Need R200 Differential Advice

[ckurtz2]

Hey Guys,

         Every time I post on this forum it's due to bad news:( I really need advice on this one though from some diff experts.  Decided to find the top speed of my car the other day and around 90mph the car started screaming from the rear. Luckily only about 2 miles from home so I limped it back. I took note that the noise was only under acceleration, and sometimes a slight grinding noise would occur. Ok, so I jacked it up, put on stands, and ran it in gear. Heard noise was from the differential. Drained diff fluid. Only about a cup came out 😭. I had  a shop swap in this diff and transfer inner stub axles about 3 years ago. Apparently, they decided checking diff oil or changing diff oil after talking about it was not a part of their job responsibility. Even though diff was delivered with open axle seals. I could spend a whole post dogging on that Datsun resto shop, but I won't. Never trust, always verify...

Here is the noise I had

Here is the diff oil removed. Mostly a dark brown color with maybe a light metallic sheen. No metal chunks or shards. Maybe like one slight flake about the size of a grain of sand. Diff internally looks ok with no gears exploded or any visible wear. The black stuff wipes off, I think it is burnt diff oil. Lots of metal sludge on fill plug magnet.

 

I pulled the diff from the car so that I can further analyze it. I don't know if the whole thing is now junk, or if I can rebuild it on my bench? I have a press and tools, but I don't know if it is saveable. At a minimum, I know the bearings and seals should all be replaced, even if they look somewhat ok. Running with almost no fluid makes that seem like a must.

I checked backlash. Absolutely zero backlash at the ring gear when holding the pinion still. Ok, so somehow I lost all backlash. Does anyone know what would cause this? Some sort of bearing failure maybe? I would think if the gears themselves failed the backlash would be much greater as they ate away at each other with no lubrication??? I just bought some gear marking paint, and I will analyze that pattern when it arrives in the mail.

Also when turning the outside stub axles, should there be any slop in the spider gears within the CLSD? I can see some movement in there. I am assuming those gears were almost completely if not completely starved of oil. Here is a video of what I mean regarding that. 

Just looking for anwers to the question above and general opinions as well. These diffs are so hard to find online and expensive its hard to just "buy another". If it is a lost cause, it is what it is:( The shop could have just ruined the OEM diff and this wouldn't have been such a big issue... 

Edited January 24 by ckurtz2

[Zed Head]

Could be bearings or it could be gears.

The pattern on the teeth looks good, but probably shouldn't be seen so easily.  Looks like wear, you might take a really close look at individual teeth faces.  If that's where the noise is coming from then you might need to move the OEM gears over to the CLSD carrier and give it a full rebuild.  Regardless I think that the CLSD portion is probably fine.

Differentials can survive and function with some pretty bad looking gears.  If it's not too noisy with a full oil level, maybe just drive it and see what happens.

[Zed Head]

By the way, not an expert, but I don't think that spider gear lash matters much.  You want to put your indicator on a ring gear tooth and move the ring gear back and forth to see how much lash there is between it and the pinion gear.

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Edited January 24 by Zed Head
I miss my spellcheck. +i

[ckurtz2]

Yes, the spider gears is more of an intuitive question, because I have never seen the inside of an LSD diff, and I am not sure if slop is allowed in those gears. If that movement is considered bad than the LSD carrier is useless, and thus there isn't even a point in saving this thing.

Regarding backlash, yep did it just like that. Zero backlash whatsoever. Interestingly enough if I instead hold the ring gear still and move the pinion flange, the pinion has slop on the ring gear. However, if I hold the pinion flange and try to move the ring gear it won't budge. Doesn't make a lot of sense to me, but that is how it is, thus indicating no backlash in the method above^.

I actually considered cleaning it and throwing it back in the car with full oil like you mentioned. However, the fact that it was completely quiet even with low oil and then started whining during that pull (likely due to high speed oil starvation) shows that I did do real unreversible damage. I even waited till the next day to film the video provided. However, it still was whining really loud on the street. Highway completely unbearable without earplugs. So i know something is amiss. Now it makes me think gears may be relatively ok and instead some sort of failure caused the backlash to completely go to zero and thus induce the gear whine. Just not sure why or if worn gears can cause zero backlash, have zero experience in the differential realm. Trying to find the best course of action. Ive thought about buying a 300zx 3.7 open diff and swapping carriers, but I also don't know if that is possible. Plus rebuilding this one %100 may be worth the money and I will never have to think about it again. Lots of thoughts.

[Zed Head]

10 minutes ago, ckurtz2 said:

if I hold the pinion flange and try to move the ring gear it won't budge.

Does the ring gear move freely without holding the pinion flange?

Might be that things got so hot that a carrier bearing race walked outward.  That would tighten up the lash as the bearings are tapered roller bearings.

Onw trick for installing new carrier bearings is to put them in the oven and drop them over the nose/mount/whatever while they're hot, instead of pressing them on.  Since you have it out you might as well remove the carrier and see if those bearings are fully seated.  You can reseat them with a drift/punch on the race.

 

 

[Patcon]

Well, you answered one of my questions. You still have the noise on a cool differential. I wouldn't get rid of any CLSD r200! If even for parts in the future. If it was me and I could afford it, I would find a rebuilder to go through it. Especially after reading inline6's thread on what he's gone through trying to do his. Call Rebello, zcargarage or Datsun spirit for a price or a recommended shop to do the work.

[inline6]

I have been rebuilding an R180 and have learned a few things. 

Regarding backlash, I don't have to hold the pinion gear.  All I do is fix the magnetic base and arms and dial gauge so that the motion of the rod on the gauge, when rocking the carrier, is vertical to a gear tooth.  You don't want the dial gauge motion to be at an odd angle to the motion of the gear.  Moving the rear carrier assembly by pushing on the gear teeth of the crown gear is easy, and the free play as the gear teeth smack into the pinion gear is very easy to measure. 

So, you have none... that is odd. 

Differential problems more often occur with the front bearings.  That said, don't go taking everything apart to investigate.  If it was me, I'd double check the lash measurement first.  If still zero, than I think I would assume that the pinion gear has moved toward the crown gear, from some kind of change (damage) one of the bearings on the pinion gear.  Pilot bearing would be the first from a probability standpoint.  The front and rear pinion bearings are very beefy.  

That said, I would not remove the pinion nut or disassemble anything relating to the pinion.  I would remove the carrier from the case, and then spin the pinion gear to check for bearing noise.  It should be quiet.  If not, then I'd suspect the pilot bearing.  

Very important - Troy Ermish recently told me that he never takes apart the pinion gear/bearings... ever.  The reasoning is basically that it is exceedingly difficult to get the pinion gear set correctly when replacing the bearings.  Part availability is a big reason for not messing with it.  

If it was me, and I confirmed noise was coming from a bearing on the pinion, I'd disassemble the pinion (hydraulic press work) and check the pilot bearing (after removal from the pinion gear and case.  When you have just the bearing in your hand, you'll be able to confirm if it is bad.  Before the next step, I'd put just the carrier back in the case, tighten everything down and check that there is some load (preload) on the bearings.  Then spin the carrier by hand to check for noise from the side bearings.  Depending on what you find there, side bearings can typically be replaced without additional issues/consequences.  

Back to pinion.  Remove the carrier from the case as you are done with testing that.  Then, I'd put the pinion gear back in with the existing gears and spacers, etc.  And I'd spin the pinion to check for bearing noise from the front and rear pinion bearings.  

If they seem fine, then I'd invest in a new pilot bearing, install that, and follow the instructions VERY carefully for setting pinion bearing preload.  When that is within spec, I'd install the rear carrier, and check back lash.  Use all the stock shims everywhere they are - change nothing.  If the lash is within spec, I'd proceed with checking the wipe pattern.  That should look good if you don't replace the pinion bearings and use all the same shims/etc.  

If that checks out, then install the diff in the car, put oil in and test drive.  If you still have a problem, I'd recommend looking for another R200.  Carriers, (your LSD unit) can be swapped to other differentials with relative ease.  

Of course, if you have gotten to the point of needing another diff, then checking out the LSD thoroughly before you swap it is ground you should have already covered as well.

Edited January 24 by inline6

[ckurtz2]

@Zed HeadFantastic idea! Maybe that could be. Is the race apart of the diff housing or the bearing itself?  I want to take things apart, but I am waiting to get that gear marking paint first. I want to get documentation on what the wear patter looks like before things come apart. Just so I have all the details. That Idea does make sense, as the zero backlash issue just seems so weird to me. Taking this one step at a time slowly, so as not to shotgun buy. I would say that the gear moves freely with some force with no weird binding points. However, I noticed my open diff spins easier comparitively, so definitely some problem somewhere.

@Patcon Do you have any idea the amount of $ they would charge? I seriously am warry of shops from here on out, whether "datsun specialists" or not. The same datsun shop that blew this diff also blew my engine due to not torquing the cam sprocket when replacing a cam. Sprocket came off and pistons met valves. I only took things to them as a last resort for my engine and they blew it... literally... lol. This diff took things to the next step in my trust issues.  

@inline6 Thank you for the detailed advice. I am just learning about the realm of differentials. They don't seem too complicated, just a very exact science like you mentioned with the pinion depth and bearing preload. Something I would like to avoid, but I never have backed down from a challenge yet. Can you describe to me which one is the pilot bearing? I can't seem to locate it in general diagrams. 

 

 

Edited January 24 by ckurtz2

[inline6]

2 minutes ago, ckurtz2 said:

@inline6 Thank you for the detailed advice. I am just learning about the realm of differentials. They don't seem too complicated, just a very exact science like you mentioned with the pinion depth and bearing preload. Something I would like to avoid, but I never have backed down from a challenge yet. Can you describe to me which one is the pilot bearing? I can't seem to locate it in general diagrams. 

 It is the front-most bearing on the pinion gear - in the nose of the differential - blue arrow. 

Also, note that this manual has been added to the resource section a couple of days ago:

 

[ckurtz2]

@inline6Thank you! I will read up on all that. This shows what I am talking about with zero backlash. There is zero back and forth action on the ring gear. I can only get slop to form from moving the pinion.

 

[inline6]

That clicking noise...  It definitely should not be there.  It might be the pilot bearing.  When you grab the front flange and turn it can you feel the "bumpiness" as you rotate it?

I see what you mean about the backlash.  

Seems to me that either the pinion has moved toward the ring gear, or the ring gear as moved laterally.  What I wrote up above would be how I would troubleshoot.  

And, yes, reading the relevant parts of that manual before diving in would be wise.

Edited January 24 by inline6

[ckurtz2]

Yes, and that clicking directly correlates to the pinion moving and tapping the ring gear. To be honest, I spun both the good-condition open R200 I have and this one. The good R200 doesn't make the clicky noises or have any slop from the pinion, but both feel about the same smoothness when spinning.