RC-51 front end installation

Correction: I paved the way for this mod after finding and researching some obscure and now lost reference to using CBR929 forks on a 5th gen, and eventually figured out you could interchange various CBR and RC51 bits in 2004 - BUT Rob did the proper job of documenting what I did after I explained it to him and he took pictures of the actual swap on his bike in 2006, so he generally gets the credit for it.


:violin:

 

The RC51 "flat" top triple will be fine, but if you want to mount your clipons on top you will have to slide the forks up enough to attach them. I got my bike back from Honda once with the forks raised waaaay up in the triples and rode it for two years like that with no problems, including railing through corners at 150km/h two-up. On Tomahawk tires LOL

I put them back down to between where they were and how I originally installed them flush with the tops of the clipons - if you want, I can measure how much fork I have showing now. The geometry is not stock, but neither is Rob`s, who last I asked him had his rear shock shimmed 8mm (?).

The CBR929/954 gullwing top clamp drops down 18mm (?) if I remember correctly, and you need 20mm for the clipons. So 2mm up in the triple clamps and you are as close as you are going to get to stock without machining your own clamps like cassandtim from vfrdisscussion.com did.

 

Larry is the guy if you want to do the R1 forks on a 3rd gen. We spent a fair while discussing how to do this together a couple of years ago. The R1 front calipers are available with three different color inserts (gold/blue/silver), and their monoblock four-piston design is vastly superior to the two-piston OEM calipers on the 3rd and 4th gen VFR750.

I was originally going to put R1 forks on my VFR800 but found a deal on a set of Ohlins forks from an RC51 that I could not refuse.

The R1 forks are the exact same length as the VFR750 forks, which are the same length as the VFR800 forks, which are the same length as the CBR600F4/F4i forks.

 

Well, many people have shimmed their rear shock 8mm, which gives you steering geometry more radical than the RC51 fork swap does.

zRoyz over on vfrdiscussion.com is the go-to-guy for the 6th gen. He has done the RC51 swap on his 6th gen, and later changed to radial caliper R1 forks. I think he has done at least a half dozen RC51/R1 swaps on 6th gens.

 

Wicked.... So the R1 forks, or RC 51 forks OR the CBR600F4/i forks will work on my 3rd gen?

I've sourced a couple RC51s, both a 2005 and a 2001 at the local salvage yard here, and they also have a broad collection of CBR600's, a CBR 954, and a CBR 929... I literally have nearly any Honda option I could ever want however they DO NOT have an R1.

I was really jiving on that Hohey Designs top triple as it would allow me to get helibars at a cut throat rate (sort of if you count it as a portion of the total cost of this mod), AS WELL as improving the feel of my bike. Is it a worthy undertaking to do this modification or should I just "settle" and find some stock VFR forks?

 

If you source some F4/F4i forks you will need the 43mm triples, the 3rd gen VFR's are 41mm. I don't agree a 8mm shock shim is more radical than stock with any of the RC fork options with the RC/954 triples. The offset of the RC/954 triples is much less than stock VFR parts, your trail will increase from around 95mm to about 105mm. Lowering the front height and/or increasing the rear height can counteract this. I went almost 1" higher, 25mm, in the rear with the SP2 forks to get a very neutral handling bike, and that is with the SP2 forks raised about 10mm above the 954 gullwing upper triple.

 

You could also use CBR929/954 forks (VFR Project).

If I remember correctly, the RC51 SP-2 ('02+) forks are a little shorter than the SP-1 ('00-'01) forks.

You can use the CBR929/954 upper and lower triple, or combine them with an RC51 lower or upper triple.

The RC51 SP-2 ('02+) lower has a larger stem and will not fit in your VFR. So only SP-1 ('00-'01) stuff if you use the RC51 triples.

CBR600F4/F4i stuff sounds like it should be easier to find and cheaper, but in my experience it isn`t. I've been told it's because they are popular stunter bikes...

I used to worry about changing the geometry on my bike, but I have seen a lot of variations and no one seems to have died yet, so as long as you follow what others have done I wouldn't lose any sleep over it.

 

I am throwing around the idea of putting USD forks on my 99 VFR800. It seems like the CBR929 parts are cheaper to come by than the RC51 parts. I am still unsure of what i need to do the swap. lets say i wanted to use CBR929 parts. i know i will need the forks and brakes. i am unsure about the wheel, axle, triple clamps, bars, and bearings. I am staring with all of the stock front end parts. Thanks for the help.

 

That's a lot to engineer if you want to mix-match parts. If you want to go with the shorter 929 forks it might be easier to just get a complete 929 front end w/ wheel, brakes, etc. But I think you will need the RC SP1 lower triple and like steering bearings. The upper 929 gullwing triple will bolt on and is almost a necessity. The bars from any of those can be made to work it's just how much you want to lean over. The front end is going to be dropped a lot with the shorter forks and the larger trail (from the offset) will make handling pretty awkward. I'd keep looking around for the longer RC front end, jmho.

 

One time I got my VFR back after having some work done and the shop had raised my forks in the triple clamps about 1.5"

Rode it like that for two years, including two-up to the Kootenay Hootenanny, and following some dude going 150km/h through some nice sweepers.

You can put the RC51 SP-1 or SP-2 wheel on the CBR forks, but you will need the CBR rotors which are 330mm vs. the RC's 320mm. Not sure if the spacers are the same, but you could compare the part numbers on bikebandit.com. Other people have related swapping the two wheels back and forth in other forums. The SP-2 front wheel is the nicest match for the VFR's rear wheel IMO, and as light as most aftermarket aluminum wheels to boot

I used a CBR600F4/F4i front master cylinder which matches the VFR's clutch master, and some RC51 calipers, although CBR600F4/F4i/900/929/954/RR all appear to be the same. There may be some small differences in internal piston diameter though, so if it really bugs you get a 600F4/F4i master cylinder and calipers. Or a matching set of CBR929/954 or RC51 calipers and front master cylinder, although these won't match the VFR's clutch master cylinder.

Also got 15,000 km + out of the front tire during the time the forks on my bike were raised up high in the triple clamps.

The RC51 and CBR929/954 axles are different, the CBR's being shorter. So you can't mix and match them. RC forks get an RC axle, and CBR forks get a CBR axle.

Upper bearing remains VFR800, lower bearing gets CBR929/954 or RC51 bearing.

Lower triple can be either RC51 SP-1 or CBR929/954. Both work equally well. I have had both on my bike.

CBR929/954 and RC51 use nearly identical front fender. RC fender has some tabs on top that apparently do nothing. I used the CBR fender because it was esthetically cleaner and fiscally cheaper.

I put a Ducati 996 front Marchesini wheel on a set of Ohlins forks from an RC51, using 748R rotors. Had to machine two sets of RC51 spacers, make an insert spacer for the smaller diameter Ducati wheel bearings, and shim the calipers and rotors to make it all fit.

In comparison, fitting a CBR929/954 wheel to a set of RC51 forks or vice-versa would be simple.

 

Correct me if im wrong. It seems that my best bet is the cbr forks with cbr triples and lower bearing. I will need the cbr wheel calipers and rotors. All that should be bolt on correct? What about controls and bars?
Thank you for the advice.

 

VFR Project shows a '90 VFR750 with a CBR929/954 front end.

Looks like he put aftermarket clipons under the top triple, but had to remove the inner fairing shroud to accomodate the cables. You will probably find the same thing on the 800.

If you like having the bars at stock height, try a top triple for the CBR that will accept tube bars.

Will try and compare a few numbers for you here shortly...

RC51 SP-1 fork length: 755mm
RC51 SP-2 fork length: 730mm
CBR929/954 fork length: 700mm
CBR1000RR fork length: 700mm
YZFR-1 fork length: 755mm

Amount of fork currently showing above my top triple is 2 in (51mm)

I originally had 1 in. (25mm) of fork above the top triple, which was the amount I needed to attach a set of Tomasselli clipons above the top triple, and the closest to the stock length of the VFR forks. The highest I have had the forks has been 2.5 in (64mm)

I have had both an SP-1 and CBR929/954 lower triple on the bike. With the forks 2.5 in (64mm) above the top triple I had the CBR929/954 lower triple, debunking the myth that you NEED the gullwing lower triple of the SP-1.

Also, note that with only 55 mm difference between the CBR1000RR and RC51 SP-1 fork length, it is possible to use the 1000RR fork safely, and indeed others have done so (see zRoyz on vfrD). The CBR929/954 fork is the same length as the CBR1000RR, so go right ahead and use them if you like. I actually have a spare set in case I ever feel like trying them myself.

The one thing you will find about the CBR929/954/1000RR forks is that due to their shorter length you will have to mount clip-ons under the top triple. I don't know how this part works, but on my bike it looks like it would interfere with the inner fairing shroud ~ if I remember correctly, some trimming is required. I would go with a tube bar on top as mentioned elsewhere in this thread.

The CBR1000RR uses 310mm rotors, although there is no reason I know of that you couldn't space the radial calipers further out to accomodate a larger rotor.

And, to throw in something completely different ~ I had planned to use 1st gen R1 forks, which have better brakes than the RC or CBR and fit in the Honda triples. I know at least one 3rd VFR750 owner who did this, and there are several Australian VFR owners who have put the 3rd gen (?) R1 forks with radial calipers on their bikes (zRoyz again).

You can also use the stock VFR front wheel with RC51 forks, but you have to use Ducati rotors.

 

OK, I put 2000 R1 forks on my 93 VFR.

Used RC51 SP1 lower triple with stem and a 2mm shim below the bearings, and ended up with RC51 SP1 uppers with VFR bearings as well as it came exactly to the top of the forks. used convertibars finally. Was going to use Ducati st4 clip-ons, but snapped on after tightening to much.

Used the OEM VFR rotors with gold 4 pot R1 calipers. 290mm rotors with calieprs for a 300mm rotor. 1mm no big deal. Work great. Used R1 fender with repaint to match the Pearl Crystal White. Looks OEM.

I ended up with Hayabusa master cylinders to clear the convertibars. All innner plastics work just fine. Hed to trim the bottom of the convertibars to make sure I was above the plastics.

Problems encountered:

1. At full lock the forks hit the upper radiator supports. Trimmed to fit with a Dremel and cutter wheel. A little gloss bloack Rustoleum and you can't even see what I did.

2. Forks hit back of oil cooler at full lock. Moved a 2nd gen (3 row) cooler about 10 mm forward with a piece of angle AL. Just fits inside fairing with a little trim of the black inner lip.

3. Had to turn down OEM VFR axle 1 MM to match R1 bearings.

4. Has to add 2mm spacer each side of forks to make fit with OEM wheel.

Look great, perform better.

Larry
VFRrider at VFRD. Go look at my pics for examples.

 

Larry is the guy who asked me about putting the R1 forks on his VFR years ago.

Just so everyone knows, the 2mm shim idea comes from veefer800canuck (Rob McKinnon). I have never shimmed the bottom bearing and have ridden 25,000 km like this.

 

What year is 1st gen for the R1. is it '98-'99? if i use the R1 forks they will just fit into my stock triples? Would i be able to keep the clip-ons on top of the top triple? Also i would have to use R1 wheel correct?

 

Lots of great info here. I completely agree if you go with the 929 forks, they'll mount up but the clipons will have to go under the upper triple. Or go with a top clamp mounted superbike bar. I'm using the SP2 forks and have them 1 5/8" above the 954 gullwing triple. 30mm shorter forks would force the clipons under the top triple and on the 5th gen I just don't see how you could do that without major fairing mods. At some point with shorter forks you start banging the oil cooler or other parts against the fender/wheel.

And to clarify, the gullwing SP1 lower triple's purpose was to clear the frame and other components. I don't know if the 929/954 straight lower triple has clearance issues, apparently not, but the fork length has nothing to do with your lower triple selection.

Handling is largely dependent on the trail, determined by fork offset and steering angle. The stock 5G had 95-96mm trail. By swapping out the OEM 43-44mm offset forks for the RC-CBR triple's 30mm offset, you'll increase trail to around 110mm assuming same steering angle. Shorter forks necessitating lower front end, along with a raised rear, provides the greater steering head angle. Even raising the rear on mine about 1" I figure about 100mm trail. Close to the stock set up but it still steers a little slower. Overall the better brakes and feel make up for the trade off imo.

 

I believe all the R1 forks are the same length. The early model forks with the non-radial calipers will be the least expensive, and the monoblock calipers were long considered some of the best. The R1 forks will fit in the RC or CBR triples, but obviously not your VFR's.

The R1 axle is 25mm if I remember correctly. The RC51 wheel has a 22mm axle. So if you want to put on an RC wheel you will have to change bearings and spacers. The CBR wheel bearings have a 25mm ID, and I believe the VFR's is 23mm. OD of the wheel bearings are mostly 47mm, and either 12 or 14mm wide.

Larry used his VFR wheel on his R1 forks by turning down the axle, as he noted.

 

Either the RC51 SP-1 or CBR929/954 lower triple works fine on the 5th gen VFR800, and there are no clearance issues. My fork tubes just touch one of the radiator hoses at full lock, but who turns lock-to-lock anyway except for at an MSF course ?

The fork length issue was mistakenly brought up by another poster on vfrD years ago that put RC51 forks on his bike and said the gullwing lower was necessary because of fork length, and this has been perpetuated as a problem, even though it isn't.

I had an SP-1 lower triple on my bike from 2004-2006, but changed to a CBR lower triple in 2007 when the upper threads on the steering stem stripped. Guess that's what you get for buying used parts, eh ?

The only real clearance issues with this conversion are with the '90-'97 VFR750's, where the wider stance of the inverted forks causes them to hit the radiator and/or oil coolers, as mentioned.

 

An alternate solution for 6th Gen !

Well having browsed some parts files & had a look at what's available, a simple upgrade for 6th gens (43mm Forks) would be to add CBR600F4/i fork lowers to VFR fork tubes, this would give Nissin 4-pot brakes which are very good & will fit the standard rotors, as they are the same as the CBR600's at 296mm.

Plus you get fully adjustable forks ! You might have to make a threaded adjuster to connect the rebound adjuster rod if its not long enough for the VFR inner fork tubes, but as its all Showa, I'd wager that the caps will use the same thread.

This would be no more work than a full fork strip & you could add springs suited to your weight & riding style are the same time.

The front wheel spindles are the same size. So the only thing that needs checking is the caliper centre line matching the disc's !

Just a mad idea I had !