i think my diff is broken

[rsx84]

lets go back to my first post to add a little more confusion, if my diff was an open wheeler would it transfer drive power between wheels which was the reason i posted this question in the first place, never seen it happen before??

[Doctor 30]

It can do. It just means that when you changed gears, for a brief moment both tyres would get grip. The one that had been spinning would be nice and hot and therefore when power was reapply the hot had more grip so the other tyre let go as that was now the path of least resistance.

Does that make sense?

Please still give us advice on the correct way to get the mechanical diff to work again

[V8skylineMAN]

rsx 84....yes....doc 30 was correct..............proper way to fix the mech lsd....rebuild it......dodgy back yard mechanic way....flog the living bejesus out of it to try and ge the plates to free up.

[Doctor 30]

should I run some cleaning agent in the diff before puttin new oil in? It is a 23yr old diff.

[rsx84]

rsx 84....yes....doc 30 was correct..............proper way to fix the mech lsd....rebuild it......dodgy back yard mechanic way....flog the living bejesus out of it to try and ge the plates to free up.

i'll change to oil as i think it'll need that, see how that goes, cars only gone maybe 100kms in total since i've owned it (2 years or so now). jason saw the pics of your car in the Qld section, nice one very nice indeed, shame mine wasn't back from the sparkies or i'd have tagged along to take the old girl for a run. :uh-huh:

[Duncan]

should I run some cleaning agent in the diff before puttin new oil in?  It is a 23yr old diff.

the most important thing is not to breathe. I just did the oil in my 24yo diff and it smelt like something had died in there long ago...horrible....and it came out looking like mud....

I just chuck the new oil in mine but I don't really expect it to be around long anyway

[Doctor 30]

let us know how it goes..

[r30drifter]

how do u tell the difference beteen a lsd and a free spinin wheel diif, i own a mr30 skyline and sometines it wll line lock 2 wheel other times only the passenger side can i have some help please,

[V8skylineMAN]

jack the car up so both rear wheels are off the ground.....handbrake off...out of gear.....(make sure you have chocked the front wheels.) spin one rear wheel....the other should spin the same way=LSD othe wheel spins the opposite way=open diff

[BensDR30]

rsx84, it simply sounds like the clutches have worn to the point of the diff becoming open. It doesn't take much actual wear for this to happen. The 2 inner clutch plates in my DR30 R20LSD were down 0.003" on each side - total wear 0.012" and that was enough for the diff to become completely open.

A pair of new inner clutch plates & possibly just the reversal of the outer clutch plates (they have friction material on both sides, but only 1 side is in use on the non-competition diffs) will probably get you back in the 40ft/lbs breakaway area. I had a couple of shims put in my diff, which measured 90ft/lbs after the rebuild. It chatters the inside wheel on slippery surfaces at low speeds, but is perfectly civil once you get going. I expect that the breakaway is a little less now (20,000km later).

This diff is destined to be re-fitted to my 240Z

I have a 4.375:1 R200 LSD that measures 65ft/lbs after reversing the outer clutches only - this one will get fitted to my DR30 & should improve acceleration by quite a bit.

Another 3.90:1 is on the way from Japan - dunno what condition it's in. But I don't care - they can always be rebuilt with new parts for only a few hundred.

Try using Castrol LSX-90 or a fully synthetic LSD oil. And try to change it every 15-20,000km.

[rsx84]

just to add insult to injury, for the last 2 days i've been driving the car around with my 17" p1s' with 235 rears and now i don't know if the diffs gone or my clutch if rooted too, just wants to rev out with no forward go at all?? might put the 205's back on to see if that makes any difference? any ideas......Matt

[V8skylineMAN]

just to add insult to injury, for the last 2 days i've been driving the car around with my 17" p1s' with 235 rears and now i don't know if the diffs gone or my clutch if rooted too, just wants to rev out with no forward go at all?? might put the 205's back on to see if that makes any difference? any ideas......Matt

Tyre size should have no effect whatsoever.

[BensDR30]

Sounds like the clutch is cooked too.

BUT

If you can rev the car in gear & have the speedo move, then the diff is COMPLETELY stuffed.

[Crimmo]

hey guys, check out http://www.howstuffworks.com/ you can find out how all types of diffs work in details, pretty interesting

[rsx84]

its the clutch for shaw got a big wiff of it today, i'll get that fixed fri and see if a top shelf diff oil will help with that.......

[Ghostrider]

lets go back to my first post to add a little more confusion, if my diff was an open wheeler would it transfer drive power between wheels which was the reason i posted this question in the first place, never seen it happen before??

Something that should be understood, right from the outset.

Nissan stock fit R200 LSD's, that were in all DR & HR30 Skylines were a SALES pitch and had absolutely nothing to do with performance.

IF you want your R200 LSD to work like an LSD is designed, you need to have some real dollars spent on it to increase the PRELOAD.

Stock, Nissan put less than 20lb of preload in their R200 LSD's unless NISMO spec, which is 50-60lb, my Cusco centre had 50lb and I had it increased to 70-80lb at a cost of $400.00 at Stewart Wilkins workshop at Windsor.

rsx84, there could be absolutely nothing wrong with your LSD, if as stock, because they are very prone to wheel spin, same as an open diff, if the preload is not increased.

As for OIL! I use Mobilube SHC 75W/90 Mobil Synthetic Gear & Diff Oil in my LSD without any problems, and it's available at any Mobil garage

If you are serious with your car, you should be using ALL synthetic lubricants. I recently rebuilt the rear axle assembly, replaced the rear wheel bearings and washed all the grease out of the new bearings and replaced it with synthetic Mobiltemp 220. Did same in front wheel bearings.

[0HR-30T]

Ghostrider-do you know the specs of an HR31 R200 LSD? My diff has not been tightened,that I know of,and it will rotate both wheels,under any circumstances from a standing start,or low speeds....

Open wheeling round medium speed corners,or when the rear is under a lot of body roll,is a different matter though.........

[rsx84]

the car is in the shop at the moment, getting clutch replaced, will get the diff oil changed as well, you know after all this time the next place its going to is the compliance place to get the seats and mod plate fitted then rego and new personal plates...

[discopotato03]

I would not be in any great hurry to put a 4.375 ratio diff in a DR30 (actually yours is the RB20 HR30) . I tried that with my FJT Bluebird (4.375 H190 LSD) and found minimal gain and lots of revs for no good reason on the highway . I always found myself trying to change from 5th to the non existant 6th . The lowest I would go is 4.1 and often wish my RSX had a 3.7 . The RB26/31 will prefer it .

Cheers A .

[Ghostrider]

4.375 or 4.4 would be a great hillclimb ratio I would have thought. I have 3.9 & 4.1 and looking for a 4.4 R200 for my arsenal, as the so called experts say 4.4 is the right diff for Wakefield Park