Seat Knobs & roll pins

xbacksideslider · Jul 5, 2011

Swooshdave makes reference to seat knobs here -
fourth-july-ride-t10115.html
and it seemed like I'd be hijacking his thread . . . so a new one.

I've never applied myself to the roll pins and seat knobs problem.

After I lost a knob on my '71 way back when, I've always just made certain they were good and darn tight but now that Swooshdave mentioned it . . . . The knobs on my '71 (long gone, the bike that is) and my '73 both fail, it appears, in their initial assembly to make any use of the roll pins.

Is the nub on the end of the bolt too small? Or, is the drillng for the roll pin too far to the outside? Maybe just drill out to the next largest size of roll pin to get some engagement with the bolt's end nub?

swooshdave · Jul 5, 2011

If you are using the roll pins you have to make sure they are installed correctly.

So you are saying with the pins in you can spin the knobs all the way on or off at your pleasure?

ashman · Jul 5, 2011

I don't use the knobs, I just use 2 nuts with 4 washers, why I do this, have you ever come out to your bike and find some mongel has stolen your seat, at leese with just the nuts they need a spanner to take your seat off, not very good riding home without a seat.

I was only away from the bike for lest than 5 mins.

Ashley

bwolfie · Jul 5, 2011

ashman said:
I don't use the knobs, I just use 2 nuts with 4 washers, why I do this, have you ever come out to your bike and find some mongel has stolen your seat, at leese with just the nuts they need a spanner to take your seat off, not very good riding home without a seat.

I was only away from the bike for lest than 5 mins.

Ashley

It could be due to your country being founded with prisioners. Mine was founded by prudes, so I think you got the better deal.

ashman · Jul 5, 2011

It don't matter where you are, if someone wants something and they got to steal it to get it, they will, I'm just glad it wasn't the whole bike they stole.

Ashley

hudson29 · Jul 5, 2011

I wonder why anyone would steal a Norton Seat? Mebbee just because they could? Sometimes ya just gotta shake yer head and wonder . . .

Vintage Paul

xbacksideslider · Jul 6, 2011

swooshdave said:
If you are using the roll pins you have to make sure they are installed correctly.

So you are saying with the pins in you can spin the knobs all the way on or off at your pleasure?

Yes, I can just spin the knobs off; the roll pins do not seem to be large enough, or deep enough, to engage that notch in the damper/seat bolt that comes through from the inner frame. Maybe they got bent by a ham handed previous owner?

DogT · Jul 6, 2011

The roll pins on my 69 don't work either. Can't figure it, as I remember they used to, but not any more, with the pins in, the knobs just screw right off. I really haven't investigated too much, not worried about someone stealing my seat yet. I just make sure the knobs are tight before I head out.

Dave
69S

Stephen Hill · Jul 6, 2011

I have experienced problems with this part on four Commandos. In some cases the roll pins were bent because the knob had been unscrewed and forced against the shoulder on the stud. When I replaced the roll pins it solved the problem.

I have also replaced the roll pins and it made no difference, because the original drilling was incorrect, as in it never worked from new. You could probably oversize the pins, but it would take a radical increase in pin size to fix this.

If the roll pin has been forced over the end of the stud a bunch of times, the shoulder on the stud will be chewed smaller. I have run a bead of weld on the end of the stud and turned it to the largest diameter that will just fit through the threaded part of the knob. Somtimes this works, sometimes not.

Tightening the knobs as you ride out of the driveway can become part of the routine. Every once in a while when I am riding my VFR I reach to tighten the seat knobs. Duh.

Stephen Hill
Victoria, BC

pelican · Jul 6, 2011

just a fyi - if you guys replace with the ss knobs they will be tight as he__. I have to put on a glove to grab it and use both hands to turn

gtsun · Jul 7, 2011

Right now Im using a Dunstall seat that has a slotted bracket on the right but the left side has a hole so the knob has to come off to remove the seat. Since this happens a lot to check the oil, I use a cotter pin on that side that I can easly remove. This stops the wear on the pin or the stud.

xbacksideslider · Jul 7, 2011

Thank you Stephen.

It's time for me to quit obsessively tightening the darn things. I'll take a closer look at my mounting bolts' ends/notches and knock the existing roll pins out. Maybe the notch's edge, the stop, should be at right angles instead of chamfered and sloped. And, maybe an oversize roll pin is less likely to bend out of the way.

Interstate · Jul 8, 2011

Hey all,

Just joined today and checking things out.

I had the same concern for my '73 Interstate seat when I bought it 38 years ago.
I don't have the machine in front of me now, but as I recall the crossdrilling in
the knobs provide the correct tap drill size for like a #8 or #10-32 thread.
Just tap out one side to match the fastener's threads then grind off half the threads to engage the other half of the knob's hole.
I used a slotted machine screw and ground down the head OD down too to fit inside the tapped hole.

Lots of hand work but it helped me retain the original seat and knobs.

maylar · Jul 8, 2011

I have stainless seat knobs and they came with pins, but I couldn't get them through the holes for anything. Fortunately they stay tight anyway.

xbacksideslider · Jul 8, 2011

Yeah, that's another way to go, drill to a larger diameter, tap, and install an allen head set screw.

pelican · Jul 8, 2011

maylar said:
I have stainless seat knobs and they came with pins, but I couldn't get them through the holes for anything. Fortunately they stay tight anyway.

i had to tap mine in pretty hard... a set screw is a better idea anyway alloy or ss

1up3down · Jul 8, 2011

I bought a set of the new smaller "knobbed" (not round) ones a while back that have the holes drilled for the pins.

I could not get the pins to prevent them from unscrewing so I pushed some wire through and this seems to work better at keeping them on, it is definitely more difficult to unscrew when I take the seat off.

So, the appropriate diameter of electrical wire passed through and secured on one side seems to work!

Seat Knobs & roll pins

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