Rear end rebuild
 

Just wondering what you guys think of my rear end :o.

I'm going through my '29 coupe's rear to see what condition it's in so I can rebuild it. Les Andrews book isn't too informative about what's acceptable as far as wear goes, so I need your help on this.
What are the acceptable measurements at critical areas?
Should all seals, bearings and races be replaced regardless of how they look?
What steps to I need to take to do the job correctly?

Re: Rear end rebuild
 

The gears all have broached faces. So they should have lines across them. If they are shiny then they have wear and you have to look much closer. They could be fine.

Look at the inside of the carrier. How worn in are the spider gear seats? Some go pretty far in. How are the faces where the axle heads press against the carrier, are they rust pitted? Now here is where the play is normal and you are just looking for excessive issues. This controls the in-out play of the axle.

Axles need to be carefully inspected. You need to look at the threads and the keyway. Sometimes the keyway has cracks inside- not good. How is the taper? Does it have lots of rings indicating it has spun? Spinning means wear and setting the hub in tighter and other issues. What about the point where the seal rides. It must be very smooth and reasonably centered. Here is where a leather seal is likely a better option if there are issues as the leather will be more tolerant of problems. The modern seals like a nice smooth surface. The seal area should be polished smooth with shoe shine method and sandpaper. How are the threads?

Have the bearings on the carrier spun? They should not be smooth and you should have clear machine marks. If they are smooth then you may need shims to get the right pre-load.

It is hard to be sure from your pictures the condition of the parts. It does not appear the spider gears have a deep wear into the carrier. It also looks like the spider gears still have the lines on their faces so they may not have a lot of wear which means the rest is likely good.

Be sure to not chase the threads on the bolts and nuts. Use the originals unless there is an obvious flaw. Do not chase any of the threads in the rear with tap and die. I hand clean all the nuts and bolts with a pick or wire brush. Keep in mind they are all tight tolerance threads. If the housing bolts are good then you should not be able to get much past 1/4 to 1/2 in by finger if the both sides are clean. If you can get the bolts all the way in by finger then they are too loose and may leak, you will have to consider a thread lock/ sealer. Yes, I went by hand and tested like150 bolts to find the ones I used on my rear. Many were worn enough I would not use them. Some of the best threads had nasty rusty heads so you will find some nasty bolts on my rear. It is about function.

Re: Rear end rebuild
 

To add yes replace all bearings,races and seals

Re: Rear end rebuild
 

agree, replace all bearings, races and seals and clean out the axle housings, your keyways look good, if the bearings can be removed easily off the carrier, they will have to be knurled. With 3 guys working to put the rear end back together, the labor was over five hours.

Re: Rear end rebuild
 

Replace all seals. Use bearings and races if they appear good, no pits in them. Inspect inner races of tapered-roller bearings, again no pits. You will likely not be driving the car for 100,000 or more miles so don't spend money where not needed. Ring and pinion ... again no pits unless really small. Your axles look fine, just smooth the ends a little with emery cloth, file any high spots. Spider gears etc. are not critical as they rotate as a unit when driving, only turning when turning. The small outer seals face outward to keep wheel bearing grease from entering the main housing. Have fun!

Re: Rear end rebuild
 

I do the same as Jim.
I do see you have a roller out of place and I see a black spot on the inner race, which may be a bad pit, so this bearing at least would seem to be bad. When one bearing is bad it may send grit into the other bearings, so inspect them all very carefully for wear, galling, or pits.

Re: Rear end rebuild
 

Everything looks good. No pits or anything like that. The axle key slots look good but it does look like the tapers have "rings" like the hubs might have spun a bit but I'm not sure if it's excessive or not. Yes the one roller is out of the one bearing, but I found it (pictured below wooden block). It looks as though a gear tooth had found it also and cracked it in half. I have both halves of the roller, and no teeth on any of the gears look damaged from hitting it. The teeth actually look pretty good and don't have any visible wear patterns, not even the ring gear where the pinion gear rides.
I measured the outside of the axle housings where the hub bearings ride and they measures 2.061 which according to Les Andrews is fine. They have no flat spots on the bottom.
But i don't know what any of the internal parts pictured are suppose to measure so I don't know what is acceptable.
Before disassembly, only the one axle had very minor in-and-out play. The other axle had none.
I don't want to spend money replacing things I don't need to.
I was just going to replace the bearings, races, and seals, and follow the assembly procedures from Les Andrews book. I just wanted every ones input so I don't miss something.

Re: Rear end rebuild
 

Jim, are you referring to the "teeth" or the area behind the teeth?
Can you clarify that for me.

Re: Rear end rebuild
 

I had good luck taking the axle housings to the car wash and pressure washing.
The drive shaft was more work. I fabricated an end plate to seal off the flanged end and put a round toilet bowl brush on a long handle. filled the torque tube with lacquer thinner and let it set over night. Alot of elbow grease to clean that torque tube.
Cleanliness is next to godliness for this operation.
Bob

Re: Rear end rebuild
 

Hi Vin-Tin,

Please do a Forum "Search" on, and acquire the latest publication on "Differentials" by Mr. Tom Endy.

It is a very user friendly publication, written in plain English for Model A owners wanting to perform this task "once" and correctly.

You will be glad you did,

Re: Rear end rebuild
 

If you're referring to Santa Anitas A's website and Tom's differential "how to" article, I have that save on my computer already.

Re: Rear end rebuild
 

Hi Vin tin,

That is it.

FWIW, seems like someone later posted that Mr. Endy either added a few additional comments or revised a few comments in this particular article.

Anyway, thanks again to Mr. Endy .......... for taking his valuable time for writing and sharing experiences with such a wonderful and detailed Model A article.

Re: Rear end rebuild
 

I see you have wired the spider gears to the 3 legged carrier . This is good as it is better to re fit on the bearing surface they came off. If you have one bad spider gear change all 3 to a known set . If one replacement is less worn than the other 2 it will take ALL the load .

John in cloudy sunny spells windy Suffolk County England

Re: Rear end rebuild
 

the one axle appears to have a raised edge at the keyway,make sure the key fits in the slot tight,the hub might be rocking back and forth,remember taper end of key toward differential with the taper down.

Re: Rear end rebuild
 

Thank you. I didn't know he revised it. I did a search and now have the revised info saved.
Yes, thank you Mr. Endy. It's wonderful "A" people like yourself who make this hobby (and website) so great!