Topic: Got any cures for fork stiction?

[wadarush]

A damper rod fork with no slide teflon bushings has to have a TON of friction while it's doing its thing... Anyone played with modding the forks and adding bushings or maybe experimented with any of the companies that do special friction reducing coatings? 

[Danno]

there is a post here about modding such forks with an  emulator pack that is all I know

[bwaller]

I think this will be a great project for you to take on and perfect these old forks wadarush.  Stiction is a way of life I'm afraid, but there are some things you can do.

Most of these 35 yr old forks are already junk, but if you have a good set.....do whatever you want to improve suspension, rebuild, emulators, etc. but make sure that the tubes are dead-on straight.

Then be certain they are perfectly parallel in the clamps. You can shim or whatever needed to remedy.

When you're sure things are straight & parallel before final clamping of the axle, work the forks up & down a few times gently, then finish tighten the clamps. Of course one forklegs position may be located because of the axle nut but just tighten the other where it rests.

Then when attaching a fender or fork clamp be sure not to stress by "pushing or pulling" the legs to fit.

Seriously, if you come up with a novel idea to modernize these things, I'll be watching intently and support you're every move!

[MCRider]

While my K1 forks have bushings, which I had teflon coated, I also did another step which would be available to those without bushings as you describe.

Cryogenics claims to have friction reducing qualities, and I had my lower legs so treated. Cheap and non invasive, and can never "wear off". While modern coatings probably won't wear off, (My first round of teflon seemed to last tens of thou of miles, a little scuffed after 50K miles) you can't help but think that something that's added, will decrease the clearance and tend to rub off.

http://www.cryogenicsofindiana.com/

[Gonzowerke]

Polishing is the old timer's first choice. Even though your tubes may look all nice and chromy, you can still do better. You'll need to go the benchgrinder/cloth wheels/jeweler's rouge route to do the job properly though, a dremel won't cut it. Start at medium to fine, and work your way up to extra fine. Keep an eye on it though, you don't want to cut, you want to polish, so don't burn through the chrome with too heavy a compound, or too much force. The more you polish, the smoother the surface of the chrome gets at the microscopic level, making it easier for the seal to slide AND do it's job. If you looked at your shiny tube under an electron microscope, it would look like a mass of jagged valleys. Polishing helps cut these peaks down, making a smooth, low-friction surface. Oddly enough, almost all the mono-shock and cartridge fork rebuilders always mention a good polish is one of the first things they do to even a new shock/fork sent to them for upgrade.

[wadarush]

While my K1 forks have bushings, which I had teflon coated, I also did another step which would be available to those without bushings as you describe.

Cryogenics claims to have friction reducing qualities, and I had my lower legs so treated. Cheap and non invasive, and can never "wear off". While modern coatings probably won't wear off, (My first round of teflon seemed to last tens of thou of miles, a little scuffed after 50K miles) you can't help but think that something that's added, will decrease the clearance and tend to rub off.

http://www.cryogenicsofindiana.com/

Interesting stuff there...  So it sounds like this cryogenic process will increase durability and decrease friction a bit by keeping the parts "in round".  I'm still interested in some kind of ceramic coating that's only purpose is to provide a slippy surface.  Their will be more internet surfing tonight !!!   

[754]

 There is a black, and a gold coating you can get on your forktubes, maybe some others as well.
 I think the first two, one or both claims to reduce stiction... search mc suspension tuning or mc fork coatings..


 The bad part.. you can buy a nice modern used USD fork for what the coating costs.... just saying..

[Doctor_D]

If you want some "too expensive to be worthwhile" mods, here are a few:

Counterbore fork lowers and have turcite bushings made. Machine in a snap-ring groove to retain the bushing.

Gun-drill and centerless grind 2024-T3 into custom fork tubes and have them a)hard anodized with an embedded PTFE coating, b) coated with a diamond-like carbon coating (DLC), or c) have them titanium nitrided.

 

Bwaller gave you the basic list.  I set up my forks that way and they're pretty supple for what they are.  I also get rid of the wipers and use gators.

[wadarush]

Yeah I'm aware that most of the options out there are way expensive and I'm just feeling out the most cost effective method...
Bwaller's suggestions are looking very appealing. 
But diamond-like carbon coating would be something to brag about.... 

[KJ790]

Fork coatings are very popular in other motorcycle racing worlds. It used to be Ti-Nitride coating that was popular, but in later years it has turned to DLC on the inner tubes and Kashima coating on the outer tubes. This equals a lot of money for very little gain however. I don't feel like it could be worth it on these old forks.

There used to be this stuff called For-slick that was cheap and could be appied once a year, but I can't seem to find it anymore. Another old trick was to wax the inner fork tubes with carnauba wax before each race, this actually did help a little with reducing fork drag.

[turboguzzi]

cost effective?

a pair of good RD350 forks, 35mm & comes with teflon bushings from stock

[wadarush]

cost effective?

a pair of good RD350 forks, 35mm & comes with teflon bushings from stock

But wouldn't converting front ends come with hidden costs of switching triples and custom bearings... blah blah blah blah...

*I've got 30mm forks up front now.

[MCRider]

What bike has a 30mm fork?

All CB/4s are 35mm, I think.

[turboguzzi]

cost effective?

a pair of good RD350 forks, 35mm & comes with teflon bushings from stock

But wouldn't converting front ends come with hidden costs of switching triples and custom bearings... blah blah blah blah...

*I've got 30mm forks up front now.

35mm RD forks fit right into most sohc triples, so only hidden cost would be only sapcers and caliper adapter plates.

but seriously, why dont you state up front that this is for your suzuki 185 racer build so people dont have to guess what are you trying to achieve?   

that said, you'd have to get up to a very reasonable level of riding in order for fork stiction to limit your race results, would spend time and money on more meaningful areas of bike preparation. look how hard people push in the honda twin 160 class with puny, bushless forks and you'll see what i mean

Only after four seasons of racing was i able to push the front of my non-bushed CB500/4 racer hard enough to get chatter. Till then, never thought that fork friction was an issue or was limiting my race results. 

 

[wadarush]

Sorry didn't mean to keep it a secret.... I am building a 1975 Suzuki gt185 racer for the 200gp plus AHRMA class.

I was prying for general suspension knowledge from this forum because as far as vintage racing goes sohc4 has countless more active members in the vintage racing series compared to most very very uneventful forums 

I assume if you want to go far in a racing series you need to study the rule book and meet all the "maximum allowances" to get the biggest edge. 

So... does it make the most sense to swap out front ends and stick some 35mm forks up there since that's the biggest I'm allowed to swap to for the 200gp plus class?

[turboguzzi]

if you could find LIGHTWEIGHT 35mm forks then, sure why not, but most stock 35ers, where designed for much heavier street bikes so it will be a heavy fork. would look for a 32-33 as an upgrade from 30

a TZ125 or MT125 fork could be nice if you can afford and find one....

or maybe look at this table for used fork options?

http://scandalon.com/2009/06/motorcycle-fork-diameter-chart/

try asking in the vintage racing section of the WERA forum, they are a helpful bunch and many race 160's & 200's

and i bet even the top runners there dont do DLC, Crio or Ti coatings

[wadarush]

Awesome!  Thank you for all the very useful input.  I really appreciate it,