What is going on here! Diff gear issue

[Roger440]

Ive done lots of these in the past. Putting a new gear set into my diff.

Genuine, new DANA gears.

As per the pic, what is the weird stripe on the three teeth?

Ive cleaned it off, had it out multiple times. Each time i get this.

Its also not entitrely smooth when rotating the diff via the crwon wheel. Fine if you turn the pinion.

Any ideas? Im stumped.

 

[Matchless]

To me that looks like a manufacturing defect, could be the pinion or ringear.

 

[Bornfree]

Is it only that three teeth ?

 

[Roger440]

Is it only that three teeth ?

Not sure. Ive not painted the whole ring gear with compound. I suppose i could?

When i did the first build up, before i dropped the pinion a touch, there was no issue, but probably, (almost certainly) a different selection of teeth.

 

[Roger440]

To me that looks like a manufacturing defect, could be the pinion or ringear.

Thats was my initial thought. But its genuine DANA, and ive done lots in the past without issue. So im questioing myself.

 

[Bornfree]

Not sure. Ive not painted the whole ring gear with compound. I suppose i could?

When i did the first build up, before i dropped the pinion a touch, there was no issue, but probably, (almost certainly) a different selection of teeth.

If its the same teeth it's a problem with the crown wheel or its mating surface on the diff.

 

[DaveB]

Surely the pinion and ring teeth counts result in evry pinion tooth meeting every ring tooth over a series of revolutions.

If so then the odd contact pattern must be down to the teeth on the ring ?

 

[Roger440]

Surely the pinion and ring teeth counts result in evry pinion tooth meeting every ring tooth over a series of revolutions.

If so then the odd contact pattern must be down to the teeth on the ring ?

My thoughts exactly. I put a drill on it and spun it for 30 seconds. No change.

 

[Turbo]

Mark those 3 teeth with a black marker, clean off the yellow stuff and redo the test a few times. If the same 3 teeth come up there must be a machining fault on the crown wheel.

Does the cw bolt on or is it part of the diff? If its bolt on it you could try bolting it on a different set of holes.

 

[Stueeee]

Does look like a machining fault on the crownwheel. Have you checked the backlash at the three teeth mesh position vs. elsewhere on the crownwheel rotation?

 

[Roger440]

Does look like a machining fault on the crownwheel. Have you checked the backlash at the three teeth mesh position vs. elsewhere on the crownwheel rotation?

No. Good idea though. I will do that this morning.

 

[Roger440]

Mark those 3 teeth with a black marker, clean off the yellow stuff and redo the test a few times. If the same 3 teeth come up there must be a machining fault on the crown wheel.

Does the cw bolt on or is it part of the diff? If its bolt on it you could try bolting it on a different set of holes.

The crown wheel bolts on. I checked the run out on it, its less than a though. Ive had them not seat corectly before.

Looking at it again this morning, and i mentioned its not totally smooth, the marks on the pinion look like the pinion is way way to low. Ie, the top of the pinion teeth look like they are in contact with the crown wheel, but the contact stops a long way short of the bottom. Yet the tooth contact on the crownwheel looks pretty good.

The pinion shims, and the position of the diff carrier are all about normal. Its extremely rare that one needs to deviate from the standard pinion shim thickness. The amount of correction i think it would need is way beyond anything sensible.

When i get it apart later, ill take a pic

 

[8ob]

The pinion shims, and the position of the diff carrier are all about normal. Its extremely rare that one needs to deviate from the standard pinion shim thickness. The amount of correction i think it would need is way beyond anything sensible.

Pinion height is normally indicated/etched on the underside of the pinion as a + or- figure from a standard. Its worth taking a squint at that. I had to make up a standard using a big mandrel that sat in the diff carrier, them milled some blocks using an original pinion so I could calibrate from that.

Bob

 

[Roger440]

Pinion height is normally indicated/etched on the underside of the pinion as a + or- figure from a standard. Its worth taking a squint at that. I had to make up a standard using a big mandrel that sat in the diff carrier, them milled some blocks using an original pinion so I could calibrate from that.

Bob

Its is. Its zero. DANA gears are always zero. Never seen any other number. What came out was zero.

Which is what makes it all so odd.

The first clue, was despit all that, i had to drop the pinion 3 thou to get the tooth contact where i wanted it. They could be fake, That wouldnt be the first time.

 

[8ob]

Its is. Its zero. DANA gears are always zero. Never seen any other number. What came out was zero.

Which is what makes it all so odd.

The first clue, was despit all that, i had to drop the pinion 3 thou to get the tooth contact where i wanted it. They could be fake, That wouldnt be the first time.

I get that, that’s where they should be. Its not where they end up though because of casing variations. Zero is the standard and pinion can be + or - from that, without the "standard" you can only guess the pinion height.

Bob

 

[8ob]

A fancy tool with a gauge but the same principle, a mandrel and block/feeler gauges will do the same job

 

[Roger440]

I get that, that’s where they should be. Its not where they end up though because of casing variations. Zero is the standard and pinion can be + or - from that, without the "standard" you can only guess the pinion height.

Bob

Yes, understand that. Thats why, logically, i always keep the shims to the case. I do have 3/4 of a DANA pinion height setting kit. Really ought to sort that out, but i might never do one again. So, with the correct shims and a zero pinion, it will be close, then tooth contact leads you to the right plsace any way. Except on this occasion where it leads to confusion.

Maybe i didnt explain myself well?

 

[Stueeee]

Is it a Dana 44 or a Dana 60. The 'high ratio' i.e. numerically lower 44 cases are machined with a deeper unshimmed pinion height because the crownwheel is larger. I've only done a couple of 60's so not sure about those.

 

[Stueeee]

A fancy tool with a gauge but the same principle, a mandrel and block/feeler gauges will do the same job

View attachment 481191

Thats fancy; I used to do lots of rear axle work, this is one of my 'gauges' I have them for most of the 'usual suspect' diffs. I found that a pile of gauge (Joey) blocks were the quickest way to get an accurate measurement.

The other bit of 'school of coarse engineering' kit was my carrier spreader. Either directly hooked into the lug holes or with a simple pair of adapter plates.

 

[Roger440]

Is it a Dana 44 or a Dana 60. The 'high ratio' i.e. numerically lower 44 cases are machined with a deeper unshimmed pinion height because the crownwheel is larger. I've only done a couple of 60's so not sure about those.

Not sure i know which it is. The pinion bearing is always shimmed though.

As a man of experience, any thoughts on my weird stripes?