Difference between revisions of "Minarelli crank shims"
Revision as of 00:41, 25 June 2019
How to measure v1 crank shims
Ok, you’ve reached this page because you have misplaced or lost your crank shim, or perhaps you are installing a sweet Treatland Crank into your Minarelli V1. The crank shim is hella important, and without it, there will be a lot of vibration and bad stuff happenin’ in your lil’ shitcycle.
What you will need:
1.) A comprehensive set of feeler gauges. Don’t use rusty ones or ones where the numbers are difficult to see. You need precision on this bad boi. 2.) A good digital caliper or a way to measure your current crank shim (if applicable), and your old gasket. 3.) A new gasket. The stock gaskets were typically .4mm in thickness, and newer ones can get gotted, but they may be a different size. 4.) Your old bearings, hopefully they are still in the cases. 5.) A hammer and punch.
Ok, so here’s the deal. A V1 needs an end play of .1-.2mm. But what does that mean? It means you need a teeny tiny little bit of clearance between your crank shim and your crank bearing (the 6203 guy).This allows the crank to seat against the bearings without heating up and causing them to bind, or pull out of their races, or e’ssplode. If you’ve lost your shim, and you did not measure its thickness, this method will allow you to replace it. If you are installing an aftermarket crank, you may find the crank is wider than stock, requiring a different shim thickness.
If you have your bearings still in your cases...good! If not, you can install your new bearings or find some decent old ones to use just for the sake of getting a good measurement. Make sure those suckers are seated and correct...treat this as if you were rebuilding a supreme race engine! What you need to do next is install your crank in the clutch side bearings. You do not need to install the rest of your engine guts at this time (the idler gears, output shaft, etc) as long as those shims are accounted for. Install your new gasket (make sure to measure it’s thickness first). Place the magneto side case on, and get it to seat. You will also need to seat your crank alllll the way against your clutch side case. You can use a hammer and punch to persuade the crank as far as it will go to the clutch side. Put the 11 case bolts in , and torque to 8 ft. lbs.
Start with a small feeler gauge ( around .1mm or .003”). Insert it in between the space where the crank shim should be. Make sure you are not hanging up under the crank lip (the lil’ machined face where the crank shim usually lives). Remember, you need a precise measurement of the space BETWEEN the crank shim face and the crank bearing. Keep trying different size feeler gauges in that area until you get one that fits snuggly. The feeler gauge should have some drag as it is inserted and removed from the shim area. Once you have found the winner, write that feeler gauge’s number down. PRO TIP: Use a flashlight to make sure you are not accidentally measuring the space UNDER the lip.
Let’s say you measured a space roughly .6mm in that area. You need .2mm of end play. That means you will need a shim that is .4mm thick. If you have a .5mm space, you will need a .3mm shim.
The Treat Crank is a well made aftermarket part, but my findings is that it is wider than some stock cranks (especially in the v1L). You will find that you may not have to use a shim. A quick reference is to use the calipers to measure your stock crank (from lip to lip) and compare the measurement of the aftermarket crank (again, lip to lip). If the width is different, be prepared to use a different shim.
It’s a lot of work to get that number, but not as much work as having to rebuild your engine every other day because some dumb little tiny piece of metal was too thick or too thin. Always remember to use stainless steel shims and not aluminum ones. You can use multiple shims to achieve your goal (ie: two .2mm shims to make a .4mm shim). Do not use more than 3 shims.