Mudguard confusion

I will take a measurement of my 7 " forks deep valenced guard for you to compare.  You will have a similar problem if you try to buy the  bridge seperately .

YES - there are two sizes of front mudguad.

The wider one will fit the narrower forks - but the first time you use the front brake, you will know that you have a problem, as all the paint will be stripped off your shiny headlight brackets, as the forks dive under braking.

Been there, done that.

My mudguard is correct for a 7" set of forks ,even so the clearance is minimal (but there) .It is also important to shim the brace with washers (if necessary)  to ensure that the forks are not loaded by the brace/guard  if the forks are to work freely and bushes are to last..------- Later,  I have tried to measure the guard but the wheel/tyre prevents me ,however the distance between the fork shrouds appears to be a shy 41/2" and the guard misses by about 1/8" each side at the valences and a bit less at the rolled edge  .  I recollect that fitting the guard was a bit like a chinese puzzle, and that a scrape of shroud paint is likely.  If you get a guard without brace you are unlikely to find a new/pattern one to fit.  An orriginal SH  white painted and rusty brace is a reasonable bet. A guard/brace from a pre 64 Navi should fit,   I do have a spare 99DL guard(no brace) if you get desperate ,but it has a distorted front lip to repair.  Your guard is probably  later 650ss 88ss, Atlas. or even Electra. ,all with 73/8" forks. Std Dommies of your period were often fitted with a standard (non valenced) front  guard from new,so another option!.

All of the Norton big twins got the wider forks for the 1964 season. The change over from 7" seemed to begin in later 1963 with some models having separate clock fork mountings. By April 1964 the familiar twin clock plate had become common on both road models and off-road versions. A little later the clocks became the Smiths magnetic type.

One of the reasons for the big twin  fork width change was to allow the front tyre to be increased from 3.00"  x 19" to 3.25"  x 19"

Hi Tony.   Due to covid worries ,not doing much at all. However if you pm me a mobile phone no I will get a photo to you . " eventually!"

That's plenty. The 90-90 Roadrunner I had was a hair's breadth from the bridge. The Roadrider I have won't fit.

The guards themselves are the same for both forks APART from the vital side indents. Lots of bikes have paint scars where tolerances have gone the wrong way with the narrow forks...

Somewhere mentioned above is some information about the muguard/slider bracing bracket. There are variations in the dimensions  of these and this generally this and the wheel rim size will affect the clearance. I would have thought that 1/4" or 5mm was fine. Tyre walls do ripple but don't generally catch and lock up the wheel. The race boys will tell you that the faster you go the thinner the tyre gets due to centrifugal or centripetal force. One of these anyway.  Just keep and eye open for serious rubbing marks on the tyre and inside the guard.

And the narrow mudguard will fit the wider forks if you use the bridge for a narrow fork and 'adjust' it outwards.

Been there, done that.

All this was brought about because in 1964 Norton thought a wider section front tyre, or knobbly tyre, would look great on the bigger Dominators. So if you run a larger section front tyre you won't be able to fit narrow forks/ fork bridge or mudguard.

Peter