Diagnose and repair a failed driveline: 1928 Standard 28-20

[28Buick]

I fixed a rusty vacuum tank and fixed an overheating issue and mistakenly thought I could sort out the tuning next and enjoy the drive. After a short trip and stop at my garage, I shifted to first and heard a ping, not loud or alarming, just a mild metallic snap. Now I have no movement in any gear at any engine speed. I was fortunate this happened in my driveway where I rigged a long rope tow to drag the Buick onto a four post lift.

 

Engaging the clutch in any gear has no effect, the car remains stationary. I think something broke between the transmission and the wheels, so I ask for advice on what to do next. When I put the car in 2nd or 3rd gear and release the clutch the speedometer shows speed. I assume the motor is turning the gears and assume the clutch is working. I can drop the flywheel cover but I don't think that will reveal anything. What do you think about opening the differential or spinning the rear wheels to locate the problem? Are there access points? What parts do you suspect that are prone to possible failure? Any opinions are most welcome.

[Edwin The Kid]

Sounds like it might be a snapped axle shaft, or some other rear axle failure. Jacking the rear end and spinning the wheels to check the differential action would be easy. 

[raydurr]

If speedometer works then you have power to the front half of the u joint. Easiest thing to remove would be the differential cover. See if pinion gear turns when running. If not then power loss is between the u joint and pinion. If pinion turns ring gear then spider gears, spider gear cross shaft, axle gears, axle shaft, axle shaft key way or rear axle hub has failed. 

Edited September 28, 2023 by raydurr (see edit history)

[28Buick]

Thanks for these replies. With both rear wheels off the ground, each turns freely with no movement on the other side. So pulled the differential cover as shown here. Turning the left wheel moves the spider gears. Turning the right rear wheel does not move anything, but I can see the shaft inside the diffy from the right wheel moving.

 

I have no prior experience with differentials. I found no metal fragments in the oil or when I peer into the case.  I removed the nuts on the right clip that I assume houses a bearing. Is this the right way to proceed? Is anything going to come out that I should have scribed or photographed? Do I need to disassemble the right axle? Can anyone predict what parts I may need to order or go searching? This failure occurred less than a mile since I filled the differential with 60:40 Lucas 90W gear oil and Lucas oil stabilizer. I don't know if that is coincident, but any insights on what lube will make this diffy happy are most welcome. 

[Bloo]

Sounds like the right axle is broken.

 

[28Buick]

Sounds like I agree. How do I inspect, remove or replace the right axle shaft? 

[Bloo]

I am not intimately familiar with that particular axle, so what follows will be very general. Here goes.

 

First, you are absolutely going to need a shop manual. Second, that bolt with the lock tab in the second pic should NOT be out. Be sure to put that back in before anything moves. It locks the carrier bearing adjustment, which affects not only the carrier bearings, but the mesh of the ring and pinion. It's extremely important, and unrelated to changing an axle.

 

Next some terms, because differential terms are weird and don't quite make any sense until you have had a few apart, and even then it is questionable. Incorrect use is all over the internet, and nobody would care except that it causes confusion, constantly....

 

The outer housing that does not move is the "carrier". The piece with the ring gear on it that spins is the "case". Those two terms constantly get reversed. The whole assembly is often called a differential normally, even correctly, but once you get inside we have to drop that because the term "differential gears" would get confusing. The "differential" is only the "case" plus the four little gears in the center, and whatever hardware holds them in. It does not include the "ring" and "pinion" that are the main drive gears. Of the 4 small gears, the two connected to axles are "side gears" and the two that are not connected to axles are "spider gears".

 

There are 2 ways the axle could be held in place. There are internal splines on the side gears that engage the axle. There also may be a thick "C clip" or a wide flat nut back inside the side gear where you can't see it. In the other method, the axle is permanently attached to the wheel bearing someplace, and that holds the axle in. In that case, the spline from the axle to the side gear just floats.

 

This is where you need either a shop manual, or someone who has been working on this exact axle. Buick has used both methods over their long history. Either way you will have to get the brake drum or hub off.

 

If the wheel bearing holds the axle in, you'll have to remove it along with the axle and then try to fish the broken piece out of the side gear with something. Rare earth magnets maybe?

 

If the axle is held in with a C clip or a nut, then the procedure is to disassemble the differential. Remember that is ONLY the stuff in the center. There is a little axle the spider gears run on. There is some way to remove it, might be held with a pin or a bolt on the "case". You would have to turn the ring and pinion to aim it, then pull the little spider gear axle out. The "center block" (metal block in the very center of the differential) can fall out now that there's no little axle holding it in, and the spider gears can come out too. They might have shim washers under them. Keep track of any shim washers so they go back the same. Ideally you would remove only the center block and shove the spider's little axle back in without the spider gears falling out. In reality, it will all fall apart. Just keep track of things. Now the broken(?) axle can be pushed in toward the center of the car. Hold the side gear in place if the spider gears are no longer holding it in. Once the broken(?) axle slides in toward the center a little, the C clip or wide flat nut will be visible and you can remove it. You'll need to fish the broken piece of axle out toward the wheel with magnets or something.

 

EDIT: See @raydurr's post. If the key is sheared you might be able to fix the problem right at the wheel end! That would be nice.

 

Edited September 28, 2023 by Bloo (see edit history)

[raydurr]

It is possible that the key at the hub has failed. Especially if there have been key way issues from the past. Removal of the hub will be required to determine this.

To remove the axle, the cross shaft and spider gears must removed from the center carrier. Once these are removed,there should be a nut in the center of the RH axle gear. Removal of this nut should allow the axle shaft to slide out.  Avoid removing the the carrier bearing cap, like you have started to do. There are adjustments that will be lost if you continue.

[raydurr]

Here are a few photos that might aid in your disassembly. 
 

[raydurr]

 

[28Buick]

Bloo, thank you for this very helpful comprehensive reply, it is just what I needed. Raydurr, thanks for the key fail possibility but that is not the problem. Instead of quoting Bloo I paste his important observations here in italic and what I found in regular font:

 

First, you are absolutely going to need a shop manual.

Yes I have the 1927 manual and 1928 supplement (both from Rock Auto).

Second, that bolt with the lock tab in the second pic should NOT be out.

Good advice the lock tab is now restored.

 

There are 2 ways the axle could be held in place. There are internal splines on the side gears that engage the axle. There also may be a thick "C clip" or a wide flat nut back inside the side gear where you can't see it. In the other method, the axle is permanently attached to the wheel bearing someplace, and that holds the axle in. In that case, the spline from the axle to the side gear just floats.

I assume I have internal splines as the new axle I just bid on is pictured below with an orange background. My side gear is held by a castle nut and cotter pin; so I don't think there is any C-clip. I removed the spider gears and pulled the cotter pin on the castle nut on the axle. Now the tricky part is unscrewing the castle nut that is on the remaining axle stub. It is tight on the side gear and both nut and gear turn with any attempts to separate them.

 

Either way you will have to get the brake drum or hub off.

Maybe not. The entire right wheel with broken axle attached pulled out of the carrier with little resistance. It gives me the creeps to think the rear wheels are retained on this vehicle with two cotter pins. Picture below is the right wheel with axle attached that simply pulled out.

 

...then try to fish the broken piece out of the side gear with something. Rare earth magnets maybe?

My long magnet will reach the broken piece on the side gear but a lot more than magnetic force will be needed here. Getting the castle nut off the broken piece is next. There is no way to get a wrench or vice grips on it. I'm going to Menards or Lowes to get a 1 1/4 inch open end wrench and hunt for a possible solution.

 

There is a little axle the spider gears run on. There is some way to remove it, might be held with a pin or a bolt on the "case". You would have to turn the ring and pinion to aim it, then pull the little spider gear axle out.

I did not understand the instruction in the shop manual that says "remove differential pinion lock screw." Technically there is no way to remove it as shown in the picture it hits the carrier bearing, so just unscrewing it allows the spider gear pin to drop.

 

The "center block" can fall out now that there's no little axle holding it in, and the spider gears can come out too. They might have shim washers under them. Keep track of any shim washers so they go back the same... In reality, it will all fall apart.

Correct, it all fell apart. I don't have any shim washers.

 

Now the broken(?) axle can be pushed in toward the center of the car. Once the broken axle slides in toward the center a little, the C clip or wide flat nut will be visible and you can remove it.

I used a broomstick to push the broken axle toward center. There is no C-clip visible or wide flat nut as shown in the photo.

 

You'll need to fish the broken piece of axle out toward the wheel with magnets or something.

Unable to fish as I need to cut bait first. By that I mean removing the castle nut.

 

If the key is sheared you might be able to fix the problem right at the wheel end! That would be nice.

The key is not sheared although that would be a faster fix. Really nice are these extremely helpful and detailed instructions.

[Bloo]

On 9/28/2023 at 6:09 PM, 28Buick said:

My side gear is held by a castle nut and cotter pin; so I don't think there is any C-clip.

Looks right. The C-clip, in cars that use it, is a very stout part just doing the same job as the nut, holding the whole axle shaft in the car.

 

On 9/28/2023 at 6:09 PM, 28Buick said:

It gives me the creeps to think the rear wheels are retained on this vehicle with two cotter pins.

Really, it is the nut holding the splined axle to the side gear. The center block takes thrust in the other direction. The cotter pin only makes sure the nut can't possibly unscrew. If the axle breaks there is nothing. This is also true of relatively modern cars, especially GM products, but many others too. They typically use C-clips instead of nuts and cotter pins, but the result is the same

 

On 9/28/2023 at 6:09 PM, 28Buick said:

I did not understand the instruction in the shop manual that says "remove differential pinion lock screw." Technically there is no way to remove it as shown in the picture it hits the carrier bearing, so just unscrewing it allows the spider gear pin to drop.

If you got the spider gear pin out, that is all you need.

 

On 9/28/2023 at 6:09 PM, 28Buick said:

There is no C-clip visible or wide flat nut as shown in the photo.

The castle nut in your case is what I was referring to as a "wide flat nut". As you mentioned it needs to come off. A broken axle really complicates this. It looks like there isn't room to get the side gear out with the broken piece and nut still attached. That's a bummer. In normal disassembly, if the axles weren't broken, once the nuts were removed and the axles pulled out, the side gears can be moved toward center (like your broken one is trying to do) and be removed, one by one.

 

I wonder if you could remove the cotter pin, nut, and axle out of the good side, and then remove the side gear from the good side? There might be room? It looks tight. With the other side gear out, maybe there would be enough room to get the first side gear out with the piece of axle and castle nut still attached? Maybe that's wishful thinking but I would be tempted to try it if nothing else is working.

 

Edited September 30, 2023 by Bloo (see edit history)

[Oldtech]

I'm likely too late with any advice but... If you end up removing the carrier MARK the big bearing adjusters with a punch before removing. You will be able to get them within a turn, and the punch marks give you the original position to adjust from. ( hopefully this shouldn't need to be done).

 The pinion shaft lock screw only comes right out if you remove the right bearing cap, but as Bloo pointed out, the pin is out and that's all that matters. 

You should be able to unscrew the nut by holding the side gear as the stub of the axle is splined to it. 

[28Buick]

20 hours ago, Bloo said:

I wonder if you could remove the cotter pin, nut, and axle out of the good side, and then remove the side gear from the good side? There might be room? It looks tight. With the other side gear out, maybe there would be enough room to get the first side gear out with the piece of axle and castle nut still attached? Maybe that's wishful thinking but I would be tempted to try it if nothing else is working.

Right you are! Removing the left side gear allowed the right gear and the broken axle stub to drop out. The gear and axle stub was still too big, but I was able to unbolt the castle nut using a 1-1/4 inch box wrench with gear stationary using vice grips and tranny in 1st gear. IMHO this tool is essential for anyone servicing the axle, so I put the picture here for future reference. The axle fractured at the side gear, so that was fortunate as it was short enough to pull it out through the narrow case opening. Now that I have the good axle out I may as well inspect it. Several nuts were loose inside the carrier as well as in the wheels, meaning only hand tight. I wonder if that contributed to the failure. If anyone has torque specs please share that. Thanks to all for great advice.

[EmTee]

6 minutes ago, 28Buick said:

I wonder if that contributed to the failure.

95 years of shock loading probably contributed.  It sounds like it broke at a stress point created at the spline transition.  You might try getting the good axle magnafluxed or dye tested in that area to see if there are any cracks already present.  Consider looking for another one to keep on the shelf - just in case... 

[raydurr]

I would definitely inspect the LH axle. I have seen heavy trucks break an axle on one side and have  early signs of failure on the opposite side.

Torque specs? Most hardware you are dealing with is not like modern grade 5 or grade 8 fasteners. Be cautious or you can do damage here.

Edited September 30, 2023 by raydurr (see edit history)

[Bloo]

Good advice from @raydurr^^. An awful lot of what we take for granted in the characteristics of ordinary steel comes from lessons learned during World War II. If you have prewar fasteners you do not specifically know the characteristics of, it is best to assume that they are soft (Grade 2 in modern terms). There are generic torque tables for steel bolts that go by size, thread pitch, and grade. 1928 is too early for torque wrenches in any normal automotive setting. The shop manual normally won't have the specs. Torque specs started appearing around 1941, and it is possible to backdate in some cases where older designs of mechanical parts were still used. Sometimes aftermarket manuals even did it for you. 1928 is just too far back for that, and you will probably have to use a torque table.

 

[Edwin The Kid]

Definitely check the other axle shaft! My friends Marmon broke a shaft, and this is what the other side looked like. 

 

[Fred Rawling]

How do you get the  broken axle out of the hub.?

 

Put the broken axle back in the car.  Put that wheel on the ground.  Jack the other wheel off the ground. loosen the nut on the broken axle to the end of the axle.

Put a 2 x 4 in front of the nut and hit it with a heavy hammer.

 

I use 85 140 gear oil.

 

Anneal the tabs on the star washer that you bent before you bend them again.

 

Tighten the axle nut as tight as you can get it.  The book says that loose nuts give broken axles.

 

The cover on the differential goes on with the filler hole below the center.

 

Do you need  another axle?

[28Buick]

Thank you to all on this thread for good advice. The NORS axle arrived and it installed nicely. Repacking roller bearings with the axle removed is quite easy. Here are pictures of the new axle (top) and the old left side "good" axle that did not break. Notice the keyway is wider and there are signs of metal fatigue. I'm not going to reinstall this compromised part so I ordered a second new axle shaft. I now wait for parts as the supplier is deservedly enjoying life.

I have time to find the proper gear oil, is 85/140 or M-533 preferred? I'm going to rinse out the case with kerosene as there is still black stuff in there. My star washer was not bent when I removed it! If I tighten the axle nut that much I will strip the threads! Thanks for mentioning the diffy cover orientation. It is not idiot proof with bolt holes that line it up either way, and if the filler hole is above center it may enable lube to flow along the axle and grease the brakes. I cleaned out the vent tubes at each brake drum that were completely closed with crap. Hopefully I will not have any brake issues (knock knock). there is an extensive two page write up in the 1928 shop manual about adjusting rear axle bevel gears, is this needed after replacing the axle shafts or can I trust prior settings?

[Oregon Desert model 45]

Definitely check the bevel gear mesh since you already have it open.   After spending this much effort replacing axles, you would not want to have an issue with the gears due to improper adjustment.   The procedure calls for using white lead to show gear contact, but you will have to substitute something else since white lead is no longer sold (unless you have a old can of white lead from years ago).  I used copper antiseize paste. 

[Oldtech]

If you haven't moved the ring gear adjustments it will be back where it was. If it was quiet, and there isn't a lot of backlash I would suggest leaving it. But Check everything while you are in there. 

[Hubert_25-25]

Prussian Blue is what you would use today to check gear contact.  I would suggest that you do check the gear contact.  I also had the brake drums rubbing on my brake hardware due to an improperly set ring gear location.  

Keep in mind how this works, as this is a 3/4 floating axle and not a full floating as used in the Master Series Buicks.

 - The depth of the pinion gear (forward and aft) into the ring gear is set thru the opening at the tail end of the drive shaft and access to the adjuster. 

- The ring gear is positioned (left and right) using the large threaded castle nuts on either side of the ring gear carrier.  The locks for each are the L shaped pieces with one bolt each.  Setting the position left and right also effects where the brake drum rides relative to the brake bands.  You also want to adjust the nuts with just a little float - like a front wheel bearing.  This is the carrier bearing float.

My suggestion is to assemble the entire back axle with the wheels and maybe 25 ft lbs on the outside axle nuts.  These will be torqued up later.  Look at the location of the brake drums relative to the brake bands.  Determine if the axles are correctly located in the left to right direction.  Move the ring gear left and/or right accordingly - keep in mind that you are effecting the pinion setting - it may need to be backed out if you run into it.   

Now set the pinion gear location.  Use prussion blue.  Run the axle in both forward and reverse (turning both wheels at the same time) and listen for the least amount of gear noise to go with the prussion blue marks. 

Attached are notes and photos to go with your shop manual.  

 

Hugh       

Edited October 9, 2023 by Hubert_25-25 (see edit history)

[28Buick]

Finally back on the road! A huge thank you to all advisors in this thread, particularly to Hugh for the invaluable instructions not found anywhere else. I'm posting a few pictures here for anyone who may have differential or axle issues to complement Hugh's write up above. Buick rewrote the shop manual instructions as their original gear contact drawing was misleading as shown below. Hugh has a good idea to leak-proof the carrier nuts, now leak-free. I also ran into the dragging brake drum issue. Hugh's suggestion to install a shim washer (I used two) between the axle and the axle shaft gear (Buick calls this the intermediate side gear) worked perfectly. I have a question about zerk fittings in the last photo. Up next are enjoyable drives in the fair Fall weather and then maybe sort out the tuning and Marvel carb.

Edited October 26, 2023 by 28Buick (see edit history)

[raydurr]

I am glad that you are making progress. The assistance and support given here is invaluable. I have the old type zerks on my 29. I use a vintage type grease gun like the one on Ebay . Item 115906286879.

[Hubert_25-25]

Nice job getting the rear axle back together.  For the pin grease fittings, I took a modern straight grease fitting and I used a punch to knock out the spring and the ball.  Then I used a drill to clean up the end, but I don't think I removed anything.  I put this on the end of a modern grease gun.  (photo 1).   This lets me connect to the old pin style grease fittings (photo 2).     Hugh

 

[28Buick]

Thanks again for the friction fighting advice. I resist the temptation to add to my grease gun collection and decided in favor of converting to an all-zerk pre-war Buick. As Oscar Zerk applied for a patent on Dec 4, 1923 (pictured) that was granted in 1929, I feel it is justified to use his innovative invention for a 1928 lube job. I hope this helps anyone who can go be-zerk.