Rocker arm end-float

[Deleted account 210214001]

So I'm a tad confused. I did my valve check last weekend -- piece of cake, by the way -- and in the process, checked the end float on my rocker arms. Where I'm confused is the location to check them. My repair manual (Clymer) and my repair DVD (the one put out by Jim VonBaden) both say to check the end float at the upper end of the rocker arm. St. Eptoe and largiader.com both say to check it at the bottom of the rocker arm.

I checked both. At the upper end, I've got about 0.100-0.120 mm. At the lower end, I'm down near 0.002-0.003mm. So by the "American" method (for lack of a better word), I'm within spec. By the "European" method, I'm below and should adjust.

Any thoughts? Greatly appreciated!

Bohdan

 

[RickG]

The clue is in the 'float' bit. The rocker arm is just a tube pivoting on a spindle so if you grab hold of it you can move it vertically up and down a little as it slides on the spindle. The only thing that limits the movement (float) are the big lumps of metal at either end that support it. It doesn't therefore doesn't matter which end you measure. The fact you got a lower reading at the bottom is because the wieght of the rocker arm makes it slide downwards and close up the gap

 

[Grizzly]

Use The End With The Largest Gap!!!!!

I think your problem is the "shape" of the wear - hence two different readings for the "same" gap simply pushed from one end of a shaft to the other
If you assume that your bike started life with the correct float, and since the parts were all new, it would be the same at both ends. But the end that wears (it could logically be the bottom - but depends on the thrust of the rocker action??) - does not wear evenly, it's more likely to be a series of circular grooves on the mating faces - so if you push the grooved ends together and the grooves nest into each other, the gap reading at the other end will be large . On the other hand if you push the non-worn ends together and check the other end, your feeler will only be measuring between the "bumps" on the two grooved faces and may only get a reading similar to spec. ie a smaller gap
Since any grooved wear will ALWAYS nest into each other during normal running you should always establish which end gives the LARGEST gap reading and then set the gap on that rocker by measuring at that end ONLY.
I hope this makes sense.
For example, using this method it's possible to reset the float on a rocker to the correct gap - ONLY measuring the end which had the BIG gap reading - when finished you should be able to REPEATEDLY insert the correct feeler into that gap to confirm your setting. BUT, if you try to check the gap at the end which originally had a smaller reading - ie had grooved wear, you may not be able to get any feeler in at all - but if you push the rocker back and forth you can feel the float is present and the reading will still be OK measured at other end.

Cheers......................Grizzly - I need a drink now!!

 

[Bronco Billy]

The idea is to set the clearance to the minimum specified.

Within the tolerances is not what your looking for.

 

[Smudge]

I think your problem is the "shape" of the wear - hence two different readings for the "same" gap simply pushed from one end of a shaft to the other
If you assume that your bike started life with the correct float, and since the parts were all new, it would be the same at both ends. But the end that wears (it could logically be the bottom - but depends on the thrust of the rocker action??) - does not wear evenly, it's more likely to be a series of circular grooves on the mating faces - so if you push the grooved ends together and the grooves nest into each other, the gap reading at the other end will be large . On the other hand if you push the non-worn ends together and check the other end, your feeler will only be measuring between the "bumps" on the two grooved faces and may only get a reading similar to spec. ie a smaller gap
Since any grooved wear will ALWAYS nest into each other during normal running you should always establish which end gives the LARGEST gap reading and then set the gap on that rocker by measuring at that end ONLY.
I hope this makes sense.
For example, using this method it's possible to reset the float on a rocker to the correct gap - ONLY measuring the end which had the BIG gap reading - when finished you should be able to REPEATEDLY insert the correct feeler into that gap to confirm your setting. BUT, if you try to check the gap at the end which originally had a smaller reading - ie had grooved wear, you may not be able to get any feeler in at all - but if you push the rocker back and forth you can feel the float is present and the reading will still be OK measured at other end.

Cheers......................Grizzly - I need a drink now!!

Wot he said

 

[GEOFFREY DEACON]

Sorry Geoffrey, completely the wrong info for oilheads - deleting it so as not to cause confusion