Anybody with chaincase problems???

[ReX]

I have a feeling the problems with failure are attributed to Yamaha's horrible engineering decision for the reverse system.

My Doo was much. more simple as far as the chaincase goes, and when I trued my Apex drivers, and took the cover off of the chaincase, I was appalled at the conglomeration of crap in there!!

I believe with all of those extra pieces, the whole case runs hotter, then burns the seal out and lubrication is lost.

I also understand the breakage when the brakes are applied hard. Because there is so much slop in the HEAVY gears Yammy uses, the chain/gears can't take the stress from throttle to full brake and they lunch.

This is unacceptable for a machine that is otherwise engineered very well.

My friend had his case cover off of his Mach Z, and there isn't even a chain tensioner in the thing!!

There is no doubt in my mind that the Mach's drivetrain is far more efficient than our Yammies and explains why (among other reasons)a well tuned Mach will dust our behinds.

I guess I can take one negative to owning a baddass Apex..................

I couldn't disagree more with some of your statements.

Prior to Skidoo coming out with spinning the engine backwards for reverse, all manufacturers were using mechanical, geared reverse systems. Yamaha's system is the most reliable and best mechanical system out there. Yes Yamaha uses some extra parts, but the extra bearing in the cover keeps the gears running true even under extreme loads and the extra bearings in the reverse system keep everything running smoothly.

I will agree with you that the current Skidoo and Polaris chaincases are much simpler (and possibly more durable because of this), but when you have a 4-stroke that can't be spun backwards you need a mechanical reverse system.

The problem with Yamaha's chaincase IMO started in 2006 when they switched to magnesium. To the best of my knowledge all prior years, their chaincases were bulletproof (if you changed the oil per the schedule).

Magnesium, while being lighter than aluminum, doesn't conduct heat as well as aluminum. This means the heat can't get out as fast and it runs hotter. The bigger and real problem is in the magnesium casting process they somehow messed up the geometry for the seal relative to the cover. I carefully measured the seal interface on an 05 chaincase and an 06 chaincase and discovered with at least these particular cases, the seal had about 0.080" less surface in contact with the flat surface in the cover and the outside of the seal didn't get pushed up tight against the outer lip on the cover (again about an 0.080" gap). The updated 07 cover fixes this by provided the best interface with the seal, but the outer retaining lip is still a little loose compared to the 05 cover (which shouldn't really matter).

So the problem is the chaincase sometimes leaks due to a combination of the reduced seal interface and the increase in temperature (which softens the seal when you run the sled hard). Over time and many high temperature heat cycles, the seal sometimes slowly walks inwards until it lets the oil leak out. After the oil leaks out, the chain overheats and fails. Note that not all sleds are suffering this fate (probably a fairly small percentage overall).

As long as the case doesn't leak and you run a quality gear oil, these things are still very reliable (even though the magnesium doesn't cool as well). The ultimate in reliability would be to run an 05 aluminum chaincase, but I very much doubt anyone will have trouble once they get the updated 07 cover on their 06/07.

 

[LuvMyWarrior]

I have an 07 Attak GT - does my sled have the new updated cover by virtue of being an 07 from the factory or do I need to ask dealer to replace to a different updated one.

Thanks!

 

[ReX]

I have an 07 Attak GT - does my sled have the new updated cover by virtue of being an 07 from the factory or do I need to ask dealer to replace to a different updated one.

Thanks!

Maybe someone will be able to answer what's on your sled, but I doubt it. Most likely you'd have to pull the cover off and compare it to pictures posted here to see which cover you have.

The second problem (if you do have the 06 style cover) is unless its actually leaking there is "theoretically" no reason to change it. If 95% of the 06 style covers never leak you can't really expect Yamaha to change everyones under warranty.

 

[Soldier'spapa]

I have had the gear crunch in reverse. Embarassing when it happens, but yes. I have noticed that you have to have the chaincase in a "relaxed" state.
I did adjust the chain tension, but didn't get much out of it. The gear oil smelled a little burnt, so I will probably change that as soon as I do a gear change.
Should I do the 23T & the 40T? What is the factory gears in my sled? ('06 GT)
I don't want to loose too much top end, but if the combo will really help midrange and low end, I'll do it.

Nate,

For a little piece of mind, I changed out my gear oil to synthetic at the start of the season... Actually I have done it twice this year once on the 07 that was wrecked and again on the replacement 07 Attak GT. The first time I changed it I spent far more time than was necessary. I pulled the cover off to drain the oil not knowing there is a drain plug on the back side of the case (Accessed from the tunnel area) All that is to say... if you are thinking of changing out the oil, it is much easier than you might think. It takes all of about 20 min.

 

[nate007]

I am trying to get out and ride this weekend, and if al hold up, I'll probably tear the whole sled down post season for the final mods and maintainence for summer. I think our season is just about over here, and since I just ordered a new Nytro this morning, I won't be modifying my Apex too much more since my wife will probably ride it more than me.
She's never ridden before, hell-uv-a first one, huh? I'll bet she goes out once, maybe twice for about 30 minutes! She says she wants to try, but I don't want to put her on anything that won't handle, or beats her up. She'd never ride again...
Nate

 

[MR.HAPPY]

My buds Attak was the 5,304th Attak built.

Mine is the 5,305th.

Mine is being checked now at the dealer, his is being rebuilt!

2,752 miles on mine, 1,700 on his!

BR

 

[shinze]

I have a 2007 Apex GT, and around 800 miles my chaincase grenaded inside, had to have everything replaced including the case. I have 1400 mi. on now and everything has been fine since. The mechanic that done the work never had a chance to tell me what made it fail so I have no idea what made it fail. I still love the sled and hope it was just a one time deal and dont expect to have any more problems.

 

[rx1pat]

For the last 2 post's, coldone and shinze, what were the conditions when the failure occurred? ie trail riding or high speed riding. Seems most are happening after long wide open throttle lake runs or on a railroad bed for miles. Just curious.

 

[xcsp]

I have a 2007 Apex GT, and around 800 miles my chaincase grenaded inside, had to have everything replaced including the case. I have 1400 mi. on now and everything has been fine since. The mechanic that done the work never had a chance to tell me what made it fail so I have no idea what made it fail. I still love the sled and hope it was just a one time deal and dont expect to have any more problems.

Next time you see the mechanic, ask him what he thinks caused the failure.

 

[shinze]

Rx1 pat I was just trail riding nothing radical fairly low speeds, It was only about 10 miles into ride when I heard a grinding noise from chaincase, I stopped pulled the dipstick and it was smoking so I was done. The conditions were great, lots of snow, I checked oil level day before it happened and it was right up to full mark on reverse side, and I did not find oil on floor of my trailer where it was parked the night before so I cant imagine what happened to make it go dry. I probably wont find out what whent bad because I was on vacation in the UP. and it wasnt my dealer that did the work.

 

[berge75]

I just got the updated cover,because the oil kept leaking out. I found the seal was bending over under the cover creating a small gap which allows the oil to seep out. The seal is shaped like a u and fits over the top of the case. The thickness of seal from the top of the case to the top of the seal is much greater than the thickness of the skirt,or sides of the seal,so if for some reason the seal is allowed to move and push over it will create a gap under the cover. The guy that said the covers aren't tight enough( not pinching the sides of the seals to the case) hit the nail on the head. I check my oil before every ride to make sure theres oil in there. My last ride it went from full to empty in 300mi. after checking it. I went all season 2700 mi wth no problems until that last ride.

 

[craze1cars]

There's lotsa guessing going on here with Nate's problem...if a problem even exists at all. So many people keep saying to just check the oil level and "keep an eye on things." IMO that's nowhere near enough for my peace of mind...all you need to do is pull the cover off and take a good look! It's pretty simple in there, don't need to be a rocket scientist to look at a chain and gears.

Adjust chain tension while the cover is off so you can watch and see how it all works together, inspect the gears carefully for damaged teeth, inspect the adjuster to make sure it looks straight and undamaged, make sure everything looks clean with no metal shavings, and upon reassembly refill with synthetic and make sure to properly adjust the reverse linkage as a few have mentioned (seems they're almost ALL out of whack from the factory, and this will cure your erratic reverse shifting problem).

If anything looks way out of the ordinary, get a dealer involved (assuming it's still under warranty). Heck, if it's still under warranty and you don't want to do this yourself, just haul it to the dealer and explain the grind...they'll check it out for free and they'll be grateful you didn't wait for the whole thing to explode before you did so.

 

[MR.HAPPY]

We do lots of RR bed, high speed running, but on the day it came apart we had been running 70s & made a pit stop for a couple hours. When we got back on the trail a little bit he said he had a noise, but thought it was ice & kept going till it came apart!

BR

 

[nate007]

Yeah, I thought there would be a few others that would come out of the woodwork to confess their issues. I understand there will be failures with any mechanical part at some point, but I guess I'll run it the way it is, and just keep my ears open.
Of you guys that have had failures, what are the costs to rebuild it? I don't have the extended warranty, adn I am wondering if (and when) it does crap out, if I should look at the belt type setup the mountain guys are running?
~Nate

 

[shinze]

Nate I got a look at the dealers price list for parts and it was over $600 dealers cost + 4 hours labor at $90/hr. so expect over a grand if its done by a dealer. This work was done by Meyer Yamaha of Ishpiming.