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5th-Gen fork Upgrades


MsRN98

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Hello All--greetings from Madison, Wisconsin! While I'm certain this topic has already been beaten to death (and I've read many of the threads), I'm going to ask about it again. With something just over 3,000 miles on my '00 VFR since November, I've come to the same conclusion as many of you--the stock suspension is barely adequate to the bike it graces. I've talked with Jamie Daugherty (picked up the bike in Fort Wayne, too), and I'll definitely go with his re-tooled 929 rear shock. For the forks, though, there seem to be a plethora of options. If I stay with stock forks, Jamie's cartridge kit will go in my fork. However, there's also the brake de-link with Super Hawk lowers and brakes, or the RC51 build, with RC51 lower triple and Super Hawk upper triple. Has anyone here experienced more than one of these options? For someone like me, who's willing with a wrench but lacks welding, fabrication or engineering skills (sorry--bioscience, languages and healthcare background), is the RC51 mod too much for me to take on? As it obviously changes effective trail due to the changed fork offset, does it radically change the character of the bike? And for someone like me, who will never race but might do a few track days here and there, is the RC51 mod overkill? I have to change my upper tubes soon (bad pitting), so I'm trying to decide on the most sensible direction to take this wonderful bike. Thanks in advance, everyone, for your input!

 

Oh--here's a recent pic of my Yellow Bird...

 

 

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I used a 600F4i rear master, and did have to cut the pushrod down to fit; a hacksaw makes short (see what I did there?) work of it. IIRC there was something in the mounts that needed modifying, maybe they were threaded and just needed to be drilled out? I know it was no big deal. 
 
You can leave the back caliper totally untouched, and just take both the stock brake lines to your new master, and use a double banjo bolt to connect them there. There is a suitable double banjo in the linked brakes that you can re-purpose for the job. The stock lines fit like they were made to have this done.

You are right about them being threaded, IIRC.

Doesn't the rear caliper have to be bridged or something?


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50 minutes ago, MsRN98 said:


You are right about them being threaded, IIRC.

Doesn't the rear caliper have to be bridged or something?


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Not if you use both lines to new rear master. 

I used a 2010 CBR250RR rear master and only had to drill out the threads from mounting holes, length was spot on. 

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Some guys use the two stock lines on the rear or some do the bridge thing. I did one stock line and the bridge ... .(I think I was first) 

 

med_gallery_8220_3361_53235.jpg

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I too used the F4i rear. Like Terry, and the others that have done this,  one needs to cut off a bit off the plunger rod,   I used a diamond Dremel cut of wheel  as I found out after I installed it,  just made it a easier to do. I thought about doing what Terry did with just attaching both lines,  thing is, in my head when using the rear brake before you only activate two pots any way, so didn't think leaving more of the what I considered unnecessary was my view.  I'm still looking at the 8th gen rear caliber and or what ever may work there in place of this huge caliber. 

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Great feedback gentlemen - thanks. Cutting an F4i rear master pushrod sounds mandatory and is no big deal.

 

Terry, I wouldn't say your humor has me rolling round on the ground, but I did laugh at your wordplay. You pointing it out made it even funnier.

 

OZ, as far as I know, your use of the CBR250R rear master is new to the party, and it's 14mm. Cool.

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Old news, but when I was working mine, I had a 4th gen. I liked the rear brake on the 4th, so for calculations, I looked for mc combinations that would come close to a model of the rear 4th gen. The 2 answers via calculator were the 14mm and the 3 pistons and then 1/2"  and the 2 pistons.  

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I feel a plan coming together, with CBR600 F4i forks, 6th-Gen clamps and bars (I assume these run essentially the same geometry as the 5th-Gen?). Not sure if I can easily run 600RR brakes; if not, F4i brakes/MC will do. I Iike the idea of the CBR250R rear MC and double banjo bolt to the stock caliper. That leaves sourcing new brake lines and a way of mounting the front fender, and eventually the rear shock.


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I started with Jamie's compression valve and springs in the stock forks, then added VTR  adjusters and a rebound Gold Valve, then moved to VTR lowers and CBR600F4 brakes, now I have CBR600F4 forks in 6G triples with 6G bars.
 
I blame eBay. Don't tell my wife.
 
The biggest step change is to the damper internals, and will make a huge difference to the bike's ability to deal with bumps with confidence. The VFR stock front end is undersprung and has restrictive high-speed damping especially in compression, that stop it absorbing bumps nicely. I use 0.9kg/mm springs, and have replaced both the compression valves and rebound. If you are happy with the VFR brakes, I'd stop right there, IMHO that is 95% of the total improvement that you will get.
 
I got the urge to add adjustable rebound damping, so I bought some lightly bent VTR forks and used the fork caps and damper rod parts. Just so I could play with the rebound bleed adjustment. The damper cartridge parts, fork seals, fork bushes  etc are all interchangeable between VTR and VFR.
 
So I had some VTR lowers just laying about...add some CBR600F4 brakes and I had the de-link going. Used the VFR uppers. Made my own fender adaptor plates. The VFR wheel and axle slot straight in. The brakes needed to be shimmed off the fork mounts by 3mm to centre nicely on the discs. CBR600 calipers interfere with the lower fork mounts, and the latter need a little filing to fit nicely. Could you use a VTR mudguard? I'm going to say probably no, the guard slips over the outside of the fork mounts, and the VFR fork spacing is wider so these just won't fit. As far as I recall, the VTR uppers are near enough to the same length as the VFR, certainly within 5mm, so near enough to interchangeable.
 
I do prefer the separate brakes, but had no problem with the linked system either.
 
Then I had another urge, to upgrade to CBR600F4 forks; these are 43mm diameter, so significantly stiffer than 41mm forks, and came with adjustable compression damping, something I wanted to experiment with. The 5G wheel/axle fit straight in, and the 5G guard fitted perfectly at the lower mount, and needed a simple bracket to mate with the top fork mounts. 
 
The problem with modifying this stuff is knowing when to stop. I would find myself riding along and wondering whether a little more rebound damping might be good, or a little less compression damping. Within reason, now I can just stop and pull out a screw driver, but the reality is once you have taken out the junky OEM damper parts and got the shim stacks right, there's not much to be gained with further fine-tuning. Jamie's recommended set-up was close to but not quite the best for me, but I think that comes down to individual preferences, and I've learned that like pillows and mood lighting, I prefer my suspension on the softer end of the scale, as I (think) tend to ride fairly smoothly.
 
 
IMG_3330.thumb.JPG.1903f013c6b4b278c9102850c39ee3a8.JPG

Terry--since it appears I'm going to short-cut to something like your setup, a few questions: do the F4i forks need internal upgrading, or are they already a significant improvement over VFR forks? Are they similar in length/trail, or did you find that they substantially changed the character of the bike? And do I recall correctly that the 6th-Gen triple just drops right in the 5th gen without mods?
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The 600F4i forks use exactly the same crappy HMAS pistons in the cartridge as the 5G, and also use a similarly weedy set of springs, so at the very least I would replace the compression valve and springs, but preferable the rebound valves too. Hit Jamie up for some parts pricing, or go to Sonic for some springs.

 

The 600F4i forks are a touch shorter, maybe 10mm, than the 5G, so you will have slightly quicker steering, but I've had no instability and no shortage of ground clearance. I also have a Daugherty shock which is longer than stock so the geometry of the bike is at the faster end of the spectrum. Of course with decent springs, the forks will probably be riding a little higher than stock, so swings and roundabouts.

 

The benefit of the 600F4i forks is adjustability, stiffness, and the ease of fitting 4-piston brakes.They also use a wider set of bushings which I think make for less deflection/stiction.

 

6G triples are a direct swap, and the only adjustment I needed was to get the steering lock to align properly; the ignition barrel was sitting up a bit high so I added a couple of washers between the triple and the ignition to move the latter down a little.

 

The 5G mudguard fits nicely to the 600F4i forks and the lower mounts line up exactly. The 600F4i fork has a top mount behind the leg, and I riveted a couple of small aluminium strips to the 5G guard to mate with these; I drilled and tapped holes in the strips to accept the mounting bolts. The other option is to get a 600F4i mudguard of course.

 

As far as I can measure/feel, the 5G wheel, axle and spacers fit the 600F4i fork without any adjustment needed, and actually I think my bike tracks straighter now that it did when stock.

 

IMG_2734.JPG

IMG_2735.JPG

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4 hours ago, MsRN98 said:

I feel a plan coming together, with CBR600 F4i forks, 6th-Gen clamps and bars (I assume these run essentially the same geometry as the 5th-Gen?). Not sure if I can easily run 600RR brakes; if not, F4i brakes/MC will do. I Iike the idea of the CBR250R rear MC and double banjo bolt to the stock caliper. That leaves sourcing new brake lines and a way of mounting the front fender, and eventually the rear shock.


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As far as I know, the 03-04  600RR brakes will be a direct fit to F4i forks, the castings of all of those 4-piston brakes looks to be the same across the 929, 954, 600F4i, SP1, SP2 and 600RR, with just some variation in piston size; they also all use the same pads. Later 600RR's use radial mount brakes which are of course unsuitable.

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A better photo of the 5G guard on the 600F4i forks, showing the mount modification for the rear. I fitted the stock nut and bolt in the unused 5G top mount just for appearnces, but they don't do anything structural. I messed up slightly with the position of the rear mount, hence the slight downward angle of the front of the guard, I'm sure it made the aerodynamics better though!

IMG_2733.JPG

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A better photo of the 5G guard on the 600F4i forks, showing the mount modification for the rear. I fitted the stock nut and bolt in the unused 5G top mount just for appearnces, but they don't do anything structural. I messed up slightly with the position of the rear mount, hence the slight downward angle of the front of the guard, I'm sure it made the aerodynamics better though!
IMG_2733.thumb.JPG.4237bcbfbd00598cef6a00db849a69fc.JPG

Thanks, Terry! I'm guessing the 600F4i fenders wouldn't fit properly?


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600F4i fender on 600F4i forks??? That will fit just like Mr Honda intended. The fork leg spacing side to side on the 600F4i is exactly the same as the 6G.

 

I actually have 600F4i fender fitted right now (not needed, just more random eBay shopping when bored...).

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600F4i fender on 600F4i forks??? That will fit just like Mr Honda intended. The fork leg spacing side to side on the 600F4i is exactly the same as the 6G.
 
I actually have 600F4i fender fitted right now (not needed, just more random eBay shopping when bored...).

Get outta here! Time to go shopping!


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Mud guard?   Do you ride in the Mud?    I see em as fenders,   you guys crack me up.. :goofy:

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What do they fend off? Ships? Evil?


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Ha! One thing they do not fend off is deer! It might castrate a sheep though. If you hit it right.

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Maxswell - have you ever heard Woody Allen's standup [audio] bit about hitting a deer in upstate NY?

 

MsRN98 I'm attaching a couple tables the guys here have shared. I believe Mello built the rear brake ratio chart. I don't recall the origin of the USD fork chart, but you're leaning toward F4i, so the USD fork data is just interesting reading.

Rear Brake Ratios.jpg

Copy of Inverted Fork Swap Data Excel 2003.xls

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33 minutes ago, sfdownhill said:

Maxswell - have you ever heard Woody Allen's standup [audio] bit about hitting a deer in upstate NY?

 

Nope. Quick search finds nothing on utube

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What do they fend off? Ships? Evil?


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Ride without them, Terry, and you'll discover exactly what they fend off. ;)


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Ha! One thing they do not fend off is deer! It might castrate a sheep though. If you hit it right.

There's nothing dumber than a deer in rut. Even a man in rut has something going on upstairs.


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Seeing as how we are posting up tables, here's one I made earlier which shows the calculated ratio of the total front brake piston area divided by the master cylinder area. This is a crude way of comparing the force at the calipers for a given squeeze. The higher the number, the more pad force is generated, and conversely the more lever travel there would be. At the low end, brakes will feel firm, wooden and not very grabby. At the high end, there will be a softer lever feel, more travel, and a grabbier brake.

 

Brake ratio calcs.png

 

The numbers given for the 5G and 6G delinked assume that you can now activate all 6 pistons from the lever e.g. with a bridging hose or bored through caliper.

 

There's more to it than just this, the pivot point/arm length geometry of the lever over the master piston, the disc diameter, and the wheel rolling circumference all play their part. I can confirm that a 330kg ST1100 with the stock brake set up (=wooden, weak) is more exciting to panic stop than a 200kg VTR1000F running CBR954 brakes.The same ST1100 is less exciting with a smaller master (= bigger ratio) and some EBC HH pads, but still demands some respect...

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Thanks Terry - that is a table I've long thought would be of great value, and so it is. The various force ratios present some unexpected results, but your methodology is sound.

 

Speaking briefly of things that fend, does anybody have experience with the front fender extender products? How are they at reducing grime accumulation and road debris impact on lower cowls, front exhaust primaries, front cylinders, etc?

 

 

7 hours ago, MaxSwell said:

Nope. Quick search finds nothing on utube

 

My bad - it's a moose. I heard it on XM radio, so I thought it was an audio bit, plus all the discussion about deer activated my fixation complex. Hitting a deer while riding a VFR sucks only slightly less than hitting a moose...

 

 

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Speaking from the perspective of an experienced twisty mountain rider with zero fabrication ability, I chose the following (for my 6th gen ABS):

 

1) Traxxion AK20 cartridges with Penske triple clicker because I wanted to maintain the VFR look with the benefits of some upgraded technology but without having to fabricate anything that added to the level of complexity.  These are pricey but able to dial in the balance of performance and comfort which I desired.  As a fellow medical professional, the cost of hospital bills far outweigh saving even a few hundred dollars on suspension.  It has paid for itself if it keeps me off the ground just once.  I don't think you can go wrong with any of the kits made by Traxxion, Daugherty, Cogent or any others.  FWIW, Daugherty seems to be the best for meeting a low price point.  There is certainly a black magic to suspension that requires a lifetime of dedication and expensive tools, and I would rather stand on the shoulders of giants for my baseline setup than try to cook up something, myself, just to save a few bucks or find some mythical level of performance and comfort that will be achieved to 90-95% of "perfection" even with extensive fine tuning that can only be done by the rider with knowledge of how adjustable parts work.  Sportrider has a fantastic article on fine tuning suspension that is worth memorizing.

 

2) Spiegler / LSL SS kit with EBC HH pads because I wanted a more upright riding position to limit the effects of being old and out of shape on a day of sport touring.  The brakes have much better feel which allows me to utilize the skill I have improved over the years and are more than enough to activate the ABS in dry conditions.

 

3) Don't forget tires, which are arguably the most important link to the road and make all of the above relatively pointless if the tire doesn't stick to the pavement.  I will forgo this discussion for obvious reasons.
 

All this being said, we reach a performance barrier the VFR simply cannot cross due to the laws of physics without infringing on ever important safety margins.  As mentioned, there are multiple options for modification, but I don't think any will allow me to run the Dragon faster than the local I chased on an R3 with only custom pegs and upgraded tires without infringing on safety margins (I rarely drag knee while touring).  A KTM supermoto will assuredly pass us all sipping a latte and this margin is even greater while riding roads that make the Dragon look straight.  Speaking from experience of another local on the Dragon and a member of this forum, going faster only ends one way and it isn't any more fun after a point. 

 

I know I am preaching to the choir on this forum, but without a doubt the best way to improve speed and safety margin is to become a better rider, through education and experience, along with the above mods.  If you haven't already, spend some time at California Superbike school or equivalent.  While riding their track-prepped S1000RR, you will become closely acquainted with the law of diminishing returns when you swing your leg over any VFR.  Nonetheless, I still ride one because speed isn't everything. 

 

I hope I didn't go too far off topic and you find your balance of cost and performance for your needs.

 

 

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