R200 Diff

[Tommo560]

Hi people,

just have some querries about the diff in my car. i know it is a 4.375 R200 diff and i read that these only came out from the nissan racing dept. and not from the factory, so i think it would be fair to assume that the diff is an LSD. BUT, the diff is not currently working as an LSD. i also read that the 300zx turbo came with an R200 diff that had a clutch type LSD.

Now my question, is the diff an LSD and if it is is it the clutch type in which the only thing i need to do to get it working again is to get it tuned or is it not an LSD??

Thankyou,

Tom.

[Mr Camouflage]

Hi Tommo,

1. How do you know that its a 4.375 ratio?

2. Maybe nissan racing dept made open and LSD 4.375 ratios.

3. Maybe the clutch packs have worn out.

4. What diff oil are you using in the diff?

I dont know, but maybe the only way to be sure is to open it up.

[Tommo560]

Hi Mr Camou,

1. the ratio is very high and the guy who installed the diff says that it is 4.375, so it stands to reason that it is a 4.375 ratio.

2. I dont know. like i said i read it (as it happens a thread on this site) and it stated that only nissan racing dept made 4.375. my assumption is that being a racing diff it would stand to reason that it is an LSD.

3. I dont know. again the man who installed the diff said it is a clutch LSD but i am unsure as the LSD feature doesnt seem to be working at all when the wheels are off the ground but that anytime i have ever had the wheels spinning it has always been both wheels. i am wondering if it is infact a clutch LSD and if it indeed does need a tune or if this is normal behaviour for this type of LSD system.

4. no idea.

sorry i cant be of more help but this is all i know about the diff.

Tom.

[Mr Camouflage]

If you are spinning both wheels when you are stomping on the pedal, then i'd say that it is working.

I dont think that the lsd feature would work off the ground with a clutch pack type lsd.

I dont know much aut them, but am under the impression they work like the pedal brake on a bmx bike. A series of plates squashed together, when one of the wheels starts slipping the friction between the plates makes them lock together.

Turning one wheel when they are off the ground wouldnt generate the friction required, I would guess.

Anyway I'm just guessing, so I'll let the people who actually know chirp up.

You going up to Wanneroo race track on saturday for the WA Z Cars event?

[Tommo560]

Sure am,

well actually dad and i are going for the speed event series event!!.

we actually went up last weekend aswell with all fours and rotaries. we were supposed to go in the zed because this will be my first racing event at a track but we got 200m down the road, got onto overdrive down the hill and the car started to make a REALLY LOUD and unpleasant sound (which is how this whole diff question has arised), worked out it was the diff and so decided to take out my dads 93 tt supra but it only had road tyres so it wasnt that great a drive for dad but still a whole lot of fun for me having never been alowed to race it before!!!.

anyways turns out when we were doing the 4 days of prep work getting the car ready dad jacked the rear left of the car on the roll bar mount and it bent the mount enough so that when on overdrive (engine braking) and the diff is pushed down slightly it was hitting the roll-bar and sending vibrations up through the whole car..... so, 4 days later and with the aid of a long bar to bend the mount back the car is now ready and dad and i are both anxiously awaiting saturday morning!!!

Hope to see you at the event, will definately try and make some time to come over to see you guys and say "Hi",

Tom.

[zguitar71]

I have an R200 4:38 LSD that came out of an R33 Skyline from the `90's. They were used in Japan and possibly other countries but not the U.S. My LSD works but the gears are not set right and the diff whines terribly. I am using a R190 right now and the LSD is much better than the 200. The factory LSD was not set with as much break away tourque as the 190 I have right now (about 85 lbs I think). The 200 only has around 45.

[jmortensen]

Anyone can buy 4.38 gears from Nissan Comp and put them in any diff. The gear ratio is not the LSD part. It's the carrier that does the LSD bit, and there is no reason why you couldn't install 4.38 gears in an open diff. All that being said, the Skyline diff is the one that I've seen from the factory with 4.38's, and I don't know that they all came with LSD but it would be kinda surprising if they didn't.

As to breakaway, it is VERY misleading. Nissan apparently had quite a few different clutch pack setups, with different breakaway pressures as low as ~10 lbs. If you want more info on breakaway, check out what I found when I shimmed my LSD: http://forums.hybridz.org/showthread.php?t=92629

[zguitar71]

The 87 300zxt used the Clutch type lsd but the 88 used the viscus type. Spend the $ and get a new LSD from Prescision Gear ($650) or Nissan ($750), I find that getting good used suff from cars as old as `87 is very hit or miss (mostly miss). I have spent more in the long run buying then fixing LSD's that are used. I have heard that the Prescision Gear carrier is the same as the Nissan, they both come from the same manufacturer. Your 4:38 r&p is most likely like mine, a 12 mm bolt ring, so the carrier from either company bolts right in. If you have the 10 mm bolt holes you will need to use spacers.

[HS30-H]

Tommo, don't get too hung up on urban legends and stuff.

The truth is that the R200 diff was always available in a very wide selection of gear ratios in the Japanese market, and clutch type LSD units were also available to be specified as dealer options ( especially in the snowier northern prefectures and Hokkaido ).

The 4.375 gear ratio 'long nose' R200 was first seen on the 1973 Fairlady Z432 ( replacing the 4.44 ratio 'R192' ) and this came from the Factory with a clutch type LSD.

The 'long nose' R200 was used on umpteen different domestic models of sedan and sports coupes, as well as lorries and pickups, with ratios from 3.1 up to 5.1 - so the 4.375 gear set ( or the whole diff ) could have come in almost anything from the Japanese home market. The LSD unit could have been specified as a dealer option on this very diff you have, or have been bought and fitted afterwards - either from a Nissan dealer or from Nissan Sports in Japan ( later called 'NISMO' ). There are many possibilities. I have bought and imported many of these over the years.

Essentially, the standard-fitment and dealer-specified option LSD units and the Nissan Sports / NISMO units were very similar ( only detail differences ) and all were made by Fuji Juko anyway, with the main differences between them being the clutch packs and breakaway torque settings. If yours is behaving as though it has a very low breakaway torque setting then it might need a clutch pack rebuild with a few extra shims / friction discs ( depending on how you want it to behave ).

Follow jmortensen's thread link for some useful and informative pointers.

Good luck,

Alan T.

[Tommo560]

Okay,

Thankyou very much guys!!!!! I think the best option for me given the advice of you guys is to take it to a diff place that was recommended to me and tell them what i use the car for and get them to set up the diff as it should be for the best performance for what i do (weekender, motokhanas and club/track racer).

Cheers,

Tom.