NOVARACING TRANSMISSIONS LTD

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NOVARACING TRANSMISSIONS LTD MANUFACTURERS OF 6 PINNACLE CLOSE, PHOENIX LANE TRANSMISSION SYSTEMS CROWLAND, LINCS, PE6 OGB,UK. FOR RACING AND Company Reg: 2438157 Cardiff DEVELOPMENT VAT NO.

1 NOVARACING TRANSMISSIONS LTD MANUFACTURERS OF 6 PINNACLE CLOSE, PHOENIX LANE TRANSMISSION SYSTEMS CROWLAND, LINCS, PE6 OGB,UK. FOR RACING AND Company Reg: Cardiff DEVELOPMENT VAT NO Registered in England No Tel: Fax: info@novaracing.co.uk Fitting Guide for Nova Honda CB72/77 Road Gearbox This guide gives a step by step guide to fitting the Nova Honda CB72/77 Road Version Gearbox

2 Contents Page Contents Page Number 1. Parts Included in the Nova Honda Gearbox 3 2. Engine Case Modifications 5 3. Fitting the selector drum and forks 7 4. Fitting the gear shafts 9 5. Fitting the selector mechanism Fitting the shifter arm assembly Fine tuning the selector mechanism Finished Nova Honda CB72/77 Road Gearbox 14 2

3 1. Parts Included In the Nova Honda CB72/77 Gearbox Gear Shaft Assembly QTY Part Description Part no 1 Honda CB72/77 Input Shaft Honda CB72/77 2 nd Input Honda CB72/77 3 rd Input Honda CB72/77 4 th Input Sleeve Gear Assembly 1 Honda CB72/77 Sleeve Gear Honda CB72/77 Clutch Rod Support BRG Drawn Cup 20 x 26 x BRG Drawn Cup 17 x 23 x Honda Oil Seal 8 x 18 x Honda CB72/77 Dog Ring Honda Splined Washer Z13 x 31 x Honda Circlip 25mm Honda CB72/77 Layshaft Honda CB72/77 1 st Layshaft Honda CB72/77 2 nd Layshaft Honda CB72/77 3 rd Layshaft Honda CB72/77 4 th Layshaft Honda CB72/77 Layshaft Drive Gear Honda CB72/77 Layshaft Sealing Bush Honda CB72/77 Layshaft BRG Bush Plain Washer 15 x 22 x O ring 19.6 x Circlip DSH 15 x Honda Plain Washer 20 x 31 x Honda Splined Washer Z13 x 31 x BRG Needle 15 x 19 x BRG Needle 20 x 26 x

4 Selector Unit Assembly QTY Part Description Part no 1 Selector Drum Assembly (1&2) [1] Honda CB72/77 Selector Drum [2] Honda CB72/77 Selector Drum End Honda CB72/77 Selector Drum Cap Honda CB72/77 Selector Fork Centre Honda CB72/77 Selector Fork Left Honda CB72/77 Selector Fork Right Honda CB72/77 Selector Fork Pin M6 x 25 Countersunk Screw Pin 4 x Split Pin 5 x Gear Lever Assembly QTY Part Description Part no 1 Shifter Arm Sub Assembly (1,2,3&4) 1 [1] Honda CB72/77 Shifter Arm [2] Honda CB72/77 Return Spring Pin [3] Honda CB72/77 Gear Lever Shaft [4] Honda CB72/77 Pawl Pivot Pin Lee Spring LE041C Honda CB72/77 Pawl Lever Circlip EXT 8 x M8 Flat Washers Thin B Version M8 Half Loc Nuts Honda CB72/77 Eccentric Pin M6 Washer M6 x 16 Stainless Cap Screw Honda CB72/77 Guide Plate

5 2. Engine Case Modifications A. It is necessary to remove some material from the protruding bolt hole in the top case by the selector drum bearing housing. Use a hand file or small die grinder to remove no more than 2-3mm of material. This is to allow clearance for the shifter arm as it will catch the case otherwise, preventing the mechanism from fully changing gear. 5

material from the area shown above; use a hand file for this.

With the mainshaft installed the 1 st gear should freely rotate and not

6 22-23mm B. With the mainshaft installed, 1 st gear catches the inside of the case in the area indicated by the arrow. C. In order to prevent this from happening it is necessary to remove 1-2mm of material from the area shown above; use a hand file for this. The remaining thickness should be 22-23mm. D. With the mainshaft installed the 1 st gear should freely rotate and not snag on the case. Remove more material if required. E. The bottom case will also require material removing from the same area by the mainshaft, as well as chamfering 2 3mm from below the threaded hole indicated above. 6

3. Fitting the selector drum and forks A.

retained from the standard gearbox. The selector drum and forks are supplied. B.

groove behind the drum end and feed halfway in.

There are two identical forks for the mainshaft and a different one for the Layshaft.

7 3. Fitting the selector drum and forks A. The drum retaining bracket and the two M6 countersunk screws highlighted above should be retained from the standard gearbox. The selector drum and forks are supplied. B. Slide the selector drum into the hole in the case, place the drum retaining bracket into the groove behind the drum end and feed halfway in. Do not load all the way without first sliding on the selector forks. C. There are two identical forks for the mainshaft and a different one for the Layshaft. The Layshaft fork should be loaded first followed by the other two. The forks should be loaded onto the drum with the pin holes facing upwards. D. Push the drum all the way in and secure the retaining bracket in place with the two M6 countersunk screws. 7

E. Locate a selector fork pin into the Layshaft fork and secure with a supplied split pin.

Splay the ends of the split pin outwards once the pin is pushed in as far as it will go. F.

Feed the split pin through from the side illustrated. Splay the ends of the split pin outwards once the pin is pushed in as far as it will go. G.

Feed the split pin through from the side illustrated, this may need cutting down first to allow it to be fed in from the inside out.

8 E. Locate a selector fork pin into the Layshaft fork and secure with a supplied split pin. Feed the split pin through from the side illustrated, this may need cutting down first to allow it to be fed in from the outside in. Splay the ends of the split pin outwards once the pin is pushed in as far as it will go. F. Locate a selector fork pin into the middle mainshaft fork and secure with a supplied split pin. Feed the split pin through from the side illustrated. Splay the ends of the split pin outwards once the pin is pushed in as far as it will go. G. Locate a selector fork pin into the outer layshaft fork and secure with a supplied split pin. Feed the split pin through from the side illustrated, this may need cutting down first to allow it to be fed in from the inside out. Splay the ends of the split pin outwards once the pin is pushed in as far as it will go. H. Rotate the selector drum to the position shown. Note the position of the smallest cut-out in the drum end and how the right cut-out lines up concentrically with the bolt head. This will move the forks to the optimum position to allow the shaft assemblies to be fitted easily. 8

bushes on each end of the shaft are facing downwards. Check that the dowels don t push through the bearing bush into the needle roller beneath.

It will be supplied pre-fitted with a 19.6 x 3 O Ring. 1 C. Fit the two shaft bearings from the standard gearbox onto the Nova mainshaft.

Make sure the external bearing grooves are on the inside nearest the gears.

9 4. Fitting the gear shafts A. Lower the layshaft down into the housing ensuring the supplied Nova replacement dowels are installed in the case, and the holes in the bearing bushes on each end of the shaft are facing downwards. Check that the dowels don t push through the bearing bush into the needle roller beneath. At the same time locate the layshaft fork into the groove indicated. B. Fit the layshaft sealing bush into the space at the end of the shaft. It will be supplied pre-fitted with a 19.6 x 3 O Ring. 1 C. Fit the two shaft bearings from the standard gearbox onto the Nova mainshaft. Check that an O ring is located inside the end of the shaft (1), if not, remove the O ring from the standard shaft and fit it into the Nova shaft. Make sure the external bearing grooves are on the inside nearest the gears. Lower the mainshaft into the case making sure the two mainshaft forks fit into the grooves indicated. D. Once the crankshaft has been installed, fit the bottom case in place ensuring all dowels are located and some form of sealing compound has been used. It is worth blocking the hole illustrated above to prevent anything falling inside the case. 9

showing, then screw the adjuster pin into the case fitting the washer

The guide plate will be supplied with an M6 washer and an M6 x 16

10 5. Fitting the selector mechanism A. Fit the eccentric adjuster pin into the case using the supplied M8 washer and M8 thin nut. Screw the M8 nut onto the adjuster pin leaving about 5mm of thread showing, then screw the adjuster pin into the case fitting the washer underneath. B. The guide plate will be supplied with an M6 washer and an M6 x 16 stainless cap screw; this should be fitted into the case as shown below. The washer should be located under the plate acting as a spacer. C. The arm, spring, bush and screw should be retained from the original assembly and fitted into its original location. D. The guide plate and arm should be joined by the spring as shown above. See step E. 10

E. Bring the arm back past the guide plate and fit it into the

Ensure at this point that the spring remains attached at both ends

The arm and guide plate assembly should look like this. G.

8 pins and a M6 x 20 countersunk screw. H.

11 E. Bring the arm back past the guide plate and fit it into the folded retaining bracket on the guide plate. Ensure at this point that the spring remains attached at both ends and doesn t bounce out. F. The arm and guide plate assembly should look like this. G. The selector cam will be supplied with five 4 x 15.8 pins and a M6 x 20 countersunk screw. H. Fit the pins into the end of the drum and locate the holes in the selector cam onto the pins. Ensure all the pins are located then secure the cam in place with the M6 x 20 countersunk screw. 11

6. Fitting the shifter arm assembly 3 2 1 A.

on the end of the short arm in between the end of the spring (3).

adjuster locates between the two arms of the spring. C.

12 6. Fitting the shifter arm assembly A. The shifter arm will come assembled, though the return spring will have to be retained from the standard gearbox. B. Slide the return spring (1) onto shaft of the shift arm and locate the pin (2) on the end of the short arm in between the end of the spring (3). Fit the shifter arm shaft into the hole in the case ensuring the eccentric adjuster locates between the two arms of the spring. C. The groove in the selector arm should fit under the drum end cap acting on the pins. D. Fit the supplied shaft support in place as shown and secure with two M6 Screws from the cover. This is to keep the shaft square to its mounting so the mechanism can be adjusted to give positive shifting through the gears. Remove this one adjustment is complete. 12

7. Fine tuning the selector mechanism A.

equidistant from either end of the slot in the arm. This is so the mechanism will shift up and down cleanly.

To fine tune the mechanism the eccentric adjuster should be turned using a flat blade screwdriver.

Once the mechanism has been tuned so it selects gears properly both up and down the gears, tighten the eccentric

13 7. Fine tuning the selector mechanism A. It is necessary to adjust the position of the selector arm, so the outside of the pins in the drum end sit equidistant from either end of the slot in the arm. This is so the mechanism will shift up and down cleanly. Too much one way will prevent the mechanism from shifting properly. B. To fine tune the mechanism the eccentric adjuster should be turned using a flat blade screwdriver. This will move the resting position of the selector arm. Adjust it to required position described in step A. C. Once the mechanism has been tuned so it selects gears properly both up and down the gears, tighten the eccentric adjuster lock nut using a spanner. Ensure you hold the adjuster in place with screw driver to prevent the adjuster from moving. D. At its fullest extent the selector arm should miss the case. This was the reason for the case modification on page 5. 13

14 8. Finished Nova Honda CB72/77 Road Gearbox If you have any problems when fitting your gearbox don t hesitate to contact us on or us at info@novaracing.co.uk. For information on any other Nova products please check out our website at 14

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