To replace, or not. That is the question....

Cider Mill

Cider Mill

Senior Member
My friend & I took my rear end apart. It was both of first time. How do you know if you need to replace the ring and pinion gears as well as the bearings? There are few, if any blemishes in any of the teeth or bearing rollers, but when I compared the ring & pinion teeth to a new set I have on hand the teeth appear to have a larger flat spot on the tops. i.e. the teeth appear to be shorter. I hate to replace if not needed (the new set is for another car).
 
If you don't see any galling, rust pits, or chipped or missing teeth, then the ring and pinion should be OK. I've never seen them wear thin.
 
My thoughts on any asembly with bearings. I have it apart, bearing replacement at this time is easy, if I put assembly back together and one of the bearings goes bad, how much work is involved to get it disassembled to replace the bearings and reassemble/install the unit. The ring and pinion should be inspected by a qualified mechanic as to it's serviceability.
 
Good time to replace all the brgs & seals.Inspect the gears like Tom W said and if good then you are not likely to live long enough to wear them out,provided it has enough oil & is not abused.Ive done numerous rear ends & always found good used matched sets of gears. Shop manuals at the parts dealers will have all the info you need.
 
All the bearings, cups and sleeves look really nice with no pitting or visual wear. I just priced new bearings and cups for the rear axles and drive shaft and it is over $300! Yikes!
 
I'm in favor of replacing bearings or at the very least resetting the preload on the current bearings. I'm not sure what the preload should be on used bearings but it will be less since they are already mated.

I drive my model A's more aggressively than most which essentially places more load on everything. Back in the 70's I knocked teeth off in the original rear end in my '29 Roadster. When I opened it up I found that the broken ring and pinion were otherwise in perfect condition. It was instantly clear that there was enough looseness in the bearings that it allowed the gears to push away from each other under a load.
 
I know allot of the bearings today aren’t domestic. So is it still worthwhile to replace older worn in but not worn out bearings with what MIGHT be inferior quality, as long as the originals aren’t wasted? My experience with bearings was with parts not from Model A's, so I really don't know. I know Federal Mogul, can be made in Japan (good ones) or Taiwan (not so good). Not sure about Timken.
 
I would think that if brgs look good and haven't spun,why ask for trouble, unless you've replaced them before in another build and/or have the proper tools. Murphy's Law. JMO
Paul in CT
 
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