Solution to the bad AC model D grader steering

[JF in MI]

I had asked this question in the Allis Chalmers section but I figured I?d post the results here. I had an AC model D road grader with manual steering and besides being a killer to turn the box was shot. Looks like the needle rollers in the worm roller shattered and fell down into the sector shaft and chewed everything to pieces. Could not find parts to rebuild it even if I wanted. Some of the AC boys said they converted theirs to power steering with a modern box. Did some research and bought a used Chevy S-10 box which had the proper (standard) rotation and had the same sector shaft splines. Got a couple of adapter fittings (to join the metric ?O? ring joints to AN-6 hydraulic) on Ebay. 26? coil of 3/8? steel tube from Autozone and some more hose adapters and a piece of 1 and ?? pipe from Home Depot. Some assorted bolts from Tractor Supply.
3 holes mounted the box to the side of the section that used to house the old box. Lengthened the steering arm about 8? to compensate for the new box position. Made an adapter to the input of the box using half the rag joint piece off the new box. Tapped into the hydraulic system before it goes to the blade control valves. Works like a dream and can steer sitting still with one finger. Only issue is the fluid gets warm real fast from being forced through the smaller tubes.

 

[JF in MI]

Forgot to add; whole mod cost under $100.

 

[Bob Bancroft]

Nice. Perhaps a priority/flow divider would help the heat issue.

 

[morgan in ar]

Nice.

 

[Adirondack case guy]

Nice job. Especially finding a match for your existing steering arm. As for the heat problem, perhaps a fined cooler in the return side side of the circuit.
Loren

 

[JF in MI]

I'm waiting to see how bad it gets when we do our "monthly" grade of the community roads.

 

[f2355j]

WOW You did a first class job on that!! Great to see something done so nice, I put a charlynn unit on mine but the gearbox was ok yet.

 

[jm.]

I am like Bob B I think a priority valve there where you hooked on the hydraulics would solve the heat problem.

 

[Case Nutty 1660]

Nice job, I agree the heat issue should be solved by putting in a flow control valve and not run full hyd flow through the sector,, it should only take 3-5 gpm to steer it fine
cnt

 

[MarkB_MI]

I like it. Nice job!

 

[DonBC]

Excellent job. I am amazed that the splines on the new box matched the grader's steering arm. Who would have thought? There must be some universal standard for steering boxes. Power steering sure changes how a person feels about these old beasts as they were a *itch to steer.

 

[Andy Martin]

Looks great, just needs yellow paint.

 

[Andy Martin]

(quoted from post at 17:46:27 05/22/16) Excellent job. I am amazed that the splines on the new box matched the grader's steering arm. Who would have thought? There must be some universal standard for steering boxes. Power steering sure changes how a person feels about these old beasts as they were a *itch to steer.

SAE standards have been around for many years, and there were not many reasons to change them. The fact that they match tell me the S-10 box is a good fit, because the loads are similar. Even big companies like GM use standard designs until they find they can make more money with an alternate design.