Transmission long shot II

[papanovember]

O.K., probably not realistic for someone to come here(Basalt,Aspen,CO) to fix my transmission. The really intimidating thing for me is the dremeling of the gears. Like I said, I have a complete spare tranny I can send to somebody and pay them to do the work. I can send all the dremel bits and compensate for any extra costs. I also have a restored Yamaha IT465 bike I'm lookin to get rid of with a ton of extra parts. Bike is crazy fast! And I'd be happy to ride with anyone who wants to visit this area...

[papanovember]

Tough crowd!

Nothing, huh? Well I'll just do it myself. If I fail, I'll post lots of goodies in the parts section....

[clcorbin]

It's not hard. I would recommend that you use a phenumatic die grinder with the right stones. They can remove the material a lot faster and cleaner than the small stones on a dremel can. For final clean up and for the non through grinds (5th gear I THINK), A 1/8" solid carbide spiral mill bit works great in the dremel. With a light touch, it can make a very nice, clean cut.

I would give you the part numbers for the bits, but they were bits I already had on hand when I did my own bike, so I don't know them part numbers.

[jetmechmarty]

finding help

There is still an archaic email group dedicated to this bike on YAHOO. Folks there seem quick to help. You may want to sign up. The traffic there is slow.

allxs11s@yahoogroups.com

OR...use the info here and do it yourself. Have confidence.

[TopCatGr58]

Hey there Papa,

I was waiting and hoping someone closer to you would offer or contact you regarding this! I've done this for a fellow in South or North Carolina, he did all of the other mechanical work, and was able to put it back together just fine, and has worked a couple of years now.

As was suggested, IF you have a big enough air tank/compressor to drive a die grinder, then it would be faster. Ken Talbot posted that technique in his tip. I posted about the DREMMEL because not everybody has a die grinder, but a Dremmel is fairly inexpensive, and with new stones, does a decent job as well.

Surprisingly the gears aren't so particular regarding the angle of grind and such. I tried to show in the diagrams in the Dremmel tech tip about doing the grinds.

IF you have a dig camera, feel free to PM me to trade email addresses, and you could send photos of the gears as or after you've ground them to show me to see if they look like they were done right.

They say the main thing is to try to do the same amount to each DOG and slot so that they engage evenly. However, once you grind thru the thin hardened surface, the remaining steel is more forgiving, and will bend/deform until all 3 contact points are even. They are overengineered and very strong, have never heard of anyone breaking a dog off after doing this repair!

T.C.

[bikerphil]

Just whip out the wallet if you can and buy some new gears, 'bout $200, and you can just throw them in. Parts 23 & 26 on the fiche.

http://www.yamahaaccy.com/parts.aspx

[TopCatGr58]

Yes,

Getting already undercut new gears from YAMAHA is another approach, but from what I've seen with 4 bikes that I've done this repair on is that the damage isn't usually limited to just 2nd and 5th gears! There is quite a bit of rounding off of 1st and 4th gears dogs as well, and both sets require "dressing" to get them to stay engaged correctly.

I think it was Catatonic Bug that had to go back into his bike because he only fixed 2nd the First time, and then 1st started acting up shortly afterwards, and had to go back in to fix it.

SO....now it can get rather $$ buying 4 gears instead of just 2!

YMMV!.
T.C.

[mharrington]

I am just the opposite. I have my XS engine out and upsidedown on a bench. I have the countershaft out and EVERY gear on it is bad. Im not afraid to dremel the dogs and pinions but I am positive I would not be able to re assemble....correctly. I bought another bike with a SUPPOSED good engine/tranny.

[trbig]

Im not afraid to dremel the dogs and pinions but I am positive I would not be able to re assemble....correctly.

The beauty of digital cameras. Take pics every step of the way. If you get stuck, take another pic and post it here and many can tell you what goes next.

Just getting another transmission isn't going to help probably. If I took the time to pull the gears, then I wouldn't put a set of worn gears back in. Sure, they may last years... but they also may last just days.


Tod

[papanovember]

Transmission

I have impact wrenches that I used with a portable CO2 tank, but not an air compressor. My die grinder will just freeze up with the CO2. So...I don't really want to invest in an air compressor. I already have the dremel and the bits that TopCat recommended and have been over his post many times. Like I said, I got a complete spare tranny that is in pretty good shape, showing only minimal wear. My plan was to dremel the spare tranny. I mean, first gear in my bike is GONE. Just spins with this awful metal grinding sound. Also, taking apart the tranny is also intimidating, but the digital camera pics is a good idea. I was just hoping I could send the four gears to someone who has done this numerous times and pay them something like $200 bucks instead of buying 4 gears at $180 a piece. Like TopCat said, I'm doing ALL the gears. I never want to go back in their again. Anyway, thanks for the advice.

[mharrington]

Actually I did take pics of the disassembly progression. I figured to replace very gear on the countershaft would be about $600. Id love to have all new steel but I can not afford this even in stages. Guy on ebay has a countershaft complete assembly for $90 I cant see see the condition of the dogs personally. Even with my pics Id be scared to re assemble. I do have the option of offering another member here good $$ to help me if I (he is willing.) My tore down engine had 185 psi across the board of cyl pressure. I need to put in a battery and install some carbs on my parts bike and start it up. PO claims there were no problems with the tranny of that bike. Whenever its up and running I plan early shifts from 1 to 2 and to use the brakes to slow down instead of relying on downshifting and engine torque.

[papanovember]

This was from the Transmission Repair Section

About Neutral and the Neutral-1st gear shift:
In addition to the popular 2nd gear problem, there has also been a number of 1st gear problems with this transmission. The cause is due to how the gears behave when in neutral, and how that effects the shift into first.

When the engine is running and clutch is engaged, and the transmission is in neutral, 1st, 2nd and 3rd gears are freespooling, but their pinions are fixed. Thus, each of these gears is spinning on the countershaft, though the countershaft is not spinning at all (remember, the countershaft and wheel have a hard connection, if the wheel is stopped, the countershaft is stopped).

Since 1st gear is so large, it has a lot of momentum, disengaging the clutch and shifting into first causes the non-spinning 4th gear to engage with the spinning 1st gear. This causes the shifts to be hard. This is why there is a loud "thunk" when shifting into 1st from neutral. To make it worse, the bike is shaft driven; on chain and belted bikes, the chain or belt will bounce to absorb some of the shock.
The way to avoid this is to wait several seconds after releasing the clutch to engage 1st gear. This will allow the gear to slow down enough or stop, so that the shift will be less brutal.


This was Posted by XS11(super moderator) and just thought everyone should read his post. This just explains why first gear commomly goes out. If you have a good tranny, this should be practiced.

[DenyP]

About Neutral and the Neutral-1st gear shift:
In addition to the popular 2nd gear problem, there has also been a number of 1st gear problems with this transmission. The cause is due to how the gears behave when in neutral, and how that effects the shift into first.

When the engine is running and clutch is engaged, and the transmission is in neutral, 1st, 2nd and 3rd gears are freespooling, but their pinions are fixed. Thus, each of these gears is spinning on the countershaft, though the countershaft is not spinning at all (remember, the countershaft and wheel have a hard connection, if the wheel is stopped, the countershaft is stopped).

Since 1st gear is so large, it has a lot of momentum, disengaging the clutch and shifting into first causes the non-spinning 4th gear to engage with the spinning 1st gear. This causes the shifts to be hard. This is why there is a loud "thunk" when shifting into 1st from neutral. To make it worse, the bike is shaft driven; on chain and belted bikes, the chain or belt will bounce to absorb some of the shock.
The way to avoid this is to wait several seconds after releasing the clutch to engage 1st gear. This will allow the gear to slow down enough or stop, so that the shift will be less brutal.


This was Posted by XS11(super moderator) and just thought everyone should read his post. This just explains why first gear commomly goes out. If you have a good tranny, this should be practiced.

Wish I had read this two years ago. I have always used down shift and engine compression to slow before applying brakes. When I got my bike there were no visible transmission issues. After about 6 months of riding she started popping out of first gear on a take off if I got on it. I found if when I stop, I shift it into neutral let out the clutch, pull it back in and drop to first before I take off it rarely happens. I hate to think my riding style has trashed my gears but I guess we learn!

Deny

[trbig]

Acceleration makes contact with one side of the dogs and slots together. Decel is a totally different contact area.. it's the other sides of the dogs and slots and won't affect the rounding on the gears from acceleration. The only thing that causes rounded gears and skipping on acceleration is acceleration.


Tod

[mharrington]

Did the other muscle bikes of that era have similar problems. I had a 78 GS 750 Suzuki and its was so much smoother than my 78 XS750. I never hear of old KZ 1000s and GS 1000s with gear problems.