boondoggle
Extreme
After a lot of researching this site and asking a lot of questions I finally bit the bullet and dove into this 151 extension project. I thought I would share the experience and maybe the info will be helpful for others considering this mod, while adding to the info already here. My maverick track has about 800 miles on it and I'm already missing a bunch of lugs and the majority of them are cracked and ripped. So I decided I would replace the track now so I won't have to deal with it during the season. I figured since I was already changing the track, why not try to do the extension mod as well. The maverick was much lighter than the new track. While I hate to make the sled heavier I have to hope that a large performance increase will overshadow increased weight.
Unfortunately I won't get to test the 151 til this winter but as far as I can tell, everything went together ok. I would have to say the hardest part of the whole job was cutting the track, and that was because of inferior equipment. A word of caution: You probably want to use a decent table saw for track cutting, not a 13 amp toy Ryobi piece of garbage like I did. The saw ended up erupting sparks and smoke and making awful noises before expiring with a section of thick rubber stubbornly holding the blade in place. I easily could have ruined the track and as it is I ended up with it being a little wider on one side than the other. I'm hoping this won't be a problem. More on that later.
For bracket extensions I went to a junkyard and found a set of steps off the cab of an 18 wheeler that were made of 1/4 inch aluminum. I disassembled the step then cut out two brackets with a hand held grinder using a thin blade. I had a 151 camoplast skidoo track, bought some nuts and bolts and washers and I was ready to go.
I found out that I do in fact have a 17 tooth top gear so I'm not going to mess with gearing or clutching right now. I'm going to ride it next season and see how it goes.
I was surprised to see when I had everything put back together that my limiter strap which before had been taut, was now completely slack. I didn't think the inch or so downward shift in skid placement would compress the suspension so much. Does anyone have any opinions or recommendations about this? The strap is in its original center position. I have two positions to go to tighten. I assume this would be enough to take up the slack if I need to. Is there a problem with running with the strap slack if I have enough ski pressure? For instance, if the sled is put in the air or is losing contact with the ground traveling over bumps, will slack cause problems? What if the sled were run with no limiter strap?
Also, does anyone think there will be a problem with having a track that is wider on one side than the other? I have clearance, but I'm wondering if the imbalance may possibly lead to problems. The difference is up to nearly a half inch in the worst spot.
I had to buy my buddy a new saw but other than that I enjoyed the project. I'm looking forward to testing her out. Thanks to the users of this forum for all the helpful knowledge and information.
Unfortunately I won't get to test the 151 til this winter but as far as I can tell, everything went together ok. I would have to say the hardest part of the whole job was cutting the track, and that was because of inferior equipment. A word of caution: You probably want to use a decent table saw for track cutting, not a 13 amp toy Ryobi piece of garbage like I did. The saw ended up erupting sparks and smoke and making awful noises before expiring with a section of thick rubber stubbornly holding the blade in place. I easily could have ruined the track and as it is I ended up with it being a little wider on one side than the other. I'm hoping this won't be a problem. More on that later.
For bracket extensions I went to a junkyard and found a set of steps off the cab of an 18 wheeler that were made of 1/4 inch aluminum. I disassembled the step then cut out two brackets with a hand held grinder using a thin blade. I had a 151 camoplast skidoo track, bought some nuts and bolts and washers and I was ready to go.
I found out that I do in fact have a 17 tooth top gear so I'm not going to mess with gearing or clutching right now. I'm going to ride it next season and see how it goes.
I was surprised to see when I had everything put back together that my limiter strap which before had been taut, was now completely slack. I didn't think the inch or so downward shift in skid placement would compress the suspension so much. Does anyone have any opinions or recommendations about this? The strap is in its original center position. I have two positions to go to tighten. I assume this would be enough to take up the slack if I need to. Is there a problem with running with the strap slack if I have enough ski pressure? For instance, if the sled is put in the air or is losing contact with the ground traveling over bumps, will slack cause problems? What if the sled were run with no limiter strap?
Also, does anyone think there will be a problem with having a track that is wider on one side than the other? I have clearance, but I'm wondering if the imbalance may possibly lead to problems. The difference is up to nearly a half inch in the worst spot.
I had to buy my buddy a new saw but other than that I enjoyed the project. I'm looking forward to testing her out. Thanks to the users of this forum for all the helpful knowledge and information.
Attachments
Very nice! I love the look of the blue and white. Your chain case oil almost looks like it may be getting a little water mixed in it? It is normal for it to turn blackish but grey usualy means water? As far as your limiter strap, it is good you droppped front bolt, you can always tighten up strap if you have to much ski pressure. It will allow it to weight transfer better also. The main thing you have to worry about is the rails stabbing the track, jack the sled up and see what kind of angle the rails take to the track? The safe thing to do would be an anti stab wheel kit witch I will be installing next spring just for insurance. It mounts between rail tips with wheels to keep tips from stabbing track. Nice Job, your going to love the new track. If you end up over rpming put the 17.3 gram rivit in your clutch arms tips, it realy seems to help.
boondoggle
Extreme
Tbyrd said:
Thanks. Your teardown advice was very good.
Yes, someone else posted that water in the chaincase was observed in his mtx. A dealer I called said it wasn't uncommon also. I guess it will be something that bears watching.
I will unweight the skid and see how the rails look in relation to stabbing. Don't really want to add even more parts and weight if I don't have to.
I guess I'll know if I'm over revving if the rev limiter keeps kicking in? It was pretty typical for the rpms to be around 12k when wide open with original set up.
12000 is to high, peak rpm to hp is 11500-11700. The rivets are about a dollar a piece x3 so for 4 to 5 bucks you can do it. It take about 15 min with a 10mm socket and a grinder and hammer. If your rpms drop a little to far you can up your secondary spring load and it will make it backshift better and hold the rpms. Mine works sweet with this setup.
Secondary spring preload starts at c1 then a1 then b1 witch is stock setuo on mtx then c2 , a2- b2 -c3- a3 - b3 and so on.
Great write up and pics! I picked up a 153 track and just ordered all my parts from OFT Racing. I am going to go with rail extensions on mine.
boondoggle
Extreme
Tbyrd said:
I may have overstated it a little. It is probably more accurate to say that I've seen it as high as 12k but mid to high 11's is more typical.
boondoggle
Extreme
Tbyrd said:
I don't know anything about messing with clutch weights and spring loads. But I'm going to bookmark this post so it won't be hard to find next season when I start riding. I'll be able to refer back to your suggestion if I find out I've got to make adjustments.
I understand the clutch engages the drive belt through centrifugal force and spring load on the clutch plates, and this is affected by rpm. But I don't understand anything about the details of what you are talking about. What exactly does lightening or weighting the clutch do in terms of rpm and drive engagement? Low end power? Top end power? How does spring preload relate?
boondoggle
Extreme
Lowedog said:
Good deal Lowedog. I saw another OFT extension post. Looked real nice.
By adding wieght to your primary clutch arms it will cause the clutch to close together faster which will bring down your rpms by forcing it to shift into a higher gear faster or put more load on motor. The secondary spring load is how tight you make the spring, the tighter it is the sooner or quicker it will down shift into a lower gear when under a load. ex: climbing or in deep snow. This is a real easy adjustment with a set of snap ring plyers. I hace mine set on C2 now so it backshifts a little quicker and keeps the rpm's up when under load.
boondoggle
Extreme
Tbyrd said:
Ok. That is very helpful info. What you have explained, in conjunction with the links I checked out below, have given me a basic idea of what is going on. It sounds like what we are trying to accomplish with the bigger track and more lugs of the 151 is better power distribution into the "low gear" range. That makes sense since we won't be in high gear when climbing/slugging through deep. However I'm still a little confused about why we would want to bring down the rpms and engage "high gear" faster with added clutch weight. What does that accomplish?
http://www.gates.com/brochure.cfm?broch ... ion_id=542
http://www.gates.com/brochure.cfm?broch ... on_id=3850
By the way, have you found out about your sled yet, diagnosis/repair?
With the amount of tork the engine makes at initial take off is more than enough for the bigger track and lugs, and mine seemed to over rev until it shifted out unless it was under perfect conditions and the track hooked up realy well. It will bring the top rpms down if it tends to hit high rpms in a WOT senerio. With the air box mod and the fuel curve adjustment mine produced enough extra power to create this problem. The befor described adjustments helped cure this problem. You will notice with the extra track in a lugging senerio your rpms will drop enough to get out of the optimum rpm range.
IMO it actually makes the sled quicker off the line by making it shift out quicker.
owenb2
Newbie
Nice! thanks for all the photos, this will be my summer project.
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