Boring Mikes 5th overdrive to proper ID?

[wannabridin]

Hey all,

I have an 81 that seems to have an earlier model transmission shaft in it? I purchased one of Mikes 5th OD's (Mikes P/N 05-0870, with .979" OD) off a member here and without checking my actual shaft diameter, the gear is too small. Lesson learned: don't take the websites information as fact!

Well since I work in a highly equipped machine shop, I'm wondering if I could take the .005" difference (other part is .984" ID) off the ID myself without any harm.

The ad mentioned something about the notches in the teeth, but I'm not sure if the different OD gears from Mikes have the notches or not.

Bottom line is, will the machining affect any properties of the gear (case hardening, coating, etc.) or cause any other issues that you guys see? It's effectively only removing 0.0025" off the surface, so unless there's a VERY thin coating, I don't think I would do too much to the hardening layer, but I can't be sure.

Please let me know your thoughts, thanks guys!!

 

[CDNTX650]

Mid year 77 was the change. The Tsb explains what you need to look for. The valleys on one set are shiny while the raised parts are dull. It's vice versa for the other set. I just can't remember what set is what without referencing the tsb

Not sure about machining. Figured I'd help ya try and identify your set.

 

[wannabridin]

I just received a response from Mikes, after providing a detailed list of information and questions: "http://www.mikesxs.net/product/05-0869.html This is probably what you need." Man I'd forgotten how nearly useless their customer service is, at least they provided a quick response.

Here's a picture of my transmission. I know it's the larger diameter shaft. My gut is telling me the 5th gear will be OK to bore out. I would really just prefer to not go through the hassle of selling this one and buying a different one from Mikes as I'd lose out on more than a few $$$.

 

[CDNTX650]

Your trans is correct for the bike. So the gear is wrong.

 

[CDNTX650]

On the old type shafts the valley is polished. The newer shafts the valley is dull. Easy to tell once you see the shafts side by side. The gear faces themselves never changed. Just the way they ride on the shafts. I run a 74 set and a 80 set in my engine. You can mix and match full sets of gears in the cases...but no gear swapping between old and new shafts.

 

[I am Carbon]

My mikes 5th gear was bored to fit in my engine. It's working just fine so far.

 

[CDNTX650]

There ya go. Bet mikes has a poor batch of those. Probably qc issue.

 

[wannabridin]

So carbon, you did the same thing as me?

And this was my fault, I didn't measure my shafts as even Mike's website recommends.

 

[CDNTX650]

I'm not sure why they need shaft measurements.....if you order the gear for 78 up trans it should fit with no issues on yours. Sounds like overseas qc. ...it fit when we checked it in 2008 at the start of manufacturing....ha.


edit

Ahh huh. You guys get one for the early trans sets too. We don't have that ordering option yet from xsdirect. So your trans is correct for your bike from the pics...so they either sent you an early od 5th or what I said before.... The correct gear you did order is manufactured wrong . I guess boring it if you have the ability to is easiest.

 

[pamcopete]

CDNTX650,

I don't think you have not been following the story here. wannabridin bought the part from a member, sight unseen. There are two gears offered by MikesXS and they caution you to measure your shaft diameter before ordering, but wanna did not order from MikesXS.

 

[CDNTX650]

Yeah I missed that. I also just learned you guys get the od gear for the earlier trans. US cdn customers aren't offered those gears from xs direct. Just the later ones for 78 up.

He also thought he had an older trans...it is indeed a 78 to 83 set.

 

[azman857]

I had the same problem with my 5th gear OD. Had to have a local machine shop hone the bore to correct size. That was about a year ago. It's hard stuff. My brake hone couldn't do the job.

 

[wannabridin]

Good to know! Azman, did they hone it to the proper size, .984"?

 

[TwoManyXS1Bs]

You could do it with a toolpost ID grinder.
Here, I'm finish polishing an 8.00° taper for my ER-32 collet chuck.

 

[chizler62]

@TwoMayXS's you gotta cover those ways up with a rag or something. That dust is brutal on a lathe or mill. I actually bought another south bend 9a to do grinding on. I face a lot of valves that way. Just put the valve in a 3c collet tighten in the spindle and use a grinder on the compound like turning a taper.

Yes, even XS valves. lol

 

[TwoManyXS1Bs]

Yeah, that was a 'staged' shot for a different forum. Needed to show other particulars that were covered-up during the 'actual' machining...

 

[wannabridin]

Just in case anyone is interested, did a hardness test on the gear the other day, and inside the dog recesses, I was getting 60 HRC

 

[I am Carbon]

well that's better than I would have thought.
I like it

 

[wannabridin]

Gear is going to get center bored with a carbide insert to within .001, then finished honed. Luckily our shop is somewhat equipped to handle odd-jobs. :-D

 

[I am Carbon]

Thats cool I have an older that me guy about 6 miles away. That has a bad azz machine shop. and he knows how use use every tool in his shop. I had him bore out a steel sleeve that some mo epoxied n an aluminum housing. He did such a good job I was amazed.