4Th Gen Fork Options

[Trevor]

Hi,

I've been reading the many fork threads for a few days now, but wasn't sure about necro reviving years old threads, so here's my question. I see a few people say the 07 and up CBR600RR is a straight boltup nothing more required, without much other info, like is the length ok? same offset as the vfr? Do you just use the 600 wheel and guard? Wondering as it seems too good to be true with complete fronts available.

I am open to other suggestions, but obviously I like simplicity, so nothing too out there, R1 forks are good I hear, but i have no idea about the required parts for those.

And yes, after years (literally) of debate, test riding many other bikes, I finally made the decision this will be my last bike, so its time to fix the stuffed front forks, and quite possibly fix or toss the triple clicker penske as well, as I have never been happy with it.

[RC36Rider]

'Straight bolt-on' seems to be a bit of an exaggeration that really means that the new steering stem fits the stock neck bearings and will snug up in position just fine.

Beyond that, you might need a host of other 'minor' parts such as the front wheel, mudguard, brake discs and calipers ... and find a solution for some other 'minor' problems such as fouling the oil cooler, the instrument cluster, incompatible steering stops, custom wheel spacers ...

Why would you want to ditch the Penske shock? Can't find anyone who managed to set it up to your liking?

I'll give you $1 + shipping for it.

[squirrelman]

Better approach might be to use Progressive or Race Tech springs customized to your weight plus goldvalve emulators.

[WestOfBen]

Hi Trevor,

Fellow Aussie here with a 4th gen. In the interest of keeping mine as stock and showroom as possible I opted for springs and re-valve for the front, re-valve for the rear. I sent the forks and shock to ProMechA in Melbourne. I weigh around the 90-95Kg mark and was prepared for a rear spring upgrade as well, Peter said it wasn't needed and he was right.

So I have stiffer front springs, re-valved and pulled the forks about 10-15mm through the triples. Much less dive, still very compliant but much more rock steady. I can feel the road texture better. I like a solid front and this delivers in spades.

On the rear, the re-valve has worked wonders. Much less squat, doesn't kick back hard at all. Again I can feel more texture but not at the expense of comfort. I've placed about 5-10mm of large washers between the top shock mount and the frame to lift the rear a bit. You can only put a few under there otherwise you risk the top shock mount rotating if it is not kept straight by the frame lugs/guides. Easy job. The reason I did this was to partly compensate for lowering the front by 15mm. I have no problems with ground clearance, but then again I don't recall touching the hero knobs down. I ride spiritedly but not that madly on public roads, no need to IMHO.

In your case, your options might be to have the Penske worked or find a 4th gen standard rear shock and have that worked. Over in the US they have the benefit of guys who modify CBR954/1000RR shocks and apparently they work super. Shipping and costs etc would turn me off that idea unless my standard shock packs it in. Only then will I consider those options.

I would stick with the standard but worked front. I don't see a benefit of going CBR forks, but that's maybe because mine work beautifully now, again keeping her as visually stock as possible was the key. I haven't read a lot about the CBR options but many of these need different front guard, front wheel and/or brakes even. Going USD is a big cost option and IMHO it changes the nature of the VFR too much. If you like the rake and trail etc as it is but it is too soft, then a re-work would be my recommended option. Going USD will change the geometry. If that's what you want and you have deeper pockets, go for it.

I'm running Continental SportAttackII front and Continental RoadAttackII rear. The profile matches really well, they wear so good and warm up really quickly. They work well with Australian "roads" *cough* sometimes goat tracks. I've seen around 10K out of a rear. I haven't been able to scratch as much with this set, so the rear has squared off slightly after about 4K. I have been riding a little harder than usual, so maybe I will see 7-8K from the rear. The RoadAttackII is the only one that comes in a 170/60 17". Dad has been running the same on his 2001 Triumph Sprint RS for as long as they've been in Australia.

But tyres are a digression. Hope my thoughts are helpful. If you have any questions I am happy to answer.

Cheers

[dogman]

Hi Trevor, as You know I think, I have done the RC51 front end swap on the 4th gen, and the biggest upfront difference is straight away noticeable is that the front end is rigid as in stiff, gone is the subtle flexing of the 41mm stock forks and of course the better damping and adjust ability.

As mentioned above most sportbike triples have less offset than the VFR (30mm as opposed to 40mm) which increases the trail and slows down turn in so you need to drop the front and raise the back to compensate. Obviously the front brake is much much better than the 4th gen front stocker.

There are issues you need to work through regarding clearances and steering stops etc, so it is not straightforward but not too much of a problem either.

The advantage of staying with Honda parts is that the steering head bearings all seem to be the same, FWIW

I have the Wilbers 641 on the rear and the ride height adjustment came in very handy, it is maxed out on mine now, with the front dropped through the triples as much as clearances allow, and the handling is sweet but the ride is bordering on harsh but no worse than a fireblade for instance.

Its a shame the vfrs dont have a just slightly steeper rake.

[Trevor]

Yes, this is exactly why I was asking about the cbr600rr being a straight swap, as they people that have done it did not mention offset, or any issues with fork length. So still in the dark there I guess.

I read somewhere that 929/954 are not as stiff, so more flex, but issues with them being shorter?

R1 might be a good option, right length, and you can always counter the offset/trail issue by dropping forks and raising the rear.

Re the Penske, I bought it second hand, so do not know what spring is on it, but feel like it is way too heavy for my 60 kilos, as no matter what I try i don't seem to be able to tune the "harshness" out of it, so maybe time to get someone to rebuild it to suit me.

[kirbster]

As mentioned above most sportbike triples have less offset than the VFR (30mm as opposed to 40mm) which increases the trail and slows down turn in so you need to drop the front and raise the back to compensate.

Yeah but trail is only one factor. Changing your offset definitely does not produce the same thing as moving your forks down through your triples, even though both changes produce the same outcome (in terms of altering the trail distance).

Reduced offset = reduced stability as well. So you've effectively lessened your stability factors twice by bolting on reduced offset triples and then reducing your trail by dropping the forks. First time you hit a decent bump mid corner might be a bit exciting...

The VFR is pretty neutral handling in stock form because it doesn't load the front as much as hard core sport bikes. So it probably won't headshake... much... But just be careful. Change one thing at a time.

[zRoYz]

Trev I just saw your post on mail list as have been away but will post some info here for you.

There is no such thing as a straight swap for 4th gen VFR to convert to fully adjustable forks especially inverted, the closest you will get in that respect is F4i. There not inverted but there a larger diameter (same as 6th gen) but come with rebound & compression remote adjustment. Parts required are: F4i forks, F4i guard, F4i axle, either F4i wheel (3 spoke) or 5th/6th gen wheel, F4i/6th/5th gen rotors, F4i/RC51/CBR954/CBR929 callipers, F4i master cylinder best match existing clutch master, 6th gen triple clamps, 6th gen clipons. This setup uses same offset as 4th gen.

R1 forks are great but you need custom spacers for axle & rotors made which complicates the process big time with the 954/929 triple clamps used, you can use the R1 triples with a special top bearing that is obtainable apparently (think there is a post here about it somewhere) so then no custom spacers required. The offset with 954/929 triples changes to 30mm, can't remember offset for R1 triples (VFR offset is 40mm).

The least hassle inverted forks are RC51 as you can use complete front end (must be SP1 triples).

CBR1000RR front ends before 08 will also work but with 954/929 triples without any custom spacers, but due to length you need forks modified which gains about 5-10mm extra length or just make slight ground clearance compromise.

There are prob more forks that work but above are what I have installed & know works, I'm sure CBR600RR forks are to short & to use you will have to make a ground clearance compromise that is the inverted ones. The early model CBR600RR before they fitted inverted maybe usable but someone else would need to supply that info.

Your Penske only requires the correct spring for your weight, you never had spring changes for your light weight when you bought it second hand so what do you expect.

[dogman]

As mentioned above most sportbike triples have less offset than the VFR (30mm as opposed to 40mm) which increases the trail and slows down turn in so you need to drop the front and raise the back to compensate.

Yeah but trail is only one factor. Changing your offset definitely does not produce the same thing as moving your forks down through your triples, even though both changes produce the same outcome (in terms of altering the trail distance).

Reduced offset = reduced stability as well. So you've effectively lessened your stability factors twice by bolting on reduced offset triples and then reducing your trail by dropping the forks. First time you hit a decent bump mid corner might be a bit exciting...

The VFR is pretty neutral handling in stock form because it doesn't load the front as much as hard core sport bikes. So it probably won't headshake... much... But just be careful. Change one thing at a time.

I have hit plenty of mid corner bumps Kirby, enough to jolt a foot off a peg, and it holds the line just great, but thanks anyway.

[Trevor]

No worries Roy, the comments I saw about the CBR600RR being a "straight" swap had me imagining that something like this would bolt straight up as the bearings were the same size. I guess I was hoping for too much. Of course I fully understand about moving the radiator and steering lock etc etc.

http://www.ebay.com/itm/07-08-2009-10-11-12-Honda-cbr-600rr-fork-suspension-complete-handle-bars-tubes-/131661364150?hash=item1ea7a0fbb6:g:bjUAAOSwt6ZWVnNR&vxp=mtr

Re the Penske I wasn't really expecting that Zeno would lie to me about it being fine for my weight just to offload it, but thats water under the bridge now. Whoever does the work on whatever forks I buy can fix up the Penske at the same time, hopefully i can keep that inside the 5K budget I've allowed for this.

Which of the above options are 43mm? I reckon 45 might be a bit stiff for the old girl.

[Trevor]

Stumbled across a writeup on the CBR600RR front, it does bolt straight up, but I think the forks being 3 inches shorter might rule it out for me.

http://www.customfighters.com/forums/showthread.php?t=62293%C2%A0

[zRoYz]

From my memory when you bought the Penske your requirement was loading with your pillion in a million & luggage, so when solo your rear would be stiff. Also a soft front end wouldn't be helping either.

[Trevor]

its doable fully loaded, but I did ask him if i needed a lighter spring for me. Thats the tradeoff i guess varying the load by 60 odd kilos, in other words double,lol. Spoton about the front, it is mush which is why I'm finally getting a round tuit.

What do you think of the cbr600rr forks being 3" shorter, too much?

[zRoYz]

I haven't really looked into the CBR600RR forks but being so short would probably be an issue for your usage touring, as the installs have been mainly street fighter conversions so pillion & luggage not a concern. Also there not as robust as most of the other options due to light weight of CBR600 which prob wouldn't be an issue but VFR fully loaded for touring is a sizeable amount of extra weight. I would be more inclined to use CBR1000RR before 08 which are longer, stronger & also bolt on affair with 954/929 triples but the wheel is 3 spoke (you can use RC51 wheel but needs mods which adds cost & those wheels are becoming hard to find so higher $$). Ground clearance with lean angle you don't really want to compromise much with the riding you do, the shorter the fork the more you compromise. Rule of thumb from installs I have done is you want 505-510mm length from bottom of head stock to centre of axle.

Honestly the most simple is F4i there the same dia as 6th gen & have all the adjustments required, they would also prob be the least $$ outlay to convert.

[Trevor]

Sounds good, I imagine if I use the F4i wheel and calipers its a pretty decent brake upgrade as well.

[dogman]

Trev, just for your info, here are some pics of the RC51 front end from Kirby on the 4th gen.

Distance from centre of axle to bottom of headstock =510mm

There is 10mm approx of fork showing above top of helibar bracket.

There is 140mm of ground clearance under the fairing "chin".

This is the setup with the front lowered 10mm as I originally had it set up with the top of the forks flush with the top of the helibars but was getting slow turn in but I didnt measure the stock setup ground clearance before doing the swap, so I just measured it against my other bike and it is very similar so maybe the

front height is about where it should have been in the first place, anyway, it all works well.

The gull wing design of the 954 top triple allows a bit more latitude for adjustment height wise.

[Trevor]

Nice to see how it translated from the 800 to the 750, thanks.

[GearWhyne]

Isn't the VTR1000F fork lowers with modded internals to suit also one of the simpler swaps for the better brakes while you're sorting the springs/damping?

Also there was a VTR fork brace that was supposed to fit, which I recall seeing somewhere around here.

[slo1]

The whole vtr1000f (Superhawk/Firestorm) forks work great on the 4th gen. Even better if they are worked over by Jamie :) Better brakes and suspension, and lets you keep the stock wheel and rotors :) Not as good as f4i or inverted, but cheaper and easy.

[750]

I have Maxton reworked front forks on my VFR, they're night and day with the standards. You'll be hard pressed to justify a big front end overhaul over simply having the existing forks resprung AND revalved (putting in stiffer springs is never going to be as good)

Get the Penske set up correctly, I have one and it's fantastic.

[Trevor]

true, its going to someone to setup both the forks and the shock for me as soon as I decide which way to jump on the front end. :-)

[750]

Save yourself a load of effort and just get the front forks revalved and resprung. You know it's all set up for the bike perfectly that way. No adjusting and relocating seemingly endless amounts of bits and bobs. USD front ends look super trick, but I'd be hard pressed to believe they offer ANYTHING over a correctly reworked standard set up, especially if you're just a normal rider who isn't doing mad time attacks or hundreds of track days a year.

I've no idea who's a good suspension expert in Aus but I'm sure there's plenty. Maxton/K-Tech are renowned over here, find their equivalent over your side of the world and you're laughing.

[zRoYz]

I will just make a comment on rebuilding the 4th gen forks that have decent mileage on them, the internal cartridge stem seal will be worn out which means the oil bypasses the valving which isn't a good thing. That particular seal isn't replaceable you either have to buy new cartridge or see if a suspension tech can modify to make seal replaceable. The problem is the valving is adjusted to compensate which isn't such a good solution as you lose response. It doesn't take rocket science to know the 4th gen forks flex which in turn wears the seal & as it's not replaceable, high mileage the seal will be toast.

If you don't believe a upgraded front end with stiffer forks that have remote adjustment rebound/compression & better brakes isn't an improvement over stock you need to ride one with those mods & you will be collecting the parts to do yours the very next day. It's like saying the stock RSV4 handles just as good as the Ohlins equipped factory.

[Trevor]

Yeah, I guess I should have put mileage on this, mine has 175K on the clock now, and at 21 years old both the forks and the rotors are pretty much toast. That said I am interested in keeping the original geometry, so F4i seems the likely way I will go now.

[750]

I will just make a comment on rebuilding the 4th gen forks that have decent mileage on them, the internal cartridge stem seal will be worn out which means the oil bypasses the valving which isn't a good thing. That particular seal isn't replaceable you either have to buy new cartridge or see if a suspension tech can modify to make seal replaceable. The problem is the valving is adjusted to compensate which isn't such a good solution as you lose response. It doesn't take rocket science to know the 4th gen forks flex which in turn wears the seal & as it's not replaceable, high mileage the seal will be toast.

If you don't believe a upgraded front end with stiffer forks that have remote adjustment rebound/compression & better brakes isn't an improvement over stock you need to ride one with those mods & you will be collecting the parts to do yours the very next day. It's like saying the stock RSV4 handles just as good as the Ohlins equipped factory.

I promise you'd be no faster on your VFR with a CBR/whatever front end than you would be on my Maxton rejigged front end. It's night and day, I have two VFR's so can compare back to back.