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Since the bevel or worm gear rear end of my ’33 836 was totally frozen, I couldn’t move the car without disassembly.
Below is a photo of the rear end center section. To get to this point I had to:
1. Remove brake drums and backing plates, brake levers and cable.
2. Remove rear axle bearing caps (not necessary I found out)
3. Remove rear spring shackles.
4. Remove axle U bolts (I found a source for new ones)
5. Remove all the nuts holding the axle housing trumpets to the center section
6. Either use a slide hammer type puller or lever off the trumpets to remove the axles. They just slide into the housing.
Access to the gears, apparently, can only be reached from the left side of the housing. There is a 1/4″ plate that has to be removed next. Be sure to match mark everything before disassembly.”
This piece is the bearing cup retainer for the bevel gear bearings.
In typical Pierce precision, you will notice castellations around the bearing opening and on the plate below. The inner set look to be attached to a ring that screws in to preload the bearing as best I can figure. There is a dog that has a pin that fits between the castellations on the beating retainer and it then has two pins that mesh with the lower track.
This fixes the preload and the plate is held in place with 2 bolts that are safety wired.
Here is the locking tab.
This is the last post for now. I have stuff soaking in 50/50% ATF/Acetone before I can go any further.
Good stuff Bill-thanks for posting this unique adventure. Keep us ‘posted’
Best-John
John,
Thanks for the encouragement. Just hope my patience holds out.
A Virginian in exile.
Bill
Good pics and great descriptions with them.
Stuff like this would be great for a FAQ or How To section of the website.
Good Job!
The best thing to do for P-A posterity is to write this up with the pics and send it off to Arnold Romberg for the Pierce-Arrow Service Bulletin.
It is certainly worthy of publication and then it will always be available for review.
BTW, the Supervising Foreman of the rear-end assembly factory at the PAMCC was a guy named Joseph Waldorf, my Uncle’s Uncle, and the first family owner of my 1925 Series 80.
They did an outstanding job of creating Pierce-Arrow cars.
Ok, the heat and 50%/50% Trans fluid and acetone did its job and I was able to remove the bearing adjustment ring on the left side. After looking at it, I think it is also used to center the bull gear relative to the worm gear (right to left adjustment).
I had to come up with a tool to remove the ring and came up with this setup. A piece of steel channel with a 1/2 hole drilled in it (could be bigger) which I loosely attached with a threaded rod with a nut and washer on the one side and a nut to hold it on on the other. I hammered on the end of the channel to loosen the ring.
Here is a photo of the ring and tool apart. I think that Pierce might have sourced this axle from Timken as the words Timken are cast into it.
To clarify, I passed the threaded rod with a nut and washer from the right side of the diff thru to the other side, thru the channel and then held on with another nut.
Now on to the other side.
Here is the Worm Gear.
Couple of dismantling suggestions based on what I ran into. There may be an easier way, but it escaped me.
1. Before you remove the axle from the car, with the car in gear, remove the worm gear adjustment cover on the lower back of the center section. Remove the cotter pin and loosen the large worm gear nut. It helps to provide better resistance as it takes a lot of force to loosen.
2. I took out the Bull gear first. This requires the removal of the carrier bearing cup, or the bearing on the right side of the Bull Gear. The carrier has a lot of side play once you take off the left bearing retainer, but I had to cut the bearing cage tops off with a Dremel/abrasive cutoff wheel and take the rollers out to get enough room to remove the gear.
3. I took the worm out last. It can only be removed to the front where the oil seal is mounted.
Bull Gear
Bad News Pits.
Here is a photo of the worst of the pits. I think they are from setting in the bottom where I think some water must have accumulated. Anyone have a spare or know of a repair shop?
Hi Bill,
I replaced the worm drive in my 836 with a 1934 hypoid assembly a long time ago (factory authorized process), because the bronze worm wheel (what you call the bull gear) was replaced shortly before I got the car with a slightly off-pitch reproduction, and it burned itself up. I still have the entire worm gear assembly (backing-plate flange to backing-plate flange), less axles, and I think (cannot guarantee because I have not taken it apart lately-but it has been in inside storage) that the steel worm shaft is still OK.
Timken made several different ratio worm gear sets (2.78 to 4.57) for Pierce, Nash and Stutz, and my ’33 was 4.29. If yours is also 4.29 (it should be), or 4.43 (the same steel worm shaft is used in both ratios – the setup may be a bit different, but just set it for backlash of 0.010 to 0.018”), I may be able to help.
I also have copies of the original Timken blueprints for both gears (revision date 1971).
A gear-cutting company MAY be able to make a new worm gear from the prints, but to set up for one gear will probably be super expensive, and to accurately make the gear may be a problem (witness Phil Bray’s high-ratio hypoid projects). The shaft was forged, then cut, then hardened in three different zones to minimum Rockwell “B” 72 (soft) on the mounting threads, Rockwell “C” 20-30 (medium) on the splines, and Rockwell “C” 57
minimum (hard) on the worm gear portion.
You are welcome to my whole assembly free of charge if you can arrange for someone to pick it up (I am in CA). I am 70 and do not want to deal with the task of shipping it, or taking it apart again. In the past (15 years ago) I have used Dave’s Transport to reasonably transport large parts to and from different parts of the country, but don’t know if he is still in business. His number was 612-441-3769, but there are many guys that do the same thing.
Your bronze wheel looks pretty good from your picture, but a knowledgeable gear person should inspect it to be sure. And as you probably know, if there is too much wear on the drive side of the teeth, you can flip the gear around, so that the seldom-abused reverse side of the teeth now becomes the forward drive side, extending the life of the gear. You probably also know that you MUST use a non-sulfur-bearing lubricant (not the typical rear end lube), so the bronze wheel does not get attacked. This is the typical failure mode for the gearset – the steel wormshaft is almost always in great shape. It would help if you know the history of lubricants used in your gearset.
Hope this helps. Happy Holidays,
Bob Jacobsen
Bob,
Thank you very much for your “been there, done that” view point. You are very kind to offer the assembly and I will take you up on it. I will get about finding a way to get it picked up from you. I will call you.
I have the opposite problem, my steel gear is pitted and has some spalling and the bronze gear is about perfect. Since the car was last on the road over 60 years ago, I don’t think it has been subjected to sulfur containing lubricants. All the oil was out, so it hasn’t been sitting in any oil. (hence the rusty bearing, non turning problem.)
I am in the process of trying to figure out how to inspect the spider gears. I have removed the rivets and am trying to separate the carrier halves from the bull gear. I have a puller designed, but those Pierce Arrow designers/engineers really like close tolerances.
I have really been interested in the markings on the components. The bronze, bull gear is stamped around the circumference with the following:
4 3/7 (which is 4.29)
C6
W12 (I think, the top is cut off by the inner radius)
29NN40 C
29S45
The outer housing is also marked.
The front of the worm gear housing is stamped A5 and the rear is +1.
The rear of the carrier housing has R2360, 730 and a number I can’t read.
There is also a cryptic stamping that looks like “X926”. but it is an over stamp and it looks like there was a 5 and some other number there before.
Thank you for your help. I know your time is valuable and I appreciate your generosity.
Bill
Hi Bill, take your bull gear, and your worm gear, and place them against each other as they would be in the differential housing.
From the photo, your rust pit is near the end or begining of the worm, And it looks like the worm contacts the bull gear only in the center of the worm.
I’m just ‘estimating’ but it looks like that rust spot would never touch a tooth on the bull gear.
I’d take a look at it either in an approximate postion, or put it loosely back in the diff housing and see where the bull gear and worm gear intersect.
Best of luck.
Greg Long
Greg,
Thanks for the feedback. I agree that the worst pit might have no contact, but there is another, I’ll call it a chip, in the middle of the gear. I have highlighted it in white. I think that it is a game changer. Your thoughts?
Bill
Finally got the bull gear apart. Everything is splined together. What a marvelous piece of engineering/machining, even if it was by Timken not PA
Parts are (from left top clockwise)
1.Bull Gear with opposite side hub bearing/spider gear carrier attached
2.Spider gear/bearing hub carrier. Note the splines on the outer rim
3.Brass thrust washer
4.Driven spider gear hub to axle. In English terms a “splined muff” with a gear attached. The splines from the axle go into this piece.
5.Spyder (for those preferring the alternate spelling) gear assembly.
6. Hardened pin holding the carrier bearing plates to the Bull Gear (
. Must have the head removed, either by grinding, drilling or?? then driven out.
7.Splined axle gear, opposite side from item 4, inverted.
I haven’t found any thing else to dismantle as I took off the wheel bearing retainers when I took off the axle housing halves. Thanks for everyone’s help to get to this point.
Now, can I get it back together? I will start a new thread as Assembly
