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Move Pinion forward and back per Les Andrews Hi Gents,
We are in the middle of dis-assembling a 1928 differential. In Les Andrews red book, page 1-95 picture in lower right hand corner he shows two gear teeth with wear patterns and text says, "move pinion forward" and "move pinion back" I don't think there is any adjustment for pinion other than Preload. Am I missing something. Thanks for your help. Al Leach, Venice, FL |
Re: Move Pinion forward and back per Les Andrews 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. Suggestion: Got to the web site of the Santa Anita A's of Arcadia, California at www.santaanitaas.org . Put your cursor on "Technical Reference" , my name will drop down below. Click on it and it will bring up a menu of technical articles. Scroll to the three on differentials. You can download them. This may be of help. Tom Endy |
Re: Move Pinion forward and back per Les Andrews Thank you Tom.
Sent you a PM earlier. Yes, I didn't see any provision for adjustment of the pinion other than pre-load. Your tutorial from earlier this year on the 1928 differential has been really an excellent guide for our project. I'm setting up a step by step list of everything to do with a check box so we don't miss anything. Thank you again. Al Leach |
Re: Move Pinion forward and back per Les Andrews Quote:
You need the 2014 tutorial, it is pretty much a check list. Tom Endy |
Re: Move Pinion forward and back per Les Andrews OK Tom, I'll get it
Thanks again. Al |
Re: Move Pinion forward and back per Les Andrews Remember, as to the ring gear tooth contact area, you try to get a PEANUT shaped area, CENTERED on the ring gear TOOTH!
Bill W. |
Re: Move Pinion forward and back per Les Andrews Thank you Bill.
We will try to get that pattern. Tomorrow we will install another members engine and then get back to the rear-end project full time. (well full time ???) Al |
Re: Move Pinion forward and back per Les Andrews 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!
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Re: Move Pinion forward and back per Les Andrews Seems to me the depth of the pocket for the pinion double cup was changed at the same time the gusset was added. either on vince's or marco's site for the drawing...
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Re: Move Pinion forward and back per Les Andrews Jim,
I think Les starts with an equal number of shims on each side and reduces from there. Your comment explains why - so the housings are not distorted. Thanks. Al |
Re: Move Pinion forward and back per Les Andrews Quote:
My technique is to bolt the right axle housing to the right side of the banjo with no gaskets and torque the bolts down to 35 ft. lbs. With the carrier assembly installed I add two .010 gaskets to the left side of the banjo and attached the left axle housing and begin pulling all the bolts down toward 35 ft. lbs. stopping periodically to check that I can turn the ring gear with my finger by reaching in through the torque tube flange on the banjo. If I feel it getting too tight I stop and add one or more gaskets. In this manner no strain is put on any of the hardware. Two .010 gaskets is the least amount of gaskets I want to end up with. Anything less and there is liable to be an oil leak. Tom Endy |
Re: Move Pinion forward and back per Les Andrews I'm putting this out there to see if I understand the procedures.
1. Carrier pre-load. Assemble and install carrier, no spider or axles, bolt up both axle housings. Add spacers under carrier bearing races in axle housings until carrier won't turn. (Is it ever necessary to shim the races?) 2. Bolt up banjo and right axle housing and set in carrier. Add minimum of two .010 gaskets, then bolt up left axle housing, maybe more gaskets, until carrier turns snugly, making sure I never bind up or distort the axle housings. 3. Now divide the gaskets 1/2 on each side and proceed to pinion and ring gear pattern and backlash. Always keeping the same gasket stack and locating the gaskets to either side as required to achieve proper wear pattern and backlash. Please correct me or confirm I got it right. Thank you Tom and Jim for your time and patience. Al |
Re: Move Pinion forward and back per Les Andrews Tom,
[1. Carrier pre-load. Assemble and install carrier, no spider or axles, bolt up both axle housings. Add spacers under carrier bearing races in axle housings until carrier won't turn. (Is it ever necessary to shim the races?)] Page 34 of your 2014 dissertation answers this question and states any shims required can go under the bearing - easier than the race in the axle housing. Next get a handle on the yoke. Wow! Al Leach |
Let's consider shimming the pinion gear 3 Attachment(s)
Sorry, I have not read Les Andrews section in his book about shimming the pinion. I am offering the following from a recent experience regarding the ill fit of a new 4:11 gearset.
Last year, early in the driving season, I lost a tooth on my 4:11 gearset when the double nuts on the pinion gear loosened. I ordered a replacement 4:11 set and installed it using Tom Endy's very detailed write-up. Upon completion and with the maximum number of gaskets shifted to lessen the backlash between the pinion gear and the ring gear, I still had an excessive amount of backlash in the neighborhood of .070". Not being satisfied with this amount, I contacted Steve Becker at Bert's who gave me the name and contact info of the manufacturer of the gearset. The manufacturer coached me on the procedure of centering the pinion gear to the ring gear prior to starting the assembly procedure. I determined I needed and then machined a shim that was .067" to place between the pinion gear and the first tapered bearing. With this shim in place and again using Tom Endy's procedure, I was able to obtain about .005" backlash with adequate but not excessive gaskets to provide a good seal to the components. The assembled rear end is very quiet and took us to Loveland and back this summer. Because of the difficulty I had with acheiving proper backlash in my own rearend assembly, I decided to put on a differential rebuilding clinic at my workshop. There were about 20 local club members in attendance for each session. I held one session where we took two assemblies apart and evaluated their condition and developed a list of repairs to complete and components to purchase for restoration. After the components were repaired and new parts purchased, I hosted two additional Saturday sessions where we assembled the differentials. One assembly needed shims at the pinion gear to get the backlash exactly where we wanted it. The other assembly did not require any shims. It is often said or assumed you can only get the backlash as good as the shifting of gaskets will allow. This statement is true if you don't try adding shims between the pinion gear and the first or rear tapered bearing you press on to the pinion. The bearing shims sold in .005" thickness for shimming the carrier races can be used between the pinion gear and the rear bearing that is pressed on to the pinion. They fit the components perfectly. During the clinic I hosted, we did use 7 of these shims to obtain the proper pinion gear centering on one differential. An interesting side to all of this was that when the pinion was properly centered and the backlash was correct, we had a good contact pattern when checking the assembled components with yellow bearing grease laced with yellow pigment. The first photo (white lithium grease) shows the contact pattern before shimming the pinion gear. It has a bad pattern with the pinion gear teeth riding over the edge or crest of the ring gear teeth. This state would not last long. This contact pattern was the best I could achieve by just shifting gaskets at the pumpkin. Excessive backlash was very evident in this case. This was a new 4:11 gearset. The next two photos show a more centered engagement on both the thrust and coast side of the 4:11 ring gear. This pattern was achieved with shims (.067") at the pinion as described above. The backlash was about .005". Good Day! |
Re: Move Pinion forward and back per Les Andrews |
Re: Move Pinion forward and back per Les Andrews Thank you Dave,
That's great information and I have filed it for our project. Our banjo is cracked at four tube mounting holes/bosses so a new banjo may require shimming. Thank you again, Al Leach |
Re: Move Pinion forward and back per Les Andrews 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
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Re: Move Pinion forward and back per Les Andrews I find it very rare to need shims under the bearings when using all factory parts. The only time I've had to shim was when setting up an early Halibrand quick-change diff.
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Re: Move Pinion forward and back per Les Andrews Quote:
Al, Like Tom I have done many rear axles... our only difference is I go ahead and split the .020 thickness and mount a .010 gasket on each side as a starting point.And adjust add subtract, change left to right as needed for proper gear contact and preload. dab 4 small points of rtv at equal places to hold the gaskets and then see where things fall. A agree with Tom that I have never had to shim or adjust the Pinion bearing/race by shimming it. Your tooth contact is dictated fine by the preload and shim of the carrier bearings by the various gasket thicknesses. Once correct gasket thickness is determined seal well with a skim of rtv including a little on the threads ( especially lower half) of carrier bolts to ensure that there is no leakage there. Good luck! Larry Shepard |
Re: Move Pinion forward and back per Les Andrews Quote:
The reason for my post and hosting an in-shop clinic was to get the info out there that an almost perfect fit can be obtained by shimming the pinion gear. Good Day! |
Re: Move Pinion forward and back per Les Andrews Quote:
Good Day! |
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! |
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 |
Re: Move Pinion forward and back per Les Andrews Quote:
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Re: Move Pinion forward and back per Les Andrews Quote:
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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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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!! |
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. |
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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Re: Move Pinion forward and back per Les Andrews Quote:
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 |
Re: Move Pinion forward and back per Les Andrews Quote:
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" |
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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Re: Move Pinion forward and back per Les Andrews Quote:
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! |
Re: Move Pinion forward and back per Les Andrews Quote:
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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_____________---. |
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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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". Tom Endy |
Re: Move Pinion forward and back per Les Andrews I cannot figure out how to accurately measure backlash. Before, I was using the driveshaft movement compared to axle movement, but there's looseness due to the spider gears that makes it appear there's more backlash than there actually is. I've read in Tom Endy's publications that you're supposed to measure backlash with the axles out of the housing, which makes sense, but if the axle tubes and pinion are mounted on the banjo, since everything is closed up, you can't see in there -- so, how is it possible to see movement between the ring and the pinion gears? Thanks.
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Re: Move Pinion forward and back per Les Andrews If you have the required preload on the carrier, any backlash between the pinion and the ring gear can be felt when turning the pinion assembly clockwise and counterclockwise.
If you are not feeling it, you may not have any backlash. Good Day! Dave in MN |
Re: Move Pinion forward and back per Les Andrews I bolt a dial gauge to the housing with the driveshaft tube off and take a reading off one of the corners of the pinion nut. Get you real close.
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