Topic: can I drill my frame?

[Geeto67]

or... how big a hole is too big?

Here is the situation. I have a 1974 cb550 in an amen rigid frame. I used to love riding this bike but the mid controls and my knees have not be getting along lately. Here are some pics (I am 6'5)





The bike needs forward controls badly, but I am out of ideas on how to mount them. The Amen frame has the front motor mounts welded to the down tubes so the conventional motor mounts are not there, and the two frame bolts I would normally use for a forward control mount is not there. I was thinking about using these TC choppers 550 forwards but I would need to drill the down tubes to use them, hence the topic title.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=150112970165&ssPageName=MERC_VIC_RCRX_Pr4_PcY_BID_Stores_IT&refitem=150101073877&itemcount=4&refwidgetloc=closed_view_item&usedrule1=CrossSell_LogicX&refwidgettype=cross_promot_widget

I DO  NOT want to do any welding on this frame, the paint on it is HOK applied in the 1970s and in great shape. It uses copper shavings in the paint instead of metal flake and it is no longer available so the whole frame would have to be repainted. Looking for a bolt on deal.

I am open to any other suggestions as to how to make/attach forward controls, gimmie your thoughts.

[andy750]

That is one cool bike Geeto - sorry I cant answer your question but I do like looking at your bike - must be fun to ride....

good luck and keep us posted with progress on the fwd controls.

cheers
Andy

[ieism]

i think drilling the frame will make it weaker.The stock frame has a metal tab there to beef it up.
Maybe you should look into some type of clamp. If you can put a clamp for each of the 4 bolts on the frame you don't have to damage the frame. And you can also move them up and down on the downtubes to get the lenght of the connectingrods for the control exactly right. This looks too big, but you get the idea.....

http://www.bikepartsusa.com/product_images/mfg_01/5/full_51767.jpg

[tsflstb]

You could bolt on some of those clamps from Dennis Kirk like folks use for rearsets.  Should give you a solid mounting point.

[merc2dogs]

go with the clips.

 To drill and keep strength requires drilling holes oversized, then welding sleeves through the tubes with an OD of the size you need.
 
 ken.

[rhinoracer]

Can you stick a horizontal piece of tube between the headers and the frame downtubes?

If you go to a pipe supply store they sell several kinds of clamps to hold one pipe perpendicular to another. These should hold up fine but you would still need to fabricate the control mounts to fit this pipe.

Just weld some tabs to the new pipe (not to the frame) to make contact with the frame tubes so it won't swivel when operating the controls.

[Soos]

Good luck on getting forward controls going there!
However if it doesn't work out, i'll gladly take 'er off your hands.... for a fee of course 
I must say, gorgeous bike there!!!


You might think of looking into a custom set.
If you have a custom bike shop anywhere near, they may be able to fab. up something for you.
Short of that, possibly a job shop(machine shop). But i would think that a machine shop would charge a arm and a leg.
However, for that beauty, it would be worth it IMO.
Using the motor mount bolts(only longer) might work for giving you a mount point for the forward controls.

l8r

[Jinxracing]

I'm chiming in with the machine shop idea too. It's too nice a bike (with very cool paint on the frame) to do something half-assed, IMO. A two-piece machined aluminum clamp on either side of the lower downtubes could clamp a horizontal bar to mount the controls is one idea.

[Geeto67]

custom sets are $500+ (Ive gotten quotes), kinda kills the whole deal.

There is already a downtube cross brace higher up the down tubes and where I want to put the forwards the oil filter sticks out too far.

I think the frame clamps are a good idea and I am going to try them, I have some vintage triumph forwards from the 70s (for pre-OIF in stainless steel) and I am going to try them with the fram clamps and see if I can make that work. The triumph forwards are the old style with a bar that runs across connecting the pegs.