The Stovebolt Site Forums The Shop Area Driveline 52 1/2 ton rearend options

OK guys, I'm new here so please pardon me if it's obvious. I've looked through the entire Driveline forum posts and can't seem to find an answer that gives me the definite warm and fuzzy feeling about which way to go. Here's my problem:

I have a '52 1/2 ton Chevy with a 235, 4-speed, closed drive shaft and the original rearend. As others have indicated, this rearend has a useless 1st gear (unless you're pulling stumps) and is screaming at 45-50 MPH. I'd like to be able to travel 70 MPH from time to time (or I'll get run over in Atlanta!) and need a rearend that will allow that. I can get a 3.55 ring and pinion set from a classic parts dealer but I suspect that will only get me to about 60 MPH comfortably. I'm thinking I'll need 3.08 to get me where I want to be. However, there are no 3.08 sets available as a direct replacement. Am I off base here? What other options do I have?

The original rear end is a 4:11, at 2750 or there about with 6.50-16" tires gets you to about 55mph. The granny gear in the 4 spd tranny is mostly for "pulling stumps" and is not really need for regular driving.
If you are wanting to cruise at 70 mph you might need to upgrade the brakes for disc on the front anyway. These old trucks really were made for 70 mph. They lack the handling and braking for that sort of thing without some upgrades.
To go with an open driveshaft rear end would also mean changing out the transmission for something newer 55-up. I believe you can change out the pumpkin with a later 55-59 truck rearend (3.90) which they do make a 3.08 conversion for.

John

And if you DO swap out the pumpkin for an open drive pumpkin, you either have to weld up the pivot-style spring perches, or weld on new solid ones (something I'm working on now)

Thx for the info guys. I know I have to upgrade the brakes and suspension some to safely drive the higher speeds (even if only occasionally). Are there variations in the 55-59 rearends or would any 55-59 Chevy 1/2 ton (or 3/4 ton) pumpkin work?

There is not a 3.08 gear set for the 1955-62 pumpkin, 3.38 is the highest that I know of.

Did GMC have a 3.08 1/2 ton 55-59 rear end?

If you install the 3:55 gears you will be able to do what you want to do. That being said, like others have stated, you will need to go through the whole driveline to update parts.. Traveling at 65-70 mph you want to make sure your kingpins, tie rod ends, draglink, all bearings, etc. are in GREAT working order.

I have an SM420 with the 3:55 setup and can run 70 down the interstate without issue. I still have original STYLE brakes, steering etc., but all are new, and well maintained.

The GMC 3.08 would be a Spicer rear end.

Thx Sweet. That's exactly what I wanted to hear. I looked at the brakes this morning and they've already been done and are in great shape. I just got the truck. It wasn't running and found out it had a bad 12v ignition conversion module (the part under the distributor cap). Just replaced that and it fired right up and runs great. I'm learning something new every day about what it does and does not need. Bearings will be replaced and all suspension parts inspected and replaced where needed.

Would a 235 have enough power to handle a 3.38??

John

I ordered the 3:55 kit from Patrick's today. Should have it in about 2 weeks (it's out of stock at the moment). Patrick tells me it's a real hot item. I'll post the results after I get it in the truck. Thx to all for the input.

Depends. If you live in flat country, you will be fine. If you drive many long grades or hilly roads, you may feel underpowered.

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Check with this guy. He has a ad on the VCCA site and has them in stock and at a good price.

I appreciate the heads up Don. Since I already ordered from Patrick's I'll just wait for the kit to come in from them. They come very highly recommended from a lot of people and supply the kits to a lot of distributors.

Please tell us if you get the set/kit in two weeks.

Did you also buy the installation kit?

The kit is supposed to have everything in it for the install (gaskets, seals, etc)

OK guys. Here's what I found out. Since my truck is a '52, I thought the rearend was a 4:11 which was standard in '52. As it turns out, my rearend is actually a '54 with 3:90 gears. As "luck" would have it, the carrier changed in '53 so the carrier in my truck won't accept the 3:55 gears from Patricks and he doesn't have anything for it. The only way I can make the 3:55 ring and pinion work is if I can find a '40-'53 rearend carrier (which will have 4:11's)and replace the gears with the 3:55's. Everything else in the '40-'53 will fit fine with my existing axels, spider gears, etc. Though there were many thousands of them sold, I'm having trouble finding that carrier in my area (Northeast GA). Does anyone have any suggestions as to where I might look? Can anyone offer suggestions as to a possible better option? Anybody want to trade a '54 rearend for a '52

It would be a problem with a three speed in first. OP has a 4 speed with granny gear, so it would probably work for him.

smallblockhead.... PM SENT

I have Patrick's 3:55 rig and pinion complete rebuild kit in my "52" rear end and everything works great. His instructions are out of date but I was able to figure assembly out with a phone call or two. The truck is complete now and runs at 55 mph the best but I have had it up to 65 & 70 for a short time with no problem. I have the new style tie rod ends installed and steering is all freshly rebuilt but still find that rough roads at 55 mph you had better have a good hold on the steering wheel. 55mph is my desired speed.

Good info. Thx

I did find the addition of a sway bar at least to the front to make an incredible difference in handling, it was cheap ($150)and easy, and quick to install. Quite easily the best money I have ever spent on the old truck. As far as Patricks gearsets go, the man is incredibly ethical, however he has a few supplier problems (I.E. getting all the pieces together at the same time), keep in mind he isn't a big business, I'm thinking more along the lines of a retired fella running a shop out of his garage type of business. So just keep that in the back of our mind when you have waited 4 months for a set of bearings. You are contributing to a worthy caring individual, rather than a faceless, greedy corporate monstrosity.

But that would involve changing over to an open drive shaft and ultimately the transmission, amongst other major modifications. Changing your rig over to a 3.54:1 ratio on the rear will get you 70 MPH, clocking the engine at around 2500 RPM. This is the setup I have in my 54 3100 (with 4 speed). I am certain I can get 90 MPH out of my rig, if I wanted to (but don't), and still have the tach under 3K. There is no need to go to great lengths to get more speed when the 3.54:1 ratio in the rear works wonderfully. You can get the 3.54:1 ring and pinion gear set from Patricks Truck Parts. http://www.patricksantiquecars.com/ Patricks speciality is inline 6 cylinder speed parts.

Hope this helps.
Walt Williams
La Verkin, UT