Norton girder fork

[esometisse]

Hi all,
I am currently restoring a Norton girder fork that came to me incomplete in parts and already sandblasted.
Being no expert on pre-war stuff this task is a first for me but I have made good progress so far.
I have sourced or made the missing parts, bushed the spindles and everything is working quite nicely now but there is one thing that puzzles me: Should the friction damping discs be greased in any way before assembly or do they work better dry? Sounds perhaps like a dumb question but I really don't know!
Thanks for any advice!
Cheers
Andy

[Rex]

I can't answer whether they should be greased if new ones are installed, but I've never yet seen one that wasn't greasy in use.
I should imagine the action would be quite harsh or jerky if the damper was clamped up on new dry discs though.

[yebbut]

YE GODS!!!!!!!!!!

ON NO  account grease the bleddy things!!!
the whole idea if them is to cause a resistance to up and down movement

if you want a stiffer or looser fork action thats what the side damper knob is for, they will only get grease on them if you go silly with a grease gun

[JFerg]

Settle down.  Think about what the dampers do and how they work.

They provide friction to damp out movement, but the last thing you want is stiction.   They want to be free-moving, yet offering firm and continuous resistance.  One of the best materials you can use for damper washers in the modern metric world is teflon.  So when using other materials, a smear of grease is good.

JFerg

[esometisse]

hmmhmmhmm....three voices, three opinions so far! Apparently not so dumb a question after all!
Many thanks for your thoughts, guys, and let's see if there is yet more advice to come.
The friction discs I will be using are not teflon, by the way (wouldn't know who provides them) but the traditional material, whatever that is, as provided by Grove Classic motorcycles.
The old-style steering dampers are working on the same principle, and the one on my BSA A65 has always had a bone-dry friction disc without any noticeable disadvantage.
But the fact that you can't prevent the spindle grease from eventually seeping into the side dampers of the forks made me wonder!

Cheers
Andy

[Rex]

Good point about the steering damper, but then if you crank the knob down too far the fork turning motion does become very jerky and "sudden"....hardly desirable in the girder movement?

Wouldn't a smooth but resistant action be best in a girder, as JFerg says?

I have a hydraulicly-damped girder-forked bike too....and that rides smoother than a nearly new GS1000 I had way back when,so thankfully no harsh damper action there

[esometisse]

I have a hydraulicly-damped girder-forked bike too....

........would that be a Vincent, then? Lucky man........

[Rex]

I wish....I'd swap some body parts quite dear to me for one of them!

No, it's a '46 Chief, but funnily enough there was a "sharing" of designs between Indian and Vin post war. Certain aspects of the forks are very similar in appearance, as is the brake drum. There were also some Vindians "officially" made by Springfield, though I'm sure a 1000cc OHV would really show up the pre-war design characteristics of the slow-turning-but-so-stable Indian chassis.
Come to think of it, the brakes could be somewhat deficient, too...

[yebbut]

All my bikes have girder forks, and I have ridden nothing else but for many years, I can't beleive this question is not a wind up?

the woven material that these were made of was very similar to brake lining stuff, and still is apart from the omission of asbestos.

yes when the material is new it might be a little "jerky" depending on the coarseness of the weave believe me it will soon smooth out the same as a brake lining would'

yes a bit of the grease from the spindle will work in sooner or later, if as seems normal you go daft with a grease gun,even then you should hardly notice it, maybe do the damper knob up a bit tighter.

girder forks go up and down a "smooth but resistant action " is a fantasy, just drive it fast-ish over some rough ground, you'll be hanging on so tight a  "smooth but resistant action "
will be the last thing on your mind.

On a decent tarmac surface they'll hardly move, and you don't want them to be bouncing up and down like a yo-yo anyway.

[rogerwilko]

Yeahbut, nobut....

[Rex]

girder forks go up and down a "smooth but resistant action " is a fantasy, just drive it fast-ish over some rough ground, you'll be hanging on so tight a  "smooth but resistant action "
will be the last thing on your mind.
Hmm, maybe maybe not. A lot must depend on the bike and it's design and where you're riding it . I know on my Triumph twin with girders (now sadly gone) your description would probably be right, but the previously mentioned Chief glides over dropped man-holes and pot holes, and is acceptable on cart tracks too (at a show ground, that was).
They all have limitations compared to later teles, but realistically, how much riding is done "fastish, over rough ground"? I don't see that you should be "hanging on" on general tarmac road surfaces, unless the side damper is too tight?

[RichP]

If these are Norton forks with the side check springs then they should give quite a nice controlled ride on the road. Mine's only a 16H so I can't comment on high speed but sensible, moderate green-laning (OK, pottering) doesn't cause any worries. It all stays nicely on line.

As Yebbut says, the discs soon polish smooth. I can imagine that if they're full of grease, tightning the adjuster won't make much difference.

[Rex]

I suppose what we need is an impartial restorer who has ridden a bike with the original 70+ year old grease-impregnated friction discs, then changed them for brand new dry ones and gone for a ride. As most riders will have only ridden bikes with the originals, or only had new discs on a completed restoration, it's hard to make a true comparison.

Unless they were worn out, all I do is petrol wash them anyway...I ain't taking it scrambling, after all.