transmission main axle noise, bearings?

[blasterd]

1991 blaster recently started making somewhat of a 'screeching' sound coming from the case which I assumed was the end of the clutches that I've noticed were slipping in higher gears. All gears still work, BTW. I ordered new clutches(Tusk kit from eBay; plates, frictions, & springs) and tore the clutch cover off. After pulling all the frictions/plates I noticed the clutch housing had serious plate marks(so bad that they looked as if they were supposed to be there) on the 'forward side', enough that the plates seemed like they wouldn't be able to fully 'engage' without hanging up if I didn't at least run the file over them to smooth them back out. I realize this may not be the best method and buying a new housing is the best bet, but I really don't want to spend that kind of money ATM(I may get a better than stock version eventually). I am glad I didn't just jump the gun and order a new high dollar clutch housing since upon reassembly I quickly realized that the noise I heard was more serious than slipping clutches and continued to be present . After removing everything for the clutch assembly off the main axle of the transmission and carefully checking things out, I have found that the noise is coming from(I believe anyways) the "conical" bearing on the opposite(left leg) side of the case. I put the nut on the shaft and spun the shaft with a socket/drill clockwise and the screeching is terrible, bad enough that the shaft would 'catch' and jerk the drill in my hands at times. With the drill in reverse(counter-clockwise) the shaft seems to spin just fine with little/no noise at all and no 'catching'. I have checked out diagrams and it seems there are 2 bearing on this shaft, one on the clutch side which I can visually see and ~seems~ fine and one on what is described as the "5th gear side" I know the blaster is a 6 speed, so I am going to assume that 6th gear isn't located at the other(far) end of the trans main axle. Anyways, I was hoping someone could offer some input as to whether or not this is somewhat of a common failure or if maybe there is something else that can cause what I have described above since I am blindly guessing without removing anything on the other side of the motor and/or splitting the motor case. Any input from someone in the know is GREATLY appreciated. If it seems to sound like the "conical" bearing on the left side of the case, is this something that a person with decent mechanical skills can complete in their backyard or is this something that would have to be performed by a shop? Sorry for the lengthy post and thanks in advance for any replies.

 

[240Fun]

it sounds like the bearing took a dump on the output shaft depending on how bad the bearing is damaged it may have put some metal bits into the tranny splitting the case is not that bad i watched the KOR videos before i did mine and had the service manual as well the KOR videos are great i would grab a seal kit and the other trans bearings as well if one is bad there probably not that far behind and they might have eaten some metal already

 

[tfaith08]

Screeching is generally caused by 2 hard materials that rub each other while one or both vibrate. A softer material will have a hard time making a high pitched sound like that unless you get it to a harmonic point that would likely be well above a human's hearing range. That leads me to believe that you have steel on steel somewhere.

I'd recommend taking the chain or sprocket off (either is fine) and spinning the trans in a few gears. The jerking makes me think that you have a problem with your shift star, shift drum, or forks. I hope you don't, but you can very well have more than one issue there. If it's jerking, I'd think that the gears are trying to engage. Combine that with the screeching and you could potentially have a gearset that has walked left or right. That would give you both symptoms. That isn't to say that you don't have 2 or more problems though. Often times, one thing breaking will cause something else to act up.

If you're patient and have the tools, I wouldn't take it to a shop unless it has to have machine work done to it.

EDIT: Agree with 240fun, too. That may be a possibility as well.

 

[Larry's Shee]

Proper amount of oil? When spinnig with drill, was it in gear? Noisy in one gear, all gears, neutral? Any different if tipped on left side so all oil is that way?
Complete investigation while assembled might help isolate the problem. It could be a bent shift fork riding against a gear.

 

[blasterd]

Thanks guys for the replies. I may not have used the correct term exactly when I say screeching I guess, but it is definitely a metal to metal sound. I didn't try tilting the atv though because there isn't any oil at all left in the case since I drained it already and removed the clutch side cover. I also removed the entire clutch assembly which leaves only the bare trans. main shaft sticking out which is what I was spinning with the drill and when I hear the noise. This same noise is why I have the clutch cover/clutch assembly removed right now. I am pretty sure that the noise is isolated to the main shaft but it could also be something(bearing?) on the drive shaft. I did try riding the atv right after clutch replacement and only got to second gear before turning around and parking it because of the noise. It reminds me exactly of a bad bearing though. It even 'chatters' a bit the same as an electric motor that has a bad bearing does as it is coming to a stop.
To answer a few of the questions above by Larry; I will admit that when I initially drained the oil before installing the new clutches I was surprised by the small amount of oil that came out. There was at the most 1/2 quart which I realize was low. The atv was in neutral when I spun the main shaft with the drill. The same sound could be heard/felt to a lessor degree even when spinning the shaft by hand, again with the trans in neutral. This is all with the entire clutch assembly removed, although it would make the same noise while pushing the atv in neutral around the yard with the clutch cover off and the clutch plates/frictions removed and the atv in neutral. Any time the main trans shaft turns, the noise could be heard to some degree. I could see the shift star rotate correctly through all the gears before I removed the clutch plates by rocking the atv and then shifting/etc/etc.

At this point, I am sure that my only choice is to completely remove the motor from the frame and open it up and start making a parts list. I did buy a set of shafts off eBay last night to have just in case both shafts have total carnage going on, but at this time I am thinking it is a bearing or all bearings associated with the main and drive shafts of the trans.

Can anyone tell me how the bearings are held in position on the other side of the case? Does the bearing on the other end of the main shaft simply sit inside a hole in the case and held in similar to the clutch side with a retainer/screws , or?
I am guessing that at the very minimum I will need to get the bearings for both shafts, but I will wait to order anything until I get it split rather than order anything that I don't need. I am on a limited budget but would like to get this blaster back running since it is my sons now.

 

[Larry's Shee]

The left bearing for main shaft is a blind hole. The problem with heating case an tapping on table is that either all the bearings will fall out, or as my luck has it, all but the one I want.
Blind bearing puller from HF.
Once you split cases you'll be able to isolate the two shafts and all bearings. Look for excessive wear/blueing on forks , make sure gears slide or spin freely on shafts.

Let us know what you find, as trans troubles are somewhat rare on these. Maybe an ocasional shift fork.

 

[Bluesman]

The gears are all constantly spinning at different speeds than the shafts, except which ever gear you are in. If someone rode it with no/very very low oil, it may have galled the shafts and gears. May be time for a whole new trans. You're gonna have to open it up and inspect. Also, worth mentioning, I'm pretty sure the main shaft that the clutch basket is on, will slide side to side, unless the clutch basket and inner hub and spacers are installed and the clutch hub nut tightened. This could affect what happens when you're spinning it. I know the Banshee is that way. I don't remember if the Blaster does also.

Also, calling the clutch basket a "clutch housing" isn't gonna get you very far.

 

[blasterd]

Thanks for the replies. FWIW, if you check the Yamaha PDF manual on section 4-7(page 77) you will find that that is exactly what they call it--a "clutch housing". I'm obviously not very familiar with atvs and figured the manual would be best to reference for part 'names' although I have always called that part a basket as well. I will keep that in mind though, thanks.

 

[Blaaster]

Unfortunately slang has a lot to answer for, the correct terminology for the basket is a clutch housing.

It can be very confusing when one like I have learnt to call a part by the name specified in the manuals.

Other terminology also becomes confusing, a cylinder being called a jug, and many others.

 

[blasterd]

I know what you mean Blaaster Using 'technical' names and then switching to slang brings up quite a few items you normally wouldn't see while searching on eBay for parts as well. I can't seem to find any vendors who offer the bearing(s) I ~may~ need for the trans main axle(shaft) anywhere on eBay. Anyone have any recommendations? I did find them through other vendors via Google searches, but I am curious if this is one of those cases where a person could get the bearing(s) WAY cheaper by going right to a bearing supplier with the right bearing cross reference numbers.
I did buy a "balancer gear" since I know the one I currently have is pretty sloppy to say the least.

I am hoping to get the motor pulled off and torn down over the coming long weekend so hopefully there isn't total carnage going on in there. I really want to get this blaster up and running again for my kid ASAP.

 

[Blaaster]

http://www.ebay.com/sch/i.html?_kw=yamaha+blaster+axle+bearing+carrier

 

[Larry's Shee]

Let us know what you come up with as to the brgs. While oem prices aren't bad, if equal quality could be had for less that would be great.

Good call on the balancer gear. Don't know if my gear ut the brg, which took out the case, or if the brg went first taking the gear

 

[blasterd]

I have decided that the noise that I heard while the motor is running and the things that I do(like spinning the trans main shaft with a drill and hear weird noises) might be completely unrelated like I originally thought(?). What Bluesman has said earlier makes a lot of sense to me the more I think about it. Maybe the shaft not being 'held' with the basket/nut/etc in place is allowing enough side to side movement which allows gears to almost mesh prematurely and explains the weird noise/jerking that I experienced at higher than hand turning speeds that the drill created. Since the motor isn't really that involved of a process to remove, I am going to install the new/used(supposed to be tight, anyways) counter balancer gear I got off eBay once it comes in or maybe just fix my current one by re-peening the mounting studs. The counter balancer gear is probably as loose as they can get before detonation (one side of the 'retaining plate' can almost be pulled right off the stud right now ). I am convinced that THIS is the noise I heard which obviously changes sound with RPMs and I thought was something with the clutches slipping. If I do this and then reinstall the engine/fill with ATF and find the noise to still be there I will just pull the engine again and dig deeper. It really won't take anymore time than figuring out what way overpriced(IMO, anyways) bearings I am going to get raped buying/mailed to me and also waiting on getting the correct(?) Yamabond (I see several different versions online, numbers 4, 5, 7 ) and also the fact that I have no experience splitting the cases and watching all the shafts/bearings/etc fall on the table then figuring out how to reinstall correctly........Anyways, hopefully the counter balancer was what started all of this for me and I know now the seal on the shift shaft is probably why the Yamalube I originally put in the atv a while back was lower than it should have been. I figure that seal at a very minimum will be changed in the very near future if all else seems OK after reassembly.
I will let anyone here know what I come up with if this is resolved or be back to ask questions if it isn't
I hate reading posts that people ask questions/get a lot of advice and then the post turns dead with no explanation as to what was found. I have read SEVERAL of those kinds of posts in the last few days

 

[blasterd]

I re-peened the 3 studs on the counter balance gear and put the bike back together and it is fine now. I am glad I didn't split the cases now