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Old 09-05-2016, 04:32 PM   #21
Dave in MN
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Default Re: Move Pinion forward and back per Les Andrews

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Originally Posted by Ed Saniewski View Post
Dave, any chance someone recorded the work session and could post it on youtube? A class like that would be wonderful to share with us. Thanks, Ed Saniewski
The clinic was filmed by one of the attendees but the editing is not yet completed. He recorded it for our Club library. If it is good enough to put out there...we would.
Good Day!

Last edited by Dave in MN; 09-06-2016 at 08:59 AM.
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Old 09-05-2016, 05:34 PM   #22
Dave in MN
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Default Re: Move Pinion forward and back per Les Andrews

[QUOTE=Tom Endy;1348631]The only way you can move the pinion forward or back is to either take a cut on the bearing stop on the pinion or add shims. I don't believe any of this is necessary. I have never found shims on a pinion and I have had a great many apart.

Once the pre-load is set on the carrier and pinion bearings a backlash adjustment is made by shifting the banjo gasket left\right. This moves the ring gear either closer or farther away from the pinion. The pinion is straight down the center line of the car and you cannot shift it left\right.


Tom,
Please consider the following:

I agree with you in that I also see no need to ever make a cut on the bearing stop of the pinion gear. I, like you, have never seen one too tight or with too little backlash.

I disagree with you that it is never necessary to shim the pinion. As you can see from the photo in my original post (#14), when studying the contact pattern with white lithium grease, the contact pattern was not even close to satisfactory. This condition was caused by excessive clearance between the pinion gear and the ring gear and that equates to excessive backlash. This photo was taken with all but one gasket moved to the other side in an effort to lessen the backlash.
I agree that it is obvious that the centerline of the pinion gear can not be changed from left to right by adding shims to the pinion but since the pinion gear has a basic cone shape, moving it towards the rear, with a shim, will decrease the clearance between the pinion and the ring gear. Just as important, moving the pinion back may better center the contact pattern of the gears.

When I was rebuilding the rear end assembly for my touring car, I contacted the manufacturer of the gearset because just shifting gaskets was far from what was needed to obtain a good contact pattern and backlash. The first thing he asked me was, "Did you visually center the pinion gear on the ring gear?" He also said: "The only way to obtain proper meshing is to complete this step and that will require shimming the pinion gear." Now remember, he was specifically talking about the gearset he manufactured. After installing and adjusting the thickness of the shim at the pinion, everything came together almost perfectly. Now remember, this gearset is a 4:11 and is likely a ratio not many people purchase new and install. The other ratio gearsets may be manufactured differently and may not require shimming to obtain an acceptable backlash.

I know you consider the backlash adjustment "the least critical of all the adjustments" and in your restoration guidelines state that: "Generally you may end up with more backlash than you want. This is usually due to the wear in a used ring & pinion gearset, and it cannot be avoided." I'm just proposing that it is possible to obtain a very good tooth contact pattern with no excessive backlash if the extra step is taken to shim the pinion when warranted. IMO: A worn/used gearset may warrant shimming the pinion.

Installing and adjusting the thickness of the shims between the pinion gear bearing stop and the pressed on taper bearing takes extra assembly time. I pressed the rear bearing on and off several times, each time adjusting the thickness of the shim, to obtain the proper mesh and backlash. It is not hard and like the rest of the rebuilding process just tedious.

By the way Tom, Thank you for your very detailed and well written Model A Ford Rear Axle Assembly Restoration (2014 Revision) Technical guideline. I used it as a manual for the differential clinics I hosted this past winter. I printed it in whole for each attendee to refer to during the clinic and to take with them.
Good Day!

Last edited by Dave in MN; 09-08-2016 at 08:42 AM.
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Old 09-05-2016, 08:46 PM   #23
Al 29Tudor
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Default Re: Move Pinion forward and back per Les Andrews

Thank you all very much.
I hope to get into the carrier this week to evaluate things inside. The outside of the carrier looks like something came loose in the banjo in the past because it is very banged up. This car was never driven by the present owner but came to him from his grand father. There are no chips or debris so it is a running unit.
I'll try to get some pictures to keep you posted.
Thanks again,
Al Leach
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Old 04-15-2018, 06:23 PM   #24
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Default Re: Move Pinion forward and back per Les Andrews

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Originally Posted by Dave in MN View Post
The clinic was filmed by one of the attendees but the editing is not yet completed. He recorded it for our Club library. If it is good enough to put out there...we would.
Good Day!
Dave, I know our Club (Rock-Ford-A's IL) would be interested in your recording, seeing the process of a rebuild and adjustment helps take the guess out of the work. No matter what the quality is it would be better then no video! We have had two members within a year that have had to do this repair. We always have lots of helping hands ideas/opinions, a video would be a huge help. This is a tough repair that most of us would have a hard time handling, seeing the tools, and the process of the adjustments would be a great help. Hope your Club will consider making the video available.
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Old 04-16-2018, 08:02 AM   #25
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Default Re: Move Pinion forward and back per Les Andrews

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Both articles by Tom and Les are very good. I do have a disagreement with Les when his book says to bolt both axle housing halves together to get a preliminary pre-load check. (or words to that effect). Bolting the halves together without shims (gaskets) can bend the housings and result in leaks. I recommend bolting the left housing on,(I use only 4 bolts at this ( time) place the assembly on end and slip the right side on. Now measure the gap between the housing and the center section. This will tell you how many gaskets to use. Now install half that thickness on both sides and check backlash. This is time consuming but worth the effort. Just my opinion!
Yes, and that process can ruin cups and cones if squeezed too hard. They end up looking like a pinion bearing that had the preload set with a rattle wrench.
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Old 04-16-2018, 08:59 AM   #26
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Default Re: Move Pinion forward and back per Les Andrews

I put the shim under the cup in the housing because we have the tool to remove it and because so many carriers are marginal re fit of bearing in the first place. I have found that we having more carriers with spun or close to spun bearings so do not want to be pulling the tapered bearing on and off any more then necessary. While there are maybe a lot of carriers out there, does not mean that they are usable. If the spider gear wear area is bad or the bearing just drops on they are toast. Sometimes they can be saved, but not all the time.
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Old 04-16-2018, 05:16 PM   #27
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Default Re: Move Pinion forward and back per Les Andrews

Dave in MN: We are rebuilding a rear end right now and have established a nice carrier bearing preload with a .010" gasket on each side of the banjo. But....there is a lot of pinion to ring gear back lash, maybe .070" or so, and no where to go on banjo gaskets. So tomorrow we are going to experiment with shimming the pinion and see what happens.
Thanks for the tip!!
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Old 04-16-2018, 07:24 PM   #28
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Default Re: Move Pinion forward and back per Les Andrews

Shiming the pinion will move it out and away from the teeth not closer. Try thinner gaskets. You can get thinner ones in the set. You would have to reset the preload. You might even have to use shim under the cup or bearing on the carrier. If you shim the carrier bearing/cup you can move it over. How are you checking you clearance? The way I check is with a dial micrometer, everything assembled except the T tube and take a reading off the pinion nut.
YOU DO NOT HAVE TO STICK WITH .010 ON EACH SIDE.
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Old 04-16-2018, 08:06 PM   #29
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Default Re: Move Pinion forward and back per Les Andrews

Starting with Timken bearings can give better results. I found that out from the last rear axle and differential I rebuilt.
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Old 04-16-2018, 08:26 PM   #30
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Default Re: Move Pinion forward and back per Les Andrews

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Originally Posted by Mike Peters View Post
Dave in MN: We are rebuilding a rear end right now and have established a nice carrier bearing preload with a .010" gasket on each side of the banjo. But....there is a lot of pinion to ring gear back lash, maybe .070" or so, and no where to go on banjo gaskets. So tomorrow we are going to experiment with shimming the pinion and see what happens.
Thanks for the tip!!

In order to reduce the backlash you need to move the pinion gear closer to the ring gear. The pinion gear is attached to the drive shaft and is located dead center of the car. You cannot move it, but you can move the ring gear. To do this you need to remove the carrier bearings and put a shim under each. This will require the addition of more banjo gaskets in order to re-establish the carrier pre-load. The additional gaskets will give you a latitude to shift the ring gear closer to the pinion gear.


Tom Endy

Last edited by Tom Endy; 04-17-2018 at 02:04 AM.
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Old 04-17-2018, 06:11 AM   #31
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Default Re: Move Pinion forward and back per Les Andrews

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Originally Posted by Tom Endy View Post
In order to reduce the backlash you need to move the pinion gear closer to the ring gear. The pinion gear is attached to the drive shaft and is located dead center of the car. You cannot move it, but you can move the ring gear. To do this you need to remove the carrier bearings and put a shim under each. This will require the addition of more banjo gaskets in order to re-establish the carrier pre-load. The additional gaskets will give you a latitude to shift the ring gear closer to the pinion gear.


Tom Endy

Tom,
Moving the pinion gear back also decreases the space between the meshing gears thus reduces backlash. The always dead center pinion gear is cone shaped, smaller at the rear...larger at the front, moving it rearward causes an area of the gear that has a larger circumference to mesh with the ring gear thus reducing clearance between the two rotating parts.

My previously described process of shimming the pinion gear to reduce the backlash is derived directly from information provided by the manufacturer of the gearset. The manufacturer of the gearset stated it was necessary to shim the pinion to get it centered with the ring gear. (See the description below that explains what "centering the pinion" means.) I followed his instructions and ended up with proper backlash, proper contact pattern and a rear end assembly that dosen't leak, whine or clunk when shifted. Following his instructions worked for me.


Back story: After following your (Tom Endy's) Rear End Assembly Tech Article to the letter, I found I had an unacceptable amount of backlash. I called Steve Becker at Bert's who sold me the 4:11 gear set. He politely offered to replace it with a set of NOS gears. I declined and asked him to provide me the name of the manufacturer. I knew that if I was having a problem, others using this same gear set would too...I wanted to make the manufacturer aware there was a problem with their gear set.

When I called the manufacturer and explained I had set up the assembly with the proper pre-loads and had adjusted the ring gear as close to the pinion as possible and had excessive backlash, the first question he asked me was: "Did you center the pinion gear on the ring gear?" I said: What?
He then said: "The pinion gear should have an equal margin of tooth protruding beyond the front and rear of the ring gear when it is properly centered. (He described a centered pinion as the condition where the pinion gear is properly aligned forward to rear (centered) with the ring gear.)
The production manager then politely explained to me the process of centering the pinion to the ring gear (moving it back) by placing shims between the pinion and the tapered bearing closest to the pinion gear.

When I took the assembly apart to inspect the centering, I could see that the pinion gear was too far forward to call it centered. I machined a shim to a thickness that was more than I needed and test fit it. Too tight...Now I had no backlash...I took it apart and machined the shim thinner. I over shot with my machining but corrected my error by adding a .005" Differential Gear Case to Bearing Shim to my machined shim to provide for proper centering and the proper backlash.

Since building up the above described assembly for my touring car, I have built 11 rear end assemblies for customers cars. I have found it beneficial to shim the pinion bearing on only two 2 of the assemblies. It appears it is not all that common a need to shim the pinion but when it is necessary, because of too much backlash, it is the solution if you cannot shift any more housing gaskets. I no longer machine shims...it is much easier to stack the number of .005" Differential Gear Case to Bearing Shims necessary to achieve proper clearances.

"And now you know the rest of the story... Good Day"

Last edited by Dave in MN; 04-18-2018 at 11:00 AM.
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Old 04-17-2018, 10:19 AM   #32
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Default Re: Move Pinion forward and back per Les Andrews

Update: I ground the inside tab off a pinion thrust washer and shimmed the rear pinion bearing with it. It's pretty thick. Reassembled the axle housing. Backlash disappeared, but it binds a little bit in one spot when I rotate the driveshaft around the entire ring gear. So now hunting for a thinner shim. Dave is correct in saying that the pinion gear is cone shaped, so shimming the pinion to the rear DOES reduce back lash between the ring and pinion. A larger question is: Is this the best way to adjust backlash? Tom Endy may still be correct in adjusting backlash strictly with banjo gaskets and carrier shims. It can be done either way, but Tom's method keeps the pinion centered on the ring gear. I will defer to the experts on this question.
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Old 04-17-2018, 11:16 AM   #33
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Default Re: Move Pinion forward and back per Les Andrews

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Originally Posted by Mike Peters View Post
Update: I ground the inside tab off a pinion thrust washer and shimmed the rear pinion bearing with it. It's pretty thick. Reassembled the axle housing. Backlash disappeared, but it binds a little bit in one spot when I rotate the driveshaft around the entire ring gear. So now hunting for a thinner shim. Dave is correct in saying that the pinion gear is cone shaped, so shimming the pinion to the rear DOES reduce back lash between the ring and pinion. A larger question is: Is this the best way to adjust backlash? Tom Endy may still be correct in adjusting backlash strictly with banjo gaskets and carrier shims. It can be done either way, but Tom's method keeps the pinion centered on the ring gear. I will defer to the experts on this question.
I also used a thrust washer to start with as a test. I also found it too thick.
Snyder's sells shims that will stack to your needed dimension. Order part A-4221-SH. Each shim is .005". Measure the thickness of your fabricated washer (it should measure between .060" and .067") and order shims to result in about .01" less. You will likely need 10 shims. You will find it works well. As you have verified, the designed and machined shape of the pinion gear allows it to be moved forward or back as necessary to "fine" tune the fit. BTW: I do not suggest shimming the pinion if the proper lash can be achieved by shifting the housing gaskets.
Thanks for reporting back.
Good Day!

Last edited by Dave in MN; 04-18-2018 at 11:01 AM.
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Old 04-17-2018, 01:59 PM   #34
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Default Re: Move Pinion forward and back per Les Andrews

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Originally Posted by Mike Peters View Post
Update: I ground the inside tab off a pinion thrust washer and shimmed the rear pinion bearing with it. It's pretty thick. Reassembled the axle housing. Backlash disappeared, but it binds a little bit in one spot when I rotate the driveshaft around the entire ring gear. So now hunting for a thinner shim. Dave is correct in saying that the pinion gear is cone shaped, so shimming the pinion to the rear DOES reduce back lash between the ring and pinion. A larger question is: Is this the best way to adjust backlash? Tom Endy may still be correct in adjusting backlash strictly with banjo gaskets and carrier shims. It can be done either way, but Tom's method keeps the pinion centered on the ring gear. I will defer to the experts on this question.
Tom Endy is an expert.
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Old 04-17-2018, 02:07 PM   #35
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Default Re: Move Pinion forward and back per Les Andrews

I disassembled a differential a couple years ago and the pinion bearing was a combination of two carrier/pinion cones, two carrier cups with a stack of two rear axel bearing retainer rings between the two cups. The pattern was great, I don't know who or when but it is still going strong.
If it ain't broke_____________---.
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Old 04-17-2018, 05:41 PM   #36
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Default Re: Move Pinion forward and back per Les Andrews

The shims sold by Snyders are for under the bearing on the carrier, at least the ones I have seen in the catalog. The outside diameter would be too small. I have resorted to making my own when shimming the carrier race in the axle housing. You would need to make your own to shim the double race in the housing, it has the same outer diameter as the races in the axle housing.
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Old 04-17-2018, 09:31 PM   #37
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Default Re: Move Pinion forward and back per Les Andrews

I have disassembled literally hundreds of Model A rear axle assemblies in the last 30 years and I have never found a shim under the rear bearing on the pinion gear.


If it is necessary to move the pinion gear in one direction it would seem that sometimes it would be necessary to move it in the opposite direction. In that case you would have to take a cut on the bearing stop on the pinion gear to achieve that.


To the best of my knowledge I have never encountered that either.


A number of years ago an article appeared in the Restorer where the author rebuilt "one" rear axle assembly and was convinced by another Model A enthusiast who lived in another state that it was necessary to "blue" the ring & pinion and center it. They shipped the pinion gear back and forth several times where the guy in the other state took a number of cuts on the pinion gear before they were satisfied it was centered. I don't believe any of this is necessary. All the article did was confuse a lot of people.


I can rebuild a Model A rear end and achieve proper carrier pre-load, pinion pre-load, and Ring & Pinion backlash with banjo-gaskets and if necessary shims under the carrier bearings. I have never had to resort to moving the pinion gear in a fore or aft direction using pinion gear bearing shims or taking a cut on the pinion gear bearing stop.


I don't think it is that critical that the pinion gear be perfectly centered on the ring gear. There is plenty of latitude in the design.


The only machining I have had to do on a reproduction pinion gear is machine the surface where the forward bearing resides. The originals have two dimensions The rear bearing should press on with an interference fit. The front bearing should be able to be moved to set pre-load. If it goes on tight you will have a devil of a time setting the pre-load. The difference in the two surfaces should be about .0015".


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