Forks again.

DogT posted a link in the current Isolastic thread and there was a mystery solved.

Now I know what the mysterious spacer is in my forks thanks to that website and the Race Tech emulator section.
http://www.members.shaw.ca/randell/cart ... lation.htm
I asked but there seemed to be no real answer and there it is,the spacer is a ground down top bushing.
That explains why it is in no fork schematic or in the rebuild kits because it is not a factory part.
No wonder the end looked hand done for some reason,it was the removal of the shoulder.
But why was it done,what is in a stock set of forks and does the damper assembly limit travel normally.
I will need to go back and check the fork travel with the spacer removed and the stock damper installed.
Plenty of folk must have been inside the forks to see this part or not or did someone at Norton have the job of grinding down top bushs for this secret part.?
Maybe someone in Washington state saw this website and used that idea on my bike as either a better top out stop or to make sure the fork tube hole is covered.
Maybe it is a common modification.

Here is my one.

Top Stop
Since the damper rod is no longer limiting the full travel of the fork, there will be an extra 1.75" of fork travel. At full extension, the spring and stock spacer are not quite long enough to keep the Cartridge Emulator seated, although there is not enough clearance for it to mislocate. You should add modified top bushes to create a top stop in about the same place as before. Using a bench grider, grind the 'top hat' collar off the outside of a pair of top bushes, leaving the length the same as before. They will be placed in the slider between the bottom steel bush and top bronze bush to stop the fork from fully extending, and should look like this..

Click to expand...

http://www.members.shaw.ca/randell/cart ... lation.htm

I'm glad you understood it. I've read that thing 10 times and I always come away knowing less than when I started. Must be old age brain rot.

Dave

The brass bush extension is a DIY version of the ancient Covertly Kit to get top out hydro stop, so supplies Al version that is loose enough it falls to bottom of stanchion. In past to take up the spring slack of gained extension everyone used to put in a solid spacer. I found a valve spring worked a treat for me but any spring would work to help hold the Race emulator mostly sealed to function. Some springs better than others, resting sag height to progressive extra resistance wise. Still need to move damper holes up the tube to get the bottom hydro stop functional.

It simply prevents the forks topping out on the damper rod, which gives a harsh clang otherwise, as Hobot says the Coventry fork modification consists of an alloy spacer which is a sliding fit, it covers the holes in the fork tubes at full extension giving a slight hydraulic lock and thus slowing things down a bit at full extension for a gentler top out. the Coventry kit also has a solid alloy plug which is hammered into the lower damper rod holes with two new holes drilled higher up the damper rod on the taper, this allows a gradual hydraulic lock at full bump, which also prevents harsh bottoming out. I have fitted these kits to my bikes and laterly making my own by simply welding up the damper rods, redrilling and fitting alloy collars made from material bought in a hardware store. It is a cheap and easy method of improving Commamdo forks.

hobot said:

Covertly Kit

Click to expand...

dave M said:

Coventry fork modification

Click to expand...

"Covenant" :wink: http://www.nocnsw.org.au/technical/norton-roadholders

Thanks for the clarification Les, I feel like I have been sent to Coventry for my error!

Hi Dave,
Like someone else said its to try & stop topping out & clunking when forks extend. RGM Motors in the UK sell an extended top bush which is all one piece. This is an atempt by someone to do the same but on the cheap by using an old ground down top bush . I have stopped mine topping out by fitting the Lansdowne adjustable damping kit. It does the job & also gives you compression damping adjustment too. Its not a cheap way to go but it makes it a bit more like a modern bike. I would suggest you buy the one piece longer top bushes from RGM Motors in UK & give them a whirl. Its the cheapest way & if it makes no difference then you have not wasted loads of money.
Happy riding , cheers Don

I Should have been out on a branch ride today but its going to throw it down so i'm staying home in the dry.

Don, I would like to try The Landsdowne kit some time, but I have to say that the simple sliding bush and altered damper mod is a very cheap and effective mod for quite an improvement in fork action. I now have a bag full of the alloy bushes and I weld up the dampers as necesary. I was intending to go for a ride today also but it's lashing down here too.

Cheers

Dave

I knew about the supposed hydraulic action but that was never going to work without two pints of fork oil.
I had first asked about this in regard to the Lansdowne inserts I had purchased,there was no answer regarding removing these spacers combined with the cartridges.
It was a little showery here today also but that didn't stop me getting out on the Hypermotard.
Thanks for the replies.

Any idea what the TIG welded lump ( I assume hole plugging) on the alloy slider is?

I installed the "upper bush upgrade" from http://www.clubmanracing.com/suspensionforksnorton.php

Seems to work well, clanking at top out is gone.

>
2010 post to hobot to keep current...

current article is at
http://www.members.shaw.ca/randell/roadholders.html
and as always, is a work in progress..

I am currently running a 'fork valve' from
http://www.mikesxs.net/
(which looks like an exact copy of the Race Tech emulator (or vice versa)) At 50 bucks a pair, good deal, you only need one. This gives me asymmetric damping, compression in one leg and rebound in the other. Best ride to date - and I've tried nearly everything.

Anyway, more in the article..

Mike R