The Stovebolt Site Forums The Shop Area Driveline HO52 3rd Member

My old '65 C20's rear axle has seen better days. It's been reliable, has taken us all over the country, so I cannot complain. Looking at the shop manual last night, except for the bearing noise coming from the rear, the 1/4 turn of slop and the occasional popping of the no-spin is normal. Last weekend, I decided to take a quick look at the HO52 in the parts truck. I have not peered inside that differential yet, but the slop on it is maybe 1/64th of a turn. It is tight compared to the HO52 in the running truck. My thoughts are this, remove the 3rd member from the parts truck and swap it into the my running truck. What I do know about full floaters is the tires can stay on if there aren't center caps for the wheels.

Other than that, is it a fairly straightforward swap? What should I look for on the apparent good 3rd member? Do I check the bearing preload to verify it's assembled correctly? Should I paint on some prussian blue to check the gear contact? If everything checks out, the swap should be a lost low cost operation, some cans of brake kleen, a couple tubes of black or grey silicone, some gear oil and some additive. I have never done this kind of swap before. Is it that straightforward? Not going to say simple, every time I say the procedure is going to be simple, it is a long drawn-out ordeal.

So y'all know, I did read, and re-read, and re-read this at least 10 times thus far. Gear Change from Tech Tips Section

I just need to know if there are any glaring items I should really pay attention to while doing the swap. This truck is used for everything, from short drives to and from work, to dump runs, to drives to Texas and back, or 1,000 mile camping trips, you name it, we use the truck for it. So it needs to be as reliable as it has been already. My thoughts on the HO52 in the parts truck, is it hasn't been in service since who knows when. I bought the truck in May 2005, and had to pay a few years of overdue registration because the PO wasn't upfront with me. So it has been in non-op status for close to 20 years, whereas, my running truck has been in service since 1965.

It is a basic swap. The only thing hard is the handling of those units. They are very heavy.
The first thing to do is examine the donor unit. See what the gear ratio of the donor unit is. Some of those are geared real low & wouldn't be good on the highway for a long trip.
Then check the condition of the donor. Sometimes when they sat for a long time they can get water in side & rust some of the parts. Check the pinion brg for play. There is no adjust ment on that one. If it has play it needs replacement. Check for side play in the carrier brgs. A small amount can be adjusted but very much needs a brg. replacement.
To remove the center section, remove the axle shafts. Disconnect the drive shaft. Remove the rear cover. Remove the nuts or bolts from the section & pull it out.
New gaskets are available but you can use RTV.
If you have more questions ask them. There are a lot of guys on this website that know a lot about this stuff.
George

Thanks for the info. I have one of those harbor freight scissor lift style transmission jacks, that should make the removal and installation a little easier, but not easier getting it up on a flat surface for inspection and cleaning. When I have changed the gear oil in the running truck, I asked my local parts store for the gasket, and they don't have a listing for it. If you guys have a number, they can cross reference it. Scratch that I saw the tech tip has a bunch of gasket numbers.

The donor truck is also a C20. I may get lucky and find a 4.11 in there. That would be a bonus. My guess is 4.57 like the running truck is. If it's the 5.14 it's a no-go. The donor has been under the truck as long as I have had it, so hopefully no water got in there. If it turns out to be a 4.11, I'll have to swap transmissions too, as the 3 speed's first gear is far too high for 4.11, it would slip the clutch a lot with the 31.6 diameter tires on there.

Pretty easy to put a 4 speed trans in there.

Ed

Not too bad. Remove the seat. Cut hole in the floor. Install transmission and driveshafts. Bolt in high hump. Install seat. Just not on the to-do-list at this particular moment, but then again, neither is the 3rd member swap...lol... Life is good at changing plans

You may be surprised at how little the difference is between 4.56 and 4.11. I know you can do the math, and come up with precise numbers, but the difference in "feel" and how it starts out in 1st gear will be what counts. If the donor is a 4.11, I would put it in and drive it for 2 weeks to get used to it, see how you like it. Try the short runs to work, and around town. Find a safe spot out of traffic and see if it can be stalled starting out in 1st gear, or what your limitations are!

Personally I went from 4.56 to 4.11, and wish I went to 3.73. but that is a project for another day.


Good luck

Jon

Depending on how you measure the changes:

4.53 to 4.11 = ~10% difference

4.11 to 3.90 = ~5% difference. I noticed/felt this difference.

4.11 or 3.90 to 3.55 = a difference you can "feel"

The "calculator" at the bottom of this page gives a good "depiction" of RPMs at with various "set-ups" at various speeds.

I have a spreadsheet with different tire sizes (diameter) showing transmission gear ratios, rear end gear ratios, and various speeds and the rpms at those speeds in direct as well as overdrive. My end goal is to have a tire and direct 1:1 rpm that turns 3,000 at 70 mph. Not exactly, but close. 4.57 is good for 70 while turning about 2,600 in overdrive. 4.11 is the sweet spot gear. 3.73 is good but not ideal. But, 3.54, that gear provides the most options, with gears between gears. 3.54, overdrive wouldn't be needed half the time as 70 mph is 2,600 rpm direct. I like 3.54, it's a great gear but not for towing. Although, with the ranger gear splitter, the 3.54 has the most options, whereas, 4.10/4.11 gets the direct drive rpm I'm shooting for.

Lots of tire sizes have been tried over the years in different vehicles with different rear gear ratios, and all of that info I compiled so I know each vehicle's sweet spot for highway cruising. Yeah, I geeked out on compiling the info, but it sure helped when buying tires.

4.11 is the only option for that rear. There are no 3.73 unfortunately.

Yeah, the spreadsheet just has the popular ratios to see the sweet spot. If I went to 3.73 I have 3.54 geared Dana 60 I could re-gear. 4.11 is a pipe dream with a '65 HO52. I may get lucky, though.

I put a 4 speed(don’t know if 420 or 465) in my ‘61 plus 300 hp ‘vette engine with 4.56 gears and big tires, kept it below 60, 12 mpg w/o load a few years back, worked well.

Ed

There has been discussion about gear ratios. This swap has nothing to do with a search for a certain ratio. If a 4.11 is what I find, then I don't have a gear change in my future. If I discover a 5.14 in the donor axle, then I have more work ahead of me, and sooner than planned. I wanted to share with you guys, PDF's of the spreadsheets I created with the tire sizes I can use for this truck. These are Load Range E tires. Being a C20, and sometimes hauling a truck load of rock dust, sand, or compost, I want tires that can handle the load.

The file name will show the diameter of the tire. 30.5 (30 point 5), or 31.6 (31 point 6).

I ran an SM 420 in my other '65 C20 from '87 to '05, actually it was already in it, so I don't know if grandpa put it in there, or what. I suspect grandpa installed it, because there was a giant hole in the floor and a piece of plywood with a hole cut to slip on the shift tower...lol... Not secured, no sides, just a piece of 3/4 plywood resting on the transmission. Many years later I finally found a high hump, but lacked the flange that goes between the hump and the firewall. It was nice not having a u-joint spinning right next your legs and an open floor, let alone the extreme heat in the summertime, and extreme cold in the wintertime. That truck had the 4.57 HO52, so the engine was turning 4,000 rpm on the tachometer to keep up with traffic on the open road. In '91 I found a '68 Dana 60 with 3.54 gears. What a huge difference! I have no idea what my mileage was while turning 4,000 rpms, but I got 14-16 with the 3.54s while cruising 70 at 2,600 rpms. Back then I didn't have overdrive, and going up steep hills or towing heavy items, the truck struggled on inclines or into strong headwinds. Other than that, those 3.54s are awesome! Now I will have a gear splitter and will have gears between gears, so that's why I generated those spreadsheets.

After getting my Jeep running so I have a vehicle to drive while the truck is down, I popped the cover on the donor. Sure enough, water. After cleaning it up with brake kleen, I found a flashlight, and saw numbers. Dumb luck that they were right at the back of the differential. 9 37. Wait, what? 9 37? Where's my phone so I can pull up the calculator. 4.11111111111 is the number. Mixed emotions. Glad for the gear ratio, uncertain because of the water.

Here's the pics...

Was able to get back at this yesterday. It's out. Now I need to clean it up. I'll have Pop take a look at it this weekend, he has seen a few of these in his days. These photos show it still in the housing, I wanted to spray off more of the crud before I removed it. Once I pulled the axle shafts out, and rotated the pinion, I could then spray off the rust. Most of it came off, these photos are before spraying the assembly with brake-kleen. This unit looks okay to me, but I don't know exactly what to look for. The bearings seem to be in good condition, not much play or backlash.

Id clean it up the best i could, and run it. Good luck.

It will most likely happen just like that. I doesn't look compromised at all. But, if the bearings are bad, or go out, I can get inners and outers from Torque-King for $220. They're special order and on the pricey-side, but available. It appears Torque-King also has other bearings, seals, etc for the HO52/HO72 axles.

Visited the parents last weekend, and took the 4.11 3rd member along for the ride. Pop looked it over, the backlash was out of spec. Adjusted that to 0.0065. Checked the wear pattern, and that was good to go. He said it wasn't in bad shape. Looks like Crusty Biscuit is getting 4.11 gears!

This weekend will be the big swap from 4.57 to 4.11. I will replace the pinion seal before the swap. I know to check the in/lb of the bearing preload prior to loosening the pinon nut so I can bring it back to the same bearing preload, and also to make sure the amount of torque to break the nut free so it all goes back together at the same specs. I will also mark the position of the nut and the pinion prior to breaking it loose just for peace of mind. I don't have a handy-dandy 3rd member bench holder. All I have is a B&D Workmate that I can set it on so the pinion nut is facing upwards. I have never replaced a pinion seal on any axle. I saw a video where the mechanic had one of those 3rd member bench holder's. He was working on a 3rd member from a 50's era Biscayne, and when he loosened the pinion nut, the pinion started dropping out the bottom. He said they normally don't do that, but sometimes do. I don't know if those rear ends in the 50's era cars had the pinion support bearing like these HO52's do. Do I need to be concerned about the pinion dropping out the bottom when I loosen the pinion nut? It looks like it might stay put, but I don't want to screw things up when all I am doing is changing the seal.

The pinion will not fall out by simply removing the nut. But I believe you're going to have trouble loosening it just on a workmate. It takes a lot of force to get it broke loose. John

Also the pinion on these does not use crush sleeves. Rather the pinion has a spacer and shims for preload. You don't need to check torque of nut before loosening. John

Thank you John. I think it might be best to install the 3rd member after verifying the preload on the bench, slide the axles in, break the pinion nut free, replace the seal, torque the pinion nut, slide the axles back out, verify preload, if it checks out, slide the axles back in, and take her for a drive after pouring in the oil, or as Jerry calls it, Moose Juice...lol...

When you get the yoke off you will need to remove the flange. It has 5 bolts. The seal is replaced from the back side the flange. You don't have to check the preload. When you tighten the pinion nut it will go back to the position it was. If there is looseness in the pinion brgs after tightening the nut, then you have a bad brg.
When putting the flange back on there is a thick cork gasket that goes between it & the housing. It takes up the gap between the flange & housing. I you can't find one you can use a thick bead of RTV.
George

Good to know. I'll see if my parts store has the flange gasket. Those 5 bolts are covered in gunk right now, can't even tell there are bolt heads there. got lots of scraping to do, then brushing with degreaser.

If one clamps the U-joint yoke(I use a 48” pipe wrench) then the nut can be removed w/o possibility of pinion falling, place in running position.

Ed

I discovered yesterday that the seal has to be ordered, as well as the redi-sleeve and they won't be here until next week. Since I also needed the SM420 gasket set, and other items, I placed an order on rock auto. I prefer to give my money to the mom and pop parts store, but had to go another route this time, as they weren't able to get a couple items I need.

Ed, I definitely don't have a pipe wrench that big, but do have a one that may work with the cheater-bar I have. I may not need to secure it like that, though, as the 3rd member will be installed on the truck when I go to do this.

I've made up simple jigs for removing pinion nuts just by using a heavy length of flat bar and drilling two holes to match the u joint trunnion clamp. Usually works pretty nicely, just bolt the flat bar to the yoke, rest other end on the ground and wrench away.

When I grow up I want to have the scrap stock handy, as well as the tools and shop/garage you guys have. Maybe when I turn 60 it'll come to fruition, only nine more years...lol...