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Gearing of panther 370

2K views 13 replies 6 participants last post by  kccats 
#1 ·
Hi, sled work fine but clutch cant fully close because of lack of engine power. From the shop manual, the gears are 18 and 44.
The sled can hit 80 mph slightly downhill on ice without overreving the engine (7200 rpm) which is dumb so i suspect the gearing are not good for this engine.
The cam arms always wears at 3/4 of its lenght wathever the clutch setup i use, done the sharpee test and the clutch can close fully.
What gears should i change and do i must change the chain to top at around 65 mph with clutch fully closed?
Thanks guys:)
 
#2 ·
18:44 is already really low geared with a 2.44 ratio. This calculator shows that ratio good for about 63 mph at 7200 (with 9 tooth drivers and 2.52" track pitch.) All sleds will go faster on slick surfaces, down hill, I wouldn't gear to that standard...

Snowmobile MPH/Gearing Calculator

The 18 tooth top sprocket chart in my Polaris manual doesn't even go to 18/44, it stops at 18/43. If you still want to re-gear, dropping a tooth on top or adding a tooth on the bottom (or both) usually won't require a new chain.
 
#3 ·
I show that in the 11 wide you can go to 16 top and out to 47 bottom.
The 13 wide goes from16 to 46 and the 15 17 to 45.
But I agree that that is VERY low already!
And you may just not have enough hp to pull the full shift?
It could even be in the spring?
I would call Greg Goodwin at (847)872-4001 and ask him!
 
#4 ·
Thanks alot for your reply guys. I will open the chaincase to see if i have already 18/44, shop manual say so but it doesnt make sens accordinly to the calculator if i have already thoses gears. Sorry what kind of chain do i have, is this the 11 wide? clutch and secondary worked last year by an established clutch guy, sled work great but narrow ratio change ending up to cam arms always rest at the same place on rollers. Sorry bad english :( i try to explain but not sure its clear for you :(
 
#8 ·
agreed with the 80 kph. I've had 2 380's and a couple 340s and the only time they went faster than 60 MPH was when they were dropped off a cliff. (aka, going down a very steep mountain).

One of the 380s was a Canadian Skidoo Touring. The speedometer didn't indicate MPH or KPH. Just had the numbers. That particular model of the speedometer was both, but you had to switch the cable from one port to the other. All that time I thought I was getting 75-80 MPH, turned out I was getting just 45-50 MPH.


How old is the motor and when was the last rebuild? Check compression lately?
Note, the smaller the motor is, the more of an effect a loss of power has. 370 with 110 PSI compression will still run, but will be lacking enough horsepower to be noticeable.
 
#10 ·
Also very noticeable would be a clutch in need of some loving care.
If it is binding you can chase carb and ignition problems until you are pulling your hair out in handfuls.
 
#11 ·
The sled goe 50 mph everyday, 60 if im lucky on very good condition. My point is that the clutch never fully close at those speed. The cam arms always wear at the same place. Yes on ice it will reach 80 mph. Just checked and yes i have stock gears, 18 and 44 so i want to change gear ratio for clutch fully closed at 60 mph or 65.
 
#14 ·
I tell ya what, does your chain adjuster have much slack, or is it fairly tight?
Do you have the external bolt adjuster?
I can hook you up (if I go that small and or large) I will send you what I have and you can try it for the cost of the ride!
If it works for you, Ill charge you Half of what new is! If not just mail them back!
If thatwould help let me know and this weekend I'll see whatI have!
But did you count not only the teeth, but also the links in the chain? What about the width, 11 or 13? Doubt it would be 13 or even 15?
 
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