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F4i fork swap for superhawk. Write-up.

Old 12-29-2011, 10:25 PM
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F4i fork swap for superhawk. Write-up.

So i decided to go with an f4i swap, mainly because i wanted externaly adjustable compression damping. Granted, ideally a set of racetech valves would have been the cheaper solution, but primarily I just wanted to tinker a little.

For the most part the swap is pretty straight forward. You will need spacers.

Components list:

F4I PARTS USED:
upper & lower triples
Axle and axle bolt
clip-ons
Steering head bearings, same as Shawk's. I'm using tapered roller bearings.
Front fender
Horn
Steering head flange nuts and top nut. Same on shawk.
Ignition lock bezel

SHAWK PARTS USED:
Wheel spacers.
Front wheel
Brake calipers and lines (S.S. lines)
Ignition lock
Switch gear
Brake and clutch lever
Bar end weights

PARTS NEEDED FOR THE SWAP:

Wheel spacer.
A 6mm wide, 28 mm OD, 20 mm ID wheel spacer for use with OEM shawk wheel spacer.
This spacer will sit next to the large OEM spacer on the right side. Fully assembled, the f4i axle will install normaly. Using the Shawk axle will cause the axle to be inset within the axle well. I used the shawk spacer because it was available at the time. Using OEM f4i wheel spacers will also require a custom spacer.

Caliper spacers.
4- 3.5 mm spacers to center the brake caliper. This should center the rotor well enough into the slots. If want, you can use a 4 mm spacer on the right caliper. This will get it the rotors to slot dead nuts center. Braking hasn't been an issue using the 3.5mm spacers.

Caliper bolts.
4- M8 1.25 x 35mm grade 12.9 or better flange bolts to accomodate the caliper spacer and thread.

FORK POSITIONING
31 mm above the triple works with my riding style. I initially started with the forks 28 mm above the top triple, which gave the same if not a close axle-to-bottom of steering head tube distance of 515 mm, IIRC. After setting sag and initial damping settings and test riding i found 28 mm a little on the heavy side. My guess, due to the increased trail. I suspect the f4i yokes have a shorter offset.


ISSUES
Clip-ons.
Using the f4i clip ons you will need to drill new index mounting holes for the throttle cable housing and on/of/start switch. The hi/lo and turn indicators slot properly into place using the existing index holes.

Switches.
The switch gear will touch the tank in the stock f4i position and will adversely affect lock to lock steering and pinch your hands and the normal return of the throttle tube. You can move the clip-on up and out of the indexing slots from the triple and rotate it or grind of the indexing tabs off completely. In anycase, there is suitable length of fork tube to work with. You will have to lose the fork retaining rings.

Ignition lock.
The ignition lock unit will have to be shimmed abt 4mm or so in order for the steering locking mechanism to engage properly.

Throttle side bar end weight.
As setup on my bike the throttle tube extends a little bit over the bar. You can install a nut between the bar end weight and lug and tighten down the screw.

So far...
Overall, my initial impression is positive. The bike looks stock. The rigidity of the forks are noticeable and as a result the bikes vibration feels different. The damping is more vesitile as now you can balance the damping rate between the rear and front ends more easily. Bear in mind i've logged about 67k miles and a trackday with the stock front end, running almost exclusively Pilot Power 2cts. So i feel i have a good basis of comparison.

More info as I progress.

250 mile update: I've ran the bike at a really fun pace on a few "control" roads of varying conditions with some finalized suspension settings. So far so good. Bike turns in virtually the same as with the OEM shawk forks, as i intended. The rigidity and whatever extra trail i gained with f4i forks makes the bike feel noticably stable in turns, although now the bike is more apt to stand up during mid corner braking.

pics here
http://bayarearidersforum.com/forums...38#post7032938

Last edited by Karbon; 01-13-2012 at 12:43 PM.
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Old 12-30-2011, 11:05 AM
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Good write up! Curious as to why you simply didn't go with the front wheel and rotors from the f4i? I understand if the wheel is the 6spoke! Great to hear about the stiffness and adjustability. I personally don't like the idea of spacers in between the calipers, I'm not an expert by anymeans but my mind says they will flex and over time, crush the spacers causing alignment issues. I don't know, just thinking. I'd love to check it out in person.
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Old 12-30-2011, 02:27 PM
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I did this swap last season. Something to note: The F4i forks are 20mm shorter than the superhawk forks. I put the F4i forks almost even with the top triple to keep the rake the same as stock. Others have tried to do what you have in using the stock clipons from the F4i and had horrible handling characteristics, and dragged the header...
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Old 12-30-2011, 02:32 PM
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I ended up using a combination of the F4i spacers and the VTR spacers, and shimmed the calipers.

The whole caliper spacer was problematic for me as well. I ended up getting run out of my lane by an oncoming bike last June, and had the front rotors both get warped when the brakes engagedas I clipped the mirror of an SUV as I bounced off its side...

If you can find an F4i wheel and rotors, I'd go that route. I highly doubt my rotors would have warped if I hadn't shimmed them.
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Old 12-30-2011, 11:28 PM
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Originally Posted by Letsrideinsc View Post
Good write up! Curious as to why you simply didn't go with the front wheel and rotors from the f4i? I understand if the wheel is the 6spoke! Great to hear about the stiffness and adjustability. I personally don't like the idea of spacers in between the calipers, I'm not an expert by anymeans but my mind says they will flex and over time, crush the spacers causing alignment issues. I don't know, just thinking. I'd love to check it out in person.
I think eventually i might go for the f4i wheel swap, for the rotors if anything else. At this point i'm looking for a bargain. If anything f4i calipers would be next on the list although braking feel and stopping power hasn't been an issue, even at a B/B+ pace at the track.

I made the caliper spacer out of steel. At 25 ft/lbs per caliper bolt it shouldn't be an issue.

Originally Posted by matt365 View Post
I did this swap last season. Something to note: The F4i forks are 20mm shorter than the superhawk forks. I put the F4i forks almost even with the top triple to keep the rake the same as stock. Others have tried to do what you have in using the stock clipons from the F4i and had horrible handling characteristics, and dragged the header...
They are probably doing it wrong or have the wrong springs, or have other issues.

Putting the forks flush in the tripple does not give the same rake. In fact it "choppers" it out and with the shorter triple tree offset of the f4i forks, makes the steering even more difficult.

Installing the f4i forks 28 mm above the tripple gives the same 512 mm center-axle to bottom-of-steering head distance as the shawk. But, because of the offset, the trail is increased, giving more stability but requires more steering effort. Installed 31 mm above the triple allows plenty of ground clearance and virtually identical turn in feel.

Last edited by Karbon; 12-31-2011 at 03:56 AM.
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