Who's done suspension mods to their VFR? Note: Long post

My next series of improvements to my VFR will be centered around revalving the front forks to the remove the HMAS valving (if you could call it that) and install a rear shock, as the stocker has 15,000+ miles on it.

I'm leaning three different ways and wanted to get input from others on what they've done to their suspension, and most importantly, who did the work.

Some background: I've been fiddling with and studying suspension on my bikes for the last 18 years. My profession as a scientist provides me with enough technical background that I can read and understand the technical literature in this domain pretty well. I know what a digressive damping curve on the compression circuit does and why it works well with respect to controlling wheel speed in a high-speed compression bump, for example. I think about how my suspension is working at all times when I am riding, and have gotten to the point where I can tell you what the rear feels like when there is too little compression damping, or if the front spring rate is too soft when tracking down the freeway. So, I have a good sense of what properly sprung and damped suspension should do and how it should feel when riding.

I've had the suspension on virtually all of my bikes redone, and can describe experiences of what worked and what didn't (like the time that I tried to convince Ohlins that the shock for a '91-'93 F2 doesn't work on a '94 because Honda lengthened the shock shaft length 5mm in '94, and didn't tell anyone. Ohlins never picked up on this, and subsequently, you simply could not use the shock they recommended for CBR600F2's on a '94 F2. Well, you could use it, but the bike literally handled like it had a hinge in the middle of the frame. I tried several times to convince Ohlins of this, but they never listened-ah merde).

Anyway, enough of this technical digression (no pun intended!)
1) Going with a known quantity: Traxxion Dynamics and a Penske shock.
I had Mike Fitzgerald when he was at Traxxion revalve the forks on my F4i and bought a two-way adjustable Penske from them. Despite my clear instructions to them NOT to spring the bike for racing, they did so anyway, no doubt because they were on autopilot doing the work, and the bike was WAY too stiff for street use when I got the forks back in and installed the shock. After getting proper straight-rate forks springs from Max (.90's) installed, and a proper rate spring for the street from Penske, the bike handles absolutely beautifully. I've had a couple of friends (ex-AFM fast guys) who have ridden the bike get off and say that it is the best-handling bike they have ever ridden. I took it to Miller last June for a track day, and had Dave Moss, who tunes suspension for Celtic Racing (Chaz Davies' team) tweak my initial settings. We set the static sag to 30 mm front and rear, then adjusted the damping appropriately for the spring preload, and the bike was f***ing on RAILS around Miller. It was incredible, I don't think I've ever ridden such a well-set up bike on a track day. I am thinking of going with Traxxion again because the valving and damping, especially on the forks, has been exemplary. If I had any fault with the suspension, I would say the stock Penske valving has a skosh too much high speed compression damping for Nor Cal's now-terrible road quality.

2) Mike Fitzgerald-aka Thermosman. Apparently Mike has left Traxxion and started his own company, Thermosman. My understanding is that he does very good fork revalving, and may be using some new Penske fork valving kits that may be the shizz-nit. He sells both Ohlins and Penske shocks for rear suspension. The plus with going with him is that he still does all his own work, and is the person who did the work on my F4i.

3) Dan Kyle
I've heard nothing but good things about Dan, and I've personally ridden a friend's CBR900RR that was set up by him and it handled really, really well. He clearly knows what he is doing as he used to wrench for Erion Racing. He is strictly Ohlins, though, and I have some questions about Ohlins. Don't get me wrong, the Ohlins stuff is superb, but I've heard from knowledgeable sources that often times Ohlins valving rates are more geared to racing applications than street applications. The VFR is strictly a street bike, and I want it to have I what I know is obtainable, a "plush" (but properly sprung) and very well-controlled ride with respect to damping rates. Some of my concerns are that the Ohlins fork valve kit and shock valving rates may be too "stiff" (if that is the right word) for street use, or should I say, for my tastes. The advantages are that Dan has a well-deserved and exemplary reputation, and he is "local" so that if I need some fine-tuning on the valving rates, he will do it and make sure it is right. But, I'd rather get it right the first time, rather than having to repeatedly yank the forks and shock on and off to get the springing and valving right because the suspension tuner still set it for racing use when I specially said it is for street use (I'm thinking of my Traxxion Dynamics experience here, not casting aspersions on Dan).

I'd be interested in what other folks have done regarding fork revalving and aftermarket shocks for their VFRs; note specifically, revalving of forks, not just replacing fork springs or changing oil weight (that does not get rid of the flawed HMAS valving design), and how it's worked for you.

What are the plusses and minues of what you've done, and how is your bike working now that the work has been done?

Regards,
-PC

 

I have Race tech re do valving with springs and oil changed to a different wt. in the forks, I did the work. WP rear shock 3way and the spring set up for my weight. then had Dave at Fluid suspension work his magic balancing it all out. Can say it's a whole different machine, all thou the freeway ride is harse at times, way worth the trouble when you find the twisty roads. only wish, but it's so close, be hard to tell if there will be any gain by adding compression damping adjustability by switching to a F4 forks. its on the list of things to try and do but still scratching my head if there is much if any to be gained as she rides like she's on rails now.

 

Thanks for the input, RVFR.

Regarding the F4 forks, if you're dialed now, there's no need. While multi-adjustable suspension is great to have, there's really only one setting that's the right one, and if you're already there, then having compression damping adjustability won't realliy get you anything more. The little adjuster only makes small changes anyway, the vast majority of the compression damping characteristics are determined by the compression damping shim stacks and the damping valves. These are internal to the fork and are not adjustable w/o dissembling the fork and re-configuring the valving by changing the shims, their arrangement, and the valve design.

As Kenny Roberts once said (and I may be paraphrasing here), "The problem with 1000-way adjustable suspension is that there is still only one correct setting, but 999 wrong ones."

Thanks for the info.

 

I've done a lot of modifications to my VFR and easily my favorite mod has been the suspension, after hitting the local twistys with the horrible stock suspension I knew if I ever was going to really enjoy the VFR I was going to have to do something about the suspension immediately!

Up here around the Seattle area we have two quality suspension choices, I went with the Ducati AMA suspension guru who set me up with Race Tech Gold Valves with .95 springs for the front and a Penske for the rear, since I've had my suspension dialed in, I've let a couple of my buddies who had stock suspension try it out and they were so impressed they ordered the exact same set up :hat:

 

RW,
Did you install the Gold Valves yourself, or did the Ducat AMA guru do it for you?

thanks for the post.

 

He did all the work, I'm not that handy with the wrench and usually seek out the most talented people to work on my bikes...

 

Understood; I've done fork work back in the day when bikes used damper rod internals (you know, back when the earth was a fiery ball of gas...), but since cartridge forks made their appearance, I've left revalving to professionals!

 

Good thread everyone; I installed an Ohlin rear 3 way adjustable shock a few months ago. I have not done anything else to the suspension as yet. At this point I am concerned about the Ohlins shock. After I installed the unit,the bike sat considerably higher in the rear,in addition the spring ,in my opinion is to stiff. Soon, I want to have the front forks re done. I have received mixed reviews on weather it would be best to convert my forks to cartrige type or just go with revalving the stock forks ,playing with the fork oil weight and experimenting with different fork springs. I would really like to hear some feedback on what really works best.I was told you really cant change the stock Honda forks to cartrige type,and then I hear of guys that did and they really like them. Just like Puma Cat I would like to hear what works and what dosent. Thanks eddie

 

Thanks Puma, I was thinking the same thing, if it ain't broke don't fix it.

That said, now I'm wondering if the brake upgrade that would come about with that swap would add much? I'm at the point where I feel I can out ride the braking.

 

Gee, I wonder if Reg has it yet?

 

Have you set the sag on that shock yet? If not, you should do so; it should help level the bike out. You might want to consider new fork springs as well.

 

It took almost two months and Reg's suspension has traveled a total of 7,000 miles and has seen eleven states but he finally received the package on December 18th. Hopefully Reg will do a thread on the install...

 

Eddie,

You should check the shock length very carefully and make sure that the length is the same as the stock shock. The Ohlins is adjustable for ride height, so you should be able to obtain the original length of the VFR shock. You will probably have to remove the shock to do this, though.

The other thing that could be making the bike sit quite a bit higher in the rear is the spring rate of your shock's spring. From your description, it seems that the spring rate is quite a bit too high for your bike. Was the shock specifically intended to be used on a VFR? If so, check with you vendor and see if you can obtain a softer (lower spring rate) spring. Many Ohlins and Penskes come from the factory with springing for racing applications, not street applications. Check with your vendor to be sure that the spring rate is correct for street use.

If the rear spring rate is too high, which it sounds like it is on your bike, the weight of the bike itself is not compressing the spring enough to get the rear ride height (a combination of shock length and rear static sag) in the correct zone. My guess is that you have very little static sag due to a spring that is too stiff. This would do both things you describe, 1) make the rear too high (effectively decreasing trail and stability in the front end) and 2) making the ride too stiff in the back end of the bike. I would also guess that the bike is not settling evenly from front to back when you sit on it as a result; both ends of the bike should go down the same amount when you sit on the bike. To get this you need a combination of the right spring rates front and rear; this will get you the same static sag; you then preload the springs to give you the same rider sag front and rear so that the bike will settle evenly front/rear with the rider on the bike.

If your rear spring is too stiff relative to the front, the front will dive more than the rear with the rider on it, further exacerbating your reduction in trail.

Whatever the static sag is on the stock shock installed is the range where you want to be with the spring on the Ohlins. A good suspension tuner can tell you what the ideal static sag is for your bike.

Regarding the shock being too stiff: Either the shock came with a spring for a racing application, or the spring rate is not correct for your bike and/or weight. You should be able to get a spring from Ohlins or your shock provider that gives you the proper spring rate. It's really key that you get a spring rate that has a certain amount of static sag so that when the spring is laden with the weight of the rider, that the spring is preloaded enough that it is in it's ideal range of travel. If a spring is too stiff, you will have to back the preload off to the point where it i is effectively topped-out, and there will be very little static sag on the bike. This will put the spring in a less-than ideal range for when the bike is laden. If the spring is too soft, then the preload you need to get the static and rider sag is so high that the spring is preloaded to the point where the spring is in the opposite end of the it's useful range of use; furthermore, you run the risk of coil bind with too light a spring. For racing applications, you need a higher spring rate because the cornering and braking accelerative forces are considerably greater than on the street. My experience is that an ideal race set-up is at the opposite end of the spectrum from an ideal street set-up. You can get a good street set-up to work well on the track, but you really need to nail the basic spring rate to be able to do this.

 

Hey Puma Cat, Thanks for your analysis, I really dont want to pull that shock out but it looks like I will need to disassemble it off the bike and possibly return it or get a lighter spring. I am not sure how difficult it is to change the spring ,but if it can be done with basic tools than I will be able to do it in my garage. In addition I want to get the front forks worked,but I think I should get the rear shock dialed in first, watta you think? eddie

 

Sorry about the metrics

G'day y'all

The Ohlins manual is available here if you don't have it already:

http://www.ohlins.com/Portals/0/documents/manuals/07241-02A.pdf

The manual gives the correct sag settings as follows:

Without rider (static sag):
Rear 10 - 20mm
Front 15 - 30mm

With rider (ride height):
Rear 25 - 40mm
Front 35 - 50mm

I'm just going through all this myself chasing the holly grail: comfortable around town and rock steady at speed.

When checked a couple of days ago the rider sag both ends was within tolerance but the front was toward the soft end and the rear toward the hard end so I've made some adjustments to hopefully bring them closer together.

I've done the test ride and it seems fine but now we have to check the sag again... And so on?

I think the people who work on shock absorbers use a special spring vice.
Showa apparently have a spring vice either side of the Repsol Honda Moto GP garage to prevent delays. It is a simple enough thing: a jig to hold the shock and a bottle jack to compress it.

It'd need to be reeeeal well made though...
I'll get the pros to do mine thanks

 

Pritch's figures from Ohlins look good compared to the numbers I used for my F4i. With respect to these numbers, the smaller amount of sag in the range (e.g. 10 mm Rear, 15 Front) would be used as a base for a more track/racing-oriented application, and the larger end of the range (20mm Rear, 30mm) Front, would be more in line with a street-oriented appplication. Rider sag would be set in the same way, less sag for racing/street use, and more for a comfortable street ride. If you carry passengers or a lot of luggage, obviously you should set the preload with the bike loaded so that the sag is the same as with just the rider, for example.
I think my F4i is set up for 30 mm sag in the rear, and 40 mm in the front.


Pritch is right, suspension tuners have a special shock vise/spring compressor jig that allows you to compress the spring, then release the circlip or spring collar retainer so you can slip the spring off.

Eddie, I wouldn't try swapping the spring yourself, it is difficult or next to impossible to do without the proper tools and set-up. Take it to a pro who has a spring compressor.

Pritch, you're right, you want to have the front and rear spring preloads balanced such that when you sit on the bike that both ends go down the same amount so that the bike sags vertically, without one or the other end sagging more than the other. Keep at it until you get it dialed, then set the damping rates appropriately. You should only set damping rates once the springs are preloaded properly because the function of the damper is to damp the oscillation of the spring in response to a bump. Because a more preloaded spring rebounds with a greater force than a less preloaded spring, you need to increase rebound damping as the preload increases. If you decrease the preload on the spring to get the sag in the right zone, you need to check if you need to decrease the rebound damping on the fork or shock. You want to be sure to use just enough damping that the front or rear returns to "neutral" without oscillating, or coming up too slowly (an indication of too much damping). Watching the suspension guys, it appears that they want the front or rear to return to neutral as quickly as the chassis is pushed down, but not quicker so that it "bounces" and not too slow so that it comes up slower than the rate at which it was compressed. If you have too much damping, there will not be enough time for the travel to recover to neutral (the static sag "ride height") and the shock or fork will "pack down" and the ride will get increasingly harsh and stiff.

You'll know when you get it right, because the bike will track over the road and it's bumps w/o the chassis being upset, and it will feel all of a sudden like you have more grip...because you DO have more grip when the suspension is dialed.