Recomendations on an ambitious project

[Williespeed]

I have decided that rear steer will make my life easier with my truck, I will be able to manuever the trailer like it wasn't there, and no more three point turns at the end of the parking lot aisle. It's a 77 w200 318 4spd full time 4x4 it will remain this way for some time before getting a 4bt conversion. It's intended usage is about 1,500 miles per year of dump runs, camping, the occasional towing. I've read a lot of opinions on why not and what not, but I have decided to do this. I am not looking to rehash the why nots but looking to build it right with a little guidance from some of you that know whats up.

My thoughts are a pair of dana 70 front axles for two reasons the rears take a lot of abuse on a rear steer so the beefier the better and two the dual 70 design will make the gearing easier as the Dana 60 and Dana 70 have different diameter ring gears. Correct?

Gearing choices and translation to relative ground speed and rpm ranges a place to scavange ideas and images of builds and links and hydraulics recomendations.

links

besides the occasional rock crawler or XXRA buggy I don't find a lot of info on rear steer

please help me from shootin myself in the foot and doing this all wrong steer me in the right direction as far as parts and thoughts but please don't tell me why I shouldn't do rear steer

[pieter]

I know you said not to tell you not to do it, but are you driving this on a public highway? I'm not sure what state you are in, but it won't be legal driving a vehicle unless you mechanically lock the rear steer while driving. You would have to either replace the hydraulic ram with a solid piece of steel or design some other type of limiting device. Might want to check on this before you begin...

Besides that, I don't know if you have the dana 70 axles currently, but you may just consider buying a set of Rockwell axles. Buy two front axles and you will have all the axle parts to do rear steer. In my opinion, that is much easier then all the work you are going to have to in adapting a front axle to work on the rear.

The Dana 70 is the closed knuckle front correct? What is the spline count on those axle shafts?

I know you can get brand new Dana 60 knuckles. If you have a dana 60 or maybe 70 rearend, you cut the axle tubes to the correct width and place a left front knuckle on the right rear. Vice Versa for the other side. You'll want to work out all the math and geometry so you don't need custom axle shafts.

This sounds like a fun project and I've seen it done, so I know it's possible.

Pieter

[Williespeed]

i found a set of Dana 70 fronts here locally for 225 a peice, would Dana 60's be a better option? I'm not sure about it being a closed knuckle design or not. I'm not even sure what that means to my project. Could I get away with dana 44's or 60's? I want it strong so I don't have to trailer it home. I am planning on running them on the road and pinning them in place when on the road until I need to parralel park it.

[pieter]

The only reason I asked is about Dana 60's is that you can get all the axle parts brand new. With an existing axle, you'll have to cut-off the knuckles. So you are dealing with cutting them off, cleaning them up and re-using them.

Another reason I would prefer the Dana 60 is that you can get 35 spline axles for it. I believe the Dana 70 has a 16 spline, but I'm not 100% sure.

If you want to use the Dana 70 front on the rear, how were you planning on doing it? Using it stock, your differential is going to be offset to one side or the other. You are also going to have to make sure you got all the parts turning in the right direction. That's why I think you might be better off using a true rear axle for the differential and axle tubes and then weld on the knuckles to be able to steer. In all, that is probably the easiest part. Making sure the axle shafts are correct will be time consuming and have to be double-checked to make sure it all fits.

Your going to want your steering arms to face the rear. If you took a stock front axle and turned it around so the pinion faced forward your steering arms would face the rear. Your differential will be on the drivers side. The rotation will be incorrect. If you removed the differential and rotated it along the axis of the pinion gear and rewelded it in, it might be correct??? I'd have to crawl under a truck and really visualize things moving to get all the rotations correct.

I've got ton's of old 4x4 magazines. If I get time, I'll sift through a couple and see if I can find any articles. I know this was done prior to the popularity of Rockwells. That won't be until next week though :o(

It will work. If you use the stock Dana 70's, you may have to get new axle tubes for the rear. All depends on how well they come apart. Ideally if you could keep the widths the same to use the stock shafts, that would be even better.

As a side note, you are not going to want Dana 44's. With a 4BT implant planned in the future, you want to be as beefy as possible.

pieter

[Williespeed]

Pieter, I appreciate all the good info, first things first, what is the Dana Hierarchy what is the most heavy duty and the lightest duty. I have looked for this but have not found a good explanation on it.

I will need 2 front ends and a rear (unless I can get aftermarket knuckles to weld on?)to make the front and rear with every thing turning right and centered (stock position) rear diff, and the added sense of accomplishment of having cut and welded the knuckles on. But then I have to have custom axles made correct or can I buy them from somewhere? because the diff is now centered and the rear axles are different from the fronts ya?

I appreciate the offer to look for an article That would be great whenever you get a chance the truck won't be home here for a couple more weeks. i won't get started on it till the weather gets a lot better.

I don't ever see the tires getting larger than 36 inches but I like overkill and hate breaking

[712edf]

From little to big; Dana 44,60,70,80. The 80 came rear only I believe. I think you will be time/money/ and effort ahead to go with Rockwell 2 1/2 tons axles if your going the rear steer route. These axles are available already "narrowed" to have a somewhat stock truck track width (try Boyce equipment in Utah). Also a company called Dedenbear may have/can fab axle components (knuckles, arms, etc.) if you go the Dana route. In addition to the problem or rotational direction being altered by reversing the facing direction of an axle ( by using a front as a rear), it also may cause strenght/durability issues within the differential as the pinion gear was designed to drive the ring gear mainly in one direction. Good luck with this!

[pieter]

As far as strength of axles, I don't know that I would classify a front Dana 70 to be stronger then a front Dana 60. Granted, the Dana 70 front has a closed knuckle design which is a nice feature. But the axle strength comes from the shafts and the spline count. This is how some dana 44's are as strong as a Dana 60... (it all depends on how you stuff them)

If you are talking strictly rear axles, then I would agree that they get stronger with the higher number. Dana 70/80's are normally running dually rear wheels.

Willie, just so you know when I mention a closed knuckle design - Where your knuckle attaches to the axle tubes, if you can see the axle shaft u-joint, that is an open knuckle. Say a Rockwell axle, you cannot see the axle shaft as it is contained within a closed knuckle. Land cruiser front axles are also closed knuckle.

There is also a Dana 50, which if I remember correctly is a dana 44 inner with dana 60 knuckles. Wasn't the most popular, nor very strong.

Pieter

[712edf]

This is true. The 70 has bigger ring/pinion & housing but the 60 has the edge in the axle shaft area, and maybe more importantly parts availability. I guess the 70 could carry more vehicle weight but the 60 handle more motor.

[rxinhed]

Have you looked into the D60 rear-steer model axle on the late 90's + GM trucks? This could solve some of the driving-on-public-street concerns for you. Second, the D80 is offered as the front axle on late model F550 trucks.

[pieter]

Have you looked into the D60 rear-steer model axle on the late 90's + GM trucks? This could solve some of the driving-on-public-street concerns for you. Second, the D80 is offered as the front axle on late model F550 trucks.

I didn't pay much attention to that rear-steer axle from GM, but I don't remember if it was controlled by driver input or if it just followed the front of the truck. I do remember that it was a very expensive option and very complicated for how little it did steer the rear wheels. I remember seeing a large surplus of them on auction because they were discontinued.

pieter

[Williespeed]

I just talked with a guy locally that thinks the 44's would be strong enough. I think with the future plans for the diesel I should run the 60's.

I think it would be cheaper to build it than canabalize it from a late model chev. I'll look for a cheap one ton I can drop my cab on.