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I got a '87 z31 LSD (w/ some questions)


Phyxius

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APOLOGY stands... thank you for accepting....

 

 

BUT!!! now that I have the unit open and sitting exposed for all to see.... I WAS RIGHT!!!! THERE IS A THRUST WASHER IN THERE>> IT WAS NOT APPARENT UNTIL I ACTUALLY GO IN THERE>>>

 

It appeared externally there was a 2 mm gap for free movement... BUT!!! mine has a spacer that does indeed set lash....the spacer is smaller than the inside diameter of the carrier side flang.. so I could not see it until I took it apart...

 

HERE iT is....THIS spacer and it's mate set lash in the side gears... so it IS INDEED STATIC... just as I assumed...

 

http://album.hybridz.org/showphoto.php?photo=5410&size=big&cat=500&page=1

 

I have installed half a dozen lockers and LSD units in off road 4x4s... I remember distinctly that the POSITRACTION units which are similar to the Hitachi units we are using... go in NON FLOATING axles... and bearing thrust and preload was set by shimming the side gears... meaning that they could not move axially...this is now a NON ISSUE...

 

I WAS RIGHT THE WHOLE TIME!

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Well that's interesting. I can tell you though that mine didn't have that thrust washer in it.

 

I had it apart and back together at least 20 times checking the preload, etc. Plus, similar to the pic I posted from Gordon's website, there is no wear surface on the outside of the side gears on mine.

 

Another thing I'm seeing is that unless you pulled the spacer out then took the picture, you have more disks than the rest of us.

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The only R200LSD parts are named as such in the album...be careful what you are looking at.

The spacers with the oil holes are for the R180 open diffs...you will see that those side gears have no slots for the cluches in the LSD... Which pertains to another post I made about how to convert ANY R160 or R180 from Subaru, late Nissans, etc.... the conversion allows you to BOLT your old 240Z stubs into the NEW snap in style R180s... which is trickier than you might think...there is no easy conversion to allow factory style halfshafts and side flanges..except mine...which seem to be ground breaking.

I checked this out today... and the R1XX tend to use the same 25 spline equal length studs... The R190s use a combination of 27 and 29 spline axles...of course the R200s use unequal legth 29 spline SNAP IN stubs...which is easy to convert to S30 chassis.

 

 

ok... welll... your side gears show no wear on the back side of the gear face either.....you see the machine marks on them.... so dont get any ideas that your gears thrust back and forth axially.... This is one of many LSD units i have set up and installed... The gears thrust clearances are set static... I have never seen a clutch type that was not... This would have been more apparent to you if you had ever seen one in use in a non floating solid rear axle.

 

 

Here is a picture of the stack on ONE SIDE...

http://album.hybridz.org/showphoto.php?photo=5414&size=big&cat=500&page=1

 

Here is a picture of the ENORMOUS side and spider gears... and the HUGE cross...which by the way allows you to pass a shaft ALL THE WAY THROUGH THE ENTIRE REAR END.... which addresses my question originally.

http://album.hybridz.org/showphoto.php?photo=5416&size=big&cat=500&page=1

 

Here is the LSD case number....

http://album.hybridz.org/showphoto.php?photo=5421&size=big&cat=500&page=1

 

Here is the ring stamping... as you can see... this is a 39:11 3.54 differential...which should get into the 140MPH mark with the T5 5 speed behind a race prepped 350 V-8.

http://album.hybridz.org/showphoto.php?photo=5423&size=big&cat=500&page=1

 

Soo... all in all.... I am putting this back together soon...seeing how it is a unit that has seen under 2 years of occasional track events with it behind the L28 ... I am sure I will be back into it after a couple of years behind the V-8 T5...

 

If there are ANY dimensions you want... call em out now.... I can get em for you... I will go no further until I hear from you guys.. but make it quick.

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ok... welll... your side gears show no wear on the back side of the gear face either.....you see the machine marks on them.... so dont get any ideas that your gears thrust back and forth axially.... This is one of many LSD units i have set up and installed... The gears thrust clearances are set static... I have never seen a clutch type that was not... This would have been more apparent to you if you had ever seen one in use in a non floating solid rear axle.

I worked for Randy's Ring and Pinion. I've seen just about every single LSD in existence from a Dana 30 to a Chevy 14 bolt, semi-float and full float axles (what is a non-float?). All of them had thrust washers on the pinions and side gears as I recall. I was very surprised to see that mine did not have any thrust washers. You've proven your case for YOUR differential, not mine. Hopefully Zfan or Phyxius will take some pics of their LSDs because I'm not about to take mine back apart just to prove what's inside to you. I already took pictures and if there were thrust washers in there I would have plenty of pictures of them. If there are no thrust washers then the side gears are basically floating. YOUR CARRIER IS FAR SUPERIOR TO MINE. That much is clear.

 

You are still wrong with respect to the thrust on the side gears on MY differential. If the gear doesn't hit the case, then the distances between the side gears and the pinions is not fixed. It just isn't. FWIW, I should apologize to you for wrongly stating what was inside your differential.

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OK then... post a picture of the INSIDE of one of the CUPS/pressure disk... lets see what kind of polish that suface has... because there is absolutly NO polish from wear on the rear face of the side gears... that was one of the big deal pics you posted...

 

if you saw soo many rear ends.. and/or you actually set up new ones into old housings... you would know that there is NO design using side and spider gears on a single cross/pinion... that would allow for axial movement of the gears... period...

 

there is no diff made using those parts that does.....err....well one... There is only one that I know of.. and it used 2 separate spiders pinions that had the ability to ramp the spiders inward /radially on the face of the side gears... this accounted for the axial displacement of the side gears in the carrier... and this design was for a FULL FLOATER axle style...

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The deal about the side gear from Gordon's site was that the area where the side gear pushes on the pressure ring was machined and the end of the side gear was not. Usually if you're going to run two pieces of metal on each other you want a finished surface. That was a brand new diff that he had pics of there I'm pretty sure.

 

I've gone back and found this picture. It isn't what you asked for, but it's all I have at this point. Unfortunately the camera I had at the time sucked donkey balls so I've since purchased a much better one. What you can see in the picture is the side gears sitting with the end that would hit the thrust washer on your diff. On mine, its pretty clear to see that they are brown on the end, stained from the oil. pressure rings are upside down, but you can clearly see that the pressure rings, the clutches, and the side gear where it hits the pressure ring are all cleaner and not brown. The end of the side gear is brown BECAUSE IT NEVER WORE THAT BURNT OIL RESIDUE OFF. Because it floats. That's all I've got for you proof-wise BJ, but it's pretty conclusive to me. That picture shows every piece inside the diff, BTW

 

explodeddiff1.jpg

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I read it and I explained it from the beginning... YOU are misinterpreting Gordon's site... the SIDE GEARS are not what spreads the pressure disks apart... It is in one of you r first condecending posts... I explained it in greater deatail to you than even Gordon's site mentioned... because I understand how it works in great detail.

 

 

 

If your gears are thrusting out of alignment axially...or in any direction... they wont last long under pressure...period... This is a basic engineering fact...

 

I can't help it if you found your rear end in some half stripped parts pile and nursed it back together... I'll bet you have some wear marks on one surface or the other now that you have been using it.....I'll bet you find a lot of metal filings in the carrier now as well... how about posting pics of the worn out spider and side gear faces after it breaks during the next track event.

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Don't be such a jerk, man! You really are insulting, and for no good reason. I got this diff out of a 300ZXT. MANY other people on this site use the same exact diff. It isn't cobbled together. It had 80 something thousand on it when I got it. I put another 40K on it and autoxed for 5 seasons and did probably a dozen or more track days. The spiders and side gears looked fantastic. It hasn't been run since I shimmed it. Just sitting there assembled waiting to go back in.

 

You're right, the pressure ring is what pushes on the clutches. But once the pressure ring moves away from the clutches, the gears will force themselves apart. What are those little things called that go behind the gears? THRUST washers? Why are they called that? Because they take the THRUST that the gears turning against each other produces. If there is nothing else holding the side gears because the pressure rings moved, then yeah, I am SURE that the gears will separate to some degree in the middle.

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I am not trying to be insulting... I have one I found in a parts pile...and it left me stranded a long way from home...verrry expensive tow...it's internals now serve as weights for gluing up woodworking...It did not have proper axial thrust clearances when I ineptly set it up in a worn out used up 14 bolt quite a while ago...

 

If the side gears are not set up right... there will be exessive slop in the drivetrain...just like a worn out set of spiders and sides..the lsd does not inherently have more slop than the open diffs.... the proper set up of the internals and the sprig plates are there to eliminate this...at least until the springs compress.

 

There is no thrust washer behind the side gear face... as I explained.. those pictures in my album with thrust washers on the back/widest flat rear are for R180 OPEN DIFFS...MY R200 LSD side gears have never come close to touching the inside cup of the pressure disk....

 

This is the R200 LSD side gear and inside of the cup...

http://album.hybridz.org/showphoto.php?photo=5416&size=big&cat=500&page=1

 

These are the side gears for the R180 open diff.. The left hand side had never turned before.. it was butt spanking brand new...notice the tumbled finish on the left hand spacer...pretty crappy ehh...and I was always sooo careful cleaning them...

http://album.hybridz.org/showphoto.php?photo=5395&size=big&cat=500&page=1

 

it should be more than obvious... that they do not have the notches for the clutches to engage...as I previously posted...

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That's not my side gear. I took that picture from Gordon's site to show you that the side gears aren't machined on the end. Apparently yours is, but up until now none of the others that I've seen have been. His site includes a complete breakdown of a brand spankin new 2 pinion LSD, I think it might be an R180. But it is not my picture, and not my gear.

 

My side gears were obviously contacting the pressure rings. Again in my sucky exploded pic above you can see the shiny backside of the side gear, but the end is brown. What part do you think was wearing???

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they do indeed look brown on the ends...This clears up much for me...Why on earth did you post that other side gear picture knowing it was new and showed ZERO wear...

 

That does possibly mean that they are supposed to operate without static lash... it is unlikely there is another static contact point...

 

but that does not change the fact that the gears wont take any abuse without static lash... that is a half *** stab at a good unit...I am seriously dissapointed... 4x4 folks have known that for years...

 

I am willing to entertain the idea that this is a FUNDAMENTAL FLAW in the notoriously weak 300ZXT LSD units. I would love to see what the wear rate is on a new set of internals during track use...

 

The stock units could be seriously upgraded with proper spacers with minimal cost.. There must be a reason.... like thin wall thickness.... the units may tend to split under shock loads when you do that...

 

 

I will measure case dimensions on the NISMO unit as well...

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The reason I showed you that side gear is because it is obvious that it doesn't ride on a thrust washer on the end there. That gear, like the gears in my diff, don't sit on the case. That was the point that I was trying to make the whole time.

 

Aside from that point I agree with you, finally. It does appear that you have a vastly superior LSD. What's weird though is that Gordon came up with a brand spankin new NISMO H190 LSD that had the same setup inside as mine. I think that diff was purchased just last year brand new from NISMO. So my hypothesis is that they're all made the shitty way nowadays. That is too bad, because yours definitely looks more stout.

 

I think the weak part of the diff is the SINGLE clutch disk, which was the point of this thread in the first place. ONE clutch just isn't enough to transfer the torque to the wheel that wants to spin. I haven't heard any reports of stripped spiders. I have heard 2 people on this thread alone with that lone clutch disk stripped of all it's teeth.

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This may have contributed to the tearing of the internal teeth on the disks in Phixius' LSD.... as the internals wore... the movement of the side gears became excessive... the teeth on the disks were being wrenched in 2 dimensions against a cheese grater quality surface and ripped off the disk...

You may gain life in these units by smoothing the notches in the side gears and limiting axial movement with some sort of case to side gear spacer.. even if it only comes into play as the unit wears out...the spacer would need a recessed area in the case.... deep enough as well...

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