devildog5001

Well my original Dana 70 at 240,000 is starting to howl under load and is starting to send vibrations through the truck. At first I thought is was just another set of u-joints gone bad but no such luck. So, to rebuild or not to rebuild and replace for about the same amount of $. I found a Dana 70 (71?) out of a wrecked '01 with 53k and disc rears. $700, seems like a fair price and less than a couple quotes I got on rebuilding mine. I've found many posts on adding disc's but not much on a complete Dana 70 swap from a later model truck. Can anyone tell me what and if I'll need a proportioning valve, maybe one from an '01? Any other foreseeable problems? Sure would be nice to accumulate all my parts before I jerk it out of there, I can only carry so much on my dirt bike, and that new axle under my left arm is going to be heavy enough! Thanks guys.

andyr354

I was going to do a simiar deal when my 70 needed work. Didn't like how far it was going to push the wheels out though. The later model axles are around 6" wider than the one in your truck now.

If you are going to do it though skip the 70 and get an 80 IMHO.

MikeThomas

Yeah, the 80 in the driveway is about 6" wider, but im looking forward to not pulling the axles to check my brakes! I think im going to run some 1" spacers up front to balance out the difference... Im certain the front is a bit wider than the factory rear.

dpuckett

I've heard a D80 C&C axle will work well in place of the SRW D70. If the wheel mount measurements are the same, I'd slip it under there. ALso check spacing on your spring perches.

Daniel

andyr354

Another swap I looked at seriously was a GM corporate 14b. They are about the right width, plentiful and cheap. Only problem is no 3.55 ratio, would have to drop to 3.73 and regear the front axle. The later model 90s vintage ones have the drums on the outside of the hub or disc brake kits are easily available if you don't mind not having a park brake.

Andy

92DuallyCTD

I hear ya on pulling axles just to check brakes, I wasn't looking forward to that either on the recently-purchased truck...so I drilled 3/8in holes about halfway up the wheel on the outer edge of the backing plate(basically just above the Bendix part number stamping there is a good open flat spot) and peeked in...like new brakes, no axles pulled!! If you decide to try this, just don't drill the hole too far inward, as I did the first try. You won't see poop! You really can't drill it too far out, just inward of the ring of the backing plate so as to allow a direct view of shoe/drum contact area. I could even read the white numbers stamped on the side of the shoe material thru the access hole, meaning shoe material of approx 1/4in thick or more. Oh, and I drilled only the rear half of the backing plates, as that should be what's considered the primary braking shoe and should wear the quickest(although ideally, both front/rear shoes SHOULD wear the same, right?). If so inclined, I suppose drilling both front AND rear gives you a view of both, just takes 2 more holes! :-) I realize that may not be the most scientific way to check, as along with simple shoe/pad wear viewing, you can also check that all other parts are present and assembled correctly, axle/wheel cylinder seal leaks, etc and all the rest if you do it right(with hubs/axles off). But for a quickie check of the linings, and then easily stopped back up with a rubber plug from the auto parts store, it serves it's purpose!

kiszka6911

I got some measurements from the axles I have access to. I would like to try and compile a list which we could post in the tech section.

These measurments can be used to make some general comparisons only.

1993 W350 DANA 70 DRW 60" from backing plate to backing plate.

1989 W250 DANA 60 SRW 53" from backing plate to backing plate.

So in this case the dually is 7" wider (3.5" per side) then a SRW axle.

Anyone else want to add to the list?

devildog5001

I went and looked at the '01 axle today, you are right on with the width, 6" wider. The spring perches are in the exact same location. The newer axle only differs in the amount of steel tubing from the perches out. It's sporting some really nice discs though, with some dual piston calipers too, talk about stopping power. The other nice thing is the cable operated e-brake setup, it will hook right up with what looks like no modifications at all. I like the idea of running it as is and offsetting the front a little with spacers, it is a little wider than the original rear. Is there any down side to this idea? I guess a guy could have the axle shortened by 3" on each side and run the original axle shafts. It's common on rock crawlers and drag cars to shorten an axle so It must be strong/work, still looking for someone that can do it on a floating axle and how much it will cost to have it done. Dana 80, if you still have the width issue what's the best solution, and how much better are they? What about the speed sensor, it has one, will it work as is? Thanks for all the help and idea's.

andyr354

I set my wheels out 3" on each side and the tires were not under the rear fenders very much. I drive alot of gravel roads and thought it would throw rocks everywhere down the side of the truck.

I prefer WMS-WMS measurements to be more accurate (Wheel Mounting Surface), but maybe that is what you meant.
The front axle is right around 68" (didn't pull the rims and measure exact), a GM corporate SRW is 67", has been a while since I measured but I think the stock D70 rear was around 65"

Another possibility I did not track down and measure were D70HD axles that chevy used in the 70s/80s. Ford also used Dana 70 rears before they went Sterling (the sterling might also be a possibility?)

Ace

Most driveline shops can shorten the housing for around $100. I'd take 2" off each side, for an overall 2" width increase. I think the stock track width looks at least 2" too narrow anyway. Not sure what you would do for axles, tho.

MikeThomas

Narrowing an axle is a lot of work. You have be very accurate to make sure everything is in line--->you dont want a spindle pointing even a degree in the wrong direction. Ive narrowed front axles before for jeep conversions, but they are easy because the knuckle press fits around the tube. I would just live with the width...im going to

devildog5001

OK, I found someone in the Denver area to do the shortening. $75! Are you kidding me, I wouldn't touch all that work for $75, I'm in. For the little extra it cost to get a custom size and not have to run spacers up front, which by the way cost more than machine work to shorten it, why not. So I picked up my new axle which is 71-1/2" WMS (Wheel Mounting Surface) with the rotors on, and stripped it. Removed everything except the pinon gear, easy enough, and It's ready to go to the shop. I have two choices for a width. Stock and re-use my axle shafts, or only take 2" off each side (Ace, I agree with you there) and re-cut the splines on the existing shafts for a little extra. I'll get more info on this shop with total cost and work done and post it after I get it done. The only down side to this new '01 rear end is I'm giving up the limited slip rear, Oh well, after 250,000 it was already the one wheel wonder. Thanks for everyone's idea's.