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Variations on a theme… CL72 Type 1 vs. Type 2 gearboxes

Standard CL72/77s use the transmission ratios/gears from the CB72/77 Super Hawks, except for this rare domestic Type 2 engine CL72. My earlier notes about only 2nd gear being unique to this engine were incorrect as I missed the 3rd gear part number references, so I am correcting my previous "correction."

Standard ratios listed in the CL72/77 owner’s manual are:

Low 2.788

2nd 1.661 1.127 step 1-2 shift

3rd 1.171 .490 step 2-3 shift

Top 1.00 .171 step 3-4 shift

The Type 2 CL72 booklet shows:

Low 2.788

2nd 1.796 .992 step 1-2 shift vs. 1.127 stock

3rd 1.312 .484 step 2-3 shift vs. .490 stock

Top 1.00 .312 step 3-4 shift vs. .171 stock

Type 2 2nd gear ratios are 23/28 instead of 24/27 = 1.217 vs. 1.125

Type 2 3rd gear ratios 27/24 instead of 29/23 = .888 vs. .793

So the steps between 1-2 and 2-3 are closer ratio than those of the standard gearbox, but the step up to top gear gets a little longer. Doing the X transmission modification uses the center 4 gears and criss-crosses them between the two shafts.

24/27 stock 2nd 1.125 on shaft M/S 24t 2nd gear /29t 3rd gear M/S

29/23 stock 3rd .793 on shaft C/S 27t 2nd gear /23 3rd gear C/S

X –pattern 2nd 1.173 on shaft M/S 23t 2nd gear /27t 3rd gear M/S

3rd .827 on shaft C/S 29t 2nd gear / 24t 3rd gear C/S

X-gear ratios on stock transmission

Low 2.788

2nd 23/29 X gearbox 1.260 1-2 step 1.528

3rd 27/24 X gearbox .888 2-3 step .372

Top 1.00 X gearbox 3-4 step .888

Stock X-d

1st gear 17.52 17.52

2nd gear 10.46 11.70

<6.92> <5.82>

3rd gear 7.32 8.26

<3.14> <3.44>

4th gear 6.26 6.26

<1.06> <2.00> Numbers include total final drive ratios

This illustrates a little more clearly how X-ing the gearbox changes the drive ratios for the 250-305cc models. These are CB/CL gearbox numbers. The C/CA72-77s have different ratios to begin with, but they also can be X-d like the other models. You can swap in entire transmission assemblies from one engine to another with no difficulties. We put a CL77 transmission into a CA77 some years ago and the owner really liked the change in ratios.

The CL72 Type 2 transmission would be a good choice for budding CB72-77 roadracers, as the gear spacing is pretty tight compared to the regular or X-d gearboxes of the Super Hawks. The ultimate street transmission is the Nova 5-speed street bike gearbox but it deletes the kickstarter function and costs $2500.

Before I bought this CL72 Type 2 Scrambler, I had no idea that there was another gearbox option other than the CB/CL and CA ratios. It shows the great lengths that Honda is willing to go to in order to make a certain market machine perform just like they envisioned.

Bill “MrHonda” Silver

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