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F3 fork mod...

11360 Views 57 Replies 17 Participants Last post by  mcasswell
There's been some discussion about this mod in the cafe forum. Some member's have already done this with very good end results. After reading that topic several times, I've decided I'm sold on the mod.

I read recently that someone sent their fork's off to racetech to have the goldvalves installed. This bike was apparently a "mule" for the project...I would assume so they can get a kit setup for our bikes.

The F3 fork's will permit more adjustability over the standard fork's as you will beable to control front ride height over a greater distance compared to stock. They are 1.375" longer than our's.

Anyway, if there's any intrest in this, I could post some pic's as I go along...once I get all my stuff.
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"Local guy has a new product that is supposed to withstand 1000* for the headpipes. Has a slight texture to it similar to the finish on the cases..."
I'm VERY anxious to see and hear more about this! I'm a sucker for that textured stuff. How hot can our head pipes get though, can't they get hotter than 1000* at the heads?
I would send the head pipes to Jet Hot for the coating, headers get hoter then 1000 degress.. Brent at NB went through this with his bonnie..

Jet Hot!
04BB, since Jet Hot (in Pascagoula, MS) is 15 minutes from where I work, I've used their services for several things. Pipes, Headers, Air Filter Covers, footpeg brackets, and now most recently the fork shrouds, and overall I've been very happy with the finish. Gives the bike a distinctive look!
Ok, this is the last time I make a post offering to make a how to available prior to actually doing the job at hand.

It's not like I dont have any mechanical ability. When I was 16, I built a a frame out of 2x12's and pulled the motor from my 74 grand coupe. Tore the top end off it, bolted it up to a new short block, bolted the trans to it. Then took a chain and a come-a-long and pinned it down to the back of my old man's pickup.

Ran a pile of wires from the motor, to the electrnic ignition module on the car inside the garage, and back to the motor.
Fired her up right on the bed of the truck just to make sure she was ok, that thing ran like stink when I was done with it.

This fork mod however is kicking my ----> (__0__)

So, off to my local dealer today to do the deed. We managed to get them built, but one is fighting us. It doesnt seem to have any rebound dampening.

First fork we built per their recommendation, felt mushy...almost no rebound dampening. 2nd fork we built shimming the gold valve a little stiffer, and then took the rebound dampener and shimmed it a bit too.

That fork came out sweet, so we tore the other one back down to re-shim it, and managed to get the compression dampening to feel pretty good. The rebound is fighting us, so, back at it again tomorrow.

No more how too mod's for me :mad:
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Trim - Sorry your having trouble with the mod. I went through the same with the compression damping - too soft from Race Tech's set-up. But had no problems with the Honda rebound damping - it is a little bit of a challenge getting that Honda adjustment rod in the right locaction during set-up/assembly, but I encountered no problems with it. Did you go with Gold Valves on the compression side as well? I did not thinking the honda adjuster would provide all I need at this point. It'll be worth the aggravation when its done. But it is a mod for people who like to tinker with settings and oils, and shim packs. Once it's dailed in though - very sweet ride. JCW
Sorry to hear about your difficulty with the forks. Whenever I embark on anything new, there always seems to be a point when I feel a little disheartened about something I hadn't expected throwing a spanner in the works. On the other hand, when I do eventually get it sorted I feel so much more confident about tackling such things again. I get the impression, from what you've written in the past, that your tendancy to think your way through such problems will see you right in the end. I hope so.
Good luck.
Ok, I'm going to attempt to explain how to do this using pictures found within Thruxtonones photo album.

24 hours after starting to tear down the fork's I think I have it figured out. The only thing not pictured are the Racetech Gold Valves. Note that these are not cartridge emulators, they are simply small plastic valve's that replace the stock valve's within the stock Honda F3 fork's. It is similar in appearence to what you will find inside the stock fork's, with differently shaped hole's for the fluid to travel thru. There is also a large assortment of shim's and such to fine tune the overall dampening effect.

I had a pretty difficult time with this mod, mainly because I did not have any anticipation of what to expect to see when I tore down my fork's. Had I simply viewed this photo, printed it, and taken it with me I would have been much further along.

I have numbered the different part's to make explaining how this work's a little easier.

Ok, what you are seeing in the picture below is the entire f3 inner assembly, along with the triumph lower leg on top ( #2 ) Again, if you are adding Racetech Gold Valves, ( not pictured ) you will need to remove the rod from the tube ( #3 ) Inside you will find 1 valve for compression, and the other for rebound. The compression valve is the valve located towards the bottom of the assembly. Racetech provide's a illustration with their product that is very...shall we say limited in the sense that it may be difficult for you to figure out exactly what your looking at. What it show's in that illustration is the compression dampener assembly...or, the lower valve assembly.

They offer varied setup's rated from c-33 to c-39 softer to stiffer respectively. We setup the first fork using c-33 which basically was the softest setting. After the fork was assembled, we found this to be too spongey. The second fork we built we added a couple more shims and found this gave a desireable end result in general just from compressing the fork on the deck after it was built.

The problem we encountered with the 1st fork not having any rebound dampening was simply...air. Apparently there was a rather large air bubble in the internal assembly and the fork wouldnt "pump" oil when compressed.

Something we noticed almost right away was the fact that there was very little rebound dampening, even when the fork was pumping oil. ( when I say pumping oil what I mean is when the fork is assembled, and compressed..oil will pump up to the top of the tube ( #3 ) inside the fork leg ( # 1 )

So, we tore this back apart and added some shim's to the stock rebound valve in a effort to stiffen up the rebound dampening. As of now the fork's have not yet been installed, I have to wait on a rubber for the headlight ear to put everything back together on the front end.

I am a novice with fork's, I have never torn them down and would recommend if you are lacking experience to take this photo along with you to someone who is ( triumph tech or not ) and ask for a hand. I've now had my fork's together and apart easily 1/2 dozen time's and am more than comfortable with doing this. Nothing beat's hand's on experience.

The fork goe's together just like it is numbered. The part's to the left of the lower leg from left to right go on just as they lay in the that order from closest to the tube to furtherest away...or right to left.

The cartridge ( #3 ) goe's down inside the top of the fork tube. The bolt at the end of the cartridge is what lock's this assembly into place inside the tube. It is inserted in the bottom of the lower fork leg ( #2 ) and snugged into place.

The fork spring ( #4 ) goes overtop the cartridge assembly ( #3 ) the spacer and washers go ontop of the spring in the same order...right to left.

#5 slide's into the top of the cartridge assembly, in the little tube that is outside the picture ( top of # 3 )

For my application we used racetech springs 85lb per their suggestion, and 5 weight oil.

I have tried to explain this as simply as I possibly can, hoping that someone whom has never taken fork's down before can make sense of all this.

Again, a big thank's to Thruxton-Up and Thruxtonone for being the trail-blazer's here with this mod. If anyone has any question's, or would like to correct a mistake I may have made in posting the info above please do so.

I'll make another post with final setting's and tuning note's once I get all my part's back from being powder coated, and the rubber for the headlight ear and get the bike back together.
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Good write up. No matter what you are working on the first time is a learning experience even when you have strong mechanical skills. We will be waiting for a ride report.-T1
That's a great account - thanks for sharing it. I think even I could do something useful with it.
I'm looking forward to hearing how they handle. :upthumb:
Hate to drag up and old topic, SCCTrim, why did you go with 5 wt oil? Are you pretty light, or was that recomended? I am 230lbs and trying to figure out what wt oil to use. I am leaning towards 10wt, stock F3 cartridge.
The 5 weight oil was a recommendation from RaceTech. I also used their springs based upon my weight..( which is light..I go about 150/155 )..we also setup the fork's using a few more shims to on both compression as well as rebound.

At this point I havent as of yet re-assembled the bike as I am still waiting on parts from this guy doing my powdercoating..( sense the frustration? ) I'm uncertain of how they are going to feel on the bike.

I'm anticipating having to make some adjustment's regarding the shim stack on the gold valves to get it right, and maybe even swap in the stock f3 springs or the progressives.

I'll post more here when I finally get this thing back together...and it get's warm enough to ride. The past 3 morning's here have been in the single digits.

BTW...never apoligize for asking questions :)
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Ok, I've gotten all my stuff back from the powdercoater and the part's look sweet. As I began reassembling the front end I ran across a major issue. Apparently the Thrux top yoke and the bonnie top yoke are different by roughly 1/4"

With the stock bonnie lower yoke and the LSL clipon eliminator kit top yoke for a thruxton I couldnt get the fork tubes both installed. Feel like a dam fool for posting this as I clearly didnt research this through. Oh mistake's are your lesson, as well as my own.

If anyone is in need of a CEK from LSL let me know...I have one for sale at a discount :mad: :hammer:

I have the stock top yoke in place along with the 2" risers installed from genmar and it appears that it's going to be very close to working out. I'll post more when I get the frontend totally assembled.
Trim - That bit of news is terrible. What would a Thrux bottom yoke assembly cost? That would get you out of the bind - could post looking for one from a wreck too.
To buy a assembly new from the dealer with bearing's and stem it's around 300 bucks. I did some checking while I was there yesterday and the bearing size's are the same.

However I'm afraid I would also need to change out the speedo drive as they are different part #'s, and since the thrux yoke place's the fork's at a slightly different position I'd need to mirror that at the front wheel.

At this point I'm going to continue assembly and see how the bike sit's with weight on it.

I used caliper's to set the fork's equally in the uppper yoke, extending them through 1.380". This leave's very little clearence between the adjusters and the bar's with 2" genmar riser's installed.
Sorry to hear of the fork issue. I am surprised this is the first time it has come up. I do not remember hearing of it in any other posts. Sounds like you should be fine with stock parts. I would set the rebound adjuster mid range to start. Good luck-T1
Just adding a update on where we stand at this point. Frontend is installed and appears to be fine with the 2" riser's installed.

I think I'll need to shorten the spacer in the fork's as I only have 13/16th's sag in the suspension and 1" is my target.

Probably need to change the shim stack a couple time's as well to get the right feel once I spend sometime on the road with her. Ride height appear's to be correct with the fork's extended through the upper yoke 1.380".

All newly powdercoated part's installed including brake/clutch levers, shifter lever, rear brake lever, exhaust etc...just waiting for my grommet so I can get the oil pressure gauge mounted up in the gauge bracket..( Thanks again John for hooking me up )...

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all that black looks good with those polished carbies.
Looking good, not long now.-T1
Couldnt stand it anymore....put the rest of it back together and took her out for a shorty. Just up to the local autozone for a jug of dot4 brake fluid, and over to the convenience store.

Man did that feel good, chilly....but good none the less. Will need abit more road time to work out the frontend but it felt better than I thought it would.
Heres a shot of how close the adjuster's actually are to the handlebars. There's still some room there, but not a bunch.

[ This message was edited by: SCCTrim on 2007-03-04 19:16 ]
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