NC21 / 24 Forks

[deequeue]

Hi Guys,


Ok, I've got hold of a fresh set of forks, as it appears the TRAC system has either collapsed or is damaged in the ones currently on the bike. One fork is in excellent condition, and the other has some corrosion on it - as is murphy's law, its the one i need.

So, i figure i have 2 choices - either switch the TRAC system from the 'new' fork to the one currently on the bike, or use the slider from the one on the bike, as it is in mint condition.

Can someone tell me if its even possible to swap the TRAC over, and if it would save me any time over dismantling both forks, swapping the slider, and re-assembling?

Also, i was wondering if there was anything overly different to dismantling the fork with the anti dive in, if it comes to that, and also if anyone had any particular advice in relation to this one side. I've taken the forks to bits on my zx6 before, and that wasnt much hassle, but i did have a haynes manual handy to see which way the components went back together - something that i dont have the liberty of having this time.


Thanks
Dale

[Neosophist]

Yeah the anti-dive comes off easy enough. Have a look at the pictures.

You might well find the plastic bush has worn oval too with time.

TRAC
The Honda TRAC system differs somewhat from the ADVS-style units. Honda maintain that hydraulic systems have two basic drawbacks. First, the additional brake-line plumbing and increased brake-lever ratios can produce a spongy feeling at the brake lever. Second, those systems are either on or off - there's no modulation of antidive effect. To get around these problems, TRAC is instead activated through the torque reaction of the brake caliper itself. This makes it completely independent of the hydraulics in the brake system. It works because one of the two front brake calipers is hinged behind the fork leg on a pivoting link, rather than being solidly attached. When you apply the brakes, the pads grip the spinning disc and this tries to drag the brake caliper around with it. The caliper pivots on the link and presses against the anti-dive activating valve which is built directly into the fork leg. From then on it, it works just like the Yamaha and Suzuki systems, restricting the flow of fork oil and stiffening the suspension. The advantage of the Honda system (they say) is that the harder you brake, the more pressure the pivoting caliper puts on the control valve, and the stiffer the suspension gets. One important difference with TRAC is its ability to deal with the bumpy road surfaces which the other systems had a problem with. The TRAC valve is a floating piston held in place by a spring. This means that if you hit a bump, the sharp and sudden increase in the pressure of the fork oil can override the anti-dive valve and force oil through the valve as if it were not applied. This means that TRAC can respond to bumpy roads whilst braking. Clever eh?

[deequeue]

Hi Neo,


Ok, have taken the TRAC off the 'new' set of forks. I am somewhat.... surprised by the lack of stuff in there......

Below are what came off the forks, I kind of assumed there would be more to it than that....

[Neosophist]

The rest of the gumph unbolts from the otherside of the fork..

http://www.cmsnl.com/honda-vfr400rj-iii ... t/F09.html" onclick="window.open(this.href);return false;

If you look there you'll be able to see a 'big' picture of the fork assembly with parts suitably labeled.

Just make sure you have everything :-)

[deequeue]

The rest of the gumph unbolts from the otherside of the fork..

Um, where....... - i assume you dont mean the damper cartridge bolt?

I only ask as that 'fiche looks a little different to what i have.....





Thanks
Dale

[deequeue]

Ok, just taken the original fork off my bike as i knew i would need to drain it.....


List of missing parts....

1x bumpstop
1x bumpstop spring
1x spring seat


I would like to find the guy who worked on this bike last, and summarily beat the crap out of him. I'm actually quite glad that i had to drop the forks now - imagine the wonders i will find in the other fork!

Still a little confused over what im missing though..... Looks like i have 2 pairs of nc24 forks, i guess?

[Neosophist]

Ooops.. no wonder your bike was handling bad :-)

NC21/24 forks are identical.. the only difference is the cap on the top of the fork.. if you look at that picture i posted you'll see in the top right of each fork a small box with the alternative (NC21) cap.. the NC24 one is pictured on the fork.

The easiest way to tell if the anti-dive is working is to put it on and see if the dampening / rebound of the forks change.

[deequeue]

Hey Neo,

The issue wasn't that it was handling badly, I've barely had the chance to ride her for the last year! From what I can see, something had failed in either the trac or the caliper mount, and allower the caliper to contact the disk, to the order of about 3mm or so.

The bike hasn't been on the road for about a year now, as I have been distracted with other things, but Its time to sort her out.

Looks like I'm going to have to remove the fork slider, swap them across, and go from there.