While I'm watching the mailbox this week and waiting for a parts order to come in, I figure I may as well do my homework so I can make quick work of the parts. The project is the rear axle for my 26 farm pickup and while I've carefully studied the rear axle book I've never done anything like this before. My rebuild will use a bunch of parts original to the car plus some serviceable original replacements and some new parts as well.
I think the most intimidating thing to me is making it all fit and mesh properly. I see references made to setting X thousandths of clearance and adjusting the thickness of washers and whatnot and I wonder how I'll ever do that in my little single car garage. My question I guess is if anyone could help walk me through it all. What will I need for basic tools for this outside of what you'd already find in a well stocked home toolbox? What's the order of operations for the differential and thrust washer assembly? Do I need to find a lathe or milling machine or would sanding/filing/grinding cut it if I'm careful enough? And so on...
Any help appreciated, I'm out of my depth right now but not afraid to learn new things. Thanks in advance!
This is the best I could do:
I hope this helps!
The hardest part for me in March was that the new spider was not at 120 degree angles; so I used the old part. Use of a machine shop is necessary for parts that need to be turned, cheaper than buying a lathe.
Tim, You greatest challenge is going to be fighting cold fingers out in the garage unless you have heat out there. A couple items I use on rear ends frequently are a belt sander, dial gauge indicator for run-out, electronic caliper, and lots of solvent for cleaning. You might also want to round up all the parts you know you'll need like thrust washers, locator pins, Hyatt bearings in great condition (no sense installing worn ones), inner seals, and a copy of the MTFCA Front and Rear Axle Rebuild book.
Tim you can do everything in a little single car garage. The most "exotic" tool you need is a set of calipers. A set of digital calipers is easy to work with and easy to read and gives you the number of the measurement directly without having to figure anything out. They're maybe $20-$30.
Highly, strongly recommend you use a Fun Projects Pinion Bearing kit. The only "machine" tool you need is an electric sander (it just takes too long by hand). The electric sander will let you get the new thrust washers skinnier, no need for a machine shop or lathe. Plus, even if you had those there's a ton of just testing the fit, then taking some more off, then testing, then more off, etc. You can do the same thing with the driveshaft bushing (yes, it's easier if you have the bushing facing tool but not all of us want to buy a $100 tool we might use 2-3 times ever).
Then, just follow the book. Start taking things apart and cleaning them up. Once clean, you can assess what you have. The book will tell you what to measure and where. If something is out of the range the book provides, get a new one.
As for the fit/mesh. The FP pinion bearing kit takes away a lot of the angst of getting the driveshaft just right, which can be tedious, but even the original style again is just a matter of putting it together, seeing if it's too tight (can't turn it by hand) and then adjusting it with the sander.
Another fit/mesh is the two axles in the carrier. I like to use a piece of brass instead of the fiber washer, but that's just me. Wether you use the original style or a piece of brass, try assembling it, if there's no play but you can turn the two axles by hand, you're set. If it's too tight, sand some more, check again.
The only other fit/mesh you have to do is the pinion bearing and the ring gear. Some guys on here get all in a fuss about saying the "gear mesh" as if we have modern gears. You have two adjustments, period. The first is pinion depth, meaning relative to the ring gear how far the pinion is to the front of the car or the rear of the car. Look at this picture, this pinion is a wee bit deep, it needs to move towards the front of the car for the top edges of the teeth to be flush. This is a Ruckstell so it has extra stuff in there but ring/pinion look the same.
95% of the time there's just not much need to adjust this, it's either dead on already or is so close it's not worth fooling with. That's why John Regan will recommend just getting the non-adjustable version of his kit, and I definitely agree. Bam, that's taken care of.
With the pinion depth set, the only other adjustment is how close or far away the ring gear is to the pinion. You set that with the thickness of the brass thrust washer on the driver's side of the rear end. A washer too thin will have the ring gear too far, too thick will be too close. With the axles vertical in the housing (like the picture I posted) you can tighten 3 of the torque tube bolts, support the torque tube so it's 90 degrees to the rear end. Then you can turn the driveshaft and feel the teeth. With your old thrust washer you'll feel it's probably too far away and as you rotate the driveshaft the teeth will knock, because they have room to move without touching the ring gear. If you use the new thrust washer, the teeth will be too close and as you turn the driveshaft it'll kind of jump over each tooth and make some noise (which, if you spin faster you can imagine will sound like the rear end howling at higher speed). What you want is in between those extremes, just enough clearance that there's no jumping/howling, but no wiggle either.
With that last part set you only have the obnoxious part left: the washer on the other side. That one determines how much the two housings squeeze the guts between them. All you can do is assemble it, and when you bolt the two halves together, can you turn the ring gear with just your thumb? (You don't need the driveshaft for this part, it'll be in the way). Most likely you can't, so take it apart and sand the washer. Try again. You get the idea.
Forget the reproduction rear axle book, and use the Ford Service book.
Thanks all, this is definitely getting me psyched up for this weekend assuming my parts arrive on Friday.
Matt, I definitely paid close attention to your thread as it was being posted and will give it another review before I start assembling.
Just to let you all know where I am with it so far: everything has been disassembled (except I left the gears on the axle shafts) and cleaned. Anything that should be black has been repainted and everything else has been oiled for now to keep the corrosion at bay. I measured everything I needed to in accordance with the axle book (the axle Hyatt's measured .497 and up while the pinion Hyatt was just a handful of pieces!) and anything that didn't make the grade has a replacement on the way. I also have a FP non-adjustable pinion bearing ready to install. Basically, I'm just waiting on serviceable parts to arrive then I can get to work reassembling.
Seth, you've really taken a load off with your explanation of how to get the gears to mesh. I was worried I'd end up buried to my eyeballs in discarded bits of plastigage and stuff but now that you mention it there really are only two things that can be changed.
Mentally walking myself through the process I have two more questions: what's the right way to set the universal joint to drive shaft rivet, and what's the best way to measure and set the adjustment for the radius rods?
Thanks again by the way for all the help so far.
A couple tools you may need that haven't been mentioned is a wheel puller https://www.modeltford.com/item/2800WP.aspx And axle sleeve tool https://www.modeltford.com/item/2509SP.aspx Do note there is a left and right axle sleeve. Also we have used these with excellent results https://www.modeltford.com/item/2511AS.aspx
Seth, that is about how I do mine. If I were building a speed car, maybe that would be different.
This is my OP;
With the original axle bearings there is going to be up-down-side movement in the axles, they just are not that tight. If the axles/drive shaft were mounted rock solid I could see getting down to the clearance some suggest.
"Some guys on here get all in a fuss about saying the "gear mesh" as if we have modern gears."
I suppose you're referring to me, either directly or indirectly. Whether you like the term "gear mesh" or not, you've described how to attain it very well. As to "modern gears", there's no such thing. Gears are gears, whether they're 100 years old, or just made yesterday, and they all need to be aligned correctly to operate well. I know you're probably referring to hypoid gears and the like, and yes, that's a lot more sophisticated.
Anyway, all good. You did a very nice job of explaining the process and obviously took some time to write it all out. Thanks!
The worst part for me was getting all the parts clean of that clingy, sticky, slimy, smelly diff grease! LOL ... I'm not a grease wuss, but I went through about a 1/4 box of latex gloves for all the cleaning!
The 2nd hardest part was getting the forward drive shaft bushing out. Going back in wasn't hard. The hardest thing was getting the drive shaft roller bearing sleeve replaced (as the end of mine by the key was cracked). Old one didn't come off hard, but the new one did NOT go on. I ended up trading my driveshaft with another local person with one that already had one on!
The 'funniest' part was I got the driveshaft and diff mounted nicely, all smooth, sealed up and painted. Then I realized I didn't have the radius arms on ... ARGGG ... so had to break the seals, crack the diff enough to get the drive shaft out and tipped enough to get the radius arms on. Got everything put back together, squared up, sealed and painted again ... then when getting ready to put in place ... I realized I didn't have the U-joint housing bowl-shaped plate in FRONT of the radius arms. It was just swinging away, 1/2 way down the driveshaft. So .... had to then break the seals again, get the radius rods loose enough for that silly thing to slide forward where it belonged, then seal everything and square up, yet again!
I was lucky on the U-joint sliding into the transmission, however. I made a thin tool for the job. You could purchase one of those, as well.
I made a very simple jig for my engine stand ....(I can post photos if you want) 2 long bolts, really, with a retainer over the end ... to hold the differential in a vertical position. You will likely need to do some trial and error when setting the top 1/2 of the diff together, so the gears all align properly, with just enough lash for smooth operation.
When all done, don't forget the diff oil!
I put new modern seals on the inboard side of the outside axle bearings.... and modern seal over the end of the axles. So far ... no leaks!
It was a good time to replace the rear spring shackles also, as you have to take them off, anyway.
Jerry, I can't remember what thread but I remembered reading one and there being a lot of argument back and forth and didn't want Tim to get caught up in that. Wasn't referring to anyone in particular and yes, I meant hypoid gears.
Mark, out of curiosity, what would you do differently for a speed car?
Tim: for the rivet just support the drive shaft and torque tube so that on the other side you can get a bucking bar through the torque tube hole. Some guys like to just use a bolt that matches the threads for the cover. Then I'd flip it over and repeat the process.
For the radius rods it's usually easier to use two people to measure (holler for your wife to come in the garage and lay on the creeper, lol, that's what I do). Have her just hold a tape measure up to the u-joint rivet hole cover. I usually end up getting a reading off of something like the rivet on the underside of the axle tube (see picture).
It doesn't really have to be any more precise than that. Then just tighten the radius rods up at the u-joint until when you measure that same spot on either side, you get the same number.
We haven't really touched on this yet so here goes: the new Hyatt bearings are terrible. You really need to get on the classifieds and find some old good ones. The originals aren't quite the same as a bearing because the long rollers are basically a really thick, strong spring. If you've ever messed with one you'll see that the groove in the roller is actually a spiral cut all the way through. This means that there's a tiny bit of give and spring in the "bearing". Conversely, the new ones are solid rollers and have zero give, and I've read in several places where folks hate them.
Bill Robinson has actually taken several sets of Hyatts and taken them apart to get a full set of good rollers and make one good Hyatt bearing.
I personally run the modern bearings on mine, but there's been several different folks who made those, some were good and some were bad. I apparently got lucky and have a good set.
I suppose I could have been clearer on my Hyatt bearings: I have brand new sleeves (and the tool) for them and all of my original rollers (or spirals, or whatever) measure just .003 below brand new (the axle book says they can go down to .020 under). The pinion-carrying Hyatt is junk but gets tossed in the trash in the conversion to the modern Fun Projects bearing anyways.
The disparity in wear and damage from one part to the next kind of makes me wonder if this axle has been rebuilt before but then the bad stuff should have warranted replacement at that point too, right?
Seth: I have a pretty long reach, can I just measure and adjust the radius rods before putting the whole assembly back under the car?
You can measure it and adjust it before putting it back under the car no problem.
Bent axle housing unfortunately are not that uncommon. This spring I made some fixtures for testing axle housings and about 15% of the ones we checked were unacceptably bent
My suggestion is that prior to diss assembly if possible remove the outboard axle bearings and seals and see if the axles remain centered. If not it is quite possible that a axle housing is bent
Lots of good info here and I echo what Les suggests. :-)
I did mine inside and out of my little 10 X 20 heated shed I built from Menard's.
The Runabout was in there too with seating space for guests! It was snug but cozy.
I had to push the axle housing crooked at the bench every time I installed or removed the axles/diff assy since the ceiling height is so short. :-)
You're gonna be fine but the notion before starting sure can get to a guy. It did me. :-)
Tim,Seth, The gear interference problem only occurs with the 39 tooth Ruckstell Ring Gear where some of the bolt holes line up between the gears. This problem is easily fixed by modifying the tip of the gear as shown in the photos. This can be done on a surface sander. All of our 12 tooth pinions are modified so this problem doesn't happen. The new 13 tooth pinions should be modified like this also.
I made two simple aids. One was a 4X8 plywood piece braced with a couple of 2X4. Cut a hole large enuf for the axle shaft to go thru. Set the plywood on two saw horses. Worked great when working on the assembled differential. The other was a 2X12 with a slot wide Enuff to slip the rear end housing thru leading to a hole about 6" dia. Set that between two ladders. Used it to set housing/differential on when setting pinion clearance. Don't know where my photos went. Biggest issue I had was getting to tired to lift the rear end up on the 2X12.
Another rear axle housing support made from a scrap 2x10 and bolted to the workbench. The extra notchout on one side is for clearance for a Ruckstell shift lock:
Tim, I managed to rebuild mine last winter. These guys will provide any tech help needed from how to make tools and fixtures to answering any questions you can think of. We are very lucky to have this forum and knowledge of its members. I made a tool to line up the drive shaft from a putty knife. Cut a notch the size of square shaft to lift and turn if needed. The only physical help was my wife pushing the floor jack forward when installing rear axle. It is not as hard as it seems. The hard part is waiting on parts. There were several rebuilding rear axles last winter. Plenty of reading old threads if needed.
RE; Mark, out of curiosity, what would you do differently for a speed car?
Something like a Model A setup comes to mind.
Timpkin bearings and cups inboard and some sort of floating safety hubs out board on the axles and Fun Project on the drive shaft.
Tim, The manual says a "couple thousands wear" is acceptable. That's .002, NOT .020. I have always used Chaffin's sleeves and they seem a little thicker than the stock variety. That helps to take up some of the slack from wear on the hyatts. I've heard of some folks using hyatts .496 or .495 on the inner bearings, but I would certainly want better ones for the outer ones. I put in hyatts measuring .498 when I did my rebuild with new Chaffin sleeves. They were a snug fit. Also don't cut corners on the inner seals. Get good ones. Good luck!
Today's the big day! Parts came in last night, my wife is out fishing with her father, and the weather is gorgeous: that axle is going back together!
But first an apology to Mr. Chaffin. I had said I got the figure of 0.4800-0 to 0.500 from his book when it actually came from a rear axle checklist I had found elsewhere on the forum. I had thought the lower number to be pretty sloppy but it was the same as the max allowed on the universal joint so I had assumed it was okay within normal shop practices. Anyways, my Hyatts that I'm installing average 0.4985 so I won't lose any sleep.
Yes, the mistake on the check list was mine. It should be a couple thousand's. Sorry about that, I wish there's a way I could edit what was already posted on the forum.
Update: fun projects pinion installed and the ring gear is installed and safety wired. Next up is the u-joint rivet just as soon as I get it packed with grease.
And no problem Matt, thanks so much for coming up with a checklist in the first place. Maybe the next printing of the axle book can have something similar on the last page.
Looking ahead, what's the right way to re-line the brake shoes for a '26? Looks to me like I clamp the lining on, mark where to drill for rivers, drill, countersink from the outside, install with the rivet tool, then Dremel off the excess lining on the ends. Am I close? Are there any precautions about leaving a little lining hanging off the ends or anything?
Buncha stuff got in the way but long story short the differential is stuck together and I'm ready to start fitting the thrust washers. That'll be a job for tomorrow.
Monday morning update: the drive shaft and axle are assembled but I ran out of time before my holidays to do any more. For the next week and a half I plan to be playing with biplanes, but that's another story...
So everything is basically back together and done? Sounds like only radius rods left (LOL make sure you put the ball flange up on the ball before installing the radius rods).
Just radius rods, brake rods, reinstall grease cups, re-line brakes, and install. Should be easy when I get back home.
Umm, biplanes? Enjoy yourself!
Re; Looking ahead, what's the right way to re-line the brake shoes for a '26? Looks to me like I clamp the lining on, mark where to drill for rivers, drill, countersink from the outside, install with the rivet tool, then Dremel off the excess lining on the ends. Am I close? Are there any precautions about leaving a little lining hanging off the ends or anything?
I clamp mine on and drill in place. But then I have a brake lining stand up drill/riveting tool to work with. When doing this type of shoe I start at the ends, this is kinda hard to explain, but I rivet the lining so it's rotated off the shoe when doing the ends.
Test fit the lining to the shoe first then rotate the lining off the shoe to drill and rivet the ends just a little short. After the ends are riveted I rotate the lining back on the shoe then proceed to drill and rivet the rest. Riveting the linings in this way will help pull the lining tight to the shoe. It is sorta the same as doing the band linings. google lining outside brake shoes, you might find some online videos.
Mark, I think I follow but just confirm for me your process is for inside brake shoes. The 26-27 cars had their brake shoes lined.
Tim, Welcome to the brotherhood. We've discussed giving some sort of certificate to anyone who does a differential rebuild. Here is a recent complete thread from start to finish of tearing down a broken differential and rebuilding it:
Headed back home after ten days of laid back flying anything I could get my hands on. The busiest day was this past Sunday afternoon when I took sixteen people for Tiger Moth rides.
Now it's time to get thinking about that axle again and to get the T safetied and on the road.
If I can overhaul a rear axle,YOU can!
Seriously, the worse problem I had was that sinking feeling when I cranked the engine and had 2 reverses and 1 forward! Be sure to put it together right the first time and save effort.
Mack C, Personally, I have never done that. Came close once, then realized I was working on a rear end upside down. But do you have ANY idea how many people I have talked to that HAVE done that?! You are in good company my friend.
Missed you for awhile? Glad to see you posting again.
Utmost care has been taken so far to ensure that the ring gear was installed on the correct side, the torque tube right side up, and the ball cap flange was head of the radius rods. Still, I'll be biting my nails until I see for myself that I have two forward speeds and one reverse.
Anyways, the story so far is that the rear end is assembled save for brake springs and oilers, and is ready to install. The hope was to do that today but work is sending me to Tulsa instead.