The Stovebolt Site Forums The Parking Lot Big Bolts front and rear axle swap

does anyone know if the front and rear axle assemblies with BUDD style one piece wheels and hydraulic brakes from a modern style (early to mid 1990's)c6500/c7500 series truck will fit under an earlier c65 truck such as a 1972-1974 model? thanks for input!BDB

What does your tape-measure tell you?

I'm guessing it will work one way or the other, not sure how much effort it will take though?

YES I AGREE ;THANKS FOR INPUT. I GUESS I WILL JUST NEED TO MEASURE THE DISTANCE BETWEEN THE SPRINGS AND MAKE SURE THAT WILL WORK,THEN WORRY ABOUT THE OTHER STUFF LIKE DRIVESHAT AND BRAKE HOSES.

Don't forget the outside of tires measurement,
You probably want the new axles to actually fit under the truck and in the fenders.
Driveshaft and brake hoses will be pretty simple.
If the brakes are much different than your old ones pickup the matching master cylinder when yo get the new axles.

Also check your caps lock key,

Grigg

YES I GUESS THE AXLES WOULD NEED TO BE ABOUT THE SAME TOTAL WIDTH IN ORDER TO FIT UNDER THE TRUCK PROPERLY WITH PROPER TIRE CLEARANCE. I HAD NOT THOUGHT OF THAT.I AM SURE SOMEONE PROBABLY HAS ALREADY TRIED IT. THANKS FOR TIPS ! BDB

I'll add something I ran into when looking for axles for my 1957. Many Chevy / GMC's c65 / c75 had an odd 10 on 8.75 bolt circle with hub mounts that it is difficult to find tubeless wheels for.

Ryan

Difficult to find used; somewhat but not impossible.
Difficult to find new; not at all... Accuride part number 28160 Page 12 on this link http://www.accuridewheels.com/completeversion.pdf

If you want some nice newer axles, look even newer. I swapped the axles from under a Chevy topkick and a small Freightliner to an F350, both axles had very nice disc brakes, and a very common 8 lug hub piloted pattern with your choice of 22.5 or 19.5" wheels. I've seen similar axles on fed-ex, ups, and similar delivery trucks. And there are some similar axles with the regular semi truck hub piloted 10 lug wheels with and hydraulic disc brakes too.
Also lots of school busses have these disc brake axles.

If you're going to swap something, make it a worth-wile swap.

Grigg

I found a set of oshkosh axles out of a 1990's step van with 4 wheel disc's and the 6 on 8.75 budd wheel pattern that is destined for my truck. At this point I just need to find a welder in or around the Kansas City area willing to narrow the front axle.

Ryan

Here are some ideas on how to narrow a front axle:
http://www.stovebolt.com/techtips/bigbolts/p30swap/

Grigg

Yes, and Thanks Grigg, trust me I would not even have gone as far as finding donor axles without it. I am not comfortable welding and am aware of this so now I have to find someone who is able to weld it correctly.

Ryan

i just went to a truck dismanteler the other day, from what i can tell the idea swap in axles are from the isuzu/gm npr/w4500 shorty box and flat beds.

they are either the 6lug budds or the small 10 lug.

disk brakes front and rear.

and because they are smaller trucks the front axles are narrower than a f5/6/700 or newer gm 45/55/65/75/8500 trucks, they are 90" wms front.

i havent measured up the perches for the springs yet tough.

i also found a pile of wide [90"] beam axles with all the patterns and disk brakes. now i need to find out how interchangeable the knuckles/kingpins are to try and get a 10 x 11.25" so i can easy slap some alcoas and 40"+ otr tires.

BE careful with the imported truck axles, the rears in particular.

Check that the bolt pattern is OK for the wheels you want. Often what looks like 6 lug Budd are really a metric version that don't interchange with our 6 lug Budd wheels.

The rear axles usually have really low gears, and I think you'll want something in the mid to high 3.xx range. I also looked at the imported truck axles for the 61 F350 I had, and ended up with a TopKick front and Freightliner rear.

For gearing comparison the 61 F350 with 6V53T had 0.80 OD, 3.73 axle gears, and 38" tires. It weighed 10,000 empty and was comfortable to drive at 70-75, but would have been more efficient with 3.54 gears.
You won't have quite the power I had, so will probably want it geared the same as or just slower that that.
I like this gear calculator, last one on the page http://www.onlineconversion.com/bigger_tires.htm

Grigg

i did some hefty math and figured 5.13 with 40" otr is 70 at 2800.

one of my neighbor hooked a line on a free/ hyper cheap npr that i will be checking out this week. if it looks good i can get both axle and there will be no budds/metric issues.


what rear axle was in your 350? d70/d80?

i am haveing a hell of a time getting the npr gear ratios, the dismanteler didnt record them, so i will need to dismantle 7 rears to find out which one i want.

I figure, 5.14,40" tires, direct drive transmission, gets you 70 at 3,000 rpm
calculate here http://www.onlineconversion.com/bigger_tires.htm

Even with an OD gear 5.14 is way to slow. Just because it's governed at 2,800 rpm doesn't mean it's a good idea to cruise at that speed, you'll just make a whole lot of noise and waste fuel. For a 6V53 non turbo 1,800-2,000 should be a suitable cruising rpm.

In the F350 I used a 12,000 lb Rockwell from a small Freightliner. http://rides.webshots.com/photo/2287711350080251109kBIUJt
I also used the Freightliner spring suspension, which might be a good idea for you too, as you want to move spring hangers any how. Or better yet find the rear axle and suspension from an ambulance, RV, or moving truck with air ride, and likely the same 12,000 Rockwell I had, which can get as fast as 3.31 gears, I had 3.73, and 3.54 are common.
Here's the front and rear axles I used in the truck http://rides.webshots.com/photo/2203512130080251109lwAcFd
And the whole album showing the swaps http://rides.webshots.com/album/558384968mIheUE

All the NPR axles I looked at were 5.something or high 4 at the best, check them by turning pinion and hubs and counting, you don't need to disassemble them.

Grigg