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Post by stinger440 on Jan 17, 2013 8:15:15 GMT -5
I'm mostly into the '71 wedge stingers. I am just curious why Scorpion ran a 21/43 gear set in the Sachs 440 chassis while everything else ran a variation off of 38 tooth lower gear. All the way up through the 1980 model year it seems everything is 18,19,20/38? I guess I just had a random thought as I was digging through gears trying to find a 21 tooth with the correct offset for the early chaincases.
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Post by obj1 on Jan 17, 2013 11:23:12 GMT -5
Pararailer told me these 440 sachs engines are wild! When you bought this sled new and checked the box for the "BIG" engine you also got the "BIG" gear. You also got the wedge hood for down force at high speed! Have you noticed that when you get close to 100 they seem to get more stable?
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Post by scorp11 on Jan 17, 2013 17:50:55 GMT -5
Methinks obj1 has been inhaling too many race fuel fumes. I didn't see his marbles layin' on the floor when I was there, so that must be it :-)
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Post by mooreperformance on Jan 17, 2013 18:42:49 GMT -5
Stinger 440
I think it may have had something to do with the chain case eccentric. The newer sleds had chain tensioners (I believe 1973 and newer). The 440 Sachs in 1971 had the eccentric to tighten the chain. I seem to recall one instance where we used a different set of sprockets and the eccentric wouldn't either 1. take out all of the slack or 2. was still to tight with the eccentric all of the way loose.
Can't remember but I don't think it was for any reason other than we couldn't actually fit the sprockets and gears into the chain case and adjust the correct chain tension with the eccentric.
Also, if I remember correctly the 1971 eccentric (first year for the aluminum chaincase) was smaller or larger than the steel chaincase. I think it was smaller (with less chain tension adjustment)!
Who can remember such things?
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Post by obj1 on Jan 17, 2013 21:32:46 GMT -5
And********21/43 is real close to the same ratio as 19/38. Heard around town there might be some 43t sprockets in a chain case or two.
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Post by stinger440 on Jan 18, 2013 8:30:29 GMT -5
MP you make a good point with the chaincase design but the other Stinger models with the same chaincase have the 38 tooth lower. OBJ1, that was my point, 21/43 is so close to 19/38 why didn't they just stick with the 38? I have 2 '71 stinger II's, one has the 21/43 and one has 19/38 with 440 sachs engines. I need to go faster so I am going to try 21/38 and see how that works. Because who doesn't enjoy driving a high speed wet noodle  |
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Post by mooreperformance on Jan 18, 2013 13:02:36 GMT -5
Just make sure that when you change your gear ratio that the clutches shift out all the way to high gear ratio and you are getting maximum engine rpm (when shifted out completely).
I believe max RPM for a 440 Sachs is 6500 (maximum horsepower is made at 6500 rpm).
It is possible to get max RPM but still be not be shifted out completely! This means you are geared too high (too much gearing)! The stock gearing should be right-on. I would suggest going the other way (gearing it lower).
You will need an accurate tachometer to read your maximum engine rpm. You will need to test the sled without a clutch guard to see if the belt is riding on the top of the drive clutch at max speed and rpm (carefully).
Have your clutch center-to-center right on with the correct length belt!
If you get everything right-on you will be very happy with the performance of a 1971 Stinger 440 Sachs!
Dennis
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Post by stinger440 on Jan 18, 2013 13:34:14 GMT -5
Thanks MP. I trail ride one of the sleds which is an actual sachs chassis with the 21/43 gearing and a 73 style drive clutch. And it runs out well. My "race" sled is a CCW chassis that I have a 440 sachs in, still running the dual inlet doneldson exhuast. Using a powerthrust II clutch with 4 washers, 19/38 gearing with a 73 style chaincase. It does run out well but there is a 440 silver bullet that I just can not keep up with. I have changed belt compound and added more traction. My tach is not that accurate but it bounces between 6500 and 7000 with a full shift out. Maybe I should swap gears and run the 21/43 and see how that works.
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Post by mooreperformance on Jan 18, 2013 17:05:42 GMT -5
I was working for a Scorpion Dealership in 1978 and we installed Power Thrust II (Duclo) clutches on quite a few sleds back then.
The sled would come out of the hole like crazy but no matter how many washers and different springs we tried we always lost a little top speed to the Power Thrust I!
We even had a chassis dyno...when testing on the dyno we always lost out on top speed with the Power Thrust II.
The Power Thrust II was better in deep snow because it would backshift much faster (downshift).
You should try both style clutches in a back-to-back test and see for yourself!
For a not-to-fancy spring loaded roller clutch (Salisbury 910 copy)...that Power Thrust I actually works pretty darn good!
Dennis
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Post by scorp11 on Jan 18, 2013 18:57:08 GMT -5
Using a powerthrust II clutch with 4 washers, 19/38 gearing with a 73 style chaincase. For anyone using or Powerthrust II or thinking of putting one on something, just be aware that starting in 1979 there were two styles of weight arms. The ones in the higher HP sleds were a heavier arm. The lower hp sleds used the pre 1979 arms. pre 79 440 cuyuna's took 8 washers on the arms. 79 and up 2 washers. If you put 8 washers on the newer arm, even a 1979 Sting won't like it. |
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Post by stinger440 on Jan 18, 2013 19:05:35 GMT -5
MP that is exactly what I have going on. That sucker comes out of the hole like a bat out of Hades. (I mean like a 71 stinger II bat ). I have a few good powerthrust I's I will give that style a try. This is great information. Was there much difference in the I's? Because I am not sure what sleds they came off of. I know my rollers are round and the center bearings run smooth.
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Post by admin on Jan 18, 2013 19:59:44 GMT -5
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Post by obj1 on Jan 18, 2013 20:48:31 GMT -5
Be careful about running with no clutch guard. I have a story about that and its also tied into the 70 stinger rear bumper designs. Ask me at waconia, i'd love to tell you. Tom
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Post by mooreperformance on Jan 19, 2013 15:22:04 GMT -5
The Power Thrust One had two different roller weights, with a solid pin and a hollow pin. Also they had a standard tension spring (left and right) and a stiff spring (left and right). I believe we had a slight decrease in top speed with both stiff springs installed but the engagement speed was much higher.
We experimented with one standard and one stiff on each roller. It was a good compromise between low speed and high speed performance.
I wish I could tell you more but I am an old man now and my memory is starting to fade! Ha!
We did a lot of experimenting back then, wish I would have written some of it down...but who knew we would be talking about it 40 years later? Besides, I was just a (snowmobile fanatic) kid of 18 attending Anoka Vocational Tech School for snowmobile repair.
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Post by mooreperformance on Jan 19, 2013 15:33:44 GMT -5
"MP that is exactly what I have going on. That sucker comes out of the hole like a bat out of Hades. (I mean like a 71 stinger II bat ). I have a few good powerthrust I's I will give that style a try. This is great information. Was there much difference in the I's? Because I am not sure what sleds they came off of. I know my rollers are round and the center bearings run smooth. "
I think if the Scorpion guys could install a driven clutch cam with a 41 degree ramp and a stiffer driven clutch spring the Power Thrust II would work better. It would upshift a little faster/easier and not lose as much top speed.
I wonder if someone could machine a standard Scorpion cam to have a steeper angle and then have someone make some stiffer springs? It would be fun!
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Post by stinger440 on Jan 19, 2013 17:11:14 GMT -5
I have a setup that I drilled a couple holes and have a polaris red spring installed. I just have not had any test time to try it.
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Post by mooreperformance on Jan 19, 2013 18:31:57 GMT -5
Now thats what I am talking about!
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Post by mooreperformance on Jan 19, 2013 18:48:55 GMT -5
When I worked for the John Deere Dealer (Scharbers and Sons in Rogers, Minnesota) the John Deere rep felt that secondary clutch spring tension was so critical that they made us buy a fish scale to check/measure the secondary sheave opening tension/pressure!
We had specs to follow!
Then I went back to work for Scorpion in 1978 and they just didn't think it was important at all! Actually didn't know what I was talking about!
Those low speed/high torque 440 CCW reed valve engines really ran better (440 Cyclone John Deere) when the 41 degree driven clutch cam was installed because they upshifted faster and utilized the torque of the reed valve engine design much better.
You could actually feel them pull harder when trail riding!
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Post by obj1 on Jan 19, 2013 21:39:29 GMT -5
Ya hit on something there MP. On our 340ss singles (we race 4 of them) we run 3 std springs and 3 hi rev springs on each clutch.
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Post by stinger440 on Feb 13, 2013 10:21:58 GMT -5
After marking the PTII and doing a couple runs I found out it was not shifting out all the way. I replaced it with a PTI, went throught the sled and made sure everything was square and there was no binding anywhere. So far I have noticed it idled much higher on the stand and engagement is lower. I had to lower the idle speed some. Saturday I will find out if it made much difference on the top end.
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