Pros and cons of installing needle bearings in the 7-tooth steeringbox?

[Johan Ottosen]

Hi everyone.
I have questions regarding installing needle bearings in the 7-tooth box.
The boring of the sector housing excluded, what are the pros and cons of the needle bearings?
- Is it more difficult to adjust?
- Is easier to steer at a stand still?
- What do I gain if I install them?

[Synchro909]

IMO, there is no up side. It being a fact that most of the time, the steering is at (or very close to) the straight ahead position with slight adjustments as we go. That leads to the rollers rocking back and forth in pretty near the same spot, wearing grooves in the shaft and/or housing. The result is the steering becomes "notchy". Not ideal!
Some ideas bring improvements, others not so. This is one of the latter.

[Johan Ottosen]

Good thinking, Synchro909. I will take that under advisement.

[BRENT in 10-uh-C]

Originally Posted by Johan Ottosen

Hi everyone.
I have questions regarding installing needle bearings in the 7-tooth box.
The boring of the sector housing excluded, what are the pros and cons of the needle bearings?
- Is it more difficult to adjust?
- Is easier to steer at a stand still?
- What do I gain if I install them?

I am going too add a tad more on this...

From my experiences, the Sector shaft surface is not hardened deep enough to provide support for the roller bearings. This causes the surface to become rippled since the needle bearing rollers are harder.

The problem that most rebuilders create when using plain bearing (a/k/a Bushing) is they do not size them correctly to the Sector shaft. Ideally these plain bearing/bushings need to be power reamed to size, -however most people use an adjustable hand-reamer to fit the bushing size. Under a microscope this creates a bearing surface that looks much akin to the teeth on a hacksaw blade. These pointed peaks do not have sufficient surface area to support the Sector, so they prematurely wear. As these peaks wear, the bushing size enlarges causing less area that is actually supporting the Sector shaft (so the friction is greater). Additionally, it can cause the Sector teeth to slightly misalign on the Steering Shaft Worm which also creates additional stress when turning.

You asked what you will gain. Generally speaking, an oil leak.

[Synchro909]

Originally Posted by BRENT in 10-uh-C

I am going too add a tad more on this...

From my experiences, the Sector shaft surface is not hardened deep enough to provide support for the roller bearings. This causes the surface to become rippled since the needle bearing rollers are harder.

The problem that most rebuilders create when using plain bearing (a/k/a Bushing) is they do not size them correctly to the Sector shaft. Ideally these plain bearing/bushings need to be power reamed to size, -however most people use an adjustable hand-reamer to fit the bushing size. Under a microscope this creates a bearing surface that looks much akin to the teeth on a hacksaw blade. These pointed peaks do not have sufficient surface area to support the Sector, so they prematurely wear. As these peaks wear, the bushing size enlarges causing less area that is actually supporting the Sector shaft (so the friction is greater). Additionally, it can cause the Sector teeth to slightly misalign on the Steering Shaft Worm which also creates additional stress when turning.

You asked what you will gain. Generally speaking, an oil leak.

I agree with that comment 100%. Moving to another application for reaming bushes on our Model As, I ream the king pin bushes till they are a bit too tight, then use the part of the old king pin that is clamped in the axle to lap them to the right size using valve lapping paste. A good clean up and they are better than would ever be possible with a reamer.

[guyd1957]

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My experience confirm exacly Synchro909 and Brent , in landing gear rebuilding we ream and hone the bore of the bushing and their life are very long , the surface contact to take the load of a needle bearing is far less compare to a bushing,

[rotorwrench]

I use the yellow series of Time Saver products on soft metals to lap. I only use an adjustable reamer if I have no multi-flute non-adjustable reamers. It's handy to have a lathe to fabricate mandrels for lapping or burnishing for a final fit when the reamer doesn't quite get it all the way to size.

Most folks don't have the patience or experience when using an adjustable reamer. The cheap ones aren't accurate enough to keep the cutting blades even enough. If a person has a good quality one, uses a proper cutting lubricant, and adjusts it properly for each pass through then they can get a good enough surface that time saver will make an acceptable finish in the end. It's sort of like the owl counting how many licks to the center of a tootsie roll pop. They tend to bite through before they get all the way done. I recommend a good multi flute reamer for most folks.

There used to be split flute reamers the had an internal ball or cone that could be adjusted to lightly expand the reamer flutes to better fit the new bushings in king pin spindles. These would get them very close for a final burnish to size. Ball burnishing is still used on some piston pin bushings. It takes special equipment that most folks don't have.

[Werner]

Needle bearings are poorly suited to impact loads. Therefore, a plain bearing is the right choice for mounting the steering.

[troubadour85]

Agreed, I did not in the past but after running needle bearings in a car I did over 10 years ago I pulled it apart a few months ago and it had significant notching which made me a believer. I'll look for pics of it.