Gearbox Issues
 

Hello everyone!

I have split the cases on my 1983 tt600 I have found a oil pick up strainer full of metal and gasket material yay!

One of the previous owners has replaced some gears in the transmission at some point, I'm guessing, because there is a few loose teeth that dont have an owner in the oil strainer.

The hurdle that I am facing in getting this bike back on the road is the pitting on the trasmission, I have been able to figure out I can still buy most of the gears, checking part numbers up until the 1989 model xt600.

The fifth pinion gear is where the problem lies, I am under the impression, from reading the forums, that yamaha changed the gear on the 1990's model making it wider. What do I have to do to replace this 5th gear in my transmission? Will it fit? Do I have to get the case machined to get it to fit, what needs doing?

I have sent an email to moorespeed inuiring about the gearsets they sell but havnt got a reply back on pricing.

Im located in Australia and any help would be appreciated.

The newer e-start transmission or gears will not fit in the older kicker TT's or XT's . The shafts are wider to make up for the wider gears and no way to make them fit in the narrower old cases. I had the 2 trannys side by side looking for any swaps , there were none . Just replace with the XT/TT gears for the bike and try not to lug the motor in too high of gear which does some of the chipping damage . The rest of the spalling is (what I believe) cavitation from the oil between two teeth as they mesh and it gets forced out. Common issue in many of these types of transmissions ,regardless of brand. Even the new gears had the same issues so the fix wasn't good enough , till I think into the 2000's model's .

Also use the clutch when shifting and don't land jumps under full power with the tire spinning , that's quite a shock load to the gears , I've seen it in quads a bit due to the 2 tires that don't spin as easy so more pressure to transmission.

I havnt been able to find a 5th pinion gear for this transmission. They seem to be obsolete from the online part stores. That is why I am looking at other options. I could get a used transmission but that is a bit of a hit and miss , hope for the best situation.

I might give this option a try. Something along this way of getting the gears to fit. I know a good fabrication place in town that'll help me out with it. http://www.horizonsunlimited.com/hub...solution-80123

I would just buy a good used one from the states, they seem to have had an easier life than aussie ones.

Here`s one for $30 bucks.

Mezo.

Most of the engines I've had apart here have had shot 5th gears , all spalled/chipped . I'm just not sure if it's from running too high gear at too low rpm and the "chugging" that the engines do it that situation or if it's from oil cavitation and what that does to surfaces . 3 of the newer 3tb's I've had now have been the same condition , even one at 11K miles showed small chips and the beginings of the issue. so doing all that work to use the newer gears isn't a foolproof solution.

I also saw this on my XL6 btw , though not as bad . DR650's get it badly on 5th and 3rd usually , sometimes ending in destroyed case. Even the aftermarket replacements with more ideal heat treatments are showing the same thing .

Get one made, there are fabricators who will make the gear for you. where are you located? there is a guy having 3 made in Australia as we speak,one of which is for me.

Im in Northern NSW, who does that sort of fabrication and is it pricy?

I got onto the one I'm having made through a post on the Tenere Tragics feces book page, it's costing about $350, however last week I was in my local Yamaha dealer getting some reasonably priced parts for my 39E when the guy behind the counter gave me info on a gear cutting workshop called Coljen, (Heidelberg, Melbourne) who was currently making lots of gears for Suzuki dealers for DRs, they make lots of bike gears and can make the 5th Pinnion.
I rang them and they may be a bit cheeper than what i'm paying, but they would need a sample. the gear I'm having made is being made from some superior metal, apparently.

i'm interested in Moorespeed's gears, but I don't think they'll work in my early bikes

I have read an article where someone used gears from I believe it was an atv, read so many,maybe it was in the srx600,also one on juggling the clearances to fit the smaller case, just cannot find the two articles.I will look tomorrow for them.

how's things going with the gearbox Jesse?

Hi Jesse,

I have had this problem in my 1984 XT600.

I too used the above article as a good starting point for solving this problem.

I have engineered my own solution, which I am near to installing and running for the first time in a few weeks.

Please, anyone, correct me if I'm wrong but i believe the 5th gears from a 2JT model are a direct fit replacement for the earlier 5th gears. Yes they have a different number of teeth than the originals (meaning they have to be replaced as a pair) but I think physically they are the same size as the earlier 5th gears and can still be sourced from MegaZip: OEM Motorcycle Parts, ATV Parts, Marine Parts, Automobile Parts.

I went for fitting the upgraded 3YF 5th gears into my gearbox, which meant thinning of the 2nd gear on the output shaft.

I guess this is a gamble, and many may not recommend this, but time will tell if this is a mistake I have made and will learn the hard way, or if all will be OK! I used a local machine shop to flat grind the gears to the required dimensions, and modified two 27mm x 0.8mm bearing shim washers to become spacers where required.

I'm happy to send over my mechanical drawings which detail my solution, and can report back in a month or so how it goes.

So far, with the gearshafts installed in the engine casings, my modifications work nicely - i.e. all gears fit, and select smoothly. But until I start putting torque through the modified 2nd gear, I won't know how it'll hold up!

Many thanks to pete_j for his work and advice!

hope i am not disappointing anyone, but just opened a 3yf motor yesterday, and 5th was shot too. badly.

i been searching quite a bit into that as i need the shorter ratio 5th for my road racer. Nova in uk used to make them, but are out of stock.... actually if there's a minimum order of five, they will redo.

so if anybody is interested in a shorter gear 5th for 3yf's, which makes less of a gap from 4th to 5th as well as logs the engine less, you are welcome to pm me....

now, the only thing that surpises me is people saying a 3yf (xtz660) 5th pair will work in a 600.... dont know the 600 that well, but i thought the 5th sits in a 600 next to 1st, in the 3yf its on the opposite side. i might be wrong of course.

looked a bit into atv gearsets, just from pics the shaft splines look different

I have just bought a gearbox out of a 4gv engine, 1993-97. I am going to transfer the gears onto the older style shafts from the tt600 '83. I have compared the lengths of the gears with a set of calipers, everything looks like it will fit up. I will have to get the 2nd wheel gear machined a couple mm thiner to fit in the case with the thrust washer from the '83 setup instead of the spacer from the 4gv. Hopefully itll all fit. A copy of your mechanical drawings would be very helpful heffho83'.