Author Topic: Undercut both directions?  (Read 1173 times)

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Offline bwaller

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Undercut both directions?
« on: June 29, 2013, 06:59:05 AM »
Is anyone using a gearbox that has been undercut both ways, as in upshift & downshift?

I've got drive side experience, but would like the impression of anyone with the above please.

Offline bjbuchanan

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Re: Undercut both directions?
« Reply #1 on: June 29, 2013, 09:18:43 AM »
Re-post to racing/performance?
The dirty girl-1976 cb750k, Ebay 836, Tracy bodykit
Round top carbs w/ 38 pilots, middle needle position, airscrew 7/8ths out, 122 main jet
Stock airbox w/ drop in K&N, Hooker 4-1

Don't trust me alone with a claw hammer and some pliers

Offline bwaller

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Re: Undercut both directions?
« Reply #2 on: June 29, 2013, 09:53:14 AM »
Not necessarily just race experience, anyone who is using one. I had an undercut (drive side only) CB gearbox waiting for when I had time to install it then in the meantime lent it to a forum member. This is the replacement, and as mentioned, is cut both sides.

Offline MRieck

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Re: Undercut both directions?
« Reply #3 on: June 29, 2013, 03:19:26 PM »
Is anyone using a gearbox that has been undercut both ways, as in upshift & downshift?

I've got drive side experience, but would like the impression of anyone with the above please.
Mine is both ways Brent (and has most of the dogs hardwelded). For roadracing it is a good thing. You are not banging downshifts when dragracing and on the street downshifts are much easier.
Owner of the "Million Dollar CB"

Offline bwaller

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Re: Undercut both directions?
« Reply #4 on: June 29, 2013, 03:31:56 PM »
Thanks Mike, I wasn't sure if yours was. I was prepared to stuff this in my race engine, but The 2 module gear (M/S 3rd/4th) has smaller diameter engagement dogs and being undercut both sides really reduces those dogs where it counts most. One positive is Fast by Gast indexes precisely so contact will be even for all three but I was nervous the use it. This gearbox is for Deb's 592, just hadn't got around to installing.  ::)

The 6spd parts made it back & I'm installing the engine tonight. I'll bloody test it tomorrow so no surprises at the track next weekend.

Offline TimV840

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Re: Undercut both directions?
« Reply #5 on: June 29, 2013, 06:50:34 PM »
Woohoo! :) Only 6 days left buddy. ;)

The 6spd parts made it back & I'm installing the engine tonight. I'll bloody test it tomorrow so no surprises at the track next weekend.
'71 CB350 - Race
'72 CB175 - Pitbike
'75 TR750 Replica - NEW Race
'85 Interceptor 500 - Street
'86 VFR 750 - Street
'96 VFR 840 - Street
'88 FZR400 - 1st Race Bike / Now Street

Offline bwaller

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Re: Undercut both directions?
« Reply #6 on: June 29, 2013, 06:58:22 PM »
Woohoo! :) Only 6 days left buddy. ;)


Oh man don't I know it, it feels like it's been a whole year off.  >:(