Main wheel nut shim

woxofswa · #1 03-28-2016, 12:26 AM

One of my main wheel retaining nuts fits perfectly with its retaining pin holes. However, the other side is ever so slightly off on the shy side leaving just a tiny bit of wiggle. Advancing to the next hole is too tight and blocks enough of the axle hole to not allow the pin through.

Some say that a tiny bit of slop is okay but I would like to have it dialed in.

I know I can drill new holes 90 degrees off the current holes, but that counting turns process is still kind of imprecise.

What I'd like to try is putting a shim between the nut and the bearing face. Something like a modified retaining ring or thin washer(s).

I was wondering if anyone else may have had the same idea and discovered a source for the right size of shim?

deek · #2 03-28-2016, 04:08 AM

You're looking for stainless arbor shims. Precision makes them in the size you need in varying thicknesses; their website lists their stocking distributors. McMaster Carr has 'em too.

az_gila · #3 03-28-2016, 11:01 AM

A 1/12 of a turn is 0.005 inch for that thread size.

Just sand a fraction off the nut and it will give you that little bit extra rotation.

If it's "almost there" like the description in your post, then removing a mere 0.001 inch should do it.

F1R · #4 03-28-2016, 11:27 AM

Also remember that unlike automotive wheel bearing set up, the bearings on RV's are supposed to be tight enough not to spin freely by hand. This prevents rotation during flight.

woxofswa · #5 03-28-2016, 11:33 AM

Thanks Gil, but unless I'm missing something, that solves the positioning against the bearing, but misaligns the holes as the hole in the nut moves inward on the axle. Since everything is close tolerance size wise, the option then becomes drilling bigger holes or getting a thinner cotter pin both of which seem less desirable than shimming at the mating surface to keep the holes that were match drilled to each other properly aligned.

RV7A Flyer · #6 03-28-2016, 11:50 AM

Not at the hangar at the moment...someone have a size for the shims? Last CI I noticed I could use *just a teeny amount* of shim on one wheel...

Walt · #7 03-28-2016, 12:01 PM

Quote:

Originally Posted by F1R

Also remember that unlike automotive wheel bearing set up, the bearings on RV's are supposed to be tight enough not to spin freely by hand. his prevents rotation during flight.

Can you provide the bearing adjustment ref. that describes that procedure?

F1R · #8 03-28-2016, 02:41 PM

Quote:

Originally Posted by Walt

Can you provide the bearing adjustment ref. that describes that procedure?

In the F1 Rocket kit the Grove Installation Instructions for the wheels

Bullet point #3 describes the Pre-Load Wheel Bearings procedure. I have not looked on line yet but I suspect www.groveaircraft.com under installation instructions will locate the document. I'll edit with a link if I can find it.

edit:
The online instructions vary from the printed version that came with my 56-1A wheels. In the paper copy, it says to rotate the wheel and tire while snugging the bearing nut until you are unable to rotate the wheel and tire. Then to back off until on the edge of rotating freely.

Walt · #9 03-28-2016, 05:35 PM

The purpose of "snugging up" the assembly is to be sure your bearing and bearing races are fully seated, but in all cases, you back off until the nut until the wheel rotates freely, this avoids excessive preload on the bearings. You can find the same basic procedure if you look at the Timken bearing manual which I have posted links to in the past. Basically the nut should be hand tight, excessive preload will drastically shorten the life of your bearing.

BillL · #10 03-28-2016, 07:24 PM

Quote:

Originally Posted by Walt

The purpose of "snugging up" the assembly is to be sure your bearing and bearing races are fully seated, but in all cases, you back off until the nut until the wheel rotates freely, this avoids excessive preload on the bearings. You can find the same basic procedure if you look at the Timken bearing manual which I have posted links to in the past. Basically the nut should be hand tight, excessive preload will drastically shorten the life of your bearing.

Walt, many applications use preload for taper element roller bearings, but in this case the hot part that expands (aluminum wheel hub/ steel shaft) will increase the preload, is that why we simply snug it up? The downside of low preload is rotation of the inner hub, does that happen?