I've come across these Model 7 plunger type mudguards with the bridges removed The two 1/4+" holes per side are where the quite large style of rivets have been removed. (As shown, one hole has a hex bolt head in it,)
The question is - what are folks doing to replace this style of rivet ? There just doesn't seem to be enough room for a bolt to to the job.
As original, they end up being a large approx 1/2" diam H-shaped bobbin, each going through those 2 holes, but how do they achieve that ?? I've not come across anything that could produce that style of rivet, short of seriously peening some soft type rod ??
I see the Indian sourced replica fenders come with these welded up, neatly avoiding this problem. Hmmm
Typically the hole is damaged, or elongated, so determine a vert. & horiz. centerline & lightly scribe the mudguard. Then weld up the hole (not braze). Centerpunch the hole & drill to the correct size in 2 steps with the first drill at 75% of final diameter. The rivet is easy to come by here in the stated from the large industrial supply houses, but only in full boxes, so it is a very easy rivet to make on a lathe with the final head shaping with a coarse, then fine file. If you dont have access to a lathe, you can cheat & use a round head machine screw with a 1/2 round head & cut to length.Then prior to painting, clean & roughen up the slotted or phillips head & fill with body filler to mimic a round head rivet. You will however need to determine the correct shaft length to be able to peen over the back side of the rivet. I have the peening tools to give me the correct interior shape (either flat, or 1/2 round), But you could cheaply make a "one use" set with a piece of steel with a spot drilled 1/2"diameter hole, 1/4" deep to act as the "anvil" for the outer 1/2 round rivet, and use a piece of round bar stock with a similar indent for the interior side of the rivet. Once formed with the interior tool, the rivet can be "massaged" into the final shape with a flatter hardened tool. I have an old hammer head (less handle) that I will sometimes use for this purpose.
If one is planning on working on mare than one or two of these rivets, there are some great air driven & cordless rivet nut tools that would be a very smart investment for this purpose. They use a anvil on the finished side of the rivet & the impact tool has a concave face to peen over the other side of the rivet. Basically your buying an air chisel, with a rivet head installed where the chisel would normally go. The cheap Chinese ones sell for $13 USD less the rivet anvil. I have also seen "pop" rivets with 1/2" heads. with a 1/2 round head, but you would want to use a little body filler to conceal the center pin.
Last edited by 57nortonmodel77; 12/24/1712:44 pm. Reason: added tool info
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Re: Plunger Model 7 front mudguards
#720096 12/27/172:19 am12/27/172:19 am
Thanks Skip. Got a pic or a link to this rivet type ?
These are like nothing I've seen before - large flat thin heads, and no indication that they have been peened at all. Its almost like they press together ? And are exceptionally thin, so as not to rub on either the tire, or the fork legs. Penny gives the scale of them. You can see from the paint quality why someone would want to remove them, to refinish it...