Help with clutch adjustment and identification on Coot

[allwheeldrive]

So I recently replaced the very worn out belt on my Coot, the original was starting to delaminate and was WAY too long (could easily pinch the middle together, in fact it could be removed buy just slipping it out of the pulleys!) Since the previous owner had installed a new engine he simply ignored the much too long belt and all the slip it had when driving, not acceptable. So I precisely measured for a new belt and installed it. The belt now fits perfect with about ½” of deflection and turns easy on the engine clutch when off. However the engagement speed on the drive clutch is MUCH too low, it is impossible to change gears and even letting the engine run down to a couple hundred RPM into a stall is not enough to disengage it.

My first machine the Scrambler had the same problem, it however had a comet clutch which I easily could pull apart and put spring tensioners in the form of sectioned pipe against the main spring to get the engagement RPM right. However on the Coot the clutch is SO close to the tub it can NOT be removed while the engine is still in place. Worse the engine is squeezed against the front brake so if I want to pull the clutch out I will have to pull the engine up and out as well )-:

Before I do all that work if anyone knows what make and model this clutch is and how it is adjusted that would be great. My old Comet when you undid the bolt the end would spring off. This one when I undo the bolt just slides back and forth on the engine shaft as one unit.

[msafi65]

The clutch appears to be a 780 series comet. I can see it's completely disengaged now. I find that loosening the belt slightly to lower the drag on the inside of the belt can help. A belt will usually squeal on the inside hub of drive clutch when driven is held or transmission is in gear. This clutch is calibrated by changing the roller weights and springs.

[wedge]

Your side sheaves look like thy could use a Polishing for sure. That would help it not pull on an idle .

[allwheeldrive]

Googling 780 series comet it does look like that model, it does squeal a lot, especially when I turn the engine over while in gear (as there is NO way to change out of neutral once the motor is running) In fact the starter will actually turn the tires the clutch engages so fast! There is sadly no way to adjust belt tension. The engine and transmission only have one place they can be bolted to the floor, the old belt was 52" and as I mentioned unbelievably lose. I made a mock up belt that fit perfectly at 42", the closest belt size I could fine that matched was 42.2" so it really was pretty much perfect. In the 1 3/16" belt thickness I'd have to drop to a 39" or go up to a 56" the is no other in betweens and I looked everywhere.

Wedge don't tell me that, it took 2 hours to get them nice and rough with some 320 grit sand paper! Lol, I really don't think the roughness is the problem, It could be contributing but I think the springs must just be set too soft. I'm really hoping it can be modded like my older Comet, anyone have pictures of one of these dissembled?

http://i130.photobucket.com/albums/p278/chriskent85/IMG_20150121_172714474_zpslgqcdtu8.jpg

Yikes this looks complicated how is one supposed to adjust this? Buy new springs? Where would I even start?

I now recall my old one was a Comet Duster. That thing was super simple, though I doubt it could even fit in the small space in the coot.

Thanks,

[msafi65]

If the movable face moves in at idle the clutch is wrong. If it truss to crawl when cranking the belt is to tight. I see several belts listed in the 42.5-44" Carlisle spec sheets. The max series belts are measures to the top width and do not taper to the edge. I run belts run them from widths listed as 1-5/32-1 7/32 top width. Also put a tacometer on engine and slowly raise speed until you see the movable face of the clutch jump in. Usually 1200-1700 rpm is in the ballpark. Then call Don Jackson 608-774-0481
He can tell you what weights and springs make up any engagement speed you want. He is at Certified Parts Corp. the company that now produces comet products. Hope this helps.http://www.hiperf.com/acatalog/beltdimensions.pdf
Check out Max3 dimensions, I see the top widths have gone away from 32 of inch from my old chart.

[allwheeldrive]

Why is this so complicated?



Ok my buddy and I are stumped after wrestling the clutch out and taking everything we could off of it (bolts, retaining c-clamp) all it does is rattle we can NOT find a way to open the unit. What are we missing? If we pull up on the outer curved case all it does is hit the flange of where the C-clamp was.

For such a popular unit it also bewilders me that we can not find any videos or "how to" in dissembling it.

[wedge]

Spray some PB Blaster on the center of the Bell where it is center shaft then Gently pry it around the lower edges to pop it off.
Looks like it is just rusted on there ?
The only thing holding the bell on is the snap ring and the 3 bolts so it should just pop off !

[dirtdobber]

Allwheel, look carefully around the center shaft and see if has any swollen spots as a result of someone driving it onto the engine with a hammer. A swollen spot will keep the outer cover from coming off. If you will take a file and dress the outer edge of that center shaft it may help you a bit, if it is in fact swollen in places.

[wedge]

Good point ! I forgot about that

[allwheeldrive]

Allwheel, look carefully around the center shaft and see if has any swollen spots as a result of someone driving it onto the engine with a hammer. A swollen spot will keep the outer cover from coming off. If you will take a file and dress the outer edge of that center shaft it may help you a bit, if it is in fact swollen in places.

THANK YOU! I wouldn't have thought that could have been a possible problem but it was what had to be done. We removed a scary amount of material before it finally slipped off. The weird thing is the metal was mushroomed out exactly as you described but from the inside edge not outside almost as if extreme force was pushing the bell housing up. Well the cover is off and now I have more questions. I see the 6 horizontal springs set in their 3 groups against the rollers they are very rusty I see no way to identify what color they once where. The thing I'm confused about is whether or not there is a "main vertical spring" Such as this: 300397C DRIVEN SPRING RED 780 DRIVEN - COMET

I don't see any big center spring like on the duster just the 6 small outer springs, is there no main spring as I linked above hidden somewhere? And if so how do I access / find it? Do I have to remove all 6 smaller springs first?

Thanks for all the help guys!

[allwheeldrive]

If the movable face moves in at idle the clutch is wrong. If it truss to crawl when cranking the belt is to tight. I see several belts listed in the 42.5-44" Carlisle spec sheets. The max series belts are measures to the top width and do not taper to the edge. I run belts run them from widths listed as 1-5/32-1 7/32 top width. Also put a tacometer on engine and slowly raise speed until you see the movable face of the clutch jump in. Usually 1200-1700 rpm is in the ballpark. Then call Don Jackson 608-774-0481
He can tell you what weights and springs make up any engagement speed you want. He is at Certified Parts Corp. the company that now produces comet products. Hope this helps.http://www.hiperf.com/acatalog/beltdimensions.pdf
Check out Max3 dimensions, I see the top widths have gone away from 32 of inch from my old chart.

Thanks for the link and info, I'll look into it once I figure out how to take this thing fully apart.

[dirtdobber]

That red spring you saw is in the driven clutch, not the drive clutch. You are working on the drive clutch.

[allwheeldrive]

OHHHH! that makes sense now

Though now I'm not sure if I should just put the clutch back together and try a bigger belt. It stinks I have no room for adjustable as it is, the coot's tub has been bent and cut to fit the engine from side to side. And it seems like 1/2" of belt makes a huge difference in tightness. 52" = a full FOOT of deflection, 49" = 1/2" of deflection. I might be able to get by with a 50-51" belt, you mentioned you can run belts from 1.156" to 1.218 wide. I'd think the wider would engage faster. Or maybe the difference is so minute it doesn't matter? The list of belts provided seems lack anything between 48-and 51 less than 1.4" wide so maybe this isn't an option after all.

Am I right to think a belt of this design will not work? With the grooves facing length wise? https://www.amazon.com/Gates-500L6-M.../dp/B00CJKB6X4

[wedge]

That is a Serp belt NOT a CVT belt .
You need a Belt for a Snowmobile .

[dirtdobber]

Allwheel, look at the chart about 6 pages into this document. http://forums.bajasae.net/forum/uplo...TY_CATALOG.pdf

This gives you the required CD (center to center distance - crankshaft to transmission input shaft) and related belt part number, all based on the type of clutch configuration you have. To get the correct belt tension, you have to get pretty close to these dimensions, because there aren't a whole lot of options when it comes to belt lengths.