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Tracks Falling Off Thiokol Spryte

4plus3vette

New member
Hello,

I am a relatively new owner to a 1970 Thiokol Spryte. It is a 1201B-41.

The cat had the very wide tracks on it (a total of 12 belts for both tracks) - I think they were each like 42" wide.

I use the vehicle in the summer and winter to get around a large piece of property I have. While traversing a hill, I noticed that the left track jumped the sprocket and all of the wheels. The track was still on, but would be falling off soon. So, I limped it up to a relatively flat part of the hill and the track fully fell off - in a pretty bad location.

This is the third time it has come off (never in the winter/snow though!). I decided to cut the tracks down to 8 total belts (2 inner and 2 outer for each track), thinking that the excessively wide track would not come off as much if it were not as wide (reducing torque, lateral pressure on the wheels, and such).

Well, I have had two more incidents (once for the left and once for the right track) with the track starting to jump the sprocket and fortunately I was able to drive it back on.

Here is some more background. I have the tracks tensioned all the way out. The tensioning bolt does not come out any further. When turning on grass, the track jumps the sprocket every once in a while, even while babying a turn.

Here are some questions that I have:

1. Should I not drive this beast if there is no snow on the ground? I worked at a ski hill where we had a 1969 Imp and used that all the time to help get the hill set up in the fall and to do mowing. It never had track skipping / falling off issues. It is, however, much, much lighter.
2. Is it possible that the shorter tracks actually dig into the grass/dirt more now than they did when they were wider?
3. Can I cut the belt shorter and remove a grouser to get more tension on the track? Is it possible that the belts have stretched out over the years?
4. Do the rubber sprockets wear down overtime and need to be replaced (if so, where can you buy replacement/rebuilds and how much do they cost?)?


Also, the right front guide tire is looking pretty worn out (both guide wheels are foam filled). I need to get a new monorail tire and have it foam filled. Where is the best place to get a tire and where to I find someone locally to foam fill them? I live in the Syracuse, NY area. While I am at it, if the price is reasonable, I was thinking about getting the other 8 tires foam filled too. Would a more solid tire help to keep the track from coming off?

Any guidance is greatly appreciated.

Thank you,

Jim
 

Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
check the spacing on the grousers the pitch should be 4 inches if it is 4 1/4 than I would guess you have excessively stretched belts. you are working it hard on hard ground those j style grousers hook up pretty good and it will be hard on them in the summer you may want to remove one grouser and over lap the belt one more position see if that will allow better track tension. the best info I can get on track tension is adjust them so the track doesn't skip on the sprocket when turning . I have a 2100 on the way and have been learning up on their track systems.
 

Melensdad

Jerk in a Hawaiian Shirt & SNOWCAT Moderator
Staff member
GOLD Site Supporter
Jim, sounds like the belts are simply stretched or too long. As Don wrote above, try to remove a grouser and overlap the belt one more place. This will also allow you to use the track tensioning system more effectively since you will be shortening your track.
 

300 H and H

Bronze Member
GOLD Site Supporter
Just like to add the condition of the drive sprockets is also important. Check them out as well, as there can be damage and wear that is not always seen easily.

Regards, Kirk
 

4plus3vette

New member
Thanks for the replies guys.

TRACK SPACING: After reading what DDS said, I went out and measured the grouser spacing. What is weird is that they are not all exactly the same. As a worst case, every once in a while one measured 4 1/4". Some were 4", some were 4 1/8", ... When I measured over 3 or 6 grousers, a more normal number of about 12 1/4" per 3 grousers was seen.

J-GROUSERS: Good point about those J-grousers. I think you are right that they really dig in. I find I have the most issues when going over tall grass or golden rod types of terrain. It's almost like that stuff forms a really strong grid on the ground that the tracks "stick" to.

SPROCKETS:
The sprocket on the right side has a loose tooth?!? I don't know if this is the right word for it, but the rubber top / point on one of them is sheared through quite a bit. Not completely, but I would say that it is certainly not nearly as strong as the others. What other things would I look for regarding wear? Where can I buy replacements / refurbished sprockets? How much do they cost?

REMOVING A GROUSER: This track is currently joined together with long bolts going through something like Flexco Hinged Conveyor Belt Fasteners: http://www.directindustry.com/prod/...teners-bolt-hinged-fasteners-14800-39328.html . My belts don't overlap. Are you guys suggesting that I unbolt two grousers, then bolt through two belt thicknesses, or just cut off 4" worth, then reinstall the Flexco fasteners?

BOGIE WHEELS:
If these run a little soft, will that cause this type of issue? If I had them foam filled, would that help? How much does that cost per wheel and where would I start looking to find someone to do it?

MONORAIL GUIDE WHEEL: Any recommendations on where to pick up one of these? The right one, although foam filled, is looking a bit ragged.

Thank you again for all of your suggestions. As long as it is not taboo, it sounds like the first step would be to remove a grouser and shorten up the track.

Jim
 

NorthernRedneck

Well-known member
GOLD Site Supporter
Thanks for the replies guys.

TRACK SPACING: After reading what DDS said, I went out and measured the grouser spacing. What is weird is that they are not all exactly the same. As a worst case, every once in a while one measured 4 1/4". Some were 4", some were 4 1/8", ... When I measured over 3 or 6 grousers, a more normal number of about 12 1/4" per 3 grousers was seen.

J-GROUSERS: Good point about those J-grousers. I think you are right that they really dig in. I find I have the most issues when going over tall grass or golden rod types of terrain. It's almost like that stuff forms a really strong grid on the ground that the tracks "stick" to.

SPROCKETS:
The sprocket on the right side has a loose tooth?!? I don't know if this is the right word for it, but the rubber top / point on one of them is sheared through quite a bit. Not completely, but I would say that it is certainly not nearly as strong as the others. What other things would I look for regarding wear? Where can I buy replacements / refurbished sprockets? How much do they cost?

REMOVING A GROUSER: This track is currently joined together with long bolts going through something like Flexco Hinged Conveyor Belt Fasteners: http://www.directindustry.com/prod/...teners-bolt-hinged-fasteners-14800-39328.html . My belts don't overlap. Are you guys suggesting that I unbolt two grousers, then bolt through two belt thicknesses, or just cut off 4" worth, then reinstall the Flexco fasteners?

BOGIE WHEELS:
If these run a little soft, will that cause this type of issue? If I had them foam filled, would that help? How much does that cost per wheel and where would I start looking to find someone to do it?

MONORAIL GUIDE WHEEL: Any recommendations on where to pick up one of these? The right one, although foam filled, is looking a bit ragged.

Thank you again for all of your suggestions. As long as it is not taboo, it sounds like the first step would be to remove a grouser and shorten up the track.

Jim

We had this issue on the Lamtrac I used to run. The tracks were worn and too loose even with the tensioners all the way out. I vote remove one grouser, run those adjusters all the way back in. Refasten the tracks using either the hinges or if you have enough rubber to overlap at least 2-3 cleats past the joint on either side you can do it that way but I'm guessing that since you already have the hinges you won't have enough belting to overlap that much. So it's looking like hinges will be your answer once you remove the grouser and cut down the rubber on each belt.
As for your sprocket missing a tooth, just guessing here but I suspect that it probably took a beating with those loose tracks jumping on the sprocket.(also had this happen)
 

Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
I concure with groomer guy at 4 1/8 inch pitch I would allow for some stretch at 4 1/4 you are getting kind of wide. a good solid tire front and rear is a good idea. one question I have is where is it coming out of the track at the front or rear you may also have some wear in the torque arm bushings. I have been working on a gotract and the amount of movement in the torque arms is unreal makes me afraid to steer to hard.
 

4plus3vette

New member
Right ggNWO, if I need 2 to 3 cleats worth of overlap, I will not have that, so I will bring the tensioner all the way in, cut off 4 inches of belt, move the fasteners, reattach the belt, then readjust the tensioner. I currently have 72 grousers per side. This will bring me down to 71.

dds - I am almost certain the track always starts coming off at the rear. I watch the front left very closely and have never seen anything there. The two times that the track started to come off most recently were both in the rear. Last year a friend of mine took it for a short test run. When he was backing up and turning - through high grass, I noticed the track starting to bunch up between the sprocket and the rear-most tire. My best guess would be, this is where the track starts falling off everytime - backing up and turning, and the track starting to bunch up by that tire. Maybe I should get those rear tires foam filled too, as you suggested.

As far a wear in the torque are bushings. That could certainly be a possibility, but I don't even know what to look for here - other than taking a wheel off each side and looking for play.

Also, I found a place locally that can foam fill tires. I don't know what size tires this thing has (I am not currently near it), but it is $65 for a 5.30 x 12 inch tire and $110 for a 7.50 x 15 inch tire. That sounds fair. Now I just have to find where to buy the tire.

When I get the right side tire replaced and filled, I will cut the track down at the same time.

Thanks again for your thoughts.
 

Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
once the track is off you can check your bushings for play, other wise watch for movement when turning if you see the arm moving around well you likely have bad bushings. I would guess you have a tension issue. get some pics next time you are up at it.
 

fogtender

Now a Published Author
Site Supporter
Thanks for the replies guys.

TRACK SPACING: After reading what DDS said, I went out and measured the grouser spacing. What is weird is that they are not all exactly the same. As a worst case, every once in a while one measured 4 1/4". Some were 4", some were 4 1/8", ... When I measured over 3 or 6 grousers, a more normal number of about 12 1/4" per 3 grousers was seen.

J-GROUSERS: Good point about those J-grousers. I think you are right that they really dig in. I find I have the most issues when going over tall grass or golden rod types of terrain. It's almost like that stuff forms a really strong grid on the ground that the tracks "stick" to.

SPROCKETS: The sprocket on the right side has a loose tooth?!? I don't know if this is the right word for it, but the rubber top / point on one of them is sheared through quite a bit. Not completely, but I would say that it is certainly not nearly as strong as the others. What other things would I look for regarding wear? Where can I buy replacements / refurbished sprockets? How much do they cost?

REMOVING A GROUSER: This track is currently joined together with long bolts going through something like Flexco Hinged Conveyor Belt Fasteners: http://www.directindustry.com/prod/...teners-bolt-hinged-fasteners-14800-39328.html . My belts don't overlap. Are you guys suggesting that I unbolt two grousers, then bolt through two belt thicknesses, or just cut off 4" worth, then reinstall the Flexco fasteners?

BOGIE WHEELS: If these run a little soft, will that cause this type of issue? If I had them foam filled, would that help? How much does that cost per wheel and where would I start looking to find someone to do it?

MONORAIL GUIDE WHEEL: Any recommendations on where to pick up one of these? The right one, although foam filled, is looking a bit ragged.

Thank you again for all of your suggestions. As long as it is not taboo, it sounds like the first step would be to remove a grouser and shorten up the track.

Jim

Before you start cutting off the track ends, first check to see where your track adjustment is at, if it is still "Short", then you may not be able to get the track together because you can't adjust it shorter. It should be already adjusted all the way out, if so, then you can cut (or overlap) to the next grouser. If it is still not fully adjusted out, then you can simple adjust it out and tighten the track where it is suppose to be at.

Foam filling the tires makes them a bit heavier, but the fact that you won't have flats is well worth the effort. Make sure you use new tires and tubes for the foaming, if you foam an old tire, it won't have nearly the life of a new one for the cost and effort you are going to have invested in it.
 

Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
Before you start cutting off the track ends, first check to see where your track adjustment is at, if it is still "Short", then you may not be able to get the track together because you can't adjust it shorter. It should be already adjusted all the way out, if so, then you can cut (or overlap) to the next grouser. If it is still not fully adjusted out, then you can simple adjust it out and tighten the track where it is suppose to be at.

Foam filling the tires makes them a bit heavier, but the fact that you won't have flats is well worth the effort. Make sure you use new tires and tubes for the foaming, if you foam an old tire, it won't have nearly the life of a new one for the cost and effort you are going to have invested in it.

he said his adjustment was extended all the way there is no way to apply anymore tension with out shortening the track.
 

4plus3vette

New member
Well, I went to the vehicle today and have some more details - AND PICTURES because we all love pictures!

TIRE PRESSURES: As I was driving away, I thought, I wonder if the tire pressures are low?!? So I went back and checked them all. You guys will probably think I am an idiot for not checking this first, but they did not "look" low. Starting on the left front and moving to the rear: Alpine Guide tire - foam filled (pictures 5 & 6), tire #2 = 26 psi, #3 = 39 psi (my only tubeless tire), #4 = 21 psi, and #5 = 25 psi. On the right side, starting at the front and moving back: guide tire - foam filled, but the tire is a mess - see the 7th picture below, #2 = 20 psi, #3 = 20 psi, #4 = 19 psi, and #5 = 10 psi :(

This machine did come with a manual which I read through tonight. The tire pressures should be 36 psi. Does anybody disagree with that number?

TIRE SIZES: What is the difference between 5.30x12, 4.80x12 and 4.30x12? I have at least 5.30x12 and 4.80x12 (pictures 1 & 2). The manual says the tire sizes are 4.50/5.30 x 12.

TENSIONING THE TRACK: The manual says this about the tension: "As a guide, the upper portion of the track should sag approximately 1/2 inch between adjacent wheels." My tracks (as seen in the pictures #3 & #4) don't seem to have any sag between the wheels which leads me to believe that the tracks are pretty tight.

OVERSTRETCHED BELTS?: Pictures #10, #11, and #12 show the distance when measuring 1 space (one of the worst), then over 3 grousers, then over 6. I would say the average spacing is about 4 1/8".

CONCLUSION: Well, the "flat" tires certainly seem to be a likely culprit here, followed by the bad spot on that right sprocket (pics #16, #17, & #18).

WHAT I NEED TO DO NOW: I think I need to buy another Alpine Guide tire. The left one was put on by the previous owner in 2006 and it looks great. Then I will have it installed locally and foam filled (for $65). Then, fill up all of the tires to the proper pressure and test the unit. It will probably take several weeks to get the new wheel installed. Does this sound like a good plan of attack? Anybody know a place that sells that tire for a reasonable price?

fogtender - If things seem to work well after the above ideas, I would consider getting all of the tires foam filled. $65/tire doesn't seem that horrible. What kind of tire (brand and such) and tube would you suggest I buy if I go that route? You will be able to see where the tensioner is and if I have any more threads left in that bolt. The reason that I think I am all the way out is that when I did it on the right side (picture #9 is the right side - #8 is of the left tensioner - maybe a few more threads left in that one), I kept turning it, but the thread would get any longer.

PICTURES: I have attached some overall pictures of the vehicle, close-ups of the tires, including the good "ALPINE GUIDE" tire and the bad guide tire, the left and right tensioners (THE RIGHT ONE IS ALL THE WAY OUT, RIGHT?), grouser spacing - over one that seems stretched, then over 3 and 6 to show that the overall spacing is not that bad (I don't think), the track fasteners, and the sprockets - in particular the sprocket with the bad tip.
 

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Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
those are not the OE j style grousers the tracks have also been narrowed. the cat looks like a nice little package boggie at mn out doors can re cover your sprockets. I believe your issues may be in your road wheels being low, and also it looks like you have street tires not snow cat tires in some positions. the street tires may not have the required side wall to stand up to the thrust on turning that long track on a sticky surface, you may also want to taper the ends down a little to give a bit more slip on hard ground
 

4plus3vette

New member
UPDATE:

OK, after taking in all of your advice and starting to dig deeper into the track issues, I did the following:

1. Replaced a Broken Tensioning Bolt,
2. Have added foam filled Alpine Guide tires to the forward most and rearward most tire on each side (4 total),
3. Replaced worn out bushings on the front axle (both sides),
4. Had one drive sprocket resurfaced with polyurethane,
5. Replaced seals and bearings (inner and outer) on the 4 axles with the foam filled tires,
6. Tightened up loose wheel assemblies on non-foam filled wheel axles and filled these tires to 40 psi,
7. Greased everything, and
8. Retensioned the tracks (I have some questions about this and will start a new thread for them).

I drove it around a little bit and it seemed to drive fine, but the side with the poly sprocket on it definitely sounds louder than the side with the original rubber sprocket. IS THIS TO BE EXPECTED?

Also, every once in a while, I would hear some sort of loud noise. Almost what I would imagine the sound of a breaking grouser would sound like. I got out to look at everything several times, but I did not see anything broken or unusual. ANY THOUGHTS?

Jim
 
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