5th overdrive gear grooves/mod?

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desmodromic

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I'm in the process of rebuilding my motor. I am doing the 5th gear overdrive, 82' transmission, as one of the mods. I'm not crazy about the looks of this overdrive gear, I'm used to changing gears in pairs. I noticed the overdrive does not have notches cut into it and the teeth are not tapered on the edge. Do you guys modify them? Anyone had any problems with the overdrive gear?
BTW the gear that is on the transimission is the overdrive, the one avobe it its the OEM
Thanks
 

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I agree, most times gears are changed in pairs, as one starts to disintigrate it usually takes the second gear with it.
If you have look at the mikesxs site there are 2 x gears that are supposed to be installed as part of the 5th gear OD install. I'm guessing you don't have the other gear.?
 
hotdog said:
I agree, most times gears are changed in pairs, as one starts to disintigrate it usually takes the second gear with it.
If you have look at the mikesxs site there are 2 x gears that are supposed to be installed as part of the 5th gear OD install. I'm guessing you don't have the other gear.?
Click to expand...

Thanks, I did not see the other gear. :doh: . What about the tapered teeth and the notches on the teeth?
 
Since these transmissions are 'dog box pre engaged' there's no need for a taper. I'd say the grooves in the OE gear are just something left from the machining process and the lack of grooves in the new gear is nothing to be concerned about.
 
From Mikes.
Note: Yamaha changed the shape of transmission gear teeth from 78 on and this is indicated by lines cut into the crest of each tooth.
 
In school in machine shop one of our advanced students was given the job of making new gears for one of the lathes. He knew how to make the gears in a way that they were noisy but still good. The noise was awful and would scare the hell out of anyone that used the lathe. He still got a good grade for demonstrating what makes a gear quiet.

Scott
 
Only one cog gets changed for the 5th gear overdrive, part no Part #05-0870.

The other gear, ( Part #05-0857), with the dogs on it is a Standard replacement for the 5th gear that often breaks the dogs

It was the splines for the shaft that was changed not the teeth,

Service bulletin
 

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650Skull said:
Only one cog gets changed for the 5th gear overdrive, part no Part #05-0870. The other gear, ( Part #05-0857), with the dogs on it is a Standard replacement for the 5th gear that often breaks the dogs

It was the splines for the shaft that was changed not the teeth,

Service bulletin
Click to expand...

I did not know that, my apologies for any confusion, I thought it was a matched set..??
 
650Skull said:
Only one cog gets changed for the 5th gear overdrive, part no Part #05-0870. The other gear, ( Part #05-0857), with the dogs on it is a Standard replacement for the 5th gear that often breaks the dogs

It was the splines for the shaft that was changed not the teeth,

Service bulletin
Click to expand...

Skull, this is at the end of Mikes overdrive 5th gear description: "This needs to be used with part #05-0857."
 
In 1977 the gearbox was changed midway through the year. before and after model no IT3-271262. ...Read service bulletin posted above.

If you have an engine no before this, then the mikes 5th gear overdrive, (Part #05-0870), or the 5th main gear, (Part #05-0857), will not be a match.

If your engine no is after this, then mikes 5th gear overdrive, (Part #05-0870), and 5th main gear, (Part #05-0857), will be a match


Mikes reads so you buy the 22 tooth 5th main gear with the overdrive cog, but in reality if your 5th main gear, ( post 1977D IT3-271262), is in good condition then why replace it......... You do not have to replace it........... it is up to you............... Of course Mikes wants you to buy them both.
 
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You don't need the mating gear if you're installing on a later model transmission. MikesXS wording is indeed confusing and misleading. I have the taller 5th gear on my 1984 engine with the 750 kit on it and it's been running great. Just put another taller 5th gear on my 1978 engine and expect no issues.

If you have an earlier engine, then you'd want either to replace the transmission with a later set or buy the matching gear, either of which can likely be done for about the same price.
 
Nope - as it says on the site:

"Fits: XS650's 1978 - 1984 Only! Note: Yamaha changed the shape of transmission gear teeth from 78 on and this is indicated by lines cut into the crest of each tooth."

I can't vouch for it, but with the mating gear 05-0857 from 650Direct (assuming as you like me are in Canada) you would be OK.

Or you need to buy a 78+ transmission set.
 
Tim of DO THE TON said:
Nope - as it says on the site:

"Fits: XS650's 1978 - 1984 Only! Note: Yamaha changed the shape of transmission gear teeth from 78 on and this is indicated by lines cut into the crest of each tooth."

I can't vouch for it, but with the mating gear 05-0857 from 650Direct (assuming as you like me are in Canada) you would be OK.

Or you need to buy a 78+ transmission set.
Click to expand...

Yep I'm in Canada, so to clarify, I can't install just the 5th gear overdrive, but I can install it on my pre 78 transmittion as long as I also purchase part number 05-0857 (Stock 22 Tooth 5th. Main Gear)?
 
Tim of DO THE TON said:
If you have an earlier engine, then you'd want either to replace the transmission with a later set or buy the matching gear, either of which can likely be done for about the same price.
Click to expand...
Not recommended in the service bulletin posted in earlier post


Tim of DO THE TON said:
Nope - as it says on the site:

"Fits: XS650's 1978 - 1984 Only! Note: Yamaha changed the shape of transmission gear teeth from 78 on and this is indicated by lines cut into the crest of each tooth."

I can't vouch for it, but with the mating gear 05-0857 from 650Direct (assuming as you like me are in Canada) you would be OK.

Or you need to buy a 78+ transmission set.
Click to expand...

Don't believe everything you read on Mikes site.

The transmission changed mid way through 77D, as i explained above.

Splines was the big change, as per service bulletin posted in previous post


bloglos said:
Yep I'm in Canada, so to clarify, I can't install just the 5th gear overdrive, but I can install it on my pre 78 transmittion as long as I also purchase part number 05-0857 (Stock 22 Tooth 5th. Main Gear)?
Click to expand...

No and No

bloglos said:
Wait this is confusing, so if I have a 77D then I can't install the 5th gear overdrive at all? Because I just ordered it and it should be here tomorrow :doh:
Click to expand...

Yes if you have the model after the gear change as per service bulletin. Bulletin posted in my previous post

PDF file on the 77D-78E-79FTransmission showing the change in the transmission shafts and gears, mid year 77
 

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