Pitting on banjo ring gear what’s acceptable?

In preparation to put together a quick change I tore down a 1940 3.78 rear end to salvage the guts. When I popped the torque tube off a significant amount of water poured out… crossing my fingers I continued disassembly. After I had all the components disassembled I inspected the damage. The teeth on the pinion gear appear to have escaped injury but here was some rust on about 6 of the teeth on the ring gear the rest were fine. I cleaned the rust off the ring gear teeth with a small wire brush on a dremal and there is some pitting on both sides of the 6 teeth. The pitting ranges from negligible to kind of bad? Attached is a picture of the worst of the pitting.

My question is how much pitting is acceptable on a ring gear? Should I try and find a new set? If it is a matter of noise that wont be a problem due to the straight cut howlers in the QC.

Any advice would be appreciated.

Thanks
Chris

 

I've run worse than that with no problem. The pits hold extra oil and help lubrication... Ha HA !

 

I say run it.
I had a 9" ford with the same deal, no problems whatsoever.

 

I'm running a '67 gm 10 bolt in my roadster that I replaced the ring and pinion in in June. About 1/4 to 1/3 of the ring gear was pitted like that and it's still together. I drive it just about every day 25 miles to work and back. Lot's of smokey burn outs too. As for them whining I don't hear any noise over the open headers. I did use 85-140 gear lube too.

 

Go for it. If you're nervous, epoxy a magnet into drain plug and check it from time to time. A small amount of "fur" on magnet is normal, impending doom will cover it in lots of metal. Good used 3.78's are pretty common, but don't worry til you have cause for worry.

 

Yah run it, I have parted out worse that were on the road. Just do the oil change after about 100-200 miles and recheck the gears. if it looks good and it did not chip of from stress. Your good. Take care, Jim

 

Yeah, I'd run that, no problem.

Do the bearings and races look OK?

Rich

 

Thanks guys.

I have had this rear for like 6 years…it has spent its life with me outside with the tube up and uncovered for a good portion of those years. It’s my own fault! I was checking the Macs catalogue and got sticker shock when I saw the price of a new set. A good portion of my spending money went to buying the QC center so I wasn’t looking forward to more spending…



the-rodster

I got new bearings and races with the QC when I ordered it so I wasn’t concerned about them…

By the way I have been studying your post about rebuilding the 40 rear. It has given me most of the confidence to put the QC together on my own. Thanks! The pictures are missing from that thread though?

I will probably be posting a few more questions regarding assembly when I get to assembling.


Thanks
Chris

 

One thing on assembly...keep and measure a section of each side gasket. If bearings are good, those will tell you the thickness needed for setup, and if you change bearings they will be a starting point that may well be right. Original gears are usually pretty easy to get set correctly.

 

I would run it, as long as it won't cause the backlash variance to be to high it will be ok.

 

holy cow, thanks for posting this. My 1940 open drive looks like that and I was worried. Finding gear sets for an open drive has proved impossible so far. Anybody know where to buy the right u-bolts for the u-joint? Seals? Thanks for the thread.

 

If that's the worst you have.....I'd say RUN IT Just make sure you put in that super thick gear oil.

A really used ring and pinion set isn't that much if you had to change them, they are still availbale.

 

Unless its an open drive. Where do you find them?