Roll pin removal

[step2534]

The head on my Triumph has 4 roll pins that should protrude from the rocker box faces. These pins have for some reason been cut off flush with the face. I understand that they are required to help stop the cover warping when hot so preventing oil leakes. Any suggestion on how to remove these pins would be gratefully recieved. Ive considered spark erosion, as I see it I couldnt just drill them out because of the hardness of the steel. Thanks in anticipation of your assistance.  Keith

[Rex]

Not so much to prevent warping, but more for accurate location.
Such a PITA to get out...but have you tried running it as it is? It may be OK.
Failing that I would suggest trying to close up the roll pin's split with a hammer and drift to loosen it's grip, then either long-nose pliers, tap or tiny self-tapper to try and get a hold on it.
Twenty minutes at Regulo 5 would help loosen it too.... just make sure the Kitchen Boss is out..

[speedo]

Slide hammer to attach to head of self tapping screw , easy!

[esometisse]

Don't waste too much time on these pins. If they refuse to come out easily, leave them be. Make sure the joint surfaces are plane and use a modern silicone gasket compound instead of the paper gaskets and you won't ever have a problem with leaking rocker boxes.
My T140 racing engine has not a single paper gasket on its engine and it is as oil tight as it was when I first assembled it nearly twenty years ago.
Cheers
Andy

[L.A.B.]

as I see it I couldnt just drill them out because of the hardness of the steel.

Roll pins are not made out of a particularly hard grade of steel. They can usually be marked with a file or cut with a hacksaw blade easily enough-so there's no reason why they couldn't be drilled out with a sharp HSS drill bit (or cobalt tipped drill bit).      

[Rex]

The Spirol type might be drillable, but a proper roll pin (or spring tension pin) is made of very hard brittle steel, and that would really take some drilling.

[L.A.B.]

The Spirol type might be drillable, but a proper roll pin (or spring tension pin) is made of very hard brittle steel, and that would really take some drilling.

Well...if you say so? As I just drilled through one with a cobalt bit-after I'd tested it for hardness by hitting it with a hammer a few times (the first roll pin I hammered over to about 45 degrees before it snapped)  so roll pins are "hard" but not that hard. Therefore it ought to be possible to drill a roll pin end-on if cobalt or similar hardened bits were used.  

[step2534]

Thanks for your thoughts, LAB I think I will try warming it up a little in oven .Then try drill . My theory is if its a little loose ,drill might rotate it ,if it does and it doesnt bring it out then self tapper probably will. I cant understand why theyve been cut off flush.  Thanks for your helpwith this matter its much appreciated.

[yebbut]

They may have been cut off flush if your rocker boxes are a mismatch and do not have the necesary holes.

It would of course have been better to drill some holes inthe rocker boxes but sad experience shows that home bike mechanics don't think like that.

On no account omit the rocker box gaskets, and if possible use wire re-inforced ones as per original if they are still availiable.

[L.A.B.]

You could try the self tapping method first, although I'm sceptical that a self tapping screw will cut a thread into a roll pin?

If you drill first and snap the bit off in the pin then it's 'game over'.

Use cutting fluid or oil when drilling and try to keep the drill bit cutting, if the bit starts skidding then the pin rapidly begins to work-harden. As you say, spinning the pin out may be your final option? I seriously suggest you use a bench drill to do this, and not a pistol drill.

[Rex]

Well...if you say so?

 Sure do. The ones in the kit pictured look like Pound Shop items (certainly look to be recently made and of Far Eastern manufacture anyway) but as the Triumph ones were most likely the of the correct hardness I think you'd struggle with them.

We use RS roll pin kits for a variety of machine uses, and the trick some use to start a tight pin is to lightly squeeze the open ends together to form a lead-in. Try that with the older spring tension pins and they snap down the middle.
I think drilling will lead to at best a blunt drill bit, and at worst, a snapped off bit...not good.

 

[L.A.B.]

The ones in the kit pictured look like Pound Shop items (certainly look to be recently made and of Far Eastern manufacture anyway)

Think what you like.

[speedo]

Stop buggerising around ,self tapper and slide hammer!

[step2534]

Job done thanks for replies. Tried drilling and tried self tapper ( I think the metal off the roll pin was too hard the self tapper didnt bite). To top it all one of the pins had a broken drill bit buried in it. In the end a engineer drilled them out with a hollow drill then sleeved the hole with a rod and re drilled the holes for the rollpins. Another job done What will be next?? Keith

[Blue]

A possibility for the home-mechanic trying to drill harder materials such as broken drill bits and ee-zee-outs is to sharpen the drilling tip of a masonry-bit.