5th gen fork conversion.

Okie dokie, I know this subject has a lot of miles on it. But. Can't help think this particular one is quite the set up, talk about looking like it belongs and look at those brakes. Nice. Since I've been going over the in and outs how and why which version seem to work best for the trouble knowing its a mission of love as well. on the short list I've narrowed it down to 3 versions
Super Hawk lowers and their brakes. and in that can be a mixed bag. F4i & brakes with 6th gen triples, RC51 A bit more work getting it all down yet? Olala. Then in reading folks are getting the 929/954 in place, those brakes are the shits http://www.vfrdiscussion.com/forum/uploads/monthly_03_2010/post-19616-126771169252.jpg

 

Speaking from personal experience as I own a VTR1000F Superhawk, and a 5th gen, and I have meddled with the forks on both. My VTR has CBR954 calipers and master, and my VFR runs VTR lowers, VTR rebound adjusters and 600F4i master and calipers.

The F4i, SP1/2 and 929/954 all use very similar calipers; there's some variation in piston size but they are more or less equivalent and use the same mount points. All these calipers can be used with Superhawk lowers, a little hand filing is needed (5 minutes/leg) to make the caliper and lower leg mount play nicely, and the caliper needs to be spaced off the mount by 3mm to centre on the VFR disc (I used 2x 1.5mm washers on each bolt). VFR wheels/axle/spacer/discs are used without any mods. The F4i master cylinder is visually identical to the VFR (different diameter piston though). The VTR lower fits perfectly onto the VFR upper forks, ended up 6mm longer overall.

I agree Superhawk brakes are not too good (hence my 954 change). 954 brakes are fabulous, F4i brakes are great too.

If you use the Superhawk legs, you'll need to fabricate a spacer so the 5th gen fender will bolt on. Superhawk fenders won't work, the leg spacing is narrower on these.

Lots of good info on brake upgrades here: http://www.vtr1000.org/phpBB3/viewtopic.php?f=31&t=15494&hilit=brake+upgrade

When you delink the brakes you'll need a new master for the back, I used a CBR600F4 part which again is visually identical to the VFR but a different diameter. I reused the original rear hoses and a redundant double banjo bolt from the CBS system so you'll end up with two hoses connected to the same master, connected as per stock at the caliper.

 

I'm thinking on going the complete F4i forks/wheel/brakes/guard, with 6th gen tripples and bars.
That way offset will remain the same, you get full adjustability with more ridgidity from the 43mm forks.
Just not sure if F4i forks are the same length as 5th gen. 10mm shorter or so would be fine.

 

I believe F4 (not F4i) forks are basically the same length as the 5G. I'm a little tempted to do this myself. I just bought some 6G bars for $1!

Some dimensions here: http://vfrworld.com/forums/showthread.php/20085-VF4iR-the-project-begins
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F4 forks only have preload and rebound adjustment, F4i are fully adjustable.
I can't see F4i forks being different length then F4.

Sorry, just checked and F4 are fully adjustable too.

 

I've read that the F4 forks are 10mm longer than the F4i. They certainly have different part numbers.

 

Yes I'm very tempted to go full on F4i, can't be that difficult for the swap, it takes 6th gen triples and clips, so other than tracking down those pieces, seems to be pretty much straight forward. but something is gnawing at me about the SH deal too, since its just a throw em on bit too, and still using f4i brakes.. Hmm??? Right now I'm dealing with the rear shock and a new rear wheel. So all is fun here.

 

The SH lowers are very easy, the hardest bit is making up brackets so you can reuse the 5G fender, the rest is bolt-on. I already had SH lowers as I bought some complete slightly bent forks just for the caps/cartridges. Cost wise, using SH parts means you only need forks and brakes, if you do the F4 swap you also need triples, bars and fender.

My problem (probably psychological) is that I love tinkering with suspension and there's a part of me that thinks having stiffer 43mm tubes and externally adjustable compression damping would be even better than what I now have....


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That's my problem too, started to fiddle with my suspension a while ago, I now have it as good as it's going to get.
The only reason I haven't bothered with SH lowers, is that I can't see the point without compression adjustment.
I have my rebound pretty spot on, and once its set to your springs, there's not much point adjusting any more.
But compression can be changed to suit riding condition or load.
F4 looks like it will do the trick, plus it will get rid of the flex problem with the 5th gen and SH 41mm forks.

 

Care to share your cartridge set-up Oz-man?


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^ that's exactly my situation, and or problem, I like to fiddle too. Thing is at the moment I've only tracked down SH lowers, to make it complete and worth the trouble, be great to find the whole unit that way all is there in one place. seems F4i stuff is around most of the time on ebay, then it's a matter what price piont one puts on it. Brakes aren't a problem, then like you 43mm vs. 41 something yanks on me saying that's the way to go.

 

Anyone know anyone who has dropped the coin on Ohlin R&T forks? The stock R&T seem like a good match for the vfr.

 

When I bought the bike it was obvious that the suspension was not up to the job.
The front end was way too soft for any weight rider.
The rear high speed compression damping was way too soft as was the spring.
I didn't know it at the time, but it was all made way worse by slop in the fork bushings.
It really made going into a bumpy corner at speed a scary proposition.
The bike woulld wallow and buck, and run wide on exit. it also bottomed out over anything substantial.
First thing I did was buy a JD rear shock, this raised the rear 10mm, and after spending a long time dialing it in it made a huge difference.
Raising the rear and having proper damping put proper loading on the front, which made things worse.
I replaced the front springs with Racetech 0.95, and went to a heavier oil.
This improved things a bit, but it was still shit.
The bike had not enough damping, comp or rebound, plus front end dive was horrendus and it would still skip on bumpy corners.
I took the pistons to a suspension shop and got them to redo the shim stacks, it was better but not by much.
I then realised that tthere was so much play in the bushings, that the front wheel would be moving arou/nd too much.
I got some HRC seals and bushings from Japan and installed them with a 7 weight oil, this was much better, but damping control was still crap.
I bought some high flow pistons and bags of shims and started to work on different configurations.
I lost count of how many times I dismantled the front end, but by this stage I could removes them, install new stacks and reassemble in 1 hr.
Started with 1.1mm bleed hole on the compression piston (rebound has 1.3mm buit in) and 5 weight oil. That's when I realised that the top bushing on the damping rods has too much play due to fork flex (and oil bypassing the stack).
There is nothing you can do about this, except getting the oil bypassing the stack to an acceptable level by using a heavier oil.
This meant going back to the drawing board with the stack set up.
So I went 10 weight oil with and 1.2mm bleed on the compression pistons.
I didn't like the action of the forks with this oil, specially high frequency bumps.
I've now settled with 7 weight (cST26@40) oil, 1.3mm bleed, rh17 stack on the rebound and c32 stack on the compression, 110mm oil height and dropped the front end 6mm using PP3 tyres.
I no longer look at the corner surface when I'm riding, its that good, and I don't have any dive under brakes.
I weigh 74kg and I think this set up is as good as the standard front will allow.

Things I've learned:

Oil weight (5,7,10) means nothing, you have to see the actual oil viscosity and sadly not many oil manufacturers display this.
NEVER EVER locktite the bottom damping rod bolts as the manual states.
Nothing will get rid of the fork flex on 41mm forks.

Hence my hunt for 43mm forks, and full adjustment.

 

Thanks Oz. Not too different to me (85kg) I guess:
0.90 kg/mm springs
120 mm oil height
5W Motul (18 cP)
Compression: DMr valve body, C33 stack (presumably 1.3mm bleed)
Rebound; Gold Valve, RH17 stack
VTR1000F rebound adjuster, 2 turns out

I find that if I wind the rebound adjuster in any more, the ride gets less supple and causes a bit of jolting. Interestingly I find the rebound adjuster has possibly as much effect on compression as rebound, but I don't understand why. Its always hard to be too analytical about this while riding but my feeling is that if I had a bigger compression bleed I could close the rebound bleed and get a bit more 'control". Hence an interest in a fork with an external compression adjuster. But it would be a lot cheaper just to buy another Gold Valve and experiment.

 

Damn OZ that was a lot of R&D and work. Still wondering if a nice set of Ohlin forks would be a better choice.

 

Wow great read there Oz.. makes one like me really appreciate what you've gone through and found out. thanks for sharing. That pretty much sums up the next move...................................Ohlins Forks?

 

It would be the best option, if I could afford it.
Ohlins front and back would be the best the VFR could get, but it would also cost around the same price as the bike.
I'm afraid my wife would divorce me if I spent that much money.
Plus there is so much more on the wish list.
Braided lines, saving a shit load of unsprung weight with different forks and brakes, new SS headers, power commander, quick shifter.

 

My c32 stack with 26 oil would be pretty close to your c33 stack with 18 oil.
The difference would be on the slow speed compression, mine would be a bit stiffer.
I don't mind that as it gives me a lot of feed back from the front tyre.
I'm also using heavier spring as a compromise when my wife climbs aboard and we are loaded up full of luggage.
Also the 110mm oil height made a huge difference with bottoming out on big hits.
My rear spring is 1100 pound, I think that is around 22kg in the real world.

 

I just found out from a friend who is an Ohlin distributor that Ohlins does not make the R&T fork for the VFR 800 but a cart kit for the 1200.
His reply to me:
"They don't make R/T forks for the VFR's

We have custom fit a 30mm NIX cart Kit into the VFR1200 though, very trick!"