Clutch Alignment

Have read many posts relating to this subject, seems they get muddled up with alignment bar differences, ways of measuring, it can't be done etc. etc. The key is understanding what's happening and how to go about it. It's simple shimming, but determining where and how much takes time to figure out. In order to keep this lenghty post as short as possible, I want to limit the procedure to the most common alignment problem, primary out .050 to .120 motor twisted clockwise in relation to jackshaft (secondary). Start by pulling primary, set aside but close by, remove bolt on secondary but leave secondary on jackshaft for now. Loosen front crossmember bolts, back out 1/8" or so, it doesn't really matter just so they're loose. Same with rear mount bolts. Back off torque stop(s) and and unhook torque link if so equipped. Now if you grab motor and jiggle it around, that is in essence what's available to shim around, but where to start? No beer breaks yet, the 900's sit in 4 point stance within bulkhead assembly, all 4 mounting points are important but the first one in importantance is rear mag side, because that's the one in closest proximity to jackshaft/chaincase assembly. If I'm seeking parallelism between crank and jackshaft this is great place to start, with the added ridgitity of chaincase, plus I have a bossed threaded hole on crankcase in which to run my motormount bolt into. So with everything loose try tightening the rear mag, and only the rear mag side. What happened? To see, slide the primary onto crank, just 'hand snug' and lay your alignment bar on it, now what is alignment to secondary? Better/worse? (add or remove shims on secondary to get accurate reading) If I were a betting man, I'm betting the alignment (motor twisted cw scenario) just got a whole lot better! Next tighten front pto side, any change? Check and verify with alignment tool. Try the front mag side, check and verify. That leaves rear pto side, in my experience, by far the biggest culprit in clutch mis-alignment. Now's a good time for a cold one.....By now you'll notice a large gap between inside of motor mount and boss of crankcase, measure it with feeler gauges. This where appropriate thickness shim/washer goes. But before that, just for giggles try tightening that bolt without shim and notice what happens. All that CW twist goes straight to the motor via the front rubber/urethane motor mounts! Is it a wonder these things fail so much, along with everything connected to them! Also check for parallelism on the vertical plane (Z axis), since ends of crank and jackshaft have been faced, spotdrilled and tapped, a good quality torpedo level is all that's needed, held flush on ends of shafts. Once these things are confirmed it's just reassembly, don't forget to set deflection, offset & float on secondary. I'm out!

Appreciate the positive response! Personally for shims, I use washers, bring a caliper when hunting, you'll be surprised how much 3/8" washers vary. Here's some pictures off my own sled, the gold colored washer on rear pto shot is approx. .120

Your welcome. Got a few inches of snow here in MN. so took sleds out on test run today, just a mile or so to check over summer work. The 900 is running strong, as is the newly acquired 600-I have to say that thing really is a potent machine also! Wow!

Good questions, glad you brought up c to c distance-11.5" when it's all said and done. The CW twist is usually, but not limited to the rear pto mount. So the way I read your description, there was only a few thousandths available for shim stack at rear pto? That's good, you gotta tight chassis, so to speak! Try different sequences on the bolt patterns when going from loose to tight, checking and verifing with align. bar after each bolt gets the wrench put to it. Look for available gaps at each of 4 mounting points as you go. When you find the best combination, which may be two opposite sides, measure with feeler gauges and shim. Personally if .070 was the best I could get, I wouldn't worry about it esp. if belt life was reasonably good. Now there are other ways to get creative but I wouldn't go there yet. With the hp & torque of the 900's, chassis flex, clutching forces etc. just back off torque stops a smudge @ final assembly. Keep us posted!

Go with your gut feeling, I wouldn't recommend slotting the holes. What's that line from the military flick where the guy is talking about his rifle.."there are many like it, but this one is mine", you've established the best motor placement for this given sled, you know this better than anyone right? Now some sleds are better, some are worse, but I would venture to say lots don't know one way or the other, not saying this to be mean but that's just the way it is. A typical human hair is .003 thick as is a sheet of standard notebook paper, so given the 900's power, 20 of either of those is no problemo! With the torque stops & link arm, not to mention the fixed front motor mounts, you'll be fine.

:boxing: Have a drink on me!