The Stovebolt Site Forums The Parking Lot Tons 'o Fun Rearend

I have a 1948 1 ton GMC dually which is very slow going down the road. It looks like an eaton rearend, What years can I go to to get a high geared pumpkin to swap out with. Thanks

Slick69, I've converted two GMC 1-tons from the 5.14 to 4.10. I refer you to the following site for a thorough "how to": oldGMCtrucks.com, on the homepage select "Technical Stuff", then select "3/4 Ton Rear End Swap" located in the middle column near the top. Pretty simple job with a 20% gain.

Simple, if you can find the rear end. Look for a 68-72 Chevy 3/4 ton with factory 350/auto. And there behind you will find a 4.10 rear end.

Still worth checking the ratio prior to purchase, it may or may not still have 4.10 gears.

I have a 48 3800 and I found a 4.10 ring and pinion from a Suburban but it does not have the entire carrier assembly. Can anyone tell me if on of these eaton HO52 gear sets will fit (bolt into) into my factory carrier or do I need an entire 67-72 carrier?
Thank you

I think the issue is the ratio. I believe 4.56 and 5.13 used a different carrier than the 4.10 and higher. Of course, the earlier ones only had the lower ratios. Since the pinion on the low geared ones is smaller, either the ring gear must be thicker or the carrier mounting flange must be closer to the pinion. A visual check should tell you if you have everything apart and can compare.

1Ton_tommy
Thank you, much appreciated

Thanks guys. That website helped. Where can one check for the #'s that are stamped on the rear end pumpkin? I have a couple here but without pulling them not sure what the gear ratio is. HG816 & U303 are the #'s of each pumpkin. Thanks again for all the help

Slick,

Be sure to check *this* site's Tech Tips, too. We have one for this that's pretty comprehensive and has a lot of photos with it. If the link doesn't work, let us know -- we've been having some issues.

It really is a simple upgrade.

Thanks, John

Many rear ends have the ring and pinion ratio stamped on the end of the pinion shaft, under the U joint, so that can be checked without taking the whole works apart, just to make sure it hasn't been changed to something else.

Did the pumpkin swap yesterday. Using the tech tip provided here helped alot. It went very well, did it in about 6 hours by myself, actual hands on time was probably 4 hrs, wife made a late breakfast about midway through, played with the grandkids a bit and went back at it. I made a jig for my floor jack to remove original and replace with the 4:10. All in all it went very well, noticeable difference on the road. Maybe I will be able to keep up with traffic now. Thanks to Stovebolt for the tech tip!

Glad to hear it, Plowboy! Thanks for the feedback! And congrats on the successful upgrade!

Do you mind me asking what the pumpkin ended up costing you?

Trying to figure out what I want to do.

Thanks,
Larry W.

Paid $180 for a complete rear axle assembly out of a 68 Chevy. I have the removed 5:14 installed in the donor axle and listed on craigs list. I also paid $41 and some change for new gaskets, gear oil, and gasket sealer. So that said got the job done for just under$225, depending on wheather or not I can sell the donor...total cost? Very happy with the results, did think about going with a newer GM 14 bolt but looked at both options, this was much easyer. However the 14 bolt does give more options for gear ratio and future brakes. My Huck brakes are very good, hopefully last as long as I do.

Lucky find! Still on the elusive search for that rare piece. Have fun in the fast lane!

That's a very good summary of the two major rear axle swap/gear options.

I like the 14 bolt swap because it gives easy access to brake parts and numerous (better) axle gear options.
That said I have been looking at another 1 ton and if I buy and drive it home the HO72 pumpkin swap in the driveway would be a real easy thing to do, make a long drive a little more fun.

Both good options, one or the other ought to fit most situations.

Grigg

Also with more options for gear ratio's on the 14 bolt one needs to keep in mind the power source, my truck having the original stock 228 with all of it's 88 HP I'm concerned about being under-powered if I went with higher (faster) gearing than 4:10

Yes, good point on the gears and which engine you have.

I drove my 1 ton with 4.56 gears and a 55 model 235 a lot. I felt it was geared just right for around town and practical use hauling firewood and whatever else you can pile in a 9' bed.
Though for longer trips I am pretty sure 4.11 would have been great, and I may have gotten by with 3.73 and my limited power.
But back at home and normal use I think 3.73 would have been to much gear for the little 235.

All that to say 4.11 or 4.10 is probably about perfect for these old trucks without changing much else.

Grigg

We just updated the Tech Tip with some new info regarding donor axles. One of the big news flashes out of the update concerns brakes -- One of the experts (Barry) tells us the brakes are a bolt-on interchange between ALL HO52/72 axles ... (SRW to SRW, DRW to DRW, etc). Would someone like to confirm this?

John. I have that rear sitting on the trailer we yanked your/our center section from. ODSS summer getaway project ? The shop is ready ! I'm game.

Thanks for sharing.

Yes please confirm. Does that mean if I get the diff out of a 67-72 c20 with an Eaton (HO53) that I can also swap all of the brake hardware over to it too? I.E. backing plates and all the hardware attached to them and the drums?

AND

Let's say I wanted to ditch the duals on my 3800. Can I use the HO52 parts (axle shafts needed?)and then go to singles front and back? Ditch the front spacers or replace the hubs?

My mind is churning with options.

I was considering the 14 bolt for newer brakes, but 67-72 brakes are good enough for me.

Larry W.

There has been discussion on other threads about the 14 bolt axle that hubs and brakes (much more modern) are more or less interchangeable with the old Eaton axles as well.
I do not recall the details or troubles but I do remember it being more or less possible with not a lot of effort.

So if you want even newer brakes- then those on a 14 bolt are sure something to look into.

Good to know too. Thanks,

I was reading "that" thread just now and unless I read wrong, there is a wheel bearing size issue that requires machine work. Now that thread is very confusing because of all of the tangents it went off on, so I could have gotten it wrong.

If it turns out that the HO53 brakes will work on the HO72, I'm in. Especially if there is a way to do the duals from one.

Larry W.

Right, these brake and axle component swapping threads tend go get off on tangents and or not wrapped up. I am guilty of that myself, start on a project and something more important comes up. Then a year or three later I forget where I was and have to start over again.

It takes a lot of work to test, document, and report back on these swapping ideas.

Grigg

[i]
Grigg and Shade Tree. Understood. Just to clarify, I meant no offense to anyone and the tips and research are VERY appreciated. I have caused a few tangents myself. I just get confused easily. People will always ask about their specific situation as will I.

Like this... LOL.

If I can find a way to swap my 1953 3800's HO72 5.14's for 4.10's from an HO53 AND put newer brakes on the HO72 while keeping my duals AND put disc brakes on the stock front axle AND have the front and rear bolt patterns match AND fit a modern 1 piece wheel... I'll be happy. LOL LOL Sounds ridiculous, but that is the real situation. My head hurts.

Larry W.

Sounds like a good plan and all possible.
The wheels I'd look for are 19.5", and run 8R19.5 tires.

Speaking of tangents...

Grigg

Thanks Grigg.

Standard 8 0n 6.5 pattern I assume? I can't measure, I wont have the truck until Sunday am.

I haven't looked at it all yet, but you have some nice tangents there!

Larry W.

Correct, found on GM and Ford step vans, 4x4 trucks, and any other 3/4 or 1 ton you're lucky enough to find them on. Certainly not found on all of those possibilities though, also by chance.

Cool,

Not sure I would have thought of the step vans, but they do have duals I guess. I think I saw some 19.5's on CL recently. I'll have to look again.

Thanks Again,

Larry W.

What about 16's Grigg? Too small? Look funny? Clear the brakes, with or without disc brakes? I think it has 18's now and they pretty much fill the front fenders from what I can see in pictures of it.

Larry W.

Not sure of the lug pattern, but I also found this set of 6 wheels and tires.

Looks like they are 8-17.5's. Not sure how common of a size that is but they seem pretty cheap for the condition.

Larry W.

Forgot the link.

https://jacksonville.craigslist.org/pts/4893368563.html

If dual wheel and you had 18" wheels you may not fit 16" wheels over the brake drums. Have to try and see


17.5" is also tubeless and desirable because of that but a little small I think.

In my opinion 19.5" wheels and 8R19.5 tires being 32-33" tall and still quite skinny just look appropriate on an old 1 ton.
Nothing wrong with the original wheels and tires but if you do want tubeless; 19.5" look "just right"... To me

Ok, Thanks.

Thought you might have tried them before. Been doing some looking and the P30 19.5's I'm finding have platinum rims or some such thing. LOL If the rims on mine look OK, I may just stick with those, at least for the near future. I don't have a grand plus to drop on used wheels and tires right now.

Larry W.