The Stovebolt Site Forums The Shop Area Driveline rear end options for 1951 Chevy 3600

Ok I'm new to Chevy restoration Ford and MG is what I have a better grasp of.

SO I have a 51 3600 with the original running gear, not a bad thing it runs good except it has no brakes so going to have to put modern brakes on it.

I'm fairly sure it has the 4.57 rear end and it has a 4 speed.

Is there any thing out there to convert the stock rear end to a higher ratio ?

Then there is the modern rear end option what 8 wheel bolt one will fit best, 250 Ford C20 Chevy.
Or just go to a F150 or C10 and swap the front hubs to match.
The goal is a driver to replace MY S10

I've heard you can go with a ford ring and pinion from a 87-93 econoline that will fit. My notes tell me to look for ID E5TW4210BJ which is a 39/11 for a 3:55 ratio. This might be what I look for also. I have a 3600 with the same basic set up.

If you want to keep the 8 lugs, you may want to update your brakes to Bendix type. I believe yours will be Huck type. Although you can get your shoes relined and new wheel cylinders, new drums are almost unheard of. Correct me here, everyone, but I think 53 and later had the Bendix set-up and can be retrofitted to your axles.
You can find a 4.10 center section which will bolt into your current rear, or go the replacement axle route to get an even lower ratio. I would suggest getting a bracket to install a dual circuit master, either way, so one leak doesn't take out all your brakes.

Try a Dana 60 from a mid-80s to mid 90s Dodge van or pickup. It'll get you a 3:54 ratio, 8 lug wheels, modern brakes. The most critical measurements are backing plate to backing plate and axle tube diameter. I put a Dana 60 from an 87 Dodge 2500 pickup into my '59 Apache. It was 3" wider than the stock rear, but it fit fine, axle tubes were the same size. I had to shorten the drive shaft ($120), buy new u-bolts ($20), and a new U joint yoke ($30), and get an adaptor to reduce the brake line from 3/16 to 1/8 ($2).

The original gears were 4:56, and I would run out of steam at 55mph with a V8. Now I can hold 70 all day long.

Chris

There are a few different options out there. Some guys will tell you to do a 1/2 ton drivetrain swap, while others will say go with the MII frontend, late model rearend. I'll tell you what I'm doing.

On my '54 3600 I've obtained some front rotors and calipers from an '07 Chevy 2500 van. The rotors slide right over the the original hub. The caliper fits and clears everything, I just need to finish making the mounting brackets for it. I'll need to plumb everything and get an updated master cylinder too. BTW- I purchased some roller bearings (not ball bearings) for the front, and I have Ford van rims. The rotor and caliper won't fit in oem rims and some later model rims.

Onto the rear; If you can find a 60-72 3/4 ton center section, you may be able to get a 4.10 or 3.90 gear, but alas they are HARD to come by. Like other posters have stated, Dodge and Ford vans have a narrower rearend option, along with the Ford trucks with the Sterling rearend (Not Dana). Chevy has a 63" WMS (wheel mounting surface) 14 bolt rearend that they used in Cab and Chassis applications that is fairly easy to come by. You can get gears all the way up to 3.42. I just recenty purchased one and plan on using it. You can find some posts made by myself and Grigg in the Ton's O Fun section.

Go to www.photobucket.com/whitedog76pics , if you want to see some of my progress on what I'm working on. I'm planning on updating the pictures too, so keep checking back.

Well found a 3.73 semi-floater out of a 89 2500 chevy nice big brake and with the extra inch of off set of the rims planing on using it should fit.
We will see in a couple weeks hopefully

Good job on your find. It looks as though you didn't need our help after all! LOL

If I remember right, the semi float axles are around 65" WMS. It should work pretty good. The 3.73 gear should improve your cruising speed dramatically, without taking away the low end.

For your rims on the back, try to look for some Dodge B3500 rims. In my junkyard exploring I've found that they have a little more backspacing. For the front rims, look in the Ford direction. The ones I have on front fit perfectly.

Well had to ask if there was any easy way before going the swap it out for a modern rear axle every bracket they put on it will have to come off.
The F250 rims have 4" off set compared to the 3" on the stock rims, LT235 16s sure fill up the rear fender LT216 16s might fit better

The new rims will also be wider than the oem rims, hence the need for more backspacing. I've heard of guys saying you can't use any more than 3.5" backspacing, but I didn't have any trouble. Right now I have 225/75/16's mounted on the truck. They fit real nicely. They are only about a 1/4" shorter than the oem 7.00/15's and the footprint is only about 1/2" wider. I have a set of 245/70/16's that came off of my Trailblazer, they are noticably wider, but about the same height as the 225's. I may just put them on the rear though. I don't how they will be with the armstrong steering. For easier steering some guys like the 215/85/16 tire, the only bad thing is that they only come in a kidney busting load range D or E.

Checkout www.photobucket.com/whitedog76pics ; I have some rim and tire comparisons. The 245's aren't mounted on a rim and inflated, so they appear a little shorter in the picture.

Change the differential center out of a '67-'72 3/4 ton automatic trany truck. It is a direct bolt in to your axle and has 4.11 gears.

Oops, "67-'72 Chevy 3/4 (of course)

I should clarify myself on the 60-72 center section. There are a few vendors (and I mean a very few) that still have 4.11 or 3.90 gears available for the 3/4 ton rearend. Most likely they are used units. Anyhow, You need the 60-72 center section, they won't fit in the earlier ones. Like WBROWNE stated, the 67-72 automatic trans. trucks came with 4.11's from the factory. I've also seen online, some heavy truck salvage yards that claim to still have HO72 4.11 rearends. The price tag was pretty steep, starting around $700 and steadily going up.

Yes big price difference only paid $400 for the 3.73 with brakes.
Worst case if the fenders aren't wide enough with the new rear axle I will just make the bed 2" wider when I rebuild it.

Inserting the stock 15" rims will actually fit the new axle

I used 1982 Chevrolet 3/4 ton semi-floater brakes on the back of a 1952 Chevrolet HO52 stock rear-end.

Here's what you do:

Remove the axles, hubs, and backing plates. Swap the backing plates. Obtain Dorman wheel studs for the 1952 dually wheels. Press the new studs into the stock hubs (I removed the shields).
I machined down some 1/2" dowel pins x 8 (4 each wheel equally spaced)to index the brake drum more evenly. The reason for the longer studs is because the newer brake drum flange is thicker. Also, the stud holes in the new drums are a larger diameter - that's why the spacers.

You will have to bend up new brakelines and/or use adapters to the 1982 wheel cylinders.

You can use all new drums and all new hardware. The 1982 3/4 ton setup you need is the "4 5/8" drum width. This will give you 13" brakes on the back.

And when it's all assembled, you'd never know it wasn't stock.

And it works awesome!

As long as the center bore of the drum is the same diameter as the pilot on the axle, no dowel pins or spacers are needed to center the drum, even with the larger lug stud holes.

Whitedog,
I viewed the photos of your rear end swap. I am confused about the axles. Which axle did you remove (stock) and which one is replacement? And what is the replacement axle from?

TO: DMGfifty:
Hi! I joined the site so I could talk to you first! Since I am a healthcare professional and a wannabe old car guy that has to hire most of the work out, I need to ask for some clarification about your post (not safe for me to make assumptions...). When you said, "

"I've heard you can go with a ford ring and pinion from a 87-93 econoline that will fit. My notes tell me to look for ID E5TW4210BJ which is a 39/11 for a 3:55 ratio. This might be what I look for also. I have a 3600 with the same basic set up."

did you mean you can just replace the existing ring and pinion gears in the stock housing, or did you mean that you needed to change the entire rear end?

I have a 50 3600 that I bought for my wife that has 456 gears in it. I also spoke with Patrick's Old Cars and Trucks (what a great guy; he was really [censored] at his phone answering machine when we were chatting...) and he gave me the exact same set of numbers. What I din't knows if that is for the whole rear end or just what is stamped on the ring or pinion gear.
I have located an '87 Ford E250 rear end complete with brakes that I can purchase and have shipped to my mechanic, but if it is really just a matter of changing the ring and pinion gears ONLY, I might be able to save considerable bucks on shipping.
What did you actually do with your truck? Thanks a million for any clarification you might provide.

Hi all. I'm looking at buying a really nice 1954 3600, but what's holding me back is being able to find a suitable replacement ring and pinion set for it. Where I live, I need to replace the 4.57 that it presently has. Ideally I'd like to go with a 3.90, 3.73, or even a 3.55 ratio. Any help would be GREATLY appreciated. I hate passing up a nice truck for this detail.

giovanniconte4258@gmail.com

Giovanni, the tallest gears that you will be able to get for the Eaton rear end on the 3600 are 4.10. You can find them if you look hard and are patient, but they are scarce. '67 to '72 Chevy C20 and C30 trucks with 350's and automatic transmissions usually came with them. The 4.10 pumpkin is a relatively easy direct bolt-in to replace your current gears.


The 4.10 will increase your actual speed at the same RPM by 10%. There is a Tech Tip on how to do it.

Larger diameter tires will give you an additional boost.

You would need to change rear ends to get the gear ratios that you want.

Matt

If original engine which is relatively low HP than really fast gears, like 3.55, might not work out so well. You need HP to push the wind out of the way to go fast, and a little faster takes a lot more HP.

My 1 ton with original 228 and swapped 4.10 gears and 32.5" tires is geared well, drives nice, don't have to downshift to much on hills and not always looking for the missing 5th gear either. One step faster at 3.73 might just be OK on flat ground and not hauling stuff regularly but any faster than that would be a mistake.

As for a good rear to swap research and read in the forum about the GM 14 bolt from a "cab and chassis" 1 ton.

Grigg

Thanks Matt. I see different comments about using ford gears or swapping for other swapping other pumpkins. Matt, would you think 50-55 mph is doable with a 235 motor without overwinding it?

Thanks for the help Grigg!

Giovanni, I have the original 235 and 4 speed in my '57 3600. I switched over to a 4.10 pumpkin about three years ago. My truck came with 17.5" rims. After a very long search, I finally found a set of factory optional 19.5" rims that allowed me to run 8R19.5 radials.

I can comfortably run 60 to 65 on the highway and have more umph when needed.

Before either the pumpkin or the tire swap, my truck ran comfortably at 50 to 55. The pumpkin increased that by 10% and the larger tires increased it by another 10%, so I picked up about 21% when compounding both changes.

I think you will be fine at 50-55 with the truck as is. You'll be able to find a 4.10 if you look hard and are patient, so you'll be able to make that change down the road if desired. Simply add 10% to your comfortable rate of speed and that will let you know what the 4.10 will do for you.

I really like my 3600. Personal preference, but I like it better than the 3100...longer wheelbase, taller stance, larger brakes, split drive shaft,etc. The disadvantages are less parts availability for parts unique to the 3600 and the 8 lug hubs create some limitations as does the rear end. There is more demand for short beds, so they tend to be worth more money.

I feel comfortable with my stock brakes after making the rear end and tire changes. I would not be comfortable going much faster without a brake upgrade.

Hope this helps,

Matt