CJ3A Ross Steering Box improvement idea

[fasilpereira]

There is a guy here in Brazil selling repaired Ross steering boxes he made with serviceable parts. I'm not going that route, but one interesting mod he does is to replace the bushings by needle bearings. Has anyone tried or heard about that?

According to him, it improves the system and it is worth the effort. The sector shaft pins are still an issue, but the busing wear issue goes away. He also reports that the gear becomes more smooth because of reduced friction under loads.

I've asked what bearing he uses and was told it is a custom made bearing. Maybe suitable bearings are not available here, because the shaft is 7/8"and Brazil is essentially a metric country.... But I was able to find a needle bearing at McMaster Carr for a shaft diameter of 7/8", outer diameter is 1-1/8".

Looking at the pictures of the case, it seems that there is enough margin to open it to 1-1/8", but I'd need to check it with real measurements.

Another thing that may be an issue is the fit between the Sector Arm shaft and be bearing. The bearing I've found has ho specified tolerance and I still have to measure the diameter of a new sector shaft to evaluate the clearance between both.

One last thing to check is if the shaft hardness is enough to take care of the small needles without crushing.

It sounds like an interesting project.....

Thank you,

Fabricio

[oldtime]

I have never heard of needle bearings being used in place of the bronze bushing. So can’t comment much on that. Also I can’t verify but I certainly expect the sector shaft to be case hardened throughout.
An original used sector shaft can often be made serviceable IF the “taper pins” are the only defect.

[fasilpereira]

On old engines, the connecting rods were all bronze bushings. The gearboxes used to have bronze bushings. All these have needle bearings on moderns applications.

Needle bearings generally the best solution to high radial loads, specially in tight applications, where the clearance between the shaft and the case is small. That is exactly the case on the Ross gearbox.

Case hardening on the shaft is also a good thing if you can find a bearing that can run directly over the shaft.

The Taper pins will continue to be part of the problem, but the bearing will not wear like the bronze bushings.

The bushing wear is responsible for the major issue I see today on my steering box.

Thank you,

Fabricio

[PES]

I would think the clearance of a fresh bushing and unworn sector shaft clearance or even partially worn would not allow a proper viscosity lubricant to leak whereas needle bearing configuration would allow more potential leakage, or place a bigger load on the outer seal. 

I see a 160 weight lube on my 3b without leaks and original bushings at 74k miles.