The Stovebolt Site Forums The Shop Area Driveline Differential carrier swap

Has any one else done the third member differential carrier swap from their 3600 3/4 ton?
Tomorrow I am going to the salvage yard to find the carrier from a 68-72 Chevrolet C-20 3/4 ton or the C-30 1 ton truck. This should be a fun day just trying to find one then to be able to remove it from the truck.

Elmo

Yes. Easy swap. Unbolt the axles at the hubs and slide them out at least 6” or all the way, unbolt driveshaft, unbolt carrier and it should pop right out. Its heavy so be ready. Install is reverse just clean up the mating surfaces and use a high quality rtv. I prefer the grey mopar stuff myself but permatex or whatever will work. Then fill with gear oil and enjoy. Im guessing you are trying to swap out your 4.56 for a set of 4.11’s?

Yes, the 4.56’s have got to go.
For me, it’s not all about more speed. It’s more about lowering the rpms cruising at 50 or 55 mph.

I hope you have luck finding a faster rear. Not many were produced and lots of people have been looking for them for years. If you are contented driving 50 or 55 you are not going to gain much with faster gears. Those old engines reached their advertised horse power around 3300 and it doesn't hurt to run them at that speed all day long. I drove them at rpm over 60 yeas ago and it doesn't hurt them today.

I sure like my 51 1 ton with 4.10s in the back out of a 72. Cruises very nicely at 55. 60-65 starts to get a little too loud for my kiddies.

Yea the 4.10’s are almost impossible to find. I had quite the search goin for mine but thanks to the great people on this site I ended up finding a set and had them hand delivered by a Stovebolt member on his way through the state. The gears did make a slight difference but honestly the best thing I ever did in mine was the borg warner overdrive. That made 10x the difference of the rear swap.

I went to the salvage yard and told the guy that works there what I was doing. He laughed and said, and so is everyone else for the past 20 years. So I didn’t find anything.
Bummer!!!!

Hahaha yup sounds about right. I found probably 3-4 looking around my area and they were all 4.56’s. Everyone i called had absolutely no HO52’s or if they did they were in a dually with 5.13’s

I have seen a few pop up on ebay but they were goin for like $1000 or more.

I live near Toronto Canada and recently posted an add looking for a 4.56 rear end , no luck but I got 2 offers trying to sell me a 4.11 rear ends , but won't work for me
Maybe I'll contact these sellers and go pick them up then when the border opens I can bring them south next time I head that way , they were asking $1.50 Canadian a piece.
I ended up finding a good 4.56 rear but had to buy a complete set of a 65 k 20 4x4 . The rear was a HO 52 but the front is something different , I'm not sure but I'm guessing that was how it was done .

John

Front is probably a D-44.

Ed

I believe your right , I just spent an hour googleing around and came up with the same results . Thanks

John

Elmo. Panel fan is definitely the guy to get it figured out! He helped me out a lot.

Elmo , there s a site on line called( OnlineConversions ), you put in your particulars and it will give you all the info you want .
For example switching from a 4.57 to a 4.11 will drop your rpm by 300 rpm at 55 mph 2800 to 2500, seems like a lot of effort for little gain .
I agree with Barnfind49 that an O/d gear would be an option although I believe more costly .
Depending on how much driving you do 3000 rpm will give you 58 mph which given a reasonable condition 235 shouldn't bother it.
I had a tired 235 and ran 500 + miles on some days at 3000 rpm with no problems .

P.S that's not noise your hearing , that's music!!

John

Panel Fan,
I just rebuilt my 235. It runs super. At 50 miles per hour seems to be it's sweet spot. I guess I'm just not use to hearing the engine practically screaming down the road at 50. Just not used to the sound.
If it's fine to drive it at 50-55 miles an hour and it won't blow up the engine. Then nuts to to changing the rear end gears.

Thank you for your information and also talking some sense to me on this topic.

Elmo

This is mine at 65mph.
Do the math with NO overdrive it would do 47mph at that same RPM.

Glad to help Elmo , I went through 5 different rear end ratios and 3 t5 O/D ratios before I got mine dialed in , and then I found the Online conversion site, it would have save a lot of labour .

Enjoy you truck

John

I recently (October 2020) purchased a complete Eaton HO52 with 4:10 gears from a 1969 coil spring C20 for $250 + $185 to ship it from North Dakota to Louisiana.

Doesn't hurt to check out some of the rock crawler forums. Ho52/72 rear ends are pretty popular for crawling with 4.56/5.13 gear sets, they don't have much of a use for 4.10's. I mailed a guy south of the boarder my 5.13s in exchange for 4.10's straight across.

A couple of years ago I tried to give away a perfectly working HO-52 rear end with 4.56 gearing. Pulled from my running truck to do a rear end swap out. I ended up scrapping it.

If you don't mind a 1/2 day drive each way, Windy Hill Auto Parts in New-London, MN has a 4.10:1 axle listed on www.car-part.com .

BE PATIENT !!!! It took Me 2 &1/2 years to 'Find' a 3rd Member. I swapped out My 5.13, for a 4.10 assembly... Same Reason.Just wanted to Drive on the Highway
Old Gear Set gave Me 47mph Top Speed.Was an Old'Farm Truck' Never Left the Farm. Talked to Owner's Son,and He 'verified'. Said it was GREAT at pullin a Stuck Cow or Hog
outta the 'Mud Pit' but Top Speed kept it Chained to the Farm,Never driven to Go into Town.. 'Good Luck' ,You WILL Find a Center-Section, just gonna take awhile. Finally found Mine on 'Craigslist" in a Farm town' outta IOWA !!!

I want to be able to drive my ‘49 3600 on the highway. I have a later 235 in it, but it tops out around 45 mph. Any idea where I could get a Borg Warner overdrive, and how hard is the installation? John

Wow, what a difference you made! Mine is a ‘49 3/4 ton with a 4 speed. Did your Borg Warner overdrive work with a 4 speed or did you have a 3 speed? Did you replace the whole transmission? How did you find it? Regards, John

John,

No clue about the O/D ... from what I've heard around here, there does seem to be a PITA factor involved (installation and calibration??). The 1/2-ton guys are pretty much limited to the O/D thing for their drivelines aren't as readilly adaptable as ours (closed/torque tube, etc). So what works for the 1/2-tons doesn't always work for us 3/4 and 1-ton guys. I think looking for a 4.10 center section for your HO52/72 is the far superior approach. The ODSS 1-tonners have had decent success in the past 5 years or so sourcing 4.10 gears (whole center sections) from the rock crawler gang.

Check out our Tech Tip on this subject in out Tech Tips section.

Regards and welcome to the Bolt. Check out the ODSS forum, too. There's a bunch of us in the MD/VA/SoPA area.

Regards,
John

The "Borg Warner overdrive" is actually a Muncie SM319 3 speed manual transmission with a Borg Warner R10 overdrive. It is an assembly.
They were available in Chevy cars and trucks from 55 through 65. A Saganaw version was available from 66 through 70. To convert for use in a 49 3/4 ton you will need to have your driveshaft modified and either find the column shift linkage for a 3 speed or locate an overdrive specific floor shift conversion kit. There is a wire loom, electrical components, and a cable required.
I specialize in these transmissions. You can send me a PM for more information.
Fred

Thanks, John. I think I’ll look for a 4:10 and think about an overdrive down the road. Also, thanks for the heads-up on the ODSS group. The annual truck show sounds interesting and it is fairly close. Hope to meet one day. Regards, John