Rc51 (Sp1/sp2) Forks Vs. Cbr1000Rr Forks

[JZH]

I've been commuting to work in London a few days a week and, though my "hot rod" FP is holding up, I've pretty much decided that I need another VFR... 

So, why not the exact same year and model I already know and love? 

 

And that means mods! 

 

So, do I go down the "tried and true" path to USD enlightenment?  Or do I really push the boat out, throw caution to the wind and experiment with another variety of early 21st Century Showa forks?

 

I have a set of 1000RR forks (I think they're usable), but when I took them apart years ago I recall thinking they seemed like cheapo imitations compared with the obvious quality of my SP1 forks.  But are they really worse?  I'm curious if anyone knows the answer to that?  Do the radial brake calipers make up for any difference?

 

(I've noticed that Honda has helpfully manufactured both a CBR954RR and a CBR600RR in the VFR's lovely PB-215C Candy Tahitian blue, so I can easily fit a matching mudguard--how convenient!)

 

Cheers,

[Switchblade]

Too bad your not state side .

https://atlanta.craigslist.org/atl/mcy/5473065566.html

[CandyRedRC46]

HHHHHHNNNNNNNNNNNGGGGGGGGGGGGGGGGG

[RVFR]

Whoa, wonder if those are Sp1s fitment.. Hmmm??? just might have to drop a note or two, yes what a find.. and I'm state side

[Ultimatevfr]

Too bad your not state side .

https://atlanta.craigslist.org/atl/mcy/5473065566.html

Oh my................

[Switchblade]

Too bad your not state side .

https://atlanta.craigslist.org/atl/mcy/5473065566.html

Oh my................

And a fair price .

[JZH]

Yep, those look extremely nice. A bit more than I was planning to pay, though. Still, there's the kid's college fund...

Ciao,

[JZH]

Okay, it's probably almost time to start a new build thread...

I've got most of what I need now, so I've decided to use the SP1 forks and other bits I already have. The only part I really need and don't yet have is a new shock to replace the tired OEM one that's currently on the bike. I've ordered the blue 954 mudguard and missing solo seat cowl from David Silver Spares in the UK (if asked, they still do the "2-3 week delay and discount" thing, making them by far the cheapest source of new Honda parts in the EU, btw), though, of course, I won't have them for another couple of weeks!

I've decided that I quite like gold fork tubes, and as it happens SP2 fork uppers are gold, rather than brown. (I believe all US-spec RC51 forks are brown, early and late.) But, I cannot afford actual SP2 forks in decent shape right now, so I'm going to have my SP1 tubes stripped, polished and re-anodised gold locally. My plan should work out if the anodising company I choose is any good...

The first step will be to get my SP1 front wheel re-powder coated NH-1 black (it is currently, er, gold). The 8-spoke rear wheel currently on my FP (which I will use on this bike) is already powder coated black, but it was done in California more than 20 years ago (!), so I will get that re-done to match the front. And then we're on our way!

Ciao,

[BiKenG]

...

I've decided that I quite like gold fork tubes, and as it happens SP2 fork uppers are gold, rather than brown. (I believe all US-spec RC51 forks are brown, early and late.) But, I cannot afford actual SP2 forks in decent shape right now, so I'm going to have my SP1 tubes stripped, polished and re-anodised gold locally. My plan should work out if the anodising company I choose is any good...

There are several companies in the UK that offer a specific service to anodise fork outers and sometimes also to nitride coat inners too and maybe a straightening service. One of them advertises on eBay, but I can send you links if you want. I must add though that I've not tried any of them myself.

In any case I wouldn't think you'd want the outers polished first as shiny gold probably wouldn't look as good as the machined/brushed gold like Ohlins. But that's JMO.

[JZH]

Thanks, Ken. From the research I have done on this, the caustic soda process by which the old anodising is removed significantly dulls the finish in the process, so if you don't polish after the old stuff is removed, the new anodising can be excessively "flat". I will discuss this with the anodiser to get their view, however. I sure don't want them looking gold-plated!

Ciao,

[CandyRedRC46]

oh thats cool, maybe one day I can do that to my r1 forks and get a nOhlins sticker :)

[JZH]

As this has turned out to be my "pre-build thread", I should mention that I sent my nearly perfect SP1 fork tubes off last week for re-anodising, and I'm off to Essex with my wheels/sprocket carrier and pressure plate today to drop them off at the powder coater. I need to wait 2-3 weeks for the fork tubes to come back, and then I can rebuild them.

In the meantime I bought a set of SP2 forks with grotty tubes, so I may swap bits around. I'm concerned about the different clamping areas between SP1 and SP2 (SP1 has a lot more!) as I don't yet know which triple clamps I will end up using. I have both RC51 SP1 and 954 uppers and lowers, as well as Helibars and Tommasellis, so I hope I have enough options to make everything work!

First step once I get the bike onto the lift will be to carefully measure the bike in its OEM state. I have Tony Foale's Motorcycle Kinematics software and I want to see what I can do to get close to the original trail figures (fitting SP1/954 triple clamps loses 10mm of fork offset immediately). As I have yet to get a shock for this bike, I may want to change the length if that will help...

[tbc]

Ciao,

[BiKenG]

I know the SP-2 fork tube clamp area is smaller, but I think you'll be ok, unless you're trying to stick a LOT of fork above the top yoke.

Regarding the geometry, the best option I've been able to ascertain is to use something with a 35mm offset, such as CB1000R and/or VFR1200F. Top yokes would be interchangeable (the former having handlebar clamps), but the Gen7 bottom yoke clamps 55mm forks and all other Honda forks are 54mm at the bottom yoke. However this can be overcome with the use of 0.5mm Al shim, or join with me and get the perfect lower yoke manufactured. I'm going to be needing a couple with 35mm offset and 54mm clamp diameter, i.e. like the CB1000R, but the Honda original's not a very nice yoke. I want one with 3 bolt clamps and not stuck on the outside how Honda tend to make them. The stem can be from a FireBlade '00 - '07 and if you'll be using clip-ons, you'll want a Gen7 top yoke.

Of course, if you're making yokes, you could have them made with the original 40mm offset, but I think 35mm will be ok and it gives you the option of using Honda parts for the top yoke. For me it makes sense as I can use the same bottom yoke on my eVo4 as on my 800 project.

Let me know if you want to join in having bottom yokes made.

[JZH]

The VFR1200 triples could work--I don't mind shims.  I haven't seen any pictures of the bottom yokes, though.  I presume it's regular shape?  The CB1000R bottom yoke is kind of a reverse gull wing...could still work, but hard to find anyway.

I agree that a 35mm offset would probably be fine (plenty of people actually use 30mm offsets, after all), but I'd prefer to avoid custom triples if at all possible--just the sound of it is expensive!

For reference, this is the VFR1200 top yoke:

And here is a CB1000R bottom yoke:

Assuming I don't find either of these on eBay for a reasonable price, I will take note of their dimensions when I've got the front end off--I should be able to extrapolate from the 954 bottom yoke I already have.

Cheers,

[JZH]

Found some pics of VFR1200 suspension:

Looks like roughly 954 shape.

Ciao,

[BiKenG]

Yes it is, but a bit beefier, 35mm offset and as I said for 55mm forks. Both the bikes in question use steel stems though so if that's important to you, factor in the cost/hassle of finding a CBR1000RR stem instead. They're all the same dimensions.

I actually have a brand new VFR1200F bottom yoke and stem. I bought it in error and now it's just sitting here. You can have it at the same trade price I paid. As I said, not actually used and only taken out of the plastic bag in order to take measurements for these discussions. I also have the 0.5 Al sheet that makes a perfect shim/collar. In fact I have pieces trimmed to the right size and you just need to slowly wrap it around the fork and bingo, one perfect fork shim. You can see them on the pictures of my eVo4 - oh no you can't, 'cos they're invisible.

Anyway, if the bottom yoke is of interest, let me know. I think you have my email address.

BTW, although it is possible to find decent stuff on eBay, fork yokes are almost always problematic with many sellers trying to shift bent items. I've had several bent top yokes and although it's possible to claim the money back, you can't recover the time wasted. 2 rulers is all you need, but some people obviously just lie. I have a CB1000R top yoke here. Before buying I asked whether it was for the early 7/8" bars or the later 1 1/8" bars. Eventually I received the terse reply 11/8, which although showing a lack of care taken when typing, is clear which size it is and that therefore it's the later yoke. When it arrived I could see just by eye that it was for the 7/8" bars. It really doesn't need to be this hard. I tried to make it easy for him, but it was still wrong. Then a second look revealed it was clearly bent.

Not the first and I doubt will be the last. Thing is, why else is a yoke available if it's not from a crashed bike.

All of which suggests a nice new one is the best way forward.

Joking aside, let me know if the yoke is of interest. No problem if not. I've been in 2 minds whether to sell or keep it, just in case I have an accident. But if someone wants, I will sell it.

[JZH]

eBay is, well, eBay...

Thanks for the offer re the clamps. Let me first try to get the parts I've got give me the numbers I want, and if I can't, well, you can then raise your price!

Ciao,

[BiKenG]

You did see my chart:-

http://www.vfrdiscussion.com/forum/index.php/topic/82954-forks-and-steering-geometry/?hl=geometry

I can plug some other figures in if you want.

[JZH]

Update:  After running a bunch of numbers through the Tony Foale program, I decided that the VFR1200 triple clamps/yokes, with their 35mm offset, would be the better choice for my RC36 build, so I relieved Ken of the heavy burden of keeping an extra SC63 lower triple taking up space in his cavernous home workshop.  <g>

[Note that the VFR1200 top yoke is not gull-shaped like the 929/954 top clamp--it just looks that way in the pics.  It is actually flat on the bottom, so it does provide a little bit more room to mount clip-ons above the clamp, but probably not as much as a 929/954 clamp.]

On this 5th gen, I will probably still try to use SP1 triples, as I can probably raise the rear/lower the front enough to get back an OEM-ish trail figure (my RC36 is already raised in the rear, so raising it more would probably be too much). 

Ciao,

[sfdownhill]

Thank you all for many explanations, good answers, and great input. After reading this entire thread twice I have three quick questions:

 

- of the RC51 lower triple clamps, are the SP1's the only ones that have the inverted gullwing configuration? [Also, is the SP2 lower triple flat?]

 

- some posts that say the RC51 SP2 triple clamps won't work on a VFR because the SP2's use a different bearing. Can this bearing be shimmed or adapted in some way to fit the VFR?

 

- does anyone have access to a set of VFR1200 forks they can measure center of axle to bottom of fork cap when unloaded/extended, and post that measurement?

 

Thanks!

[BiKenG]

Well I know the answers to all your questions. But you know what, a moderator (Hispanicsomethingorother) has 'warned' me about my language. Huh? How can I put this politely? People on here need to grow up.

 

I probably know more about Hondas than anyone else on here and I enjoy being able to help, but there are idiots who insist on being argumentative and now I'm the one being 'warned'. This aggravates me more than having to argue against the idiots and I REALLY don't appreciate such patronising censorship. So unless the mods apologise, I will not be offering my help to anyone. Sorry. Blame them. Good luck getting answers elsewhere.

[JZH]

11 hours ago, sfdownhill said:

Thank you all for many explanations, good answers, and great input. After reading this entire thread twice I have three quick questions:

 

- of the RC51 lower triple clamps, are the SP1's the only ones that have the inverted gullwing configuration? [Also, is the SP2 lower triple flat?]

 

- some posts that say the RC51 SP2 triple clamps won't work on a VFR because the SP2's use a different bearing. Can this bearing be shimmed or adapted in some way to fit the VFR?

 

- does anyone have access to a set of VFR1200 forks they can measure center of axle to bottom of fork cap when unloaded/extended, and post that measurement?

 

Thanks!

 

The SP1 lower triple differs from the SP2 in that the stem has a larger diameter and the bearings are correspondingly larger.  I believe the alloy part is the same shape, if not identical, but given the diameter difference I have not paid much attention to them.

 

The SP1 clamp requires a non-OEM lower bearing to fit what is a somewhat larger OD steering stem into the same ID frame, but there happens to be a common bearing that has the same OD but a larger ID.  However, this bearing is approximately 3mm thinner than the OEM lower bearing, but this can be addressed with spacer(s).  With the SP2 lower clamp it may be that there is no readily-available stem bearing that will fit both the much larger diameter stem and the VFR frame.  (I'm sure this question has been answered in the numerous fork swap threads in VFRD, but I cannot find it.)

 

Ciao,

[SEBSPEED]

6 hours ago, BiKenG said:

Well I know the answers to all your questions. But you know what, a moderator (Hispanicsomethingorother) has 'warned' me about my language. Huh? How can I put this politely? People on here need to grow up.

 

I probably know more about Hondas than anyone else on here and I enjoy being able to help, but there are idiots who insist on being argumentative and now I'm the one being 'warned'. This aggravates me more than having to argue against the idiots and I REALLY don't appreciate such patronising censorship. So unless the mods apologise, I will not be offering my help to anyone. Sorry. Blame them. Good luck getting answers elsewhere.

 

See ya!

[Switchblade]

6 hours ago, BiKenG said:

Well I know the answers to all your questions. But you know what, a moderator (Hispanicsomethingorother) has 'warned' me about my language. Huh? How can I put this politely? People on here need to grow up.

 

I probably know more about Hondas than anyone else on here and I enjoy being able to help, but there are idiots who insist on being argumentative and now I'm the one being 'warned'. This aggravates me more than having to argue against the idiots and I REALLY don't appreciate such patronising censorship. So unless the mods apologise, I will not be offering my help to anyone. Sorry. Blame them. Good luck getting answers elsewhere.

I have read alot of your posting and never read anything I would find to be argumentative, I have reported for worst and some were done by one moderator  and nothing was done. Please done stop offering your help. 

[Switchblade]

2 minutes ago, Switchblade said:

I have read alot of your posting and never read anything I would find to be argumentative, I have reported for worst and some were done by one moderator  and nothing was done. Please done stop offering your help. 

 

 

And striped of about 4000 post !!!!

[sfdownhill]

Ken, I've only seen you share sincere assistance and good insight here. You've offered knowledge way beyond most of our experience, saving us time and perhaps resulting in better results on our projects.