Rocker arms - shimming end float

The Other PaulG · Jul 11, 2005

Morning -

After a few attempts to get my valve clearances correct, I realised that the slight rattling I'm hearing is probably/certainly due to the rocker arm end float rather than valve clearances. The arm on the exhaust side has about .15mm of end float, which is visibly more than the other 3 rocker arms and is much more than what Haynes describe as healthy.

So......

Please can anyone help with these questions -

* Do any of our usual suppliers sell a mixed packet of shims, so that I can muck around until I get the right clearance?

* Can I add a shim to the existing one to create the right clearance, or must I use a single thicker one?

* Anything I need to know on re-assembly? (I can see the holes in the shaft that'll no doubt need to be carefuly re-aligned)..

* There is a bit of 'rotational' movement too, i.e. if you grab the rocker you can turn it a bit in the same plane that a clock's hands move, so am I wasting my time shimming when I really need a new shaft and rocker arm?

Cheers,

Paul G
(the other)

Antti · Jul 11, 2005

Bearings in rocker arms can be changed, so for that reason they don`t need to be replaced.

I have used shim plates wich are meant for industry use, at least from Wuerth i have bought those.

Don`t pull shaft fully out from arm, needles are hard to find from floor

Steptoe · Jul 11, 2005

you can use multiple shims,

measure the gap that you have in the rocker arm, and order the shims that you need from james sherlock, or your local BM dealer.

Check the specs for the gap allowed .

mikyh · Jul 12, 2005

No shims needed

You can adjust end float by inserting the right gauge foil, push the studs against each other with a vise (lightly) and than close down head bolts to spec.
I've done it lots of times, real easy, and even with my worn down valve guides my heads are relatively quiet.
Miky

Sean Kelly · Jul 12, 2005

Hi

I think I do the same as Miky but without 'foil'. If you loosen the head bolts, there should be some free movement in the rocker mounting pillars, squeeze them together 'lightly' to take up any float, retighten the head bolts (carefully, not to overtighten and strip the threads in the crankcases, ahem!!!!!) and check float again. Worth a try and a lot less hassle than changing shims.

Sean

Steptoe · Jul 12, 2005

Sean Kelly said:
Worth a try and a lot less hassle than changing shims.

Sean

I see your point, 10minutes is a big hassle .

Sean Kelly · Jul 13, 2005

Hi all

Erudite and apposite as ever

Strangely the Bajaj dealer in Delhi didn't stock suitable shims when I had more slack in my rockers than Steptoe ever cut anyone on this site

This approach was actually recommended to me some time ago by a BMW dealer, claimed he hadn't needed to use or sell a shim for a boxer in years.

Regardless, if after waiting for two weeks for your packet of shims to arrive, then bribing their way though customs and then taking the 10mins to fit them, would you still need to press the rocker pillars together to take up any float? Or can you actually work it all out and shim it accurately so that it all just 'slots' together?

Cheers

The Other PaulG · Jul 19, 2005

Done

Shhhhhhhhhh.... what's that?

That's my airhead going past with its smooth rocker set-up, that's what!

Thanks everyone for the advise and opinions - invaluable as usual.

Paul G
the other

scribbles · Nov 22, 2008

how much float should there be though? cant find specifications in my clymer manual, maybe im going blind!!?

Rob Farmer · Nov 22, 2008

scribbles said:
how much float should there be though? cant find specifications in my clymer manual, maybe im going blind!!?

0.05mm plus or minus 0.02mm

You can simply squeeze the rockers towards each other, however the idea is that if the tension on the arms is released and they are shimmed then the clearance will be maintained when the engine gets hot. They do always seem to be quieter when they're shimmed.

cookie · Nov 22, 2008

Rob Farmer said:
0.05mm plus or minus 0.02mm

You can simply squeeze the rockers towards each other, however the idea is that if the tension on the arms is released and they are shimmed then the clearance will be maintained when the engine gets hot. They do always seem to be quieter when they're shimmed.

my experience is, that even when shimmed correctly, doing up the head bolt will ruin it as the nut rotates and moves the support.
i shim it more or less right,insert feeler guage for gap, then squeeze the supports together with G cramps. tighten studs, done.

i wouldn't worry too much, i bet the rattling is something else anyway.

scribbles · Nov 22, 2008

thanks for the tips, my bike is stripped bare now trying to look for rattles. bet they'll still be there when its all together again!!! hopefully not the rockers though and i'll have a newly powder coated frame and if it rattles i'll know it's meant too. unless i botch it:[

Rocker arms - shimming end float

The Other PaulG

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Antti

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Steptoe

What a waste.

mikyh

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Sean Kelly

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Steptoe

What a waste.

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The Other PaulG

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scribbles

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Rob Farmer

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