The repinch process is not as much voodoo as people think. Ibelieve I was the guy Proanti was talking about who was using tool holders off of a high speed machining center to repinch my own and all my friends and family's cylinder sleeves. It works better than most people would think... you really have alot of control over how much you compress the top of the sleeve - and it only takes 5 or 10 minutes if you take your time.

Here is a pic of a similar tool holder that we use in the shop. The shows a complete tool holder with a collet installed. The nut (which takes a spanner wrench) tightens down over top of the tapered collet, which is setting inside of a tapered hole. As the collet is forced down into the hole, the diameter in the center gets smaller. All collets have a range in which they will work precisely to hold different diameters, and there are many different sized collets.



Here is a link that shows a picture of just a collet:


Now, there are different types of collets, and different types of holders. The ones we use at the shop are about the most accurate and most expensive type that you will find - most of the work I do requires extremely precise runout of the cutting tool as we commonly use endmills in the .005" to .010" in diameter... that cost $175 each. In order to make a tool that small and that expensive last, it has to be running almost perfectly true. That having been said, I suspect that someone could find a cheap tool holder on ebay for less than $50 that would do the job for pinching sleeves. Finding a lone collet the size you need might be a little tougher on ebay, but you can get them new direct from the manufacturer. One thing to remember... the inside diameter of a collet when not compressed is the largest diameter you can accurately hold inside that collet. You can generally go a mm or so smaller and still get good accuracy, but squeeze it more than that and accuracy starts to suffer quite a bit.

Now... when you pinch the sleeves with one of these, you can't just slap it in and pinch it straight... you would end up compressing the entire sleeve creating interference on the entire stroke of the piston. What you would need to do (this is what I do) is simply cut a short piece of precision shim stock, say .003" thick and .150" wide, to wrap around the top of the sleeve before you put it into the collet. When you tighten the nut on the tool holder, only the top of the collet will now engage the sleeve, prividing the taper you desire. You can actually put index marks on the tool holder nut so you can "sneak up" on just the right amount of pinch with tremendous accuracy by checking, pinching, checking, pinching, etc etc. . Actually, if you know the thread pitch and the taper of the collet and holder, you can trig out the exact amount you are compressing the sleeve for any amount of revolution of the nut. It is so accurate that you can literally go about .0001" on the diameter between checks. The shallower the taper, and the finer the thread pitch, the more accurate you can be on the pinch.

I am finding out that there is not really any need to put so much pinch back into the fit that you need to break the engine in again. The piston will already be shaped to the sleeve when you remove it, and you won't really change the shape of the sleeve with one of these precision holders... so all you need to do is pinch it enough so that you just get a little drag on the piston at the top portion of the stroke. If you measured it, you might only see .0002 to .0004" total shrink on the sleeve diameter. I have done this for a few people now, and it absolutely restores power. Since the pinch is kept to a minumum, you don't have to go through the break in process quite so drastically as on a new motor so you save all that stress and wear on the connecting rod and wrist pin.

Ihave not had to apply heat to get the repinch to hold.

At any rate, I really think that this is something that anyone could do if they get the right tools and take their time. As in any industry, sales and marketing people like to make the average citizen feel like their product or service offers something that can't be had anywhere else... that it's different beyond the wildest of our imaginations... Most of the time it's an exaggeration at best, and a flat out lie at worst. Stuff is usually simpler than we think.

Cheers.