37 Chevy Dually Deluxe

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That's one of my problems. I spun the rear tire 1 revolution and the pinion only spun 2.25. Its a Eaton Axle and my plans are to test it, even though its not ideal.

Eaton axles are fairly common in the trucking industry. There are a lot of 3.55, 3.73, and 3.90 ratios. I sold trucks for over 10 years and I speced a lot with those ratios. You should be able to find what you need. There is a formula that will give you speeds based on ratio and tire size. I no longer have one but a truck salesman should help you out, I would think.[S

I never saw a 2.25 ratio. Don't think thats right. That wouldn't pull a load downhill. LOL

Lynn
 
Eaton axles are fairly common in the trucking industry. There are a lot of 3.55, 3.73, and 3.90 ratios. I sold trucks for over 10 years and I speced a lot with those ratios. You should be able to find what you need. There is a formula that will give you speeds based on ratio and tire size. I no longer have one but a truck salesman should help you out, I would think.[S

I never saw a 2.25 ratio. Don't think thats right. That wouldn't pull a load downhill. LOL

Lynn
By my estimation, that would be a 4.50 ratio, not 2.25. He turned the axle, not the yoke.
 
I had to double check and my results where different but not good. Help me to clear this up if im doing this wrong.
I marked the tire and spun the it 1 full revolution. As I spoon the tire I watched the yoke turn about 2.75 times. I would guess that my rear end ratio is somewhere around 2.75?
 
I had to double check and my results where different but not good. Help me to clear this up if im doing this wrong.
I marked the tire and spun the it 1 full revolution. As I spoon the tire I watched the yoke turn about 2.75 times. I would guess that my rear end ratio is somewhere around 2.75?

not familiar with the guts in that rearend..but if its got spider gears like a car/pickup rearend, then 2.75 x 2 would be close to your axle ratio, or 4.50's..may not be exactly x2, but that should be close..

Tim
 
First up. Bad. Badder than Bad.. Only real way to confirm your gearing is to remove the diff head and divide the number of teeth on the ringgear by the number of teeth on the pinion.... when figuring my rough final drive I google tyre size calculator, there are heaps. They are normally on speedway forums etc....
 
Ratio

You are right, Mackaz. That's the only way to know for sure.
Probably gonna be a 4.33 or sumthin close to that. A work truck ratio. Most "highway trucks" ratios are 3.55, 3.70, 3.90, sometimes 4.33 on trucks like city freight, local delivery, and logging. 3.90 and 4.33 are really low....not much top end speed but pull really well. But, as I said, if a swap is necessary, it shouldn't be too hard to find what you need.
I hope this is a help.

Lynn
 
If you don't want to take the rear apart, jack up the rearend, you can turn one wheel a friend can turn the other one revolution. You count the number of turns the yoke makes and that will get you really close.

Jim
 
Dually Is Running the Highway

I took the dually out on the highway for some high speed testing. 60mph @ 3000 rpm. It rolled smooth, no major vibrations other then the expected. Some minor engine smoke coming from the oil dip stick. Mostly cause I crushed it by mistake with the header. Over heating issue has been solved with my home made expansion tank.
 

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Insanely sweet!
What did you fuigure out on the gearing? You runnin a posi? How much does she weigh? B A D A Z Z Dude!!:D RR
 

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