Triumphrat

Kev_England · 12-30-2009, 12:11 PM

Hi lads,

I've got the parts for my stop light switch that is supposed to be bolted to the chainguard.

Anyway, my chain guard has been powder coated and either the PO didnt have the switch on there or he bought a new chain guard because I cannt find any evidence of any holes in the thing.

So, I dont know exactly where to drill holes for the 2 switch bolts.

If someones got a couple of minutes and has an unmolested original chain guard, could you please give me the measurements of where the factory drilled the two holes for the bolts? E.g. height, distance from right end.

As always, thanks very much.

texjj · 12-30-2009, 01:27 PM

Hi Kev,

The bolt holes on mine are 10.5"-11.0" from the left cutout. On mine the left side has a cutout where there is a straight edge. I measured from the left straight edge. It is probably more important to have it line up with the brake operating rod (F7386) in the resting position. Lemme know if you want more pics.

link to larger pic
larger pic - unobstructed view

pic of mine - from a stock '68 650 Trophy

Kev_England · 12-30-2009, 01:43 PM

Many thanks txjj.
So fast as well!

My chain guard looks slightly different. Mine has a hole in the front where yours appears to have a plug in it. I wonder if this if mine is not original???

If possible, and sorry to be a pain, could i get another pic with the tape measure going vertical up the side of the switch unit

Thanks again mate.

P.S. This is an old pic -- I know that pipe should not run by the sprocket!!!

shrugger · 12-30-2009, 02:36 PM

It's just a rubber plug.

F5536
82-5536

texjj · 12-30-2009, 03:25 PM

Kev - not a problem at all. After taking these pics of the left side - it really needs to be refurbished...lots of rust. I know for a fact this is original equipment, so maybe you can order the rubber plug and carefully cut the hole for it. I noted the part number appears to be F5536 for the "grommet".

I measured the bolt holes, but you should know that the chain cover slopes to become wider (more metal on bottom) near the back. So it matters where you measure. Anyhow where mine is located, the measurements from the bottom edge are:
- bottom hole: 1x3/4"
- top hole: 3x1/4"

Links to larger pics:
Front of chain cover showing rubber plug
Measuring vertical location of holes

Front of chain cover:

Vertical measurement of brake switch:

Kev_England · 12-30-2009, 03:34 PM

TexJJ - many thanks for that. Very kind of you to take the trouble.

Yeah, I just looked in the parts book and saw the grommet! Wonder why they put a hole in there -- is the fixture nut on the other side of the grommet. I.e. is it a way to get to the nut on the back of the guard? Im guessing yes (at work right now so cant look).

Bikes like yours TexJJ are invaluable since they are original and have not been molested or (and dont mean to sound rude

) revamped or refurbished. Digital cams bring out every tiny imperfection. Your bike is perfect as it it, imho

Ill print this lot out and take it to the garage tommorow!

texjj · 12-30-2009, 04:12 PM

Thanks Kev. I am cleaning mine up a bit at a time.

Yes, the grommet+hole provides access to the bolt on the inside of the chaincover. That bolt attaches the chaincase to the bike. It looks blocked by the chain on mine, so maybe the chain has to come off or be heavily loosened first.

Snakeoil · 12-30-2009, 09:26 PM

Kev,

No disrespect to Texjj, but his dimensions will just get you close, and he basically said that. A line drawn thru the two bolt holes does not appear to be square to either the top or bottom of the chainguard. The line is actually square to the axis of the brake rod, which does make sense when you think about it.

I went out to measure my '66 which is the same, and found that you really cannot get accurate layout dimensions with it on the bike.

I'm a formally trained machinist and also an engineer so I'm very familiar with how to layout things like holes on oddly shaped pieces, which this is. You need some type of reference points. Right angles are the easiest way. So, I've made up a sketch that allows you to take dimensions off the top and bottom of the chainguard using a simple combination square to locate your two holes. If someone on the forum has a spare or a bike that is apart, they could give you the dimensions as shown in the attached sketch. The sketch shows the bottom hole being measured and the lines that would be scribed on yours from those dimensions.

Using the square, you just scribe lines with the square by running it along the bottom and top edges and set at the dimensions given by someone who can measure theirs off the bike, and the intersection of those lines is where you put your holes.

If the instructions or the sketch is not clear, let me know.
Hope this helps.
regards,
Rob

texjj · 12-31-2009, 01:09 AM

I agree with what Rob said. It is too bad they did not layout and drill the holes for your new chainguard prior to bending it into shape.

henryanthony · 12-31-2009, 02:46 AM

Kev,

You can infer the placement using the Switch Lever and Brake Operating Rod. The placement of the switch mounting holes is dependent on the height of the spring hole in the Switch Lever which is attached to the Brake Operating Rod and the fact that the holes should be perpendicular to the Brake Operating Rod so that the spring and sliding part of the switch is parallel to the Brake Operating Rod. You should have the Brake Operating Rod in place before locating any holes. So, using a square or wooden block set against the Brake Operating Rod, draw a line perpindicular to the rod 10.5" (measured from a '70) from the front of the chainguard. Center the switch mounting holes over this line and slide the Switch Lever along the rod. Position the sliding part of the switch at the same height as the spring hole in the switch lever. Mark you holes. Might be a good idea to remove the guard before drilling it.

Henry