

i have this in my car as well.

best 4$ ever.

they're special order sometimes - i have an extra if anyone cant get a shim.

[s13dan]

Tourqe specs for ring gear?

hey my VLSd (I know for sure its lsd)dosnt work at all never has no matter what fluid i use... So do you guy think i should just get the biggest shim. Im doing this asap ill be waiting on the dealership im sure.

[RUTH'LESSDET]

im all over this!!!