Poly 318, NP205, Dana 70 axles.

[Deathdeelr]

Since they are facing each other, wouldn't that mean the axis(pl) of their centerlines form an 8 1/2 degree angle?

Bucky, this is what I thought in the beginning. However even though the t-case is tipped up so long as both yokes have the same angle (measuring from the vertical) no matter what that angle is (lets not get crazy, we're talking less than 5 degrees) and both yokes are in phase you won't get any binding or vibration.

Jonas from what you're telling me you have 2.5 degrees of positive caster which puts the contact patch of the tire behind the axle. I got a quickie measurement on my 880 a little while ago and got 4 degrees negative (D44; contact patch is in front of the axle). The diff case is pointed almost level; less than a degree down maybe. I can almost guarantee that the yoke on the t-case is slightly up just an eyeball measurement. I had an alignment done on my wife's Jeep not to long ago and the caster reading is 4 degrees negative.

I'd say go ahead and get your driveline angles matched up and continue the build. Then the only real test will be a drive down the road. If the truck is wandering and hard to control then you need to think about getting that caster pushed into the negative. If the truck drives fine then great, the positive caster isn't affecting the overall setup.

[712edf]

I'll throw in there the notion that factory prefered caster settings changed when power steering became more popular. The older manual steering trucks were designed a bit differently.

Bucky

[Deathdeelr]

That might explain the measurements. A truck with positive caster would be easier to steer than one with negative measurements. Power steering and negative caster would make the vehicle more stable at higher speeds. Since the axle was probably never designed to exceed 50 mph and without power steering the designers pitched it forward to make the steering as easy as possible. You learn something new every day.

JONAS, BUILD ON!!!! YOU'RE ALL RIGHT!!!!

[712edf]

The gospel according to Chilton

According to Chilton's Manual 8662 1967-88 Dodge & Plymouth Full Size Trucks.

" Caster is the backward or forward tilt from the verticle plane of the steering knuckle centerline at the top, measured in degrees. A steering knuckle tilted backward has positive "+" caster, while one tilted forward has negative "-" caster. Positive caster produces greater directional stability and requires greater steering effort, since it increases the self centering effect at the steering wheel.
Caster cannot be measured without professional equipment."

The chart shows the prefered caster reading for 1972-74 W300 (which would have a Dana 70 front) to be at 3 degrees positive caster.

And yes Chilton's has been known to be incorrect before.

Bucky

[712edf]

A poor visual aide

The front "casters" on a shopping cart are a good example of NEGATIVE caster (tilted forward at top). They turn very easy and have very poor directional stability.

Of course this is an apples to oranges analogy since auto wheels and shopping cart wheels aren't attached to same in respect to "pivoting" vs turning. But I hope this gives a good picture of "caster".

Bucky

[Deathdeelr]

I guess I reversed my positives and negatives. No wonder my shoes don't fit right :)

[Jonas Smith]

Custom Bumper and Capstan MU-2 winch installed...
Waiting on drivelines from the driveshaft shop.

[Jonas Smith]

Pictures of Progress...

Rear Bumperettes.



NP205 tcase with PTO installed>



Hanging Pedal MC (maybe)

[Jonas Smith]

Cab and hood fitment.

[Kevin Mienke]

The project is shaping up real nice. I like the nice high look of the cab. It appears to be a few inches taller than stock.

The M/C looks very clean, but I wonder if you'll want a dual reservoir M/C with the potential speeds this truck will have.

I envy you to be elbow deep in such a neat project.

[Jonas Smith]

Yep, you are right about the dual MC and especially since there is no hand brake yet.
I'm going to run with the juice brakes and a micolock system until I can figure out a way to hook a driveline brake up to the transfer case. And a set of wheel blocks.