Inliners International Forums General Discussion Truck Talk 3/4 ton rear end gears

Hi,

I am hoping someone can help me on this one. I have a friend that has a 1960 3/4 ton frame. He stated he checked the gear ratio by turning the wheel and counting the turns and came out to 4:11. It does have coil springs 10 bolt pattern on front and back cover just like the one in my 54 gmc. The main question is will this third member swap into my rear end as just a bolt in. I have read about the 67 to 72 3/4 ton rear gears that you can bolt right in.

Thanks for the help Steve

Dear Steve;

It might be easyer to change out the whole rear end. Sounds like It's the same.

If not; Check with Patrick's, they should know.

Good luck.

Steve, from what I've read Eaton was the rear axle used for many years. There was a good thread on stovebolt identifying these axles. Unfortunately they have upgraded their software and for the time being it does not appear to available, I'm checking on it.

Look on the passenger side front of the rear axle tube near the pumpkin, I believe you should find model and ratio there, see if the models are the same. I haven't read of any problems swapping other than splines, maybe. Wish that thread was there.

I found the thread it seems to confirm that you can use up to a 72 Eaton in your 50s truck.

http://www.stovebolt.com/ubbthreads/ubbt...=true#Post84246

Larry

It should fit.

Pull the axles (they are both full floaters right?) and count the splines. If there are 17 involute splines, then it's the "Eaton" HO52 / HO72 axle. It'll swap out perfect. Swapped a 72 pumpkin into my 58 axle no problem.

Hi,

I want to thank everyone for your help. We are going to pull it the weekend after Thanksgiving. I am sure I will pull it apart confirm the ratio I will look for the ratio on the passenger side first, and probably tear into it and see if it will swap out. If not I will see about trading out the whole rear end. I will let everyone know how it works out in case others have the same question down the road.

Thanks again Steve

I,m new to this question asking on chat lines,but here goes. I have a 51 chev 3/4 ton.It has 235 in it,but it has about 5.12 gears in it.Can someone recomend a rear end that would be about the same width and 8 hole wheels,but with 3.50 or 3.73 gears? I may pull my 18 foot trailer with similar year truck on it. It would be short trips of less than 50 miles. Is the 235 up to it? motor is in good shape.

Renegade,

You likely have the 5.13 gear in it. 4.57 gears are easy to find. 4.10 gears are a bit difficult to find. 3.90 gears are scarce as hens teeth. I once heard a rumor about a mythical 3.38 gear. If you can find a 4.10 "third member", buy it and you'll at least be able to drive 60 mph without burning up the engine. Swapping out third members on these axles is a piece of cake.

I don't have any recomendations for a rear swap, except to go to a reputable yard and start looking. A GM 14 bolt is a good strong axle that will accept a load that a 3/4 ton truck might need to deliver.

Make sure you find a new axle with the same stud pattern or you have to buy new wheels. Your wheels likely have 1/2" stud holes, while newer ones will have 9/16" holes, be ready to drill. Are your wheels stud piloted or hub piloted?

I'd be scared to pull too much with your truck. That sounds like a lot of trailer and load to haul. A 3.50 gear will really reduce your torque. If your 235 is stock and worn out, it won't have excessive torque to begin with. I'd be at least as concerned about your ability to stop that load. How good are your brakes?

Hi to all,
I wanted to give an update now that this is all done. I finally got this rear end in. The numbers on the gears were 4 65 9 37 which I take to mean 4 could be the month 65 the year 9 37 equals out to be 4.11 it bolted up real nice. On my original the numbers are 4 54 7 32 which is 4.57. It has been running real nice without any problems. someone down the road may have the same question and hopefully this could be helpful to them. Thanks again to everyone that helped out. The only other thing I want to do is finish setting up the three speed overdrive and my drive train will be complete. I should be able to do better on the freeway which is a very rare thing for me and also get better gas milage which is my main goal.

Steve

Glad to hear it all went smoothly. You'll find the overdrive a big help, best thing I've done so far.

Larry

Here is a link about Camaro Rear Axles.
http://www.nastyz28.com/2gcog/rearaxle.html

About 3/4 down the page is a photo of the numbers stamped on the
ring gear and pinion gear. It has a chart to the left of that,
that tells how to do the math to figure your ratio.

I have trouble counting teeth... I am from Arkansas