Rear Diff Carnage,, and questions (16 Viewers)

[fueller42]

I just had to edit the title......for what sanity I have left lol


Hey, just to preface this, I want to say, I'm not an engineer, metallurgist or any kind of physicist. I'm just an old dude that's built, modified, repaired, designed and imagineered a bunch of s...tuff.
I have no doubt that there are more than a couple people elbows deep in trying to figure out what's going on with the RWR rear ends (and those others that have grenaded in the past).
I have seen more than one image showing the pinion housing basically destroyed. My question is, which pinion bearing is taking the transverse load, ie: the push or pull of the pinion shaft. Is the bevel gear pushing the pinion outward, or pulling it inward? I know the couplers are designed with a small amount of play in them, so I don't imagine they have anything to do with it (binding etc.), and my mind keeps coming back to the pinion being pushed out by the bevel gear, or, more accurately, the pinion forcing itself away from the bevel gear.

Am I completely out to lunch??

 

[Ponyhntr]

The theory is that pinion teeth are breaking off and then getting lodged in between the pinion and ring gear, thus blowing the pinion out of the front of the housing.

 

[Butch]

Any idea on how's making Nitro ring and pinions still?

 

[Ponyhntr]

Any idea on how's making Nitro ring and pinions still?

Motive, Richmond, and now Boninfante.

 

[stitcherbob]

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[Butch]

Motive, Richmond, and now Boninfante.

So I'd think RWR is running the Boninfante gear set.
I remember Richmond from back in the years but none of the other.

On the statement about checking the gears after Q1, I would think you'd have to Magnaflux them, visual isn't gonna show much other than the obvious.

 

[fueller42]

The theory is that pinion teeth are breaking off and then getting lodged in between the pinion and ring gear, thus blowing the pinion out of the front of the housing.

For the last 10 years, I've been working with salvage farm equipment (40,000 + part numbers). A bunch of the stuff we sell is bevel and pinion sets. We take cores in. Part of my job is to disassemble the cores, and determine what is good, what is junk. I've seen hundreds of front 4wd axles come in, and the same for rear diff housings/assemblies, and, from what I can recall, pieces either trashed the inner bearing, broke bevel teeth, or just ended up in the bottom of the pumpkin. That being said, the rpm is significantly different, and I can imagine the centripetal force on the "chunks" could very well be slinging them back into bevel gear, effectively forcing the inner end of the pinion sideways, putting a HUGE side/torque load on the inner bearing, breaking the snout there??
Obviously, I don't know, I'm just spit-ballin'. It also seems odd to me that it seems to be happening after the first couple seconds of the run, not at the hit. I know lock up is a huge change in torque applied, so, there's that?
I would LOVE to see any results/conclusions to what the ultimate issue is..never too old to learn something.

 

[none]

The load is MUCH bigger out at a 1.8-2.4 seconds, when the engine comes out of retard and the clutch starts to apply. That's where everything breaks. If you remember when wheel studs used to break that was always at that same spot.

Alan

 

[fueller42]

The load is MUCH bigger out at a 1.8-2.4 seconds, when the engine comes out of retard and the clutch starts to apply. That's where everything breaks. If you remember when wheel studs used to break that was always at that same spot.

Alan

I wondered about that Alan. I would be interested to know, has Chrisman or Strange ever done any kind of testing, comparing the face load on the gear tooth, or optimal helix, shock load at the hit vs. max torque load? Have there been any changes in geometry, or are the gears just the same as they've always been,(excluding physical size) just because it worked OK in the past?

 

[Harry]

Alan is correct. My first thought was when the clutch "hits" its a shock that cannot always be absorbed. As a tool and die maker I remember cutter sharpening, gear/cutter hobbers and other critical machining. Its strenuous work. The pinion is enduring some amazing workloads. Wiping across the ring gear with insane pressure. If the pinion moves away from the ring gear even a few thousands its over. Christman builds a great rearend and they will solve this. Gears are a science all of their own. Aircraft gear in Chicago destroyed many good machinists. I feel for those in the stands.

 

[Jim]

I saw the subject line and thought this thread was about contaminated lettuce and explosive diarrhea.

 

[65 Goatboy]

Well so much for your interesting thread Ed Burgers, it just got flushed.

 

[Cliff]

Hey Jim, saw on the news that the Feds had a "false positive" on the lettuce, apologized to the lettuce companies. Now the lettuce guys have to absorb the cost of the recalls. arghhhhhhhhhhhhhhhhhhhhhh

 

[fueller42]

I saw the subject line and thought this thread was about contaminated lettuce and explosive diarrhea.

OMG....I'm getting old. Twenty years ago, i would have realized how I phrased that..........and laughed my a$$ off!!!

 

[stitcherbob]

In the late seventies, cars started using more recycled steel and when we started restoring them in the nineties we had to deal with the rust and contamination during welding or painting. Is it possible the metal just isn't as good as used to be? I mean on a molecular level.

 

[Harry]

The pinion bearing on the nose may be getting destroyed and causing the gear destruction. The pressure there is insane.

 

[none]

Richard,

Two things.
Thing one: A Pro Stock car "Hits" harder than a TF car. Because the gear set is stationary and when the clutch is dropped at 6500-7500 that is a huge hit. A TF car with the centrifugal clutch the gear set is already loaded so even though the power level is much higher, it's more of a big push. The "Hit" or "Shock" is less. That's why they put rosin on the starting line every pair in PS and not in TF, because that "Hit" takes the rubber off.

Thing two: You may be right about the pinion bearing on the nose being the issue. (I honestly don't know) But if so, WHY????? That load isn't any different than it has been for years.

So the question becomes: "What changed?" Manufacturing? Metallurgy? Heat treat? Assembly specs? Something is different, that's what everyone is searching for.

It seems from my outsider perspective, that the Strange rears had the problem a couple of years ago and now it's the Chrisman rears. They are very different, so again, what changed? And whatever fixed the Strange, is that the fix for the Chrisman?

Alan

 

[Butch]

Allan, do the two different rear ends use the same gear set or are they completely different?

 

[none]

They are different.

Alan

 

[Marchboom]

And why is this problem primarily with Rick Ware Racing?