RGS Marzo 38mm slider bushings

[ksoholm]

Lads,

These old forks of ours do not have bushings at the tops of the sliders for the fork tubes to operate against; the fork tubes seal directly against the sliders w/o bushings. Is there a reason why bushings can't be installed with machining? Not enough material in the sliders? Just wondering as my forks head to Race Tech for the work-over.

Thanks-

Kristian

 

[Vince]

From what I have heard the issue is doing the bottom bush that's the big issue, finding someone who wants to do it and then paying for the tooling to do it. There are a couple of top-flight Machinists on here that have looked at it and decided the expense isn't worth it. There is some bloke in Holand who did a few forks on the Bevelhead list but isn't interested any more and the bloke from Vacy who builds and races Bevel Ducatis did his race bike but said its a horror of a job and again isn't interested. If your going Race Tech in the USA they do Hard Anandising that apparently works well at reducing stiction. I found a place in Oz that does it as well and has got my Panath done but haven't tried it yet.

 

[sfcpiet]

The sliders don't wear much near the top, most wear happens where the end of the stanchion runs in the slider.  Very apparent with a close look at a used stanchion.  Bushes would need to be installed on both stanchion and slider for any noticable advantage, stiction reduction being the major boon.  No problem with the stanchions, but modding the sliders will be more than the average DIY'er can manage.  Worn sliders can show rather frightening behavior under heavy braking, should be enough NOS or good used bits left to keep 'em going for the coming decades.

piet

 

[Vince]

I think another issue is our raked out steering angle produces way more stiction than modern more vertical setups as well. It takes a far bump to start them moving so they will always be harsher than more vertical modern applications even with bushes. It's the tiny movements of the wheels where high-end suspension becomes better.

 

[Paul Marx]

The sliders don't wear much near the top, most wear happens where the end of the stanchion runs in the slider.  Very apparent with a close look at a used stanchion.  Bushes would need to be installed on both stanchion and slider for any noticable advantage, stiction reduction being the major boon.  No problem with the stanchions, but modding the sliders will be more than the average DIY'er can manage.  Worn sliders can show rather frightening behavior under heavy braking, should be enough NOS or good used bits left to keep 'em going for the coming decades.

piet

Agreed.
Quite enough parts around to keep our bikes running well after us, and petrol reserves for that matter.

Paul

 

[piranha-bro2]

Agreed.
Quite enough parts around to keep our bikes running well after us, and petrol reserves for that matter.

Paul

But will there still be companies willing to dig up said petrol?! Might go the way of print film - still available I guess, but I wonder how the theorwtical cost comparison would compare ... eq to 20 euro a litre?

And with forks fitted with teflon bushings, there is no bushing in the fork leg lower. As Piet says, the only bushing in the slider is at the top. Not sure if that means you could use staunchions with lower bushings on a std fork leg or not. Is machining for the top bushing a problem? Surely a lot easier than for one down the bottom of that deep dark hole!

Didn't GPZ900-R Kwakas have 38mm forks? If so, would they have had a lower teflon bush? I would hazard a guess yes. All starts sounding a tad tricky. I guess that's why I threw away my rivets and have fitted various more modern front ends in search of betterness    Hopefully my latest (46mm Paioli conventionals and Kayaba Yamaha OW01 superbike USDs are the bee's knees.

 

[piranha-bro2]

And ... I must pull my 38mm M1Rs apart and see if they have bushings a la the 41.5s. Those staunchions would probably be a good for for a std Marzo?

 

[ksoholm]

See, I just knew this issue had been well and thoroughly thought about and dealt with. I'm having the sliders anodized, so that'll do just fine. Thanks-

Kristian