Another Fork Thread

[DaveK]

Hi I was reading something about using 175 ml instead of 150 in the fork is that better? I refilled my forks last year and they have been crappy ever since...make a loud bang when the forks extend over a rail way track or curbs or other things and diving on the down stroke...... Seems like no dampening, like I am just using the spring........I filled with 150 ml ......I used 10/30 as per my manual.


Someone told me that if you fill your forks from the drain hole they work better...this guy trying to get a laugh from me or what?


Thanks guy

 

[ashman]

Replace your springs with Progressive springs and you won't have any more problems with it.

 

[DaveK]

I am looking for a "dont buy more stuff" solution for now :roll:

 

[ashman]

I got a set sent over from RGM to Australia all up less than $100 with shipping and is the best thing I ever done .

Ashley

 

[Guido]

I am looking for a "dont buy more stuff" solution for now :roll:

Don't make me laugh. You own a Norton, don't you?

 

[DaveK]

Ok, Thanks

-

 

[GRM 450]

Hello Dave,
I used progressive springs in a Mk3, I've never used the original springs as they were badly rusted and was told that the progressive springs were much better.
All I can say is the original springs must be terrible, because the progressive springs still clunk over driveways and the forks are lacking any feel at all. Worst forks I've ever encountered.
I realise the springs aren't the problem, rather the old design and poor damping.
I was advised to try heavier oil and then more oil but that just deadened the things worse.
There are some lengthy discussions on forks here to read. My humble opinion, different grade oil and different springs are just covering up an old design.

graeme

 

[L.A.B.]

I refilled my forks last year and they have been crappy ever since...make a loud bang when the forks extend over a rail way track or curbs or other things and diving on the down stroke......

Doesn't that point to the oil change being the cause of the problem?

Seems like no dampening, like I am just using the spring........I filled with 150 ml ......I used 10/30 as per my manual.

In the fork section (G10) it says to use 150cc of SAE20 oil. The alloy damper caps also wear which eventually reduces rebound damping.

 

[zotz]

Replace your springs with Progressive springs and you won't have any more problems with it.

I'm using progressive springs and have replaced my damper assys and still get clunking, even with various grades of oil.

 

[DaveK]

Hi L.A.B.

Ya I think the oil change is the problem as you say....

I never found the oil type in the Fork section I did find it in the front of my book page 4 or 5 something like that. Just blind I guess.... If a guy would use 10/30 you would expect some dampening action no? I pour it in the top of the fork tubes, wait 1 hour put my hands over the tubes move them up and down (to help get the oil down??) and then install the chrome nuts....am I missing something?


Greaeme,

I am sure the progressive springs are an upgrade (from old rusty ones HEHE :twisted: ) but the forks still work on oil right??? so the dampening effect would be the same ....none in my case....

 

[L.A.B.]

I pour it in the top of the fork tubes, wait 1 hour put my hands over the tubes move them up and down (to help get the oil down??) and then install the chrome nuts....am I missing something?

No, I doubt you've missed anything, (that's assuming the damper rods are connected to the fork top nuts when you refit them?) although I've never waited an hour, I would simply compress the forks slightly and gently work the damper rods up and down until the dampers re-primed themselves, however they will re-prime automatically once the forks have been pumped a few times. Refilling the forks isn't a job you can get wrong as the oil will always find its own level.
The advice you were given to "fill through the drain holes" I've certainly never heard of before.
Maybe try some SAE20 fork oil or 20w/50 engine oil and see if that is an improvement.

 

[jseng1]

The way to get rid of the ”clunk” is to install aluminum sleeves so there is a hydraulic stop at the top & bottom of the fork travel. This eliminates the metal to metal contact. The sleeves I offer just slip into place and they are cheap. But you have to drill a hole in the damper tube just above the conical section as in the photo. Some late model Nortons already have the damper tubes corrected so there is a bottom hydraulic stop (hole moved up into the conical section). Unlike other sleeves - these sleeves are slit and have tension in the slider so they stay in place where they are supposed to be located and do not move.

for more info go to:
http://www.jsmotorsport.com/technical_sleeves.asp

Dave K – pull your springs, grab the damper rod, push it up and down to make sure its working. There should be resistance on the up stroke.

 

[Hobot]

Top out noise is the damper valve on end of damper rod striking the underside of the damper cap. Two way to solve that, one as Jim says apply the old Convent conversion which is a kit with the loose AL sleeves and plugs for the bottoming clank too. Another way that has ~$100 cost is Greg Fuaths Kit with spring spacer and longer rods and bottom damper plugs. 3rd way with rather higher expense is Landowne cartridge kit that's race proven winner over the un-converted pack.

Fork capacity is ~180 ml so 175 ml is about tops or it hydrualic locks up about 1/4 mile down the road as air pocket get pumped down to jerk fork about dangerously.
I use a cattle size syringe to dribble in measured amounts w/o much spillage or waiting on fluid to settle in. Factory worn sloppy clearances in Roadholders like the 20-30 grade range and multi grade is fine especially in winter freezes. Getting close to almost full forks helps the compression phase of forks more than the top out you can get just lifting on center stand at times.

 

[pete.v]

10 - 4 The covent kit will do the trick. I got this variation from Rocky Point. Good instrictions. No more top out.
http://www.rockypointcycle.com/Merchant ... y_Code=N11

 

[jseng1]

Yes - the covent kit is the easy cheap way to fix top out, and several people sell them.

I'm trying to improve the kit by making them as split collars so they have tension in the sliders and stay in place without moving. And use the same split collar idea on the damper tube bottom so you just slip them on no-brainer style.

 

[Hobot]

Jim is correct the cheap effective Convent solid spaces are a loose fit so fall right to bottom of the stanchions which also covered those holes when not topped out. I do not know the significance of this expect even I couldn't bring self to do that which eventually lead to valve spring instead. Don't know if Jim's stay up spacers matters or not but makes prefect sense to me even if it don't. I'll be trying his slick bushes in Ms Peel for sure, but already have uncanny indefinite soft reversals of fork travel so never even notice Peel's forks anymore. I do expect to gain tighter fork fit w/o the slight slack in top bush and bottom steel bush by JIm slip collars.

 

[lynxnsu]

easy way to fill your forks

kawasaki 650 (70's bike ) forksprings work very well in raodholders
, as does 20/50 grade oil