1970-74 Owatonna 1200 mustang

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r8183594

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Sep 16, 2006
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I'm looking for any kind of service, or repair manuals for this old skid steer. I've found an owners, and parts book for it, but nothing as far as service or repair. The parts book illustrates most assemblies through exploded views, but no troubleshooting, or testing procedures. The problem I'm trying to remedy is a "jerking" or surging through the drive wheels, ..not hydraulics, when pulling up a slight incline under load. I'm thinking my problem is in the clutches, and more than likely are past due for replacement. I'd just like to clarify this before tearing into it. Anyone have any information? My email is:[email protected], and any info is greatly appreciated!
 

r8183594

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Sep 16, 2006
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Well, I've discovered the cause is in the variable drive system. It doesn't appear to be "squeezing and releasing" the belt drive pulleys very smoothly and thus allows the belt to slip. Have to tear apart and get a better look. Am I the only one here that has this old of a machine? I couldn't beat the price, ..it was free!
 

Tazza

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Well, I've discovered the cause is in the variable drive system. It doesn't appear to be "squeezing and releasing" the belt drive pulleys very smoothly and thus allows the belt to slip. Have to tear apart and get a better look. Am I the only one here that has this old of a machine? I couldn't beat the price, ..it was free!
Well the price was rite!
It may be worth throwing a new set of belts at it, the ond ones could be worn?
 

skidsteer.ca

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Jan 20, 2006
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Well the price was rite!
It may be worth throwing a new set of belts at it, the ond ones could be worn?
Any Polaris atv or snowmobile dealer could give you a few tips on variable belt drives as all there atv and snowmobiles use them.
It is basically a matter of balancing the centifugal (RPM) activated weights against the force of the springs. One in the drive clutch and one in the driven pulley. I have no particular on your machine but have dealt with atvs and sleds using a belt drive.
Make sure the bushing that the sheeves slide on are not wollowed out and that they have some lubrication (no so much that it gets on the belt) These need to slide freely, without binding so the upshift and down shift are smooth and predictable and controled only by engine speed and not friction.
The springs that hold the clutch disengaged at idle and control the upshift from low to high ratio can get weak over time and allow the upshift to come at a lower engine rpm causeing bogging the engine.
Take the drive and driven apart and clean and lubricate the clutch and driven pulley. Look for worn weights, weak or broken springs loose bushing and any binding that prevents the smooth movement of either pulley.
Also it is good to have a new belt to compare the % of wear of your used belt against. This is the most common problem. As the belts wear down they come “higher“ in the clutch before the drive engages and lower in the driven. (the belt acts too long) Which results in a loss of your low gear and your high gear ratio. (you only have the middle ratios left, sort like starting off in 2nd gear and missing overdrive, which results in more belt slippage and a higher wear rate and poor performance)
Hoffco Comet Industries http://www.hoffcocomet.com/ made many of these belt drives for all types of vehicles and may be a source of parts and information. I've found their tech people quite helpful, though they are geared more to manufacturers then to end user. If they didn't build the drive for your mustang, there is a vary good chance they could supply a replacement should that become necessary.
Regards
Ken
 

r8183594

Member
Joined
Sep 16, 2006
Messages
5
Any Polaris atv or snowmobile dealer could give you a few tips on variable belt drives as all there atv and snowmobiles use them.
It is basically a matter of balancing the centifugal (RPM) activated weights against the force of the springs. One in the drive clutch and one in the driven pulley. I have no particular on your machine but have dealt with atvs and sleds using a belt drive.
Make sure the bushing that the sheeves slide on are not wollowed out and that they have some lubrication (no so much that it gets on the belt) These need to slide freely, without binding so the upshift and down shift are smooth and predictable and controled only by engine speed and not friction.
The springs that hold the clutch disengaged at idle and control the upshift from low to high ratio can get weak over time and allow the upshift to come at a lower engine rpm causeing bogging the engine.
Take the drive and driven apart and clean and lubricate the clutch and driven pulley. Look for worn weights, weak or broken springs loose bushing and any binding that prevents the smooth movement of either pulley.
Also it is good to have a new belt to compare the % of wear of your used belt against. This is the most common problem. As the belts wear down they come “higher“ in the clutch before the drive engages and lower in the driven. (the belt acts too long) Which results in a loss of your low gear and your high gear ratio. (you only have the middle ratios left, sort like starting off in 2nd gear and missing overdrive, which results in more belt slippage and a higher wear rate and poor performance)
Hoffco Comet Industries http://www.hoffcocomet.com/ made many of these belt drives for all types of vehicles and may be a source of parts and information. I've found their tech people quite helpful, though they are geared more to manufacturers then to end user. If they didn't build the drive for your mustang, there is a vary good chance they could supply a replacement should that become necessary.
Regards
Ken
Excellent!! I have seen this type of pulley arrangement in snowmobiles, and am kicking myself for that not occuring to me before!! You are exactly right, ..I was up at the shop just last night looking for more grease zerks and other lubrication points that I may have over looked. I started it up again and without moving, I actuated the "high-low" drive. The belt has about a 1/2" "flop" on the top during the transition, and never rides out on the top edge of the engine pulley. The thought of tightening the belt out of experimentation had then crossed my mind. Top ground speed now is comparable to a normal walking pace, and I know this isn't right. If the engine pulley had more squeeze, the belt would ride out further on that pulley increasing the speed. Low speed is there, but slips on slight loads. After shutting down last night, I tried rotating the pulleys by hand to look for any other lube locations and about burned the hide off my hands. An obvious indication of a lot of friction or slippage. Your diagnosis is right on! I'm planning on splitting that bottom pulley apart and having another look. Thanks for the reply!!
 

skidsteer.ca

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Jan 20, 2006
Messages
3,853
Excellent!! I have seen this type of pulley arrangement in snowmobiles, and am kicking myself for that not occuring to me before!! You are exactly right, ..I was up at the shop just last night looking for more grease zerks and other lubrication points that I may have over looked. I started it up again and without moving, I actuated the "high-low" drive. The belt has about a 1/2" "flop" on the top during the transition, and never rides out on the top edge of the engine pulley. The thought of tightening the belt out of experimentation had then crossed my mind. Top ground speed now is comparable to a normal walking pace, and I know this isn't right. If the engine pulley had more squeeze, the belt would ride out further on that pulley increasing the speed. Low speed is there, but slips on slight loads. After shutting down last night, I tried rotating the pulleys by hand to look for any other lube locations and about burned the hide off my hands. An obvious indication of a lot of friction or slippage. Your diagnosis is right on! I'm planning on splitting that bottom pulley apart and having another look. Thanks for the reply!!
I'd start with a new belt though (or at least compare the width of yours to a new one, 1/8“ less width will make a difference, and at 1/4“ to 3/8 narrower the belt is likely worn to the point you will loose low and high gear), the lack of tension may just be because your old belt is worn down and is now 2 narrow. Remove it and spray the shaft areas of both pulleys with “fluid film” or some other spray lube. Wipe the exess off to prevent it from getting on the belt surfaces. Try to move the sheeve manually. Do they seem to slide freely and do the springs return them to open for the clutch and closed for the driven?
Belts do tend to create heat, but if they are slipping they will heat up quickly and should smell the burnt rubber. Does the belt drive quit turning the driven sheeve at a idle on these machines or does the belt turn when ever the engine runs?
Good luck
Ken
 

r8183594

Member
Joined
Sep 16, 2006
Messages
5
I'd start with a new belt though (or at least compare the width of yours to a new one, 1/8“ less width will make a difference, and at 1/4“ to 3/8 narrower the belt is likely worn to the point you will loose low and high gear), the lack of tension may just be because your old belt is worn down and is now 2 narrow. Remove it and spray the shaft areas of both pulleys with “fluid film” or some other spray lube. Wipe the exess off to prevent it from getting on the belt surfaces. Try to move the sheeve manually. Do they seem to slide freely and do the springs return them to open for the clutch and closed for the driven?
Belts do tend to create heat, but if they are slipping they will heat up quickly and should smell the burnt rubber. Does the belt drive quit turning the driven sheeve at a idle on these machines or does the belt turn when ever the engine runs?
Good luck
Ken
According to the Mustang distributor, a new drive belt measures 1-3/4" in width, and 68.6 or 68-5/8" in circumference. My belt measures 1.620, or about 1-5/8" in width which is about an 1/8" less than new. One thing I'm noticing is that the jackshaft sheeve isn't opening at all during the speed change, and this pulley was the cause of the previous owner wanting rid of it. A new belt is going to run me $135.00, and I'll gladly buy it once I'm sure this bottom pulley is for surely operational. It was a nice surprise to hear that parts still are available for this machine!! Thanks again for the reply, ..it definitely shed some new light on my dilemma!!
 

sar4937

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Joined
Jun 28, 2005
Messages
21
I just typed in Owatonna 1200 Mustang on my MSN search engine and found several sites that say they have manuals for your Mustang.
 

r8183594

Member
Joined
Sep 16, 2006
Messages
5
I just typed in Owatonna 1200 Mustang on my MSN search engine and found several sites that say they have manuals for your Mustang.
Thanks! I too have searched for manuals, and currently have the Parts Manual, and have a copy of the Operator's Manual coming. I was hoping to find something more service and repair oriented, ...like a service or shop manual. I'm told this operator's manual describes alot of adjustment procedures so my fingers are crossed!! Thanks again!
 
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