The Stovebolt Site Forums The Shop Area Driveline 3/4 ton gears

I’m sure like many guys, I’m looking for a drop out with 4:10 gears. Seems to be quite a long shot finding one, I’d be open to swapping the ring and pinion if I could find one.

Does anyone have a source for either?

Thx Don

Eaton axle?
Unless someone makes these gears again, haven't heard of such and seriously doubt anyone does, then they haven't been made in years, so you're looking for used parts.

Please post your parts wanted add in the Swap Meet

Grigg
I’m looking to have them made. The other options at this time are just too costly. Too bad I didn’t know this when I replaced both wheel bearings and wheel cylinders.

Thx

What other options do you speak of as being "too costly" compared to having one off custom ring and pinion gears made?

If you do, or have, contacted aftermarket ring and pinion gear suppliers about this project I'd be interested in what you learn.

Grigg

I've posted this before, never any feedback so not sure if anyone has followed through, but this site shows several 4.10 sets. You'd have to pay shipping and I'd ask the seller to provide the best pictures possible of the ring gear to help access wear (possible noise issues).

The search criteria I used was;

1971 Chevy Truck-20 Series , 1971 down to 1967
Carrier
Rear Axle

Good Luck,
Ron

Don't forget 14 bolt axles, plentiful, inexpensive, various ratios.

Ed

Are they close to the same width? Will I find one I can use my breaks and wheels on?

Thx Don

A 14 bolt from a “cab and chassis” truck is same width at the wheel mounting flanges.
Uses same wheels.
You might could adapt your old brakes, or stick with modern ones with readily available parts.

Have a look around the Tons of fun section for discussions on this swap.

Thx Grigg because I’ve got to do something.

Don

About a year ago, I found a 3.72 posi 14 bolt off an early 90's 3/4 ton Suburban. It would have been a direct bolt in for the '57 GMC one ton panel that I was working on based on the measurements of the spring perches and the WMS-WMS width. It had eight lug drum brakes that fit the stock 17.5" rims that came on the '57. If you can find one of those Suburbans (or pickups) and want to check the gear ratio and whether or not it has posi, there is a tag inside the glove box that gives the rear end code which can easily be decoded on the interent...much easier than getting out the jacks, crawling under the truck, turning the tires and counting the revolutions!

The rear end on that Suburban had the cable operated ebrakes. The truck I was working on had the drum ebrake assembly on the SM420 tranny, so I was didn't need the cable operated ebrakes, but I made a mental note that the rear end would be a great swap for someone who didn't have the ebrake assembly on the tranny.

Sharing simply as an fyi,

Matt

PS--I ended up using a Dana 60 rear end that was also a direct bolt in (even had the cable ebrakes that I didn't need). It was a 4.10 non-posi. I bought a NOS Dana 3.54 ring and pinion set off eBay.

What year truck in question?

I was speaking to a swap for 48-54 3/4 and 1 ton in particular.
58 might be wider rear axle, not sure?

Don, if you want to keep the swap real simple, hold out for a 4.10 pumpkin. They are out there...just takes some patience and some searching. I've done it both ways...changed out the pumpkin on an Eaton HO52 from a 4.56 to a 4.10 and changed out the entire rear end. One is a Saturday morning plug and play job, the other is more involved.

The disadvantage of the Eaton is that the 4.10 rear end is still a low gear ratio if you do highway driving, and that is the tallest ratio available. If you want a taller ratio, you will need to do a swap.

If it were me, I'd make the decision based first on what I wanted for a gear ratio. If the answer to that question is 4.10, I'd stick with the Eaton for simplicity. If the answer is anything taller than 4.10, I'd take on the extra work and do the swap.

The pumpkin swap will probably cost you about $250 for the pumpkin itself and another $50 for gaskets and gear oil, so figure on about $300 total, more if you have to pay to have the pumpkin shipped. You can compare that to the cost of a replacement rear end and whatever it will take to do the swap.

Matt

My Eaton is a 5:14 with 36/7 on the ring and pinion. The motor is a 216 cid with the Muncie 4 speed granny. I just finished repairing the breaks and bearings and don’t really want the expence of doing that again.

What about putting a overdrive transmission in place of the SM420? I’ve read a lot of posts here about it but not finding any about how it worked out what was involved. Anyone actually made this swap and was it worth it?

Don

Don, here's some good news...if you have a 5.14, the swap to a 4.56 pumpkin is exactly the same procedure as the swap to a 4.10 pumpkin...and the 4.56 pumpkins are realtively easy to find compared to the 4.10's. Switching to a 4.56 would give you an 11.3% increase in top end over the 5.14. Switching from a 5.14 to a 4.10 would give you a 20.2% increase. That's a pretty big jump. Since you are running a 216, you might want to give a 4.56 a try before jumping all the way to a 4.10.

I could point you toward several 4.56's here in Arizona if you want, but finding one closer to your home would be a better bet because the pumpkins are heavy (over 100 pounds) and shipping isn't cheap. If you find a local one and can buy it right, it might be worth trying. If the gearing is still too low, you can always continue to look for a 4.10.

You probably know this already, but another way to increase the top end is to go with larger diameter tires. I wanted about a 20% increase on my '57 3600 that had 4.56 gears and 17.5" rims. I ended up with about 21% by doing the 4.10 pumpkin swap and changing over to 19.5" rims with 8R19.5 tires. After I did the conversion, I discovered that my clutch was too tired and slipped during take off, so I had to use the granny 1st until I put in a new clutch. Everything worked OK with the original 235, but it strained it a bit. Since then, I installed a 261 and it is a very nicely matched set up. I share this only because these old trucks sometimes respond better to changes in small increments instead of large ones. Components can get strained that we don't think about as we dream up improvements. For example, I had no idea that my existing clutch wouldn't be able to handle the pumpkin/tire conversion. The ankle bone is connected to the knee bone, the knee bone is connected to the hip bone, etc.

Incidentally, I forgot one expense item in an earlier post that you will have regardless if you swap the pumpkin or change the rear end. Add in about $100 for either one to get a speedo adapter.

Matt

PS--The rock crawler crowd is always on the prowl for the 5.14 gears. They are valuable, so you should be able to sell them to recover a good chunk of your conversion cost.

Matt
Switching to a 4.56 gives me around 5 mph gain. So I’d be going the speed I need to keep from being a nuisance 50. While still screaming with high rpms. Probably not worth the trouble.

I’m going to find a 4.10.

Thanks for the advise.

Don

Don
Remember , the taller the rear end gears the bigger the space between the gears in the tranny. This can make getting up to higher speeds difficult , even living in relatively flat lands.
Check out the numerous sites on switching to a t 5 tranny on this site this will give you the top speed your want as well as the ability to get up there easier .

The T5 transmission is arguably not big enough for a 3/4 or 1 ton truck, they came in an S-10 pickup.

I also switched from 5.14 to 4.10 and 8r19.5 tires in my 1 ton, with original 228 GMC. It does very well, and we live in the mountains.
4.56 is some improvement, but better to hold out for the 4.10.
I bet the 216 with 4.10 gears in flat Florida works out great.

I suspect your right about the t5 out of a s/10 , but the v8 camaro and firebird t5 s will work for sure. I have a one ton panel weighing in at about 5,700 lbs with camaro t5. I've put about 10,000 miles on in the last 2 years with out a problem. Its hooked up to 4.57 gears and 30 in tires which space the first 4 gears nicely, but the .63 o/d is a bit severe with this rear end so over the winter I plan to switch to .73 gears if I can find them .

"The T5 transmission is arguably not big enough for a 3/4 or 1 ton truck, they came in an S-10 pickup."

Grigg, Please tell me why you say this. I've got a T5 to put in my 3600. My rear end ratio is 4.1 and I'm using a 250 to push with. No one ever has said anything like this. Why is it OK for a 1/2 ton and not for a 3/4 ton? Is it the weight of the truck?

I don’t believe they are referring to the empty weight of the truck but more importantly the loaded weight. JMO

Not to be argumentative at all, but I've got several thousand miles on a .72 5th gear T5 out of a 1993 S10 in my stock engine 3600 with zero problems. The rear gears are 4.10 Eatons from a 1967 Chev C20 found in a friends classic salvage yard. Very happy with the two upgrades since I now have a very happy 60-65 mph cruiser (althought 60 mph is my normal cruise speed).

In my best info-commercial voice, the T5 is often maligned due to urban myths about it's supposed fragile nature. Many Mustang's are going 11's with a stock T5. That's not to say that strip/street abuse with slicks and 500hp (even much less sometimes) won't cause failure. Sometimes stuff breaks.

Point of information. I built a 1990 Miata with a Ford GT 5.0 (302 for the well seasoned in the crowd) that's near 300 rwhp and I've been running a T5 from a 4 cylinder Mustang for the past 5 years with no issues. It's been power shifted (old term I in know...shift without getting off the throttle, just tap clutch and shift) through 3 and sometimes 4 gears more times than I care to guess...a lot.

If you look at my little 4 cylinder unit, rated for 240 ft.lbs, no way it should still be showing up for work. I believe The thing that makes it live is my car has very little traction in situations that would stress the drive train. Wheel spin takes the load off and components last. No spin usually equals breakage. My 3600 doesn't spin, but at 85hp, it ain't gonna stress things either.

Now all the above said, I'm about to upgrade the Miata to a 2002 World Class unit that rated at 310 ftlbs primarly for the better gear ratios as in I'm currently running a .85 5th gear and will have a .68 with the upgrade.

Added in edit.... lots of info here.

To add to what Martin said in the previous post; Work a 3/4 ton or larger truck at it's GVCW rating with a T5 on a regular basis and yep, you would likely have problems. My truck still hauls 2,000 lbs of square hay with no issues, but I wouldn't spec it as it's currently set up for a freight yard or farm back in the 50's.

As already explained, and is my opinion too, that if used regularly as a real 1 ton truck the transmission from a 1/4 ton truck may not last.
I understand they’re not weak, and in high HP, but light, cars they do well.
A car is not a truck though.

If they were a suitable transmission for a larger truck I believe GM would have saved themselves some money and used the T5 in bigger trucks. They didn’t, probably because they didn’t think they would last long enough.

The 5 speed overdrive from a 3/4 or 1 ton that is a reasonable swap is the NV4500.

Just my opinion

Wondering how many here actually use their 3100-3600 AD trucks as haulers anymore... seems like there is a spectrum, with some creating cruisers, others hot rods, some just trying to keep them alive, and then some who are long-in-the-tooth employing them as haulers.

I went with a T5 because I knew there was only a small chance that I'd be hauling anything heavier than an engine block in the back, and would probably never be towing anything heavier than a motorcycle trailer with it.

I’ve already changed the tires out to 215/85/16. Any bigger and I will need a step stool.

Don

Thanks so much for the input. I tried to search the threads but really didn’t get answers that pertained to my 3600. Lots of people talking but not so many doing.

If I found a 4.10 pumpkin, I’d stop right there and be happy.

If I swapped the tranny, it would be a NV4500. Which one should I look for? My motor is a 216. I’m not hauling duke.

If I look for a 14 bolt complete. Out of which vehicle should I be searching for the easiest best fit? I am an experienced welder.

Thx Don

Don,

Read back to Grigg's comment about which 14 bolt to use to fit your truck.

Ed