king pin question

[David Anderson]

At the Eagle rally a guy showed me how to check for loose kingpins.

I tried that and found about 1/16" play on both wheels. Just enough to hear a slight bump when I use the pry bar Is that ok?  Seems like they should be tight as a drum.   Or do I have new kingpins and bushings in my future?   I lube the coach ever 6k miles per the Eagle manual instructions, and these were replaced in 2001, 120,000 miles ago at Krause Bus Sales in San Antonio.
Unfortunately they won't work on Eagles anymore, only school buses.   

If I do need to replace, which parts will I need and where do I get them?  I attached the eagle diagram

Thanks,
David

[David Anderson]

I had my wife pull up and down on the prybar while I stuck my head around the wheel. I don't think there's any slop in the king pins at all.  I think it is wheel bearing movement. How much of that is acceptable? My seals are not leaking and the wheel hubs are full of oil as they should be. I may be worrying about nothing. Thanks David

[Jim Blackwood]

Wheel hub bearings are Timken type tapered bearings. This type bearing is designed to operate with a certain amount of preload, meaning that clearance or freeplay is less than zero. If they are run with clearance it allows the rollers to skid which causes flat spots and dramatically shortens the life of the bearing.

Jim

[David Anderson]

Probably need to change the title to wheel bearing check.  I went through the preload procedure when I changed my bogie wheel bearings last year. https://www.busconversionmagazine.com/forum/index.php?topic=33821.45

Looks like I'm going to have to pull the wheels, bring out the dial indicator and check the play.  Better to do it now in the barn than out on the road

http://autoam.timken.com/techseries/trb_pages/TRB%20Adjustment%20RP-618.pdf

[chessie4905]

You need a large prybar or a piece of pipe long enough to get good leverage. 4 ft long works with about 10 inches under tire.  Remember that you have a heavy wheel and drum there.. Do it before greasing.. Check up and down and rock in and out. You can snug up wheel bearing temporarily  to eliminate slop in it. I've  seen 1" slop on medium duty trucks that were really worn.

[David Anderson]

Ok, so the king pins are tight as a drum.  The little bump I could feel is wheel end play, so I took the hub off and put the dial indicator on and it was .003 which is within stemco's specs.  Therefore, all is well.

But there is 120k miles on those bearings and seals.  Should they be replaced?  Nothing leaking. 

In the picture, that is as close as I could get the needle to the center because there is a pilot hole in the center of the axle.

[chessie4905]

should be ok, but I would pull them out and inspect them if it were mine. be sure to check the surface under the rollers for pitting. Many over look the inside race. Wouldnt hurt to do new seals while you are in there.

[dtcerrato]

should be ok, but I would pull them out and inspect them if it were mine. be sure to check the surface under the rollers for pitting. Many over look the inside race. Wouldnt hurt to do new seals while you are in there.

Never really thought like that of the "inner" race... I always assumed if the bearing rollers were looking good the race under them.would be as well. Never had one bite me back...

[luvrbus]

1/16 of play could be the upper or lower a frame bushing too on a Eagle you are not dealing with a straight axle setup like most older buses used with  a king pin through the axle

[chessie4905]

Ive seen them already with deep pits and rollers looked ok.

[David Anderson]

1/16 of play could be the upper or lower a frame bushing too on a Eagle you are not dealing with a straight axle setup like most older buses used with  a king pin through the axle

I can't feel any play other than the end play on the wheel.  What should the king pin play be?  I figured zero or none.

David

[Jim Eh.]

King pin play is about .020 max
When checking for wheel end play with the axle (or lower control arm) raised and supported, have a helper apply firm but steady brake pressure. This will tell you if any play is king pin or bearings. When you apply the brakes it takes up any bearing play and anything left is strictly in the king pin.
Tip: If you have an I beam axle, just raise and support the side you are checking. No rocking = better diagnosis.

[Jim Blackwood]

I went to Timken's tech site and registered just to check and see if anything has changed. It has. In the old days Timken had directions for setting tapered bearing preload that appeared to be written by a bearing engineer or doctoral candidate. But once you plowed through all the jargon what was left was a rather complicated and precise method that most shops would not have the equipment for. The adjustment range seemed to be pretty tight, and I expect that about the only place where those procedures are actually used is in aerospace and similar critical type applications. Certainly not in the transportation industry.

Today, they still recommend using a dial indicator to set the bearings but they no longer insist on preload. Instead, for commercial hubs they give a spec of .005" or less of end play. What this means in a practical sense is that they have recognized the impracticality of asking industry service members to set bearing preload to accurate standards, and have accepted that a small amount of clearance can still give reasonable bearing life. Apparently they have determined that roller skidding is not quite the problem it was expected to be, and is in fact less of an issue than having too much preload, resulting in bearing damage. No doubt temperature changes and the common use of aluminum hubs also played a part.

So there you have it, the modern stance of the most well known bearing manufacturer in the world, as given in their training program.

Jim