VCCA Home Forums TECHNICAL - 1945 AND NEWER 1949-1954 Help with 53 Bel Air differential

I recently acquired a 53 Bel Air 4 door hard top with 3 speed manual transmission. The car originally had a 216 engine and the previous owner took that out and put in a 235. The rear end however is a 4.11:1 differential. I have been trying to find a 3.70 ring and pinion gear set or a used 3.70 third member and torque tube but all I can find is the 3.55 ring and pinion for the power glide. I live in Central Virginia and I think 3.55 would be too much for this area even with the 235 engine. I would really like to go with the 3.70 set up that was offered for the 235 with manual transmission in 1953. . Where can I find these parts? I've checked all the usual suspects- Filling station, Chev's of the 40's, ebay, summit, speedway, restoration supply and can't find any mention of the 3.70 ring and pinion. Any help will be greatly appreciated.

When you checked The Filling Station and Chevs did you just peruse the catalog or did you call them? They often have access to used and NOS parts they don't put in their catalog. Also on ebay it may help to contact sellers who are parting out cars in the age range you're looking for. They may have the parts but they just don't have them listed.

I have sent you a PM.

IN 1953 ALL CARS HAD 235 ENGINES. THE STICKS HAD A 3.70 RATIO AND THE pOWER GLIDES A 3.55...The stick 235 had cast iron pistions, rod dippers and solid lifters. The Power Glide had aluminum pistons and full pressure oiling and hydraulic lifters. The engines looked almost the same. When new the stick was painted dark gray and the PG blue.
The differential also has a number code stamped into the front of the banjo housg,right side facing forward in line with the right axle.

You are correct, a 3.70 is a good choice for a 235 stick unless you live in the plains.

NEVER SEEN A 53 CHEVY 4 DOOR hardtop. can u post photos so i'll know i'm loosing my mind? or you "53" is a typo. thanks, mike

I assumed he meant sedan as opposed to a soft top convertible. I could be wrong but that's the way I took it. With folks today calling anything with two doors a "coupe" it's easy to be confused by the lexicon.

I had a 1950 convertible with a 1951 235 engine and 3.55 rear end. I drove it from Denver to the Grand Junction Anniversary Meet and that was just one of many trips over the continental divide in the 25 years I owned it. It went to the top of Pikes Peak (14,115 feet above sea level) with me and a passenger twice!
My point is that the 3.55 gears are fine with a 235 engine. Yes, the 3.70 gears would give you more power.

How sure are you that you have 4.11? The original engine couldn't have been a 216. It was only offered in sedan deliveries and pickups in 1953.

Many years ago I had a 53 Bel Air sedan with a 235 stickshift, and 3.70. At the time I believed it was a 216 and 4.11, but as previously mentioned by Chev Nut the 53 stickshift cars had a 235 but with low pressure oiling and cast iron pistons like a 216. Maybe the previous owner confused it with a 216 like I did.

Those 53 stickshift cars all had 3.70. Are you sure it is 4.11? If you have 4.11 someone changed it. My guess, having made the mistake myself long ago, is that you already have 3.70. If it is geared to slow for you, maybe the 3.55 Powerglide gears would be about right.

So either its a different year/model than what's on the title and has the bel air trim or some other thing is going on. The engine, from what I can tell is a 235, however, as you can see in the pictures, the serial number isn't stamped in the block so all I can tell is the year but not the decade it was made. The radiator is not the original because there isn't enough clearance between the fan and the original radiator. The guy I bought it from told me he removed the 216 and had the 235 that's in it rebuilt (I have the shop invoice) and then put a thinner more modern radiator in to get the fan clearance. I have the original radiator though. The reason I feel the differential is a 4.11:1 ratio is because when checking the speedometer against a GPS, it reads 10 MPH faster than actual speed. At a measured 55 MPH, the engine is screaming, rpm's are way too high to be a 3.70 rear end. I pulled the speedometer drive out of the transmission and it has 11 teeth if that helps with this investigation. By the way, I haven't been able to find different size speedometer driven gears either. Anyway, I'm still trying to find 3.70 rear end or ring and pinion for it within a coupe hundred miles of Lynchburg Va.

I plan to pull the back cover off the differential as soon as the new gasket arrives just to make sure there isn't any garbage in there. I can count the ring and pinion gear teeth then and know for sure.

That car in the picture is definitely a 53 Bel Air, and the engine is newer, most likely a 235. It could be a 261, but those are sort of uncommon. I don't know how to decode the numbers either.

As built by Chevrolet, it would have had either a 1) 235 with low pressure oiling and 3 speed manual and 3.70, or it would have had a 2) 235 with high pressure oiling, a Powerglide, and 3.55. Those were the only 2 options and you didn't get to mix and match as far as I know.

Either one of these 235 engines would have had the old 2-bolt valve cover like a 216. Later 235s do have a water pump/radiator clearance problem, so that makes sense. The 235 (or 261) in the car is likely newer.

The egine iis a 1955-1958 235.
seeing there are no vent holes in the valve cover (as the 1954 valve cover had) the oil filler cap should be of the breathing type used in 1955 and later.as it provides a means for incoming air.
The differential gears can not be exchanged by replacing the center section like a 1955. Either the ring gear and pinion has to be replaced or the complete rear end. torque tube and all. Seeing you have a shop manual see the front pages of the manual for numbers location,
iF NO NUMBERS STAMPED IN IT MEANS THE SHORT BLOCK WAS REPLACED AND NUMBERS NOT TRANSFERED.

When you say you cant swap out the center section, are you talking about the torque tube/pumpkin as an assemble or just the carrier? It was my understanding (probobly incorrect) that I could take the torque tube/pumkin complete assembly and put it in the axle housing that I have as well as keep my existing axle shafts.

Yes, remove torque tube and carrier....housing stays in place.

First remoe the cover and make sure it is a 4.11.

The 1953 and 1954 sticks had a 3.70

I still need topull the cover and verify the gears but I'm looking for a Torque tube/pumpkin/differential complete assembly with 3.70 gears for this 53 bel air.

Hi Rust Buster,

I’m confused by your last post. Why will you need a different 3.70 rear end if you determine that the one currently in the car is a 3.70?

I haven't pulled the cover yet but I'm convinced what I have are 4:11 gears in the rear end. The speedo reads 10 MPH higher than actual speed and the engine RPMs are very (too high) high at 55 mph. Going by the comments above, if I'm correct, I can't put the 3.55 pinion and ring gears on a differential that has 4.11 gears on it? I really would like to have the 3.70 anyway. So, yes, I'm still looking for the whole torque tube/differential assembly with 3.70 gears so I can pull out the one that's in there now out and put in what it should have as an assembly.

Changing the assembly would be the way to go.

As for putting a taller ring gear on the 4.11 diff... Maybe, but probably not with Chevrolet parts. The differential case (rotating part the gear bolts to) is definitely different for 3.55 as Chevrolet built it. The offset on the flange is different, so you need the (rotating) case for the 3.55 gears. I *think* 3.70 takes the same one 3.55 does (different than 4.11).

Now there are aftermarket 3.55 gears, and I *think* those bolt to the same case as 4.11. That would be a question for the vendor, and in any event, probably not the economical way to go.

There is a way to check what the ratio is without taking the cover off, but it takes 2 people. Take all the spark plugs out. Jack up ONE (only) rear wheel. Put the transmission in high. Mark the top of the harmonic balancer with a piece of tape or white out or something.

One person should stay at the front of the car to watch the balancer.

At the back, rotate the wheel carefully just enough to take all the slop out of the gears without actually turning anything. Do this in the direction the wheel would turn if the car was moving forward, in other words, if you are on the driver's side, rotate the wheel counterclockwise. Hold the wheel so the gear slop is removed. Verify with the person in front that you have not moved the balancer. Mark the top of the wheel with a piece of tape (or the bottom if you wish, it might be easier that way on a 53 Chevy).

Now rotate the wheel very slowly in the same direction as when you took the slop out, while the guy in front counts turns of the balancer. Rotate the wheel exactly TWO full turns. Have the guy in front note exactly how many full turns of the balancer were made. Look at the position of the mark on the balancer.

If you are just past four turns, it's 4.11. If you are not quite 4 turns, it's 3.70. If it only went about 3 1/2 turns, it's 3.55.

Popped the cover yesterdat and I have a 37 tooth ring gear and a 9 tooth pinion which says to my math 4.11:1 rear end. I'm working with a gentleman in Pa. on a 3.70 torque tube/hogs head assembly. I'm going up to look at it this week end. I'll keep you posted.

I wonder if that is a truck axle? The 3100 had a 4.11 in 1953.

I doubt it's a truck axle but am guessing it was replaced with one from an earlier vintage like 49-52. My 51 had a 49 axle under it though being a std was the same ratio 4:11. I think the torque diameter might help to identify the vintage.
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I doubt a truck axle would fit, would it? Maybe a sedan delivery, those still had 216s in 1953, so probably had 4.11 too. My guess is it is just an axle out of a slightly earlier car.

A truck just plain would not work. Any 1941-1952 stick torque tube and carrier would and had a 4.11. and they were a dime a dozen.

Not likely to be a ”˜49-”˜50, as those have the Huck brakes. No one in their right mind would put those under that car! I may change those out on my ”˜50 one day. I have a ”˜54 rear end from an automatic car. Unfortunately I think the ratio would be too low for driving in East Tennessee.