worn ring and pinion?

[zguitar71]

I have an r200 (long nose) 4:38. I got it from a guy who originally got it from Arizona Zcar a while back when he was selling JDM r200's. Anyway when I got it it whined pretty bad. I have not used the 4:38 for a few years. I have no idea how long the diff was used in that condition, I put about 50 miles on it and gave up on it. I would like to put it back together with new bearings, lsd, a total rebuild. The ring and pinion have a wear pattern on them that is visible and on the pinion appears to be not in the right area. Is it possible the pattern is too engraved into the gears for them to be set up properly. I can feel the pattern with my finger tips, no dips or gouges or anything like that just a very smooth area where the gears contacted and not as smooth where they did not. How can a person tell if the gears are too worn to be used? Thanks for any info.

[JMortensen]

Yes, it is possible that a ring/pinion set gets worn in the wrong position, and then even if you set it correctly, they still make noise.

 

That said, I would suspect that what you have is bearing noise more than gear noise. I say this only because I know the R200s tend to lose the ball bearing at the nose of the pinion gear and it is noisy when it goes. I'd say this is especially likely if your 4.38 was set up by Nissan (if it was a 4.38 out of a Skyline or something like that - which it should be if it came from AZC).

 

As far as patterns go, there are some really wacky patterns that are actually considered OK. You can check the pattern against this pdf that has pictures of acceptable patterns in the last few pages: http://www.ringpinion.com/Content/HowTo/TechnicalInstructions/Yukon_Installation_Kit_Instructions.pdf

[zguitar71]

Thanks for the info Jon. That was exactly what I needed to see. The diff is from a Skyline. I think I am safe on the R&P gears, the patter is not all that weird after all compared to some of the illustrations. I think new bearings and a Kaaz or Cusco are in order now. Thanks again.

[preith]

Not sure if this is the best spot to post this but I thought I'd share my recent R200 rebuild experience. My diff on my road racer was howling real bad on decels. Jon's previous posts pointing to the small ball bearing up front were probably right, it did need replacing and remaining bearings seemed ok, but I already had those too and decided to take the plunge and swap them all including races.

 

I've read other posts stating if the ring and pinion were reused you'd most likely be ok, but that was NOT the case with the pinion preload as it was definitely too high. I ended up replacing the smaller "fine tuning" washer with a slightly thicker one from an old rusted 3.54 diff (which just happened to be thicker) and the preload was right at the lower end of the FSM specs. I have to wonder if the washers may see a little wear when the pinion bearings get "loose". The increased thickness of the replacement washer was only about .0007" more. I never did check with the dealer to see if these are still available.

 

The races came out quite easily and they went in very easily after sitting in the freezer for a bit. When I was all done the ring and pinion backlash and contact pattern was identical to before the rebuild.

 

Most importantly, even though it's a solid spacer, the pinion nut torque has an adverse affect on the pre-load. I liken it to the stub axle bearings. I would not suggest attempting a rebuild without an accurate inch pound torque wrench.

 

I have one successfully race weekend on the new diff and it's performing flawlessly.

[JMortensen]

Most importantly, even though it's a solid spacer, the pinion nut torque has an adverse affect on the pre-load. I liken it to the stub axle bearings. I would not suggest attempting a rebuild without an accurate inch pound torque wrench.

How do you figure that the pinion nut torque affects preload? What part is being affected by the torque and changing the distance between the tapered bearings?

 

There just isn't anything in there that can crush or distort so as to change preload, so I'm going to stick to my guns and say that I think you're wrong.

[preith]

How do you figure that the pinion nut torque affects preload? What part is being affected by the torque and changing the distance between the tapered bearings?

 

There just isn't anything in there that can crush or distort so as to change preload, so I'm going to stick to my guns and say that I think you're wrong.

 

Thanks Jon. I suppose I should have taken a vid for you or something. I saw it with my own two eyes, the higher the torque, the higher the pre-load, there was no arguing it. The results were repeatable too. How does the pre-load change on the stub axles? Granted they're not taper bearings but it has a solid spacer as well. Is your experience different?

[JMortensen]

Thanks Jon. I suppose I should have taken a vid for you or something. I saw it with my own two eyes, the higher the torque, the higher the pre-load, there was no arguing it. The results were repeatable too. How does the pre-load change on the stub axles? Granted they're not taper bearings but it has a solid spacer as well. Is your experience different?

I had to change my driveshaft flange when I installed a 300ZXT diff in my car around 1994. I "torqued" my driveshaft flange with an IR 231 impact wrench set on 5. Same with my stub axle nuts when I changed my rear wheel bearings around the same time. I then ran them for many thousands of miles 5 or 6 seasons of autox and some track days.

 

As far as taking the diffs apart, I've done that too. In fact I've set pinion preload with a crush sleeve on a diff that has one as well, so I have that experience as well. I was specifically trained on the difference between the two systems when I started working for Randy's Ring and Pinion. I was a salesman, but we all spent a solid week in the shop building diffs.

 

From that experience I know that something has to change the distance between the bearings in order for the bearing preload to change with the nut torque. There just isn't anything that is going to change in either case (diff or stub axle). In the case of a crush sleeve, they are throw away items, so once you go past the amount of preload you want you take the thing out, throw it in the trash and get another one. If you can loosen the nut and change the preload and tighten it again and get more preload, that would mean that there would have to be something springy in there causing the change that could give repeatable results. I've had both the diff and the stubs down to their component parts, and I haven't seen any springs in there.

 

Even if the pinion shaft or the stub axle itself stretches this would not change the preload on the tapered bearings. Only the thick solid spacer in between the two bearings is responsible for setting preload.

 

I just checked the 82ZX FSM, no mention of preload changing with pinion nut torque. It says change the spacer length to change the preload. Interestingly, it also has no mention of torque changing the preload on the stub axles. I think that recommendation from the 240Z FSM which Coffey has quoted before may come from the copper spacers which would crush and were no longer used in the ZX. Again, the ZX manual says if the preload is wrong, change the spacer.

 

The only thing that I've found that changes the preload on either bearing is drag from the seal, or the dust lip on the seal if the seal isn't fully seated all the way. I'm sure you believe what you saw, I'm just not sure what you saw. I think you know that I mean that in the most respectful way.

[JMortensen]

Sorry to bring this up again, but I just downloaded the 73 240Z manual from carfiche (it wasn't available for a couple days) and it also has no mention of torquing the stub axle or pinion nuts to adjust preload:

 

From the FSM:

Diff pinion preload:

"Adjust preload of drive pinion with spacer and washer between front and rear bearing cones, regardless of thickness of pinion height adjusting washer. This adjustment must be carried out without the oil seal inserted."

 

Wheel bearing shows no spring scale type device as Coffey has described in the FSM he has. It just has some dimensions for the spacers in between the bearings along with end play and preload (should really be drag) specs and says "Readjust as required". No mention whatsoever of the torque on the stub axle nut affecting preload.

[johnc]

Wheel bearing shows no spring scale type device as Coffey has described in the FSM he has

 

The spring scale device is something I use based on something I remember seeing in a FSM of some kind (maybe not Nissan). If I earlier implied that it was in a S30 FSM, I apologize.