Forum bmwbike.com

Latly I disengaged both push rods' protection tubes from my R26's cylinder.

I cleaned with a brass gun brush protection tubes' holes into cylinder, because they was pretty dirty.

I gave both protection tubes to re-chrome.

But now, freshly re-chromed protection tubes move as freely into cleaned holes, as a piston in a cylinder.

The question is how to fix and seal proof push rod's protection tubes into cylinder ?

Any help appreciate,
damien

The problem was the chromed process.
May be you can seal it with some Locktite chemical fixation, or may be you can rechrom it.
The chromed process have a polish step, this one can't be applied to the inside section.

I've had this problem too. The chrome has to be a very specific thickness to fit properly into the cylinder head. The correct solution is to use new pushrod tubes. They are not too expensive. It's too bad, because the rechromed tubes look great, but they just won't fit properly.

Thanks for your comments !

If I understand you both, I should have asked for a more thick layer of chrome (or may be of brass underneath).

So I'll see if I find a good sealing stuff, other wise I'll have to ask Mark some new tubes.

Thank any way,
damien

Damien,..what are you doing?

The chromers strip off the old chrome, grind and polish the substrate, nickle plate followed by chrom plating the tube. If the diamter of the tube is too small afterwards, it means that they ground to much away. You can not say that they did not chrome thick enough, as the secret is a thin "Hard chrome" layer which is a totally different galvanising process.

The chrome tubes are originally precision ground and "Hard chromed". The portion that is pressed into the cylinder is a precision interference fit. You can't just go and rechrome the tubes and hammer them back in. If you do and it works, you were only lucky. That is why we make these tubes new out of stainless, as it is cheaper than a correctly done hard chrome job and precision grinding of the hard chrome. Instead, we especially had a stainless seamless tube of the correct diameter drawn, we precision grind the part that has the interference fit, press on the retainer ring, and polish the whole lot.

Best regards,

Mark
Mark Huggett GmbH

»What are you doing?«
Well, I had a batch of pieces to send for rechrome, so I put these «Protection tubes» with it, as they weren't so nice looking.

Any way, Thanks for your comment, I'll ask two of these V2A tubes in my next order.

damien