Help! quick question on my rear end

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SinnerS hot rods

Well-known member
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Mar 18, 2012
Messages
172
Ok i have picked up a 40s chevy truck and want to run a huge Chevy dump truck rear axle in it from the 70s my question is how hard will it be to make function as its a 2 speed vacuum shift rear end or should i go a different route? Its a dually rear end on 20s so i would love the look and its 87 inches wide so would look mean but im not sure on how easy i could adapt it to say a 350 turbo automatic trans
 
May want to price out those tires first and see if you are still game.

I don;t see why it would not be easy to get it functional if you have a good functional rear end, I do believe, however, that parts are not cheap for those axles.
 
20 inch tube type tires sucks!!! god i hated choping them off the wheels, the tire of choice now is a 22.5 fits the same hub or spider.
The 2 speed will work but there slow.
 
First off, is it vacuum or is it air shift? Could be either, if the rear has air brakes, more than likely it's a air shift.

Second, what kind of wheels does it have, 8 or 10 stud hole "Budd" style wheels, or does it have the spyder with the nuts that take the special wedges to hold on the wheels, also know as "Dayton" style wheels? Most all Budd's I've ever seen were one piece rims, and most, but not all, Dayton's are two or three piece rims. Stay away from the multi piece Daytons if you have no experience with them, they can kill you!

Third, you should be able to find driveline parts that will fit a Turbo 350 and the rear, as many city dump trucks were automatics.

What is the gear ratio in the rear? I'd bet it is pretty low, and even with the two speed in high, it still will be about 50-60 mph top speed. Those rears are geared to pull a load, not for high highway speeds.
 
tall

you would need some real tall tires and a overdrive to be able to go faster the 4OMPH and not be turning 6OOORPM.

l know, l had a turbo 35O amd 4:56 gears with 25 inch rear tires on my 66 chevelle and this is exactly what it did, so changed to a 0D tranny and 3:36 gears just so my motor would live more than a week.

many sites offer these:

A MPH Calculator from RPM and Gearing

http://www.angelfire.com/fl/procrastination/rear.html

Later :cool:
 
First off, is it vacuum or is it air shift? Could be either, if the rear has air brakes, more than likely it's a air shift.

Second, what kind of wheels does it have, 8 or 10 stud hole "Budd" style wheels, or does it have the spyder with the nuts that take the special wedges to hold on the wheels, also know as "Dayton" style wheels? Most all Budd's I've ever seen were one piece rims, and most, but not all, Dayton's are two or three piece rims. Stay away from the multi piece Daytons if you have no experience with them, they can kill you!

Third, you should be able to find driveline parts that will fit a Turbo 350 and the rear, as many city dump trucks were automatics.

What is the gear ratio in the rear? I'd bet it is pretty low, and even with the two speed in high, it still will be about 50-60 mph top speed. Those rears are geared to pull a load, not for high highway speeds.

Bamamav all 20 inch truck wheels have a lock ring, 22.5 took thrir place in a tubeless tire. and your right on the ratio i would say 50 mph would be winding her up pretty good!
 
I'd take heed in what's been said....

Ok i have picked up a 40s chevy truck and want to run a huge Chevy dump truck rear axle in it from the 70s my question is how hard will it be to make function as its a 2 speed vacuum shift rear end or should i go a different route? Its a dually rear end on 20s so i would love the look and its 87 inches wide so would look mean but im not sure on how easy i could adapt it to say a 350 turbo automatic trans

Some of those rear ends are high 5's to mid 6 ratios....mighty tight for a 350 350 combo....even if it is "two speed"...yep, some were air some were vacuum....and 22.5's would be the way to go....no split rims....killers..literally speaking....that's why they were aired up in a cage... :eek:...might want to rethink it to a conventional dually axle.....and you can put 22.5's on them too.... again...JMHO....
 
I would also pass on the 2 speed rear. I had one. The two speeds consist of low and lower... something like 6:30 and 8:70. :eek: (and the vacuum operation sucks, too)

If you're stuck on the big diff, take a look at older motorhomes. P30 GM chassis have 4:10 ratios if memory serves me.

.
 
Bamamav all 20 inch truck wheels have a lock ring, 22.5 took thrir place in a tubeless tire. and your right on the ratio i would say 50 mph would be winding her up pretty good!

Been a long time since I 'e seen any 20's, all my trucks have had 22.5's on them the last 20 years or so. I know the containers still run them, but I thought they had one piece rims now, maybe not...........
 
I'm a firm believer in the old addage....

Your only as old as you feel...... that being said....most days I feel really good about what I can still do...(in my mind) then my body reminds me that it isn't quite the same.....I'll pray for both our healths....and have a Guiness to celebrate it too!! :D
 

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