stock 58 apache rear end question

[billo92]

okay so i got a 58 apache 3100 for $500 delivered. pretty sweet except it was rotted out all over. this was about 6 months ago and after getting 99% of the body work done its time to start mach-up and building the motor, so my question is will the stock rear end out of these trucks handle decent power? this isn't going on the strip or anything but i want to be able to get on it once in a while- i'm throwing in a low compression 350 out of a monte carlo that i'm gonna put a semi aggressive cam in, high rise intake, holly built to 750 cfm, and full length headers. all i really need to know are two things- will the rear end handle this at full throttle (im hoping for around 350-375 hp) and what is the ratio in these things? i've been looking online and haven't had much luck finding specs or anything. ill keep trying though and thanks in advance for any help you guys give me.


-Bill

[raycow]

This rear is quite strong and will handle a decent amount of power. In fact, if you take it apart you will find that the ring gear is larger than on the 12 bolt which replaced it. When Chevy had a factory race team in the 50s they used the 1/2 ton rear in their race cars.

I have had my 60 C-10, with the same rear as yours, for about 10 years now. I tore it down when I got it, put in new seals, and it hasn't needed any other work since.

Its main drawback is that it was last used in 62, and most parts other than bearings, seals and gaskets are getting hard to find. The most common ratio is 3.90, with 3.38 and 4.10 as options. The 3.38 is quite scarce.

If you are building on a budget and can live with the ratio, go ahead and keep it for now. It may never break, but if it does, you will probably have to replace it with something newer because of the parts situation.

Ray

[OrrieG]

Ray is right, some guys in the 60's ran 3/4 ton truck rear ends with 4:56 ratios too. Others ran Old's which if I remember right had larger ring gear bolts. Those old Chevy rear ends will take alot of abuse, I field tested them in 55, 57, 60 and 63 Chevys! Weak link were the universal joints, especially the center carrier in the 63. Never blew a rearend but carried spare universal joints and tools to replace them all the time.

[billo92]

awesome thank you guys and i just found a chart to match up the serial numbers to find out my exact ratio. thanks again, once this thing starts going together ill put some pictures up

[dwcsr]

Originally Posted by billo92

awesome thank you guys and i just found a chart to match up the serial numbers to find out my exact ratio. thanks again, once this thing starts going together ill put some pictures up

The ratio is stamped on the ring gear. It would appear similar to 41-10 for a 4:10 ratio. It most likely is a 4:56, rarely a 3:90

[billo92]

well if anyones curious according to the serial number and the chart i found it should be a 3.55 ? heres the link to the chart i used-http://www.348-409.com/differential.html#1958 - the code on the dif was AA. im thinking this chart could be for cars only? but my rear end did have AA before a 4 number code which i dont remember now

[raycow]

Yes, that chart is only for car rears.

Here is a quick way to find the ratio, and you won't have to take anything apart.

Put matching marks on the pinion yoke and differential housing. Jack one rear wheel off the ground, put the transmission in neutral, and the parking brake off. Turn the wheel exactly TWO revolutions and count how many times the driveshaft turns, estimating any fractional turn as closely as possible. That number is your axle ratio.

If the wheel is difficult or impossible to turn, you may have posi. In that case, jack both rear wheels off the ground and turn either of them only ONE revolution. Count the driveshaft turns the same way as for an open rear.

Ray

[billo92]

its definetly not a posi, i had both wheels up and they turn free of each other so i know its an open dif. and theres no motor/trans/driveshaft so that test should be pretty easy. ill see what i come up with tmo, thanks

[soupernova]

if you are going to inspect the gears prior to installing divide the number of teeth on the ring gear by the number of teeth on the pinion and that will give the ratio. ex 41/15=2.73 this is the gear ratio in my72 nova

[billo92]

Originally Posted by soupernova

if you are going to inspect the gears prior to installing divide the number of teeth on the ring gear by the number of teeth on the pinion and that will give the ratio. ex 41/15=2.73 this is the gear ratio in my72 nova

ill keep that in mind, cause i definetly want to open it up and check stuff out in there before i run it. thanks for the help everyone

[billo92]

also im considering flipping the rear axle to save money (i wanted to do mono springs but im just out of highschool and moneys tight) ive heard strong opinions that its not safe, since the u bolts are then going to carry all that weight. however i wanted to hear some of your opinions and tips on what to look out for if i go that route

[raycow]

Originally Posted by billo92

ive heard strong opinions that its not safe, since the u bolts are then going to carry all that weight. however i wanted to hear some of your opinions and tips on what to look out for if i go that route

That's the stock setup used on leaf spring cars. The U-bolts are more than strong enough to carry the weight.

As for tips, just make sure of your pinion angle before you weld on the spring mounts

Ray

[billo92]

sounds good. now that i finally tracked a few kits down ill probably just mono the front and flip the rear axle. which means more money for the motor thanks for your help