Topic: Undercut transmission, or rev limiter?

[Retro Rocket]

Nah mate, it's the "piston to cylinder wall" clearance that'll (possibly) be tight, due to the ceramic coating adding a couple of thou to the OD of the pistons. i don't know what the clearances are now, but I'm guessing .001 - .0015? Cheers, Terry.

After i posted i thought you would say that, i was only planning on coating the piston tops...

Mick

[Terry in Australia]

OK mate, that sounds like a good idea. Cheers, Terry.

[scottly]

I just got the quote back Mick, $225.00 plus GST to cryogenically treat the whole gearbox, sweet! I'll drop it off tomorrow!

Wouldn't it be best to do the undercut before the cryo treatment?

[Terry in Australia]

Apparently it makes no difference, as the cryo treatment is not a "coating" or "surface hardening", but changes the whole molecular structure of the steel, so you won't cut/grind through a thin layer of hardening. If the dogs are in good condition though, I'm wondering if they'll need to be undercut after cryo treatment? What are your thoughts mate? Cheers, Terry.

[scottly]

With a big motor and used gears, I think I would go ahead and undercut, just to be safe. My concern about doing the undercut first would be heat generated by grinding might(?) change the molecular structure back.

[Retro Rocket]

With a big motor and used gears, I think I would go ahead and undercut, just to be safe. My concern about doing the undercut first would be heat generated by grinding might(?) change the molecular structure back.

Interesting, i would probably cut first. I wonder if this Cryo treatment can be used on bearings and chains...?

Mick

[Terry in Australia]

OK mate, I'll think seriously about it, they do say in their blurb that components can be machined afterwards with no ill effect, but I did wonder about it at the time. Cheers, Terry.

With a big motor and used gears, I think I would go ahead and undercut, just to be safe. My concern about doing the undercut first would be heat generated by grinding might(?) change the molecular structure back.

Interesting, i would probably cut first. I wonder if this Cryo treatment can be used on bearings and chains...?

Mick

I think Ron (MCRider) did get his done Mick, but I'm not sure. Cheers, Terry.

[Terry in Australia]

Well Paul in Sydney (K2 836) put me onto an engineer who'll undercut my gears for only $185.00! Woohoo! I rang him a moment ago, he's an older guy and seems to know what he's talking about, so I'll send them off on Monday, thanks Paul!

[Bill/BentON Racing]

I believe MCRider did his.I too would undercut and do it first.Bill

[Terry in Australia]

Yep, that's the plan Bill, get 'em undercut, then Cryo treated. Has anyone got a pic of a CB750 transmission with the gears numbered? Scottly said not to get first gear undercut, so I'll need to pull it out before I send my gears off. Cheers, Terry.

[mick7504]

Terry
How are you mate
I haven't got ém numbered but they're all laying together on their shafts.
This is the job that Big Jay did for me.
Still smilin' 
Mick

[scottly]

It wasn't me...

Don't bother undercutting the first gear set either Terry, it just makes it tougher to find neutral.

[MCRider]

With a big motor and used gears, I think I would go ahead and undercut, just to be safe. My concern about doing the undercut first would be heat generated by grinding might(?) change the molecular structure back.

Interesting, i would probably cut first. I wonder if this Cryo treatment can be used on bearings and chains...?

Mick

I'll answer multiple questions here. My Cryo texch said they do everything, chains, (even ORing) gears, shafts, pistons, valves, cams, etc, engine blocks (says the drag guys get 3X more runs from a cryo block than non cryo, before they have to re-linbore it).  Sprockets, rotors, cam blocks, I did it all. They prefer machining be done first, then Cryo.

Only caveat on the chains was they want to do new ones. Used ones may have damage and so I had my used ones magnfluxed, and then they were OK to cryo. On the ORing chain, they say just be sure they know, key is simply don't move it till the cryo is done or the oring shatters. duh.
Caveat on bearings is the grease and rubber seals. If internal tranny type, then no problem to cryo.

On the undercutting,  APE charge for 4 cuts. So I asked Jay to cut 1-2, 2-3, 3,4 and 3-2. I figured why 4 to 5? Never a problem there. I have had the 3 to2 jump out on me so I picked that one. Heck they will do all 8, anything for a price, but not for me.

[Terry in Australia]

It wasn't me...

Don't bother undercutting the first gear set either Terry, it just makes it tougher to find neutral.

Oops, sorry Scottly, you're right mate, it was Brent Waller. Cheers, Terry.

[Terry in Australia]

With a big motor and used gears, I think I would go ahead and undercut, just to be safe. My concern about doing the undercut first would be heat generated by grinding might(?) change the molecular structure back.

Interesting, i would probably cut first. I wonder if this Cryo treatment can be used on bearings and chains...?

Mick

I'll answer multiple questions here. My Cryo texch said they do everything, chains, (even ORing) gears, shafts, pistons, valves, cams, etc, engine blocks (says the drag guys get 3X more runs from a cryo block than non cryo, before they have to re-linbore it).  Sprockets, rotors, cam blocks, I did it all. They prefer machining be done first, then Cryo.

Only caveat on the chains was they want to do new ones. Used ones may have damage and so I had my used ones magnfluxed, and then they were OK to cryo. On the ORing chain, they say just be sure they know, key is simply don't move it till the cryo is done or the oring shatters. duh.
Caveat on bearings is the grease and rubber seals. If internal tranny type, then no problem to cryo.

On the undercutting,  APE charge for 4 cuts. So I asked Jay to cut 1-2, 2-3, 3,4 and 3-2. I figured why 4 to 5? Never a problem there. I have had the 3 to2 jump out on me so I picked that one. Heck they will do all 8, anything for a price, but not for me.

Thanks Ron, and I've got new primary and cam chains here, so I'll get them cryo treated while I'm at it. Cheers, Terry.

[72hondacb750]

Iwould kill for a good how-to // diy on undercutting .. I get some missed shifts and pops on mine but don't gave the means right now to dump 300 + shipping + downtime into my bike .... If I did myself I'd just get another set of trans gears.

[mick7504]

Iwould kill for a good how-to // diy on undercutting .. I get some missed shifts and pops on mine but don't gave the means right now to dump 300 + shipping + downtime into my bike .... If I did myself I'd just get another set of trans gears.

Mate
It is serious dough for a serious job.
What Big Jay can do for you will kick butt and plenty of it. 
Mick

[Terry in Australia]

I got mine back from Sydney Mick, brilliant job, and only 185 bucks, woohoo!

[mick7504]

I got mine back from Sydney Mick, brilliant job, and only 185 bucks, woohoo!

Did you end up getting the Cryo done on it as well mate?

[72hondacb750]

What if someone made a guide and a block to check your work with.. .. Anyone here have the means ? I'll prepay for one.

[Terry in Australia]

I got mine back from Sydney Mick, brilliant job, and only 185 bucks, woohoo!

Did you end up getting the Cryo done on it as well mate?

I will, it's just that having sold 4 bikes to mostly interstate buyers I've been running around getting freight quotes and packing up spares Mick, but once I get some time I'll get it all across for Cryo treatment too. Like you said awhile ago, it's only money! 

[kos]

Apparently it makes no difference, as the cryo treatment is not a "coating" or "surface hardening", but changes the whole molecular structure of the steel, so you won't cut/grind through a thin layer of hardening. If the dogs are in good condition though, I'm wondering if they'll need to be undercut after cryo treatment? What are your thoughts mate? Cheers, Terry.

For a racing machine we undercut gears, as it makes for a very positive shifting machine, but remember, you are removing the heat treat and or surface hardening and the dogs will wear at a much higher rate than OEM non modified gears. Unless of course you go back and re-treat dogs. We used to touch up (regrind) dogs on our M3 racing machines every winter when we had engines down for inspection and that seemed to work well, but if we skipped this procedure, it would come back to haunt us with missed shifts and constant slipping out of gear while in the hunt! And this made our rider, very unhappy!

KOS


KOS

[Terry in Australia]

For a racing machine we undercut gears, as it makes for a very positive shifting machine, but remember, you are removing the heat treat and or surface hardening and the dogs will wear at a much higher rate than OEM non modified gears. Unless of course you go back and re-treat dogs. We used to touch up (regrind) dogs on our M3 racing machines every winter when we had engines down for inspection and that seemed to work well, but if we skipped this procedure, it would come back to haunt us with missed shifts and constant slipping out of gear while in the hunt! And this made our rider, very unhappy!

KOS

Thanks for that mate, re: the situation of cutting thru the surface hardening, have you tried the Cryo treatment? From what I can gather, it hardens the material right thru to the core, so I assume that this would negate the need to regrind the dogs on a regular basis? Cheers, Terry.

[MCRider]

Terry: Not actually hardness in terms of "Rockwell" but stabilization and other characteristics that might provide the same results.

http://www.cryogenicsofindiana.com/

Would be good to know. I hadn't thought of what KOS brought up, but I have had my gears Cryod after the undercutting. I doubt that I'd put my tranny thru in a lifetime what KOS sees in a season or less, so mine won't be a good test..

[scottly]

Use a transfer dye on the edge of the hole the dogs engage, fit the gears together and note where the dye shows on the dogs; the contact should be closest to the gear. Using a Dremel with angled stones, carefully undercut the dogs, making sure to remove the same amount from each dog, so the load is evenly distributed. The dye will guide you. Work slowly. Only a small amount of under-cut is necessary: too much will make shifting difficult without "floating" the throttle.
By the way, this process is only for those with more time than money.

Iwould kill for a good how-to // diy on undercutting .. I get some missed shifts and pops on mine but don't gave the means right now to dump 300 + shipping + downtime into my bike .... If I did myself I'd just get another set of trans gears.

Mate
It is serious dough for a serious job.
What Big Jay can do for you will kick butt and plenty of it. 
Mick