250 Monza Cam nut removal

[Snakeoil]

Need a little info/guidance. Book calls for tool 15 to “lock the cam” in order to remove the nut over the bevel gear. It says to insert the tool thru the cap (bearing carrier) end. Looking at that end of the cam, there is no hex, slot or other method with which the tool could stop the cam from turning while the nut is loosened. I do see a slot in the camshaft on the nut end, but suspect that is for a tach drive used on some machines.

The picture of Tool 15 gives the impression that there is a tang on the end of the cam or a couple of pins that would engage the slots in the tool. But I’m thinking that the tool picture is probably not accurate.

My guess is that tool 15 is a cylindrical tool with a cut-away that allows it to slip over the cam lobe and engage the ramps to hold it from turning. My only other thought is that there is a tool that engages the slot on the bevel gear end and a long bolt goes thru the cam to pull it into the slot snugly and prevent it from slipping out as torque is applied to the wrench.

I did a search here on the subject and found the tool mentioned, and that the nut is a LH thread (nice omission in the manual), but no details on the tool or how it works.

Would appreciate info on this.

Thanks,
Rob

[ducwiz]

Your first guess (cutaway agains cam lobe) is right.

..

[Snakeoil]

Thanks. Guess what I'll be making today?

regards,
Rob

[Snakeoil]

One cam wrench ready for the shop.

[ducwiz]

Perfectly looking, congratulations ! When do you start a small series production ?

cheers Hans

[Ventodue]

Nice work, Rob (insert Thumbs Up smiley ...)

Craig

[BDang]

On a related subject, the 4 and 5-speed single Workshop Manual has this photo with wrong information on the thread direction. I have no experience with this but since the crank rotates CW on this side then the nut thread should be left handed, and so the arrow direction is wrong I think. I hope this prevent someone from disaster.

lower_bevel_nut.PNG

Regards,
Brian

[BDang]

Using this tool is the official way, but I also read somewhere that one could use strips of wood to wedge the cam lobe to the head (with wood wedge placed the opposite side to prevent flexing the shaft up/down). Some people just use an impact wrench (I assume the head still bolted to the engine with all the bevel gears connected). Could the impact wrench shock break the bevel teeth? What is your favorite method?

Regards,
Brian

[Snakeoil]

Thanks. But aluminum was the wrong material. Flank taking the load tore. Should have been steel. Head was off the engine. One of three I am stripping down to pick the best. Not sure I would use an impact on those bevel gears. The nut on this cam was TIGHT!
Regards
Rob

[BDang]

The nut on this cam was TIGHT!
Regards
Rob

Hi Rob,

Could be someone had used Loctite on the thread? If it was tight then I would tried a torch on the nut and if it gave then must be Loctite was used. Also I would think Aluminum tool is safe of not dent or scratch the cam.

Regards,
Brian