Transmission Undercutting

Undercutting a transmission involves machining angles on the engagement dogs and slots to prevent the transmission from jumping out of gear under load. There are three types of undercuts available from APE

This cut is performed on the side of the dogs that are loaded on acceleration. Recommended for hot street bikes and drag racers, dwarf cars, etc.

Up and down cut....
Both sides of the dog are cut to also prevent jumping out of gear on down shifts. Recommended for road racing.

Under cutting notes... Some of the newer sportbikes are coming from the factory with undercut gears in the transmission. When you send us your trans, if it has factory undercut that is adequate, you will not be charged for undercutting that gear or gears.
If dogs are rounded off due to repeatedly slipping out of gear of missed shifts, they can not be undercut. You will be notified by APE tech staff if any of your trans parts are unusable.

There are times when small things like clips and spacers are unusable. These parts will be replaced at a nominal charge when servicing transmissions.

We also operate a complete aerospace-type CNC machining facility in which we manufacture our world-famous racing products. These facilities are all on-site at the APE race shop. Besides the services listed below, APE also offers:

Complete Machine Work Service
Crankshaft Service
Cylinder Head Service

Call APE to place a transmission work order. (661) 256-7309

Please read our shipping instructions carefully.

Include an APE work order form when sending parts for labor.

Ship parts to:
7347 Rosamond Bl.
Rosamond, Ca. 93560

What exactly is undercutting?

The transmission gears lock together with a series of "dogs' or "dogs and slots" The photo below shows several of the dogs engaged together so that both gears turn together. Under hard use, the gears can began to separate until the dogs become disengaged, this causes the transmission to jump out of gear.

Now notice in the above photo the dogs that are in the circle. They both have angles cut on them where they meet. This causes them to lock together. They cannot separate without first backing up to unload the angles. This is an undercut. On APE transmissions, all of the dogs get these precise angle cuts.

Road race "up and down" cuts have angles machined on both sides of the dog so it works the same way under acceleration load and deceleration load.

LC55-2   367.00
LC55-3   374.00
LC55-4   465.00
LC56-2   403.00
LC56-3   413.00
LC56-4 . 473.00
LC57-1 (undercut 2nd gear only) 175.15
LC58-1 Pro-cut Hayabusa Trans. 451.00
LC58-1X2 Pro-cut Hayabusa Tran. (up and down cut) 827.00
LC61 Magnaflux transmission 135.00
LC850-Trans Hardweld trans. gear (ea) 140.00

Up and Down cuts double price.
CB750 sohc LC55-3
CBR600 LC56-3
CBR900 LC56-3
CBR929 LC56-2
CBR1100XX LC56-2
GS1000 LC55-2
GS1100 / 1150 LC55-2
GSXR600 / 750 LC56-2
KATANA 600 LC56-2
RF600 LC56-2
SV650 LC56-2
GSXR1000W LC55-2
GSXR1000 (2001) LC56-2
HAYABUSA 1300 LC58-1
HAYABUSA 1300 - STD undercut LC56-2
KZ900 / 1000 LC55-2
GPZ/J models LC55-2
ZX6 THRU 97 LC56-2
ZX6 98 LATER LC56-3
ZX7 LC56-2
ZX9 THRU '97 LC56-2
ZX9 '98 LATER LC56-3
ZX1100, ZRX1100 LC55-3
ZX11 LC56-2
ZX12 LC56-3
FJ1100 / 1200 LC55-3
FZR1000 LC55-3
FZR400 LC56-3
R1 LC56-4
R6 LC56-4
V-MAX LC55-3

APE provides online pricing as a service convenience only. These prices are not binding and are subject to updates without notice. Though we try hard to maintain accurate up-to-the-minute online pricing, it is best to call APE and check with the desk for pricing if you have any questions.