ring and pinion

[chkolar]

I have to repair the rear axle because the pinion gear has many teeth broken. Also the ring gear is damaged. My question is, I have a used ring gear with the same number of teeth and a good pinion gear that also has the same number of teeth. Can I put them together or do they have to be a matched set? They are from different rear ends.

[V4F]

just be sure you check the new wear pattern . looks good do it . they don't know that they are from different mothers

[BRENT in 10-uh-C]

Let me go this way, a matched set (which wasn't a Ford practice in Model-A era) only takes away the possibility of a noise (whine) from mis-shaped teeth. If you are OK with a slight whine from the rear end either on accel, -or more likely on deccel, then go for it. Many, many Ring & Pinions have been installed with mismatched parts and they never made a noise whatsoever.

[Tom Wesenberg]

I agree that many mismatched gears have been used, and with success, but I thought I saw pictures of ring and pinions being wired together when new to keep them as a set. I also thought they have some marks engraved to identify them as a set.

[d.j. moordigian]

Originally Posted by Tom Wesenberg

I agree that many mismatched gears have been used, and with success, but I thought I saw pictures of ring and pinions being wired together when new to keep them as a set. I also thought they have some marks engraved to identify them as a set.

.......Bingo!........

[larrys40]

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I concur that as Tom noted the pinions had a stamp number in them and the ring gears had an engraved script handwitten style writing on the flat of the ring gear. It is had to see on some but they do in fact match. I try to keep to that but have on occasion as necessary used a mismatched pair of gears and they do fine. I believe this was indeed a common practice in the day to just repair what was broke, both by Ford dealers and of course other repair shops that had parts around to sell and use.
The key is to use good gears, replace bearings and races, and set your bearing preloads and check and adjust clearances to tolerance. Doing all of that will produce a favorable result. Not doing it will most certainly result in a crap shoot and a wast of time and money.

Rear axles aren't that complex but there is a process.... One of my specialties and have done many and haven't had any issues yet.
Larry Shepard

[Roger V]

Originally Posted by Tom Wesenberg

I agree that many mismatched gears have been used, and with success, but I thought I saw pictures of ring and pinions being wired together when new to keep them as a set. I also thought they have some marks engraved to identify them as a set.

I have two sets of NOS Ford R&P's. Both have etched numbers matching ring to pinion. I don't know what the process was back then to cause Ford to do that. It seems if the thought is to have matching "used" ring & pinions because they ran or wore together, that's only good if the reuse has the mating exactly the same tooth to tooth. That would be near impossible at best so if not, the result wouldn't be any better than installing a ring and pinion that wasn't from the same rear end.

[BRENT in 10-uh-C]

Originally Posted by larrys40

I concur that as Tom noted the pinions had a stamp number in them and the ring gears had an engraved script handwitten style writing on the flat of the ring gear. It is had to see on some but they do in fact match. I try to keep to that but have on occasion as necessary used a mismatched pair of gears and they do fine. I believe this was indeed a common practice in the day to just repair what was broke, both by Ford dealers and of course other repair shops that had parts around to sell and use.
The key is to use good gears, replace bearings and races, and set your bearing preloads and check and adjust clearances to tolerance. Doing all of that will produce a favorable result. Not doing it will most certainly result in a crap shoot and a wast of time and money.

Rear axles aren't that complex but there is a process.... I have done many and haven't had any issues yet.
Larry Shepard

Originally Posted by Tom Wesenberg

I agree that many mismatched gears have been used, and with success, but I thought I saw pictures of ring and pinions being wired together when new to keep them as a set. I also thought they have some marks engraved to identify them as a set.

Beginning in the early parts books, A-4209-* (AR, C, & D) was listed as MATCHED. On the part drawings I have , I find no mention of them needing to be matched. Now for example, in the Oct '29 parts book it lists 3 different gear ratios, which two of the three use the 9 tooth pinion, --however the two 9-tooth pinions listed are of a different gear pitch which are not interchangeable. Then to add additional confusion, the standard 3.70 ratio and the 4.10 ratio (A-4209-D) both shared a 40 tooth count ring gear but they are not interchangeable, ...AND further complicate things, Ford also manufactured a 9-39 and a 9-41 teeth ratio. As stated above, none of the 9-teeth pinion gears are interchangeable with the different teeth count ring gears. Therefore, to avoid confusion & malfunctions, it was likely best for Ford to just say they are matched.

But suppose for arguments we said they 'were' matched. So exactly what would they have needed to do during that day & time to make them "matched"? Ford's machining capabilities were extremely good back in the day, and tolerances were held to a very high standard in both his manufacturing and assembly methods. His transmission gears were not "matched", nor was the crankshaft & timing gears, -and the steering gear box gears were not matched. I believe we all agree that Ford did not waste time nor money on procedures that were not necessary, and we all seem to agree that mismatched Ring & Pinions work perfectly well without any excessive lash or noise. Therefore, I think there are some of us who have come to the conclusion that a listing of "matched set" was more about ensuring the correct pinion gear was mated with the correct ring gear, ...and not that the two items received any special machining process to "match" them.

.

[BILL WILLIAMSON]

Originally Posted by Tom Wesenberg

I agree that many mismatched gears have been used, and with success, but I thought I saw pictures of ring and pinions being wired together when new to keep them as a set. I also thought they have some marks engraved to identify them as a set.

Early Datsuns came with a very mild, ULTRA fine abrasive, in the diff oil, to "lap" in the teeth, for a "precision" contact pattern. It was MANDATORY, to change the oil at 500 MILES!!!
DON'T TRY THIS AT HOME!!!!!
Bill Quiet

[BRENT in 10-uh-C]

Originally Posted by forever4

Your reply should state that 3.70 and 4.11 both used a 37 tooth ring gear, not 40 tooth.

Refer to the link for lots more info on Model A and B rear axle gears.

http://www.fordgarage.com/pages/rearaxleratios.htm

You are absolutely correct. Too many teeth counts to keep up with.

[Roger V]

Originally Posted by forever4

Roger,
I may be misreading your statement. If so, I apologize.

If you notice rear gear ratios, they are not evenly divisible tooth counts, so the tooth-to-tooth contact progressively changes and all teeth meet-and-greet all other teeth in a regular sequence. This helps enable even teeth wear and minimize noise, steel to steel.

In contrast, crank and cam gears are evenly divisible, and there is no progressive movement of contact teeth. The is also why one gear is fabric, to take the brunt of the wear and to help manage noise.

Agreed. I wasn't clear. I meant the depth or position of any pinion gear tooth in its contact with any ring gear tooth. While its adjustable with gaskets, but to get it exactly the second time so the teeth mate like originally seems unlikely. Hopefully, I didn't muddy my answer more!

[BRENT in 10-uh-C]

Roger, to muddy up the waters some , inspection cameras for iPhones are now under $20 that have very good quality. These can be used to go in thru the differential (banjo) housing oil fill/drain holes to see exactly what the teeth engagement looks like. A little LED bulb on the end of the camera illuminates the area for the camera lens to see.

[Roger V]

Originally Posted by BRENT in 10-uh-C

Roger, to muddy up the waters some , inspection cameras for iPhones are now under $20 that have very good quality. These can be used to go in thru the differential (banjo) housing oil fill/drain holes to see exactly what the teeth engagement looks like. A little LED bulb on the end of the camera illuminates the area for the camera lens to see.

Never thought of that and I do have a regular inspection camera outfit though I don't know if mine will fit. While my "muddy" was regarding the point I wasn't making very well, yours makes accomplishing the task more "clear".

[john charlton]

Interestingly in the English parts book the diff carrier halves are sold separately . The left side cost one shilling and sixpence more expensive than the right non ring gear side . You would think they should come in matched pairs but they dont ,not in England anyway .

John in dark cool Suffolk County England .

[Tom Endy]

Originally Posted by john charlton

Interestingly in the English parts book the diff carrier halves are sold separately . The left side cost one shilling and sixpence more expensive than the right non ring gear side . You would think they should come in matched pairs but they dont ,not in England anyway .

John in dark cool Suffolk County England .

There are two different Model A carriers, an early and a late. The early carrier halves were identical. You can put the ring gear on either half. The bolts for the early carrier had a dome head and went in the carrier in the opposite direction. The late carrier halves were two different part numbers. The ring gear can only go on one side. The bolts were also different with a rectangular head and went through the carrier in the opposite direction from the early carriers.

The only parts that are interchangeable between the early and late carriers are the nine castle nuts. However, people often try to interchange some of the parts.

I do not believe that the carrier halves were ever matched at the factory. The reason it is important to mark the carrier halves when taking one apart is that the back side of each spider gear creates its own wear pattern. Sometimes the wear pattern is so severe that it is prudent to discard the carrier for a better one. I have matched up orphan carriers a number of times. The secret is to have somewhat equal wear patterns on each side.

Tom Endy

[Juggler]

Originally Posted by john charlton

Interestingly in the English parts book the diff carrier halves are sold separately . The left side cost one shilling and sixpence more expensive than the right non ring gear side . You would think they should come in matched pairs but they dont ,not in England anyway .

John in dark cool Suffolk County England .

[john charlton]

My English parts book has A-4205-B for the left and A-4206 for the right . My early dif carriers are for sure the same as you say but mine have a steel peg on the right side carrier which would prevent the ring gear being installed . It does mystify me why this would be done . Maybe to prevent the assembly line installing two ring gears on the same complete carrier !!! Only kidding .
Will try to post peg pic .

John in same place same weather .
PS Clever son posted peg pics .

[john charlton]

When I said matched pairs I meant machined and bored as a unit not to be mixed with another half carrier . Here the early carriers did not have the "step" where the two halves meet as the later ones do .Even later ones had a hole drilled to help lube the axle gear flanges . I always mark the carrier halves before splitting and mark the spider so it goes back where it came from
the same way up with the same spider gears in the same place on the spider . Probably does not make a blind bit of difference but I do it anyway , makes me feel better !!!

John still in same place with same weather .