The Stovebolt Site Forums The Parking Lot Big Bolts 8 lug dana 70HD

i have a dana 70HD out of a '77 Chevy C30 with 8 lugs is it possible to swap the hubs and drums off of a 10 lug axle or is the spindle a different size?

Believe it on not I was just discussing this with a friend 2 minutes ago... here are my thoughts:

"You may not be able to swap 10 lug hubs and disc brakes onto a 70HD with 8 lugs and drum brakes, as the spindles may be different, and not sure if they even have 4" axle tubes like the 10 lug versions do?"

So, does your axle have 4" diameter tubes? if so then chances are looking better.
Take a look in my webshots axle swap folder, there should be pictures of my 70HD with the hubs removed, do they look like the same?
Then go to NAPA and see if they use the same bearings, my axle is from an 88 P-30 chassis, with disc brakes and 10 lugs.
And finally if all that checks out you'll have to give it a try and see if they will.

Grigg

was their a 10 lug with drum brakes or disks with the emergency/parking brake on the axle instead of the transmission? i haven't measured it yet but the tubes look like they are 4"

As far as I know the 10 lug Dana 70HD axles only have disc brakes with no provision for a parking brake.

Grigg

Breathing life into this half dead horse I can say no, Dana 70HD brake componenets do not fit on a Dana 80.

The spindle on the Dana 80 has 1/4" less distance from the rear axle flange to the inner wheel bearing race. The Dana 70HD inner wheel bearings are the same as the Dana 80 but the outer wheel bearings and outer spindle are a smaller diameter on the 70HD. If you try to space out a 70HD hub on a Dana 80 by using a 1/4" spacer the sealing service is not in the correct location.

Needless to say after many phone calls to axle guru's my 70 is staying a 70hd and my 80 is staying a 80, no hybrids.

Ryan

What kind of hubs are on the 70HD you are comparing? With what hubs on the 80?

Both could have 8 lugs, both could have the GM 10 lug, both could have 6 lug Budd, and the 80 could have a ford 10 lug pattern. (did I miss any?)

I wouldn't expect 8 lug hubs to swap with 10.

I'm curious if the GM 10 lug hubs interchange between the 70HD and the 80?

Grigg

Grigg,

I have a Dana 80 out of a 1995 Chevy with 10 lug hubs and rotors and a Dana 70HD out of a 1994 Oshkosh Stepvan with 6 lug budd hubs. I thought i had it made, swapping the 70HD hubs onto the 80 axle, no moving spring perches, right gear ratio, etc. The 80 was a 37 spline axle, 70hd was a 35 spline axle. Side gears I believe are interchangeable between carriers.

Differences.

1. On the Dana 80, the spindle is a different diameter for the outer wheel bearing race, larger on the dana 80, smaller on the Dana 70HD. Not a deal breaker as I suspect the outer wheel bearings from the 80 could be used in the 70HD hubs.

2. On the spindle for the Dana 70HD, the distance from the caliper bracket mounting flange to the inner wheel bearing is 1/4 inch more on the Dana 70HD than it is on the Dana 80. Inner wheel bearings are the same. The offset off the rotor hat to the hub puts the 70HD rotor hitting the caliper mounting bracket (both Dana 70 and the original 80 caliper brackets tried) when used on the Dana 80 axle, not by much but the 1/4 inch is needed to space out the Dana 70HD hub / rotor. My fix would be to make a 1/4" spacer to space out the inner wheel bearing. Problem is you have to space out the sealing surface 1/4" as well so the seal has a place to ride but when you space it out, the seal rides at the joint from the original housing and the spacer.

Long story short, called several people knowledgeable on axles and they all said no easy way to put 70HD hubs on a Dana 80.

By the way, thanks again for the axle swap article. My front axle is in process as I write, already cut and soon to be rewelded. The rear I am waiting on spring perches and hub studs / gaskets to reassemble and install it. Hydroboost is sitting on the garage floor, only waiting on finding a steering box. The cabover is proving to be a little problem since the box needs to ride on the top of the frame I think, not the outside. I have a topkick steering box from a mid 80's truck that I will be picking up in 2 weeks that hopefully will work but if not, I will be checking out buses in force to find one that will work.

Ryan

Thanks for the info and research.
So if I understand it right 70HD hubs/disc brakes don't work on 80 axles.
But 80 hubs/disc brakes might work on a 70HD with a 1/4" caliper bracket spacer?

Glad you liked the Tech Tip and found it useful.
Where did you find spring perches for 4" tubes? I looked and looked several years ago with no luck, ended up reusing my old ones which was quite easy.

On the Topkick steering box.
I had one and couldn't find any way to use it on my 48 Chevy, just to large and not enough room between frame and wheel.
I was able to use it on the 61 F350 when I swapped axles on it, but it was still not ideal. It worked great to the left, but to the right the tire would rub the pitman arm, as seen here http://rides.webshots.com/photo/2847676020080251109UIqFJU I changed the pitman arm and adjusted the steering stop and it worked better, but still not as well as I would have liked.
If you are able to mount it completely in front of the tire and use the pitman arm that really wraps down around the steering gear box to get closer to the frame you might be OK.
They are good strong boxes, makes steering really easy.

Grigg