[mrennie]

Make sure you load the gears as much as possible when checking the pattern. If you just turn it lightly the resulting pattern will not replicate what it does under load.

Not sure the best way to do this with an open carrier. With a LS carrier you can have someone "choke" the pinion yoke while wearing leather gloves, and turn an axle with a prybar.

[dataway]

mrennie, I'm hoping the pinion preload will provide enough load ... it's substantial, I can't turn the ring gear by hand right now, I have to use a wrench on one of the ring gear bolts. I can probably rig up something to add some resistance to the pinion.

Shiny, I'd normally agree that .010" is a huge amount of wear to see in a straight roller bearing, but a tapered roller bearing being a steep angle cone, if you lose .001 on the inner race, .001 on the outer race, and .0005 on the roller surface (x 2 since in contacts on both sides) ... it allows the roller pack to drop dramatically into the cone. Well, not dramatically .. but as an example .001 wear on the outer race equals about .002 reduction in bearing width, haven't done that math for the inner race and rollers but my guess is when you stack the parts up I'd bet you lose .003" in width for every .001" in surface wear on the components. The old bearings were pitted on both races and all the rollers, under magnification all the components were "micro" pitted over their entire surface in addition to the large visible pits.

I hope to find out soon ... working with your pinion depth measurement ideas, and looking around on the internet I think I see a good method. I noticed one pinion depth tool kit included a piece of metal with a magnet in it that you stick to the end of the pinion, there was no explanation, my "guess" is it's a calibrated block you stick to the end of the pinion to "average out" the roughness of the pinion face. Then you add the thickness of that metal block to the pinion depth measurement.

I'm going to lay a ground bar across the carrier bearing cap surfaces, and use a Starrett depth gauge to measure to the pinion face and then do the math to add the thickness of a niobium bar magnet I will use on the pinion, and subtract the thickness of the ground bar ... should work right?

A depth gauge comes with calibrated extensions ... so I should be able to read the pinion depth stamp off the pinion and then pick the appropriate extension to start with.

[dataway]

Nightly Update

Well, there is a new twist in the plot. The pinion has no pinion depth stamp or marking that I can identify after long and extensive, neck aching examination. So ... would a pinion depth reading have any value to me now? So, I didn't measure it ... had all the materials to make a tool laid out and decided to check for a stamp before I started drilling and cutting. Perhaps the pinion depth stamp is also found somewhere else on the pinion? Now that I think about it .... it did have something stamped on the shaft between the bearings. Sucks that I can't see that with it installed.

So .. being an impatient type I tried some lithium grease to get a rough idea of gear contact. It didn't work as well as I hoped it would, but what I could see appeared to show a LOT of gear contact.

Take an image of what is usually considered a proper contact pattern .. an oblong patch centered between toe and heel, and between high and low .. take that image .. and expand it symmetrically till it covers 85% of the entire tooth, both drive can coast side. That's what I'm seeing.

The optimist in me says that's what I would see on properly set up gears that spent 100k miles getting know each other.

Tuesday night I should have the marking compound to check better.

I sure was hoping the pinion would have a stamp on it so I could at least practice measuring the depth.

Shiny I see no reason why your method of measuring would not be a perfectly valid method that does NOT require a $450 tool set. Replace the caliper with a depth gauge, piece of ground steel can be had on McMaster, drill some holes to mount it to the bearing saddles, if you want drill a hole in the bar to send the depth gauge/caliper though, use a niobium bar magnet on the pinion face if necessary, do the math ... and I bet you are within a few thousands of the best tool out there.

I've been on a streak of good luck lately .... maybe it's still going

PS. If anyone is looking for good info, I like this article: https://eastcoastgearsupply.com/file...structions.pdf

[Shiny]

Sounds like you're almost there and the marking compound can only add confidence.

No reason to measure depth if you have no target!!

And yes, a small amount of roller and/or race wear would create a lot of slop in the width direction. Trigonometry can be hated but not discounted.

Loading up the gears is good advice. After looking at all the online guides, I struggled to consistently match those "clean" pattern images and concluded I just didn't have enough torque being transmitted across the gear faces. Let's just say I was lucky the gear set I bought (U.S. Gear) was marked clearly.

I'm optimistic your re-assembly with original shims will land you in a happy place.

As to depth measurement, the right tools would probably make it easy and definitely be more accurate. I just didn't need a second mortgage. I wasn't ever sure if the mating surfaces of the carrier bearing saddles were an accurate indicator of the ring gear CL. If not, the magnitude of that error would be good to know!


Mike

[dataway]

Yep, I wondered about flange surfaces .... but heck ... they gotta be real close to centerline I'd think or the bearing would not fit into either the saddle, or the cap ... gotta be similar to a main bearing cap/saddle ... when you think about it, every bit as critical.

That article I posted was pretty interesting, guy said he doesn't worry about heel to toe pattern at all, only the top to bottom (face to flank).

I might have to get the wife to crawl under there and hold onto the pinion for me, otherwise maybe I'll wrap it with a rag and put a big hose clamp on it or something.

Wonder if I could take a rubber bungee, loop it over the yoke and hook the ends to something so it would act as a brake.

[Shiny]

Our assumptions are aligned on the bearing saddles.

And thanks for the link. That is excellent practical guidance on setup.

[dataway]

Well here's the first set of contact patches.

I'm fine with the coast side. (a bit high)

Drive side is down on the flank more than I'd like, but centered nicely.

Very little info out there for acceptable patterns for well worn gear sets. Most of the time the advice is to just get them the same as they were before, for which I have no data point.

Going to do some reading, but honestly my inclination at this point is to assemble the way it is. This car will never see a drag strip, or a road trip, and will probably get a new posi carrier and gear set when it's settled down in TN.

If my research shows things can be improved by carrier shims I'm going to be more likely to address it. The idea of going through the pinion shim dance for minor improvement on worn gears isn't very appealing.

[dataway]

Just came across a couple of tips from "gear heads"

"Usually a good used gear will have a sharp line all the way across the root of the tooth on the drive side and more of a centered pattern on the coast side."

That is just what I'm seeing.

And ... from Yukon Gear "When testing your pattern on a used gear, it is often difficult or impossible to get a good pattern on the drive side of the gear. The reason for this is that through use the drive sides of the gears wear and won’t show you the pattern clearly. The solution is to check the pattern based on the coast side of the gear"

[Shiny]

[dataway]

I miss "Five-O", going to have to find a few old episodes to watch.

Well, based on the results above and what I've read about used gear sets ... I'm going to go with this setup.

Without going through this whole thread ... I know one person said to put the old shims back in and button it up and it would be fine most of the time. Seems to be the case.

So, I'll be pulling the carrier and pinion back out, installing the pinion with sleeve and seal, carrier back in and reassembling all the associated axle parts.

In about a week I should have another "on the road" report. If it still makes noise I'll have to look elsewhere for the source because this setup is staying in place until if/when I decided to upgrade the carrier.

Thanks for the assistance and information everyone.

[dataway]

Slight delay ... my Richmond Gear bearing kit had the wrong pinion seal ... looks to be a front crankshaft seal ( apparently there is some part number mix up with those two seals).

Bought some 75-140 gear oil this time. Evidently the original OEM specified lube, something like straight 90 wt GL-5 is no longer available. Supposedly 75-110 is the closest to the original OEM spec. Going to try the thicker stuff for these old worn gears.

[geeteeohguy]

Originally Posted by dataway

I miss "Five-O", going to have to find a few old episodes to watch.

Well, based on the results above and what I've read about used gear sets ... I'm going to go with this setup.

Without going through this whole thread ... I know one person said to put the old shims back in and button it up and it would be fine most of the time. Seems to be the case.

So, I'll be pulling the carrier and pinion back out, installing the pinion with sleeve and seal, carrier back in and reassembling all the associated axle parts.

In about a week I should have another "on the road" report. If it still makes noise I'll have to look elsewhere for the source because this setup is staying in place until if/when I decided to upgrade the carrier.

Thanks for the assistance and information everyone.

A few years back, I re-watched most of the Hawaii Five-O series, from the first season in 1967 going forward. In one episode, they used a Fontaine Blue '66 GTO hardtop as a COP CAR. With a gumball light and siren, the whole thing. I was amazed.

[dataway]

Well here is the follow up.

Below is a "before/after" video posted to YouTube showing a drive down the same section of road.

Not sure if you can tell from the terrible audio but, rear end is now absolutely silent, in fact probably one of the quietest diffs I have ever heard (or not heard).

Checked the temp of the pinion bearing area of the diff case when I got back from the drive. It was warm, but by no means hot, no leaks (YET, as I did neglect to put sealant on the yoke splines).

Can't tell from the video with all the wind noise and weird stuff the phone picks up, but it was seriously, absolutely silent.

Video is here: https://www.youtube.com/watch?v=C8mMl5NHUPI

[Shiny]

Excellent!!

Nicely done!

Hope you feel good about annihilating that whine and another big accomplishment.

[b-man]

As expected.

Nice going!

[Greg Reid]

Very impressive dataway!.... but I expected no less.

[PunchT37]

There`s only 10 bada$$ people in the world. And you get 9 Christmas cards?

[dataway]

Hehehe ... thanks guys. Certainly made me feel better, I was preparing for the worst and hoping for the best.

Frankly I'm amazed that it made that much noise before with no discernable slop in the pinion. I guess that pinion bearing is under enough stress that those pits are all that's needed to let it move off the ideal location.

[PunchT37]

Those are decent pits in a bearing. They will make noise wherever they are.

[Shiny]

I expect the noise was related to both the pitted races and the loss of preload.

Noise is tricky and, in my experience, very technical. As I understand it, something in the mechanism has a resonance in an audible frequency range. That's not a problem as long as it dampens out quickly and vibrates with "low amplitude".

My guess is the pinion bearings got a little rough, got a little sloppy, and suddenly you are "feeding" that resonance. A little energy pushed into a resonant vibration gets amplified and you get to hear the whine.

Whatever you did was good and I'm glad you got it tamed the first time. Nicely done!