The Stovebolt Site Forums The Shop Area Driveline Differential Ratio question

Members:
I have my truck up on jack stands with the diff. cover off to flush and change gasket and fluid. This is a new truck for me and I would like to know what rear end I have.
I have read in the past about tire turning and counting?????
Can someone please remind me on what to do to find this out.
Thanks...Truck info is below

Try this page and see if it won't answer your question.
http://www.ringpinion.com/Calc_GR.aspx

Heres another page that will help.
http://www.stovebolt.com/techtips/calculate_rpm_tire_axle.htm

Hy Jimmi V, if you have the cover off, you should be able to find the part numbers and the ratio numbers stamped into the ring gear, just clean it off.

Or just count the teeth on the ring gear and pinion gear

Guys:
Thanks for the info...I'm on duty now and not with the truck... I do have pics of the rearend in my albums ( Internal Parts Sub-album). Are those the #'s your talking about ( Stamped.. in pics).
Also,If I count...which gear do I count...the Large one on the left. Ring gear?
Thanks

Just went to the sights listed above.......should have done that first,before I ask a stupid question...Sorry.
Thanks again for the info.

4:11 is what I have.....So, I DO have to change to a high gear to go freeway speeds....Hmmmmm after reading the tech tips I think I might just drive her for awhile and muster up my courage and cash to tackle this.... Man the seals & gaskets cost as much as the new gear set up.....
Thanks Again for pointing me in the right direction.

Jimmi, you do not need an antique vehicle supplier for the seals and gaskets. Auto parts stores stock or can order Fel Pro gaskets and bearing suppliers have the seals. Don't get ripped off by somebody telling you those parts are obsolete and, therefore, expensive.

Setting up the gears is no big deal either. You will only need artist's titanium white oil paint, a shim assortment and a dial indicator on a magnetic base. There are many print and online sources of information on doing that job.

"So, I DO have to change to a high gear to go freeway speeds..."

Is your 54 a 1/2 ton with an open driveline? If so, freeway speeds are achievable by swapping out transmissions for an OD transmission. There are plenty that will nearly bolt in to give you that freeway speed. An MY6 4 speed (A833) would be high on my list.

If you have a closed driveline, you would have to swap both the transmission and the rear axle to achieve this.

Ray, thanks for the words of encouragement....I'll have to do more research before I tackle that project...I'll just drive slower for awhile and maybe next winter I'll tear into her.

Big Daddy, I have a closed driveline. You're saying I need to change both rearend and tranny to achieve freeway speeds?....I thought I just had to go to a 3:55 rearend to achieve this ?
Please enlighten me on this.
Thanks

3.55 will increase your speedand drop your rpms, and its not a bad option. Your truck would look stock, and your existing rear and torque tube would be overhauled.

If you found a the pumpkin from a 55-62 rear, it will interchange in your housing giving you an open drive 3.90 ratio. Some welding will be required. the 3.90 open rear coupled with an OD transmission will drop your rpm a lot more on the freeway. The 3.90 gears are better for acceleration than the 3.55 gears.

Bigdaddy, thanks for the info. I'm really not ready to tackle that project...both talent and coin lacking....not really interested in keeping the truck stock...I thought it was stock when I bought her...1954 3100...After cleaning engine and tranny,got help here on the forum with the #'s...53 car block, 56-62 high compression head and 47-62 tranny...So, stock is out the window.

"47-62 tranny"

What transmission is in there? The reason I ask, I am unaware of any torque tube transmissions after 1955.

I posted the # off the tranny on the forum and that is what I was told...it is a SM420 4 speed...
Tranny # 591665

Please clarify for me...
Thanks

Gorgeous truck by the way: 54 3100 5-window. I love that paint job! As for the transmission; it's very possible that someone transplanted a later SM-420 case and guts with the original tail shaft made for the torque-tube. You can install the 3.55 gears but a 54 3100 has 3.90 gears already. Right? 53 was last year for 4.11 in 1/2-tons. Did you run the differential number?
Correct me if i'm wrong about the 3.90 in 54.
I looked it up: 3.90 rear gears in 1/2-tons started in 54
http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0447.html
By the way, I built a 235 from parts of at least 4 motors for my 55-1 3600 and it had a 53 head on a 56-62 block. A lot can and does happen over 50-60 years.
Good luck

Frank:
Thanks for the complement on Jaunita...I think she's gorgeous. Having a blast this winter going thru her to clean up engine compartment,wiring,fluids,brakes steering etc...ongoing project.
As for the tranny,while I was changing the rear end gear oil and gasket I counted the gears and used a ratio calculator and got 4:11 for a ratio.....
I would like to put the 3:55 in her...just have to wait,more important things to do first.
Thanks