The Stovebolt Site Forums The Shop Area Driveline Axle 3104 1/2 ton 54 4 gears

How identify rear axle on my 3100 54
I Want my chevy running faster and minor consumption
4 gears transmition
Tires 6.50 R 16 C
How calculate the ratio?
Thanks
Frenchie chevy

Bon Jour, Frenchie

If you have an enclosed drive-shaft, you most likely have the original 1954 1/2 ton 3.90 ratio rear end.

You could convert to a 3.55 rear end. SWEET wrote an excellent Tech Tip for this.
You might want to buy the Ring & Pinion from Mother.Trucker (a member of this discussion board) and buy an installation kit from Classic Parts (or others).

You also will need to buy a used ring-gear carrier (used in earlier 1/2 ton 4.11 rear ends).

If you want to calculate your "effective final ratio" - other members will post explanations.
I often use the calculator at the bottom of this page.

Hi tim
What do you mean ; an enclosed drive-shaft ?
Any photos to illustrate
Best regards
Frenchie

Can you see a universal joint (u-joint) ?
If yes, you have an open drive-shaft.

An open drive-shaft became standard equipment in 1955st trucks

There is a possibility that your drive-shaft and rear-end/differential was changed, if you have a 1954 1/2 ton truck.

What is the code that is pressed/stamped into your engines block - in the flat ledge behind the distributor.

I'll find a post an illustration of the enclosed drive-shaft/drive-line 3100 trucks.
enclosed drive-shaft u-joint ball/bell/cover

Bonjour à tous
I think it’s an anclosed drive shaft !

Stay home ,wait and see ,in france it’s became critical

Frenchie chevy

You have an enclosed drive-shaft (an enclosed u-joint).

You have a nice truck.

Most likely you still have the 1954 3100 rear end.
It would be a 3.90 ratio.

Nice photos.

Dear Tim ,

You said that i will need to but a used ring gear carrier (used earlier 1/2 ton 4.11 rear ends) what for?
Thanks. Amitiés

Nice 54 1/2-ton pickup with original torque-tube drive. Congrats! The only way to get your truck “running faster” and keep the original rear axle is to change the gears. But changing to 3.55 will reduce the engine speed only 9% for any particular speed.

Whatever you do to make it go faster be sure the brakes and steering are the best they can be.

The 3.55 R&P set is made for the 4.11 ring gear.

The ring gear changed in 1954, when the ratio changed from 4.11 (earlier) to 3.90 (1954 and later).

The earlier 4.11 ring gear carrier will bolt right up inside the 1954 rear end.

Here is another Stovebolt.com 3.55 concersion Tech Tip. It also does not refer to the 1954/55st ring gear being different.

Best Regards, Alain

Thanks
For yours answers
It’s dificult for me to formulate what’s the matter
My problem is: the first gear is very very short, the second and third to ,the fourth much longer
I think that RPM is to hight level and increase consumption

I hope someone anderstand me
And find a solution to minor RPM and consumption and make the 1 2 3 gear litle bit longer
Tires 6,50 R16 C gear box 4 speed+R ratio 3.90

Amitiés. Frenchie chevy

If you've got the original 4 speed gear box, it's essentially a 3-speed with a crawler or "granny" gear. First is just for starting out with a big load or on a steep hill. For Normal driving just use 2-3-4.

This link has lots of information about your 4-speed transmission, the SM-420. www.novak-adapt.com/knowledge/transmissions/manual/sm420 It has the gear ratios written (to one decimal place) and you can see there's quite a jump between 1st and 2nd (that's why you say it's short), but less of a jump between 2nd and 3rd. As was stated, in most cases you can start out in 2nd.
Installing an Overdrive transmission, such as a T-5 would get you going faster and slow engine rpm -- and there's lots of stuff on the internet about that swap -- but that requires changing the rear axle as well... All of which is probably difficult and expensive to source in France.
Or you could just enjoy the slow lane and drive it as is.
Good luck!