The Ford Barn

Dune Country · 01-31-2012, 04:33 PM

I received the ring and pinion and carrier, thanks Brentwood Bob.

in setting the proper backlash the contact is way to the heel (inside) of the ring gear teeth.
I started to shim the pinion in and of course when you do that you have to move the ring gear (and axle) out.

So far I have shimmed the pinion out .060 and it looks like I need to go out another sixty or so, I have ordered some .010 and .020 shims.

I don't see a problem with this although the carrier bearing has .030 under it and will need much more.

Where I see a problem looming is with the axle gasket which now is .135.
I have some heavy gasket material and plan to cut a heavy gasket out of it but moving the axle tube out that far might create a problem at the taper end (hub fit)

I cannot post a picture (slow dial up) but can when I get back to the office.

or am I just being to anal?

Lawrie · 01-31-2012, 04:51 PM

Are you using a ford r&p or a repro one.
I just set up a repo gearset from Snyders for a mate,it only needed the backlash adjustment,no pinion depth adjustment .
Only had .015 total gasket thickness.
are you sure about the pinion depth.
Lawrie

Brentwood Bob · 01-31-2012, 05:09 PM

Are the races seated in the banjo? Bob

Brentwood Bob · 01-31-2012, 05:12 PM

Check the depth of the race seat for the axle housings. The later housing is not as deep. Bob

Dune Country · 01-31-2012, 05:19 PM

R&P are used, pretty sure OEM.
axle tubes are original I think, but will check the races. carrier bearings look great and the pinion bearings and race are new
this is kind of troubling because the R&P and carrier that came out showed wear and galling way out at the toe of the ring gear.

columbiA · 01-31-2012, 08:38 PM

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You should not need that huge amount of shimming.Are you sure you have a matched set of gears?4.11 & 3.78 gears both use a 9 tooth pinion,but the pinions are a slightly different size.Many years ago a friend gave me a ring & pinion to rebuild a rear end & I could not get the gears to mesh properly & I found that I had the wrong pinion for the ring gear.

Tom Endy · 01-31-2012, 09:20 PM

The shimming values you specify have me somewhat confused. In most cases I have never had to put more than a .010 shim under each carrier bearing. I have never had to shim the pinion gear and I have never taken one apart and found a shim there, and the number I have taken apart is well over 300.

There was an article in the Restorer a few years ago where a person rebuilt one rear axle assembly and wrote an article that went into great detail about how he blued the ring & pinion and either added shims under the pinion bearing or machined some material off the pinion sleeve, I forget which way it went. When I read the article my opinion was that none of this was necessary and it would tend to confuse a lot of Model A hobbiest.

Usually the only reason I have to add shims under the carrier bearings is because the old bearings had spun on the mounts because someone put the assembly together with no regard for proper carrier pre-load and probably had the carrier locked up. Henry's 40 horses spun it loose along with the bearings.

Most every assembly I take apart I found the carrier mounts spun. I replace the carrier with one I sent out and had knurled. The machinist usually takes a cut on the bearing stops, hence the need for shims. The trick is to determine how much he took off, so I can add the proper thickness of shim. It is a trial and error effort

The two axle housings should be bolted to the banjo with the carrier inside with out any banjo gaskets. The ring gear should lock up when the bolts are tightened. This tells you that by adding banjo gaskets you can achieve a proper preload. If you cannot, then you have to take it apart and add more shims under the carrier bearings. Once it locks up you add banjo gaskets until the proper pre-load is achieved. You should end up with somewhere between a total gasket thickness (for both sides) of between no less than .020 and no more than around .050

Once you have set the pinion preload by adjusting the two large nuts, bolt everything together with the carrier inside, still without the axles, and check the backlash by turning the drive shaft by hand. You should be able to feel a slight "click" as you turn the shaft in both directions. This is the space between where a tooth on the pinion just taps both sides of the valley of a ring gear tooth. You want to make this check around the full 360 of the ring gear to make sure there is no binding. You increase or decrease the backlash by shifting the total banjo gasket stack from one side to the other.

I would not be concerned about where on the pinion gear a blue pattern showed up. Apparently Henry didn't either, because as I said I have never found a shim on the pinion sleeve. Believe me it will be in the ball park where it work just fine.

Since Brentwood Bob sent you some parts I assume you have the discertation I wrote. If not, go to www.ocmafc.com. On the menu at left click on "tech articles". It will bring up a new menu. At the top is my name, click on it. A new menu will appear. Scroll to the article about differential rebuilding.

Tom Endy

Dune Country · 02-01-2012, 12:11 PM

Thanks for the replys,
I do have your wright up Tom and it has been a lot of help.The many time I have put it back togeather I always shot for 7 to 10 on the backlash. I guess where I got confused was a drawing in Les Andrews book 1-95 showing gear pattern.
Back to square one, how can I tell which pinion I have?

Dune Country · 02-01-2012, 12:57 PM

the pinion has 9-34 stamped on it I assume it is for a 34 tooth ring which I have
thanks again

Tom Endy · 02-01-2012, 02:19 PM

It is best to keep a ring and a pinion together as a set. There is folklore in the Model A hobby that R&P's were matched at the factory. The only way they could have done that would have been to run them together with lapping compound. I doubt they did that. What they did was put matching numbers on them (in most cases).

Quite often you will find a 3 or 4 digit number on the end of the pinion. On the flat side of the ring gear often there will be a corresponding number that has been scrawled on in large numbers with a vibrating tool. I have seen this so often to make me believe it was a factory practice. The numbers on the ring gear are difficult to read. I bead blast all the R&P's I remove from an assembly. By holding the ring at an angle to the light you can see the number.

Most reproduction R&P's on the market today have corresponding numbers stamped into them.

If you try to match up a worn ring with a worn pinion that did not spend their days together you will likely end of with a rear axle assembly that will be very noisy.

A 378 R&P, which is the most common, has 9 teeth on the pinion and 34 teeth on the ring. A 411 has 9 teeth on the pinion, but 37 on the ring. The two pinions, though they both have 9 teeth, are not the same dimension. You do not want to mismatch these two pinions. Often you will see 9-34 stamped on both the ring and the pinion.

I once put a rear axle assembly together with an R&P I picked up at a swap meet. The seller assured me they came out of the same rear axle assembly. I could not find matching numbers on them. When I had the project complete just rotating the drive shaft with a socket wrench told me this was a very noisy rear axle assembly. I had to tear it down again and replace the R&P with a known matched set.

Tom Endy

01-31-2012, 04:33 PM	#1
Dune Country Member Join Date: Sep 2011 Location: Winchester Bay OR Posts: 93	Setting up a diff I received the ring and pinion and carrier, thanks Brentwood Bob. in setting the proper backlash the contact is way to the heel (inside) of the ring gear teeth. I started to shim the pinion in and of course when you do that you have to move the ring gear (and axle) out. So far I have shimmed the pinion out .060 and it looks like I need to go out another sixty or so, I have ordered some .010 and .020 shims. I don't see a problem with this although the carrier bearing has .030 under it and will need much more. Where I see a problem looming is with the axle gasket which now is .135. I have some heavy gasket material and plan to cut a heavy gasket out of it but moving the axle tube out that far might create a problem at the taper end (hub fit) I cannot post a picture (slow dial up) but can when I get back to the office. or am I just being to anal?

01-31-2012, 04:51 PM	#2
Lawrie Senior Member Join Date: May 2010 Location: Qld, Australia Posts: 4,529	Re: Setting up a diff Are you using a ford r&p or a repro one. I just set up a repo gearset from Snyders for a mate,it only needed the backlash adjustment,no pinion depth adjustment . Only had .015 total gasket thickness. are you sure about the pinion depth. Lawrie

01-31-2012, 05:09 PM	#3
Brentwood Bob Senior Member Join Date: May 2010 Location: brentwood, ca Posts: 4,420	Re: Setting up a diff Are the races seated in the banjo? Bob

01-31-2012, 05:12 PM	#4
Brentwood Bob Senior Member Join Date: May 2010 Location: brentwood, ca Posts: 4,420	Re: Setting up a diff Check the depth of the race seat for the axle housings. The later housing is not as deep. Bob

01-31-2012, 05:19 PM	#5
Dune Country Member Join Date: Sep 2011 Location: Winchester Bay OR Posts: 93	Re: Setting up a diff R&P are used, pretty sure OEM. axle tubes are original I think, but will check the races. carrier bearings look great and the pinion bearings and race are new this is kind of troubling because the R&P and carrier that came out showed wear and galling way out at the toe of the ring gear.

01-31-2012, 08:38 PM	#6
columbiA Senior Member Join Date: Nov 2011 Location: B.C. Canada Posts: 1,746	Re: Setting up a diff Sponsored Links (Register now to hide all advertisements) You should not need that huge amount of shimming.Are you sure you have a matched set of gears?4.11 & 3.78 gears both use a 9 tooth pinion,but the pinions are a slightly different size.Many years ago a friend gave me a ring & pinion to rebuild a rear end & I could not get the gears to mesh properly & I found that I had the wrong pinion for the ring gear.

01-31-2012, 09:20 PM	#7
Tom Endy Senior Member Join Date: May 2010 Location: Southern California Posts: 3,168	Re: Setting up a diff The shimming values you specify have me somewhat confused. In most cases I have never had to put more than a .010 shim under each carrier bearing. I have never had to shim the pinion gear and I have never taken one apart and found a shim there, and the number I have taken apart is well over 300. There was an article in the Restorer a few years ago where a person rebuilt one rear axle assembly and wrote an article that went into great detail about how he blued the ring & pinion and either added shims under the pinion bearing or machined some material off the pinion sleeve, I forget which way it went. When I read the article my opinion was that none of this was necessary and it would tend to confuse a lot of Model A hobbiest. Usually the only reason I have to add shims under the carrier bearings is because the old bearings had spun on the mounts because someone put the assembly together with no regard for proper carrier pre-load and probably had the carrier locked up. Henry's 40 horses spun it loose along with the bearings. Most every assembly I take apart I found the carrier mounts spun. I replace the carrier with one I sent out and had knurled. The machinist usually takes a cut on the bearing stops, hence the need for shims. The trick is to determine how much he took off, so I can add the proper thickness of shim. It is a trial and error effort The two axle housings should be bolted to the banjo with the carrier inside with out any banjo gaskets. The ring gear should lock up when the bolts are tightened. This tells you that by adding banjo gaskets you can achieve a proper preload. If you cannot, then you have to take it apart and add more shims under the carrier bearings. Once it locks up you add banjo gaskets until the proper pre-load is achieved. You should end up with somewhere between a total gasket thickness (for both sides) of between no less than .020 and no more than around .050 Once you have set the pinion preload by adjusting the two large nuts, bolt everything together with the carrier inside, still without the axles, and check the backlash by turning the drive shaft by hand. You should be able to feel a slight "click" as you turn the shaft in both directions. This is the space between where a tooth on the pinion just taps both sides of the valley of a ring gear tooth. You want to make this check around the full 360 of the ring gear to make sure there is no binding. You increase or decrease the backlash by shifting the total banjo gasket stack from one side to the other. I would not be concerned about where on the pinion gear a blue pattern showed up. Apparently Henry didn't either, because as I said I have never found a shim on the pinion sleeve. Believe me it will be in the ball park where it work just fine. Since Brentwood Bob sent you some parts I assume you have the discertation I wrote. If not, go to www.ocmafc.com. On the menu at left click on "tech articles". It will bring up a new menu. At the top is my name, click on it. A new menu will appear. Scroll to the article about differential rebuilding. Tom Endy

02-01-2012, 12:11 PM	#8
Dune Country Member Join Date: Sep 2011 Location: Winchester Bay OR Posts: 93	Re: Setting up a diff Thanks for the replys, I do have your wright up Tom and it has been a lot of help.The many time I have put it back togeather I always shot for 7 to 10 on the backlash. I guess where I got confused was a drawing in Les Andrews book 1-95 showing gear pattern. Back to square one, how can I tell which pinion I have?

02-01-2012, 12:57 PM	#9
Dune Country Member Join Date: Sep 2011 Location: Winchester Bay OR Posts: 93	Re: Setting up a diff the pinion has 9-34 stamped on it I assume it is for a 34 tooth ring which I have thanks again

02-01-2012, 02:19 PM	#10
Tom Endy Senior Member Join Date: May 2010 Location: Southern California Posts: 3,168	Re: Setting up a diff It is best to keep a ring and a pinion together as a set. There is folklore in the Model A hobby that R&P's were matched at the factory. The only way they could have done that would have been to run them together with lapping compound. I doubt they did that. What they did was put matching numbers on them (in most cases). Quite often you will find a 3 or 4 digit number on the end of the pinion. On the flat side of the ring gear often there will be a corresponding number that has been scrawled on in large numbers with a vibrating tool. I have seen this so often to make me believe it was a factory practice. The numbers on the ring gear are difficult to read. I bead blast all the R&P's I remove from an assembly. By holding the ring at an angle to the light you can see the number. Most reproduction R&P's on the market today have corresponding numbers stamped into them. If you try to match up a worn ring with a worn pinion that did not spend their days together you will likely end of with a rear axle assembly that will be very noisy. A 378 R&P, which is the most common, has 9 teeth on the pinion and 34 teeth on the ring. A 411 has 9 teeth on the pinion, but 37 on the ring. The two pinions, though they both have 9 teeth, are not the same dimension. You do not want to mismatch these two pinions. Often you will see 9-34 stamped on both the ring and the pinion. I once put a rear axle assembly together with an R&P I picked up at a swap meet. The seller assured me they came out of the same rear axle assembly. I could not find matching numbers on them. When I had the project complete just rotating the drive shaft with a socket wrench told me this was a very noisy rear axle assembly. I had to tear it down again and replace the R&P with a known matched set. Tom Endy