1972 3/4 4x4 rear end questions

[Seventy468]

Swapping axles out of a 79 3/4 4x4 into a 72 1/2 4x4, (in regards to the rearend) and I've already noticed that one, maybe both, of the shock mounts need to be relocated, and am now wondering if the spring pad widths would be the same. If I have to relocate them as well it wont be the end of the world, just posting to see if anyone had any photo's or info on the actual 72 3/4 rearend. Thanks in advance for any info/tips.

[Mike C]

This is a recurring thread. Spring centers on 67-72 4x4 is 40.5", the same as a 73-87 one ton truck. 73-87 1/2 and 3/4 ton trucks have 42.5" spring centers, the same as 67-72 2x4 trucks.

So yes, you will have to move not only the shock mounts but the spring mounts. I preferred the 72 shock mounts on my Jimmy and used them on the '86 Suburban 9.5" 14 bolt that I swapped in. The SF 14 has 3 1/4" axle tubes so I reused the 86 spring pads.

[jeffahart]

As long as you have to move the spring perches on the new axle pay attention to the angles. You can have the pinion angle dialed in on first pass. Don't just move the perches over without verifying the angeles. Plus my last 2cent tip is read all angle and distance yoke to yoke. Then reread angles after install. It's nice to have a baseline to work off of since you already got an assembly in the truck.

[Vintage Windmills]

Unless you are after a ratio other than 4.10 or 4.56, I'm curious why you are putting in a heavier, weaker, less convenient to work on (no 3rd member), and less ground clearance axle? Also, being a 72, you can still buy brake drums and shoes for it. You could convert your HO 52 to disc brakes with probably the same amount of work for 300 or so FYI.

[RedRoad]

I am pondering the same swap as well. If I could find some reasonably priced bearings for my 72 HO52 I would just rebuild it. While I had it out I would drop in a detroit and put in some 14 bolt axles

[Seventy468]

Originally Posted by Vintage Windmills

Unless you are after a ratio other than 4.10 or 4.56, I'm curious why you are putting in a heavier, weaker, less convenient to work on (no 3rd member), and less ground clearance axle? Also, being a 72, you can still buy brake drums and shoes for it. You could convert your HO 52 to disc brakes with probably the same amount of work for 300 or so FYI.

I should have specified its a full floating corp 14. We run them behind 700 hp big blocks and rarely have issues, figured it could handle a 300 hp SBC on the street no problem. And as far as why not find a 72 axle instead of 79? Availability. Used to find 3/4 axle sets all day for $250, and then they all dried up. Got lucky enough to find a good 79 donor truck with 3/4 axles and jumped on it. Had I realized the 3/4 axles weren't all the same for 67-72 to the 73-87 I would have looked harder and would have most likely had to buy one out of state and have it shipped to me. Around here a 72 donor truck goes for $2-3500, which is out of the question. HO 52.. isn't that a 3/4 axle? Im going from 1/2 ton to 3/4, or 6 lug to 8 lug. Obviously I didnt do my homework well enough and now im paying for it with time and labor, no biggie. I'll also have to go back and double check the front end now also.

[Seventy468]

Originally Posted by Mike C

This is a recurring thread. Spring centers on 67-72 4x4 is 40.5", the same as a 73-87 one ton truck. 73-87 1/2 and 3/4 ton trucks have 42.5" spring centers, the same as 67-72 2x4 trucks.

So yes, you will have to move not only the shock mounts but the spring mounts. I preferred the 72 shock mounts on my Jimmy and used them on the '86 Suburban 9.5" 14 bolt that I swapped in. The SF 14 has 3 1/4" axle tubes so I reused the 86 spring pads.

I know the topic has been warn out thank you. I did a quick search and found mounds of threads asking "what will I have to do" type questions, which isn't what I was looking for. However you have provided me with great info, and that's appreciated. Thank you.

Originally Posted by jeffahart

As long as you have to move the spring perches on the new axle pay attention to the angles. You can have the pinion angle dialed in on first pass. Don't just move the perches over without verifying the angeles. Plus my last 2cent tip is read all angle and distance yoke to yoke. Then reread angles after install. It's nice to have a baseline to work off of since you already got an assembly in the truck.

Thanks for those tips, I'll keep an eye out and will eventually put together a "build" thread on this chassis resto.

[Seventy468]

Vintage, I just realized my mistake. I'm swapping the axles into a 72 1/2, not 3/4. My apologies.

[Mike C]

What size tire do you plan to run? What about transmission? While the HO52 is a neat axle, the 14 bolt will be cheaper to swap in as well as getting a locker for if that's what you want.

Why not swap in the front axle from whatever your donor was? That way ratios are the same and no money spent. Especially $700! 10 bolt is as strong as the Dana 44 for the most part.

[Seventy468]

Originally Posted by Mike C

What size tire do you plan to run? What about transmission? While the HO52 is a neat axle, the 14 bolt will be cheaper to swap in as well as getting a locker for if that's what you want.

Why not swap in the front axle from whatever your donor was? That way ratios are the same and no money spent. Especially $700! 10 bolt is as strong as the Dana 44 for the most part.

285/75/16s, SM465. I took a corp 14 and a dana 44 from the donor truck to install in the 72. What I didn't initially realize was that they wouldn't just "bolt in". There was nothing wrong with the 1/2 axles originally in the truck, nor do I think we would ever actually tear the original 1/2 axles up, but we wanted 3/4 axles from the get go, so that's where we are at.

[Seventy468]

In an effort to help anyone with looking for good info, I found thread today.

http://67-72chevytrucks.com/vboard/s...d.php?t=536119

[Vintage Windmills]

Originally Posted by RedRoad

I am pondering the same swap as well. If I could find some reasonably priced bearings for my 72 HO52 I would just rebuild it. While I had it out I would drop in a detroit and put in some 14 bolt axles

Ive heard that before but I got new bearings from rock auto, all timkens, for what I thought was a pretty good price. I think it was 100 or so. Can look at receipts when I get home.

Originally Posted by Seventy468

I should have specified its a full floating corp 14. We run them behind 700 hp big blocks and rarely have issues, figured it could handle a 300 hp SBC on the street no problem. And as far as why not find a 72 axle instead of 79? Availability. Used to find 3/4 axle sets all day for $250, and then they all dried up. Got lucky enough to find a good 79 donor truck with 3/4 axles and jumped on it. Had I realized the 3/4 axles weren't all the same for 67-72 to the 73-87 I would have looked harder and would have most likely had to buy one out of state and have it shipped to me. Around here a 72 donor truck goes for $2-3500, which is out of the question. HO 52.. isn't that a 3/4 axle? Im going from 1/2 ton to 3/4, or 6 lug to 8 lug. Obviously I didnt do my homework well enough and now im paying for it with time and labor, no biggie. I'll also have to go back and double check the front end now also.

Gotcha, thought you had the Eaton already.

Originally Posted by Seventy468

In an effort to help anyone with looking for good info, I found thread today.

http://67-72chevytrucks.com/vboard/s...d.php?t=536119

There are some errors in that thread, particularly on the stud size and brake size on the 71 and 72 4x4 ho52 rears. 72 Had larger drums (12 x 2.5) And 71 had (11x2). Both had 9/16 studs.

[RedRoad]

[QUOTE=Vintage Windmills;7003196]Ive heard that before but I got new bearings from rock auto, all timkens, for what I thought was a pretty good price. I think it was 100 or so. Can look at receipts when I get home.

I would appreciate some part numbers.

Thanks

[Seventy468]

http://www.showmetheparts.com/timken/

not sure on the price but you can go here and find the correct part numbers.

[Mike C]

The front is just a bolt in. And the rear mods are not that difficult or expensive. I'd continue on the path you are on as a good strength improvement for low cost.

I don't wheel my Jimmy hardcore, but the 35's were hell on 12 bolts. Actually 2 broke with stock tires on it. One in a freak backfire as my dad was letting the clutch out. I wish I had upgraded years ago instead of building and rebuilding 12 bolts...

[RedRoad]

Thanks for the Timken site. I was able to get the bearing numbers and as usual the tapered pinion bearing for load bolt style 3rd is the killer at $255

Here is the list in case anyone is looking in the future

Differential bearings
388A

Diff pilot bearing
M5205EL

Differential pinion bearing
55197-90030

Pinion Seal
411330N

The kit at Rock Auto is $481 plus shipping and looks to only add the pinion nut

One thing on the Timken site is that they mentioned 2 pilot bearings are needed, I would think only 1 is required but anyone know for sure?

[RedRoad]

Originally Posted by Vintage Windmills

I think it was $100 or so.

Please let me know where you found this price on the bearings, RA is the cheapest I could find but like I posted above the kit is $481.

I could get a 2010 14 bolt with factory disks for $250 around here and a rebuild kit for $152 and still be into it less than a rebuild kit alone on the Eaton.

Thanks

[Vintage Windmills]

I was referring to the hub bearing sets. I haven't had one yet that needed pinion or differential bearings fortunately. I wasn't aware the pinion bearings were that ridiculous. Luckily, I have a couple spare 3rd members with good bearings. I would think you could find a 3rd member for about $150 that is ready to run?

Front D44 and rear HO52 part numbers. Sorry I don't have them separated here but Rock auto will sort it out if you go to the website.
TIMKEN 388A Wheel Bearing $ 20.79 $ 0.00 2 $ 41.58
TIMKEN SET45Wheel Bearing $ 8.99 $ 0.00 2 $ 17.98
TIMKEN 362A Wheel Bearing $ 8.68 $ 0.00 2 $ 17.36
TIMKEN 382 Wheel Bearing $ 11.59 $ 0.00 2 $ 23.18
TIMKEN 368S Wheel Bearing $ 20.79 $ 0.00 2 $ 41.58
TIMKEN 368A Wheel Bearing $ 14.90 $ 0.00 2 $ 29.80
TIMKEN 362 Wheel Bearing $ 11.25 $ 0.00 2 $ 22.50
VICTOR REINZ 49435 Wheel Seal
Wholesaler Closeout -- 30 Day Warranty $ 5.09 $ 0.00 2 $ 10.18

Here are some pics and part numbers for the wheel bearings. Also one of my finished disk conversion for inspiration.

[RedRoad]

Yeah the wheel bearings are fairly cheap, got my Timken sets and seals from autozone for $90 delivered.

HO52/72 thirds have pretty much dried up on the west coast when scrap prices went up, I can still find the occasional non load bolt 4.56 third for $150 or so but the bearings for that one are even more expensive, the 4.10 load style are in high demand so pretty hard to find and expensive these days.

Dont get me wrong I love the Eaton but if I ever did trash something in mine it would be near impossible to get another third or axles while on the road. Im always looking for spares but not willing to pay $400 or more for some.

[Seventy468]

Originally Posted by Vintage Windmills

Here are some pics and part numbers for the wheel bearings. Also one of my finished disk conversion for inspiration.

Nice disc setup!

[Vintage Windmills]

Originally Posted by RedRoad

Yeah the wheel bearings are fairly cheap, got my Timken sets and seals from autozone for $90 delivered.

HO52/72 thirds have pretty much dried up on the west coast when scrap prices went up, I can still find the occasional non load bolt 4.56 third for $150 or so but the bearings for that one are even more expensive, the 4.10 load style are in high demand so pretty hard to find and expensive these days.

Dont get me wrong I love the Eaton but if I ever did trash something in mine it would be near impossible to get another third or axles while on the road. Im always looking for spares but not willing to pay $400 or more for some.

If you're ever in MN I've got a spare 4.10 3rd for half that price. Too bad shipping is so much.

Originally Posted by Seventy468

Nice disc setup!

Thanks!