Apex GT - changed upper gear - whew!

[BigMac]

My 2007 Apex GT came with 24-38 gears. Various posts here and elsewhere indicates little downside and fairly big upside to a lower gear ratio, so I picked up a 23 tooth upper gear from my dealer last time I was there. I'm pretty good with a wrench, but I was emboldened for this project by my son being here for the weekend - he's a Yamaha bronze level tech..still a little green (just finished training) but confident in the project. The step-by-step with photos here on TY Technical Pages was a big help.

Lot's of little steps, kind of a PITA, but it went fine. Biggest challenge was the big nut on the upper gear ... that crow's foot adapter would help for sure. I didn't have one, so I used a big honkin' crescent wrench with Jess holding the driven clutch. Several big taps on the wrench with a ball peen hammer and it came off fine. Only other challenge was hooking the reverse dogs in the the reverse gear as the case cover went back on.

One thing the step-by-step doesn't mention is that those cover bolts are all loc-tighted on with high-strength bond. Really had to crank to get them off. I reassembled with a touch of red Loc-Tite on each bolt and torqued them meticulously. It does slide into reverse easily after getting the linkages hooked back up. We'll see if it does actually go into reverse. God, I hope so.

My other two projects for the day were changing the spark plugs to CR-10EKs, and switching the sway bar to a 13mm. After finishing up the work, I really wanted to ride the thing. Problem is (other than the fact that's it's minus 15 degrees) - I found out, after wrestling the spark plugs out and replacing three of them, that of the 4 plugs that my dealer had sold me, only three of them were CR-10EKs. Anyway, I'll be interested to get the thing out on the lake and see if I can notice the changes.

 

[Shivesy]

I was the one that did the write up in the Ty Tech section last year. Today I went back into the chaincase to swap out the 23 tooth gear and I put the 24 tooth gear back in. Your right about the outer case bolts being hard to get out. I don't remember them being that hard to get out the first time around. You might want to reset your reverse linkage as a preventative measure. I did notice that the 23 tooth gear was a little more worn than what I expected. I have about 2,500 miles on that gear and some of the sprocket teeth looked worn and somewhat bent over. I always check my chain for tightness before every trip I take so to keep the chaincase parts from wearing prematurly, but that gear looked to worn for the miles it had on it IMO.
The reason I went back to the 24 tooth gear was because the Apex is now the wifes sled and I have a new Attak. Over the X-mas holiday while sleeding in Maine we both had filled up with gas at the same time. The Apex ran out of fuel at about 110 miles. We both jumped on the Attak and headed another 10 miles to fill up the Attak. I filled up the Attak with 8.5 gallons and headed back to siphon some fuel over to the Apex. We were back up and running in no time but I feel that the 23 tooth gear really makes the engine run at a higher RPM and therefore hinders fuel milage. I know I have heard to have the clutch sheaves shaved to allow the clutches to go into overdrive but the wife really doesn't need this type of mod. So back to 24T in hopes of regaining better fuel milage.

 

[BigMac]

I was the one that did the write up in the Ty Tech section last year. Today I went back into the chaincase to swap out the 23 tooth gear and I put the 24 tooth gear back in. Your right about the outer case bolts being hard to get out. I don't remember them being that hard to get out the first time around. You might want to reset your reverse linkage as a preventative measure. I did notice that the 23 tooth gear was a little more worn than what I expected. I have about 2,500 miles on that gear and some of the sprocket teeth looked worn and somewhat bent over. I always check my chain for tightness before every trip I take so to keep the chaincase parts from wearing prematurly, but that gear looked to worn for the miles it had on it IMO.
The reason I went back to the 24 tooth gear was because the Apex is now the wifes sled and I have a new Attak. Over the X-mas holiday while sleeding in Maine we both had filled up with gas at the same time. The Apex ran out of fuel at about 110 miles. We both jumped on the Attak and headed another 10 miles to fill up the Attak. I filled up the Attak with 8.5 gallons and headed back to siphon some fuel over to the Apex. We were back up and running in no time but I feel that the 23 tooth gear really makes the engine run at a higher RPM and therefore hinders fuel milage. I know I have heard to have the clutch sheaves shaved to allow the clutches to go into overdrive but the wife really doesn't need this type of mod. So back to 24T in hopes of regaining better fuel milage.

Thanks for that write up. It was very well done and saved me a lot of puzzlement, I'm sure.

I wonder about your gas mileage, and if the gearing is the culprit. The Attak comes stock with 23/38 gears and clutching is the same as the Apex...at the same time it's pushing more weight and spinning a heavier track. I'm puzzled as to why an Apex with 23/38 gears would get that much worse gas mileage than an Attak with 23/38 gears.


Edit: Actually, I see there's a difference in the secondary between the Attak and the Apex...but with a white secondary spring and dropping the twist to 60 degrees, the power trains between the two sleds would be identical.

Did you change your secondary when you dropped to the 23 tooth on your Apex?

 

[justinator]

I dont know if the white spring would do much. It has more torsional force than the pink to prevent a drastic drop in rpms when spinning and grabbing traction which is a problem with the 136 track. Its wound at 60 to have a similiar finish rate as the pink wound at 70 I believe. Just my thoughts as Im not 100% positive.

 

[SharkAttak]

with the excessive wear on the top gear going to 23, would you be better off changing bottom gear instead

 

[BigMac]

I was the one that did the write up in the Ty Tech section last year.

By the way, I congratulate you on that 36 mm wrench that you used. That sucker is hard to find. I finally located it online at an import auto specialty store...it's called a "36 mm axle nut tool". It's made by EMPI and I found it at Bow Wow Imports http://www.bowwowimport.com/products/36mm-axle-nut-tool. Apparently it's a relatively obscure tool whose application is removing the axle nut on Volkswagons earlier than about 1963 and costs about $12. I have been looking for an impact socket deep enough to slide over the shaft and get to that nut, but haven't found a thing so far. With an impact wrench, removing it to get the upper gear off would be an easy one-man job. In my (very limited) experience, it's a rather difficult two man job with just a wrench.

 

[ApexerER]

Why didn't you just use a 36mm wrench? Available at Sears and any Autopart store..................

 

[87gtNOS]

Why didn't you just use a 36mm wrench? Available at Sears and any Autopart store..................

Good luck with that.

 

[ApexerER]

Why didn't you just use a 36mm wrench? Available at Sears and any Autopart store..................

Good luck with that.

Why did you say that. Thats what I used. It worked fine

 

[87gtNOS]

Why didn't you just use a 36mm wrench? Available at Sears and any Autopart store..................

Good luck with that.

Why did you say that. Thats what I used. It worked fine

Not sure how you got it on there and was able to yank it without the wrench being interfered with by other things....

 

[BigMac]

Why didn't you just use a 36mm wrench? Available at Sears and any Autopart store..................

That's what I used.....a big crescent wrench adjusted to 36 mm. I'll get a 6 point box end for later just in case. Several blows to the wrench with a ball peen hammer and it finally loosened enough to spin it off. That nut is on tight, though, and the jackshaft needs to keep from turning so it requires someone to hold the clutch. Plus, I can't use a torque wrench on it. So, I dropped $12 on the axle nut remover. I'd like to find a 36 mm socket with a deep enough well that it would fit over the end of the jackshaft so I could use an impact wrench, but I'm skeptical that a socket that deep exists.

edit: looking for 36 mm box end wrenches, I think I'll stick with the axle nut tool for $12 rather than dropping $45 on a box end wrench I'll rarely use.

 

[badlarry]

How did it perform as compared to the 24t gear top end #'s and or times??

 

[ZR800EFI]

Why didn't you just use a 36mm wrench? Available at Sears and any Autopart store..................

That's what I used.....a big crescent wrench adjusted to 36 mm. I'll get a 6 point box end for later just in case. Several blows to the wrench with a ball peen hammer and it finally loosened enough to spin it off. That nut is on tight, though, and the jackshaft needs to keep from turning so it requires someone to hold the clutch. Plus, I can't use a torque wrench on it. So, I dropped $12 on the axle nut remover. I'd like to find a 36 mm socket with a deep enough well that it would fit over the end of the jackshaft so I could use an impact wrench, but I'm skeptical that a socket that deep exists.

Ulmer sells the socket...I have one.

 

[Shivesy]

One thing that I did not mention in my post above is that during the 23T gear install that I did last year on the Apex was that I also installed Ulmers clutch kit at the same time. Like I said yesterday I swapped back to the 24T but I am going to leave the clutch kit on for now. At the time Allen suggested that the 23T gear was an asset to the clutch kit. I'm no longer out for ultra quick performance. What is important at this juncture is better fuel milage. No fun leaving your $8,000 Apex on the trail. I quess I'll see how the MPG is with the Ulmers kit compared to my stock Attak.

 

[Shivesy]

How did it perform as compared to the 24t gear top end #'s and or times??

I really didn't like the performance compared to stock. I really believe that the top end suffered and the combo that was installed seemed to rev to high, this is all speculaton because I don't have any numbers to back it up with though. Like I mentioned before, I probably should of had the sheaves shaved so the machine could go into overdrive. Maybe that was the problem. It's all a mute point to me now and I'm leaving the Attak stock. I don't live up north so I don't have that great of a chance to just go out and drag race. I quess I'm a touring junkie with high performance sleds. Most any time you gear for speed fuel milage suffers and fuel milage is whats important to me.