budd

all interesting thoughts about the principles of suspension tuning and I respect them I really do i'm sure in your mind it all ,makes sense but I've being involved in this longer than most, I bought a VTR 1000F (Firestorm ) brand new in ’98 and the fact is it was a awful handling bike out of the box, so I set about trying improve it.

Firstly the front forks on the VTR1000 are lightly sprung for maximum comfort and overdamped to control wheel movement. In order to achieve the correct level of rebound damping on my Firestorm the adjustment needed to be set to minimum. Also the compression damping can go solid under hard braking as I very nearly found to my cost, at Croft race track with the brakes full on the forks dived and locked solid, even on a relatively smooth race track front tyre bounced along as the wheel momentarily locked-up every time it skipped off small ripples..... not good!!
I think this all to do with the weak OE spring and compression damping that just goes violent. Push down on the forks stationary and it doesn't feel that bad. But on the brakes the cartridge compresses and the valve inside appears to completely shut off to make the forks go absolutely solid.
Now bear in mind that at the time the VTR was a relatively new bike (my bike was less than a year old) so thoughts of forks swops etc simply didn’t come into it, so I decided to experiment with oil weights and air gaps.
Firstly Change Oil for 5wt with standard air gap, wind in preload to set static sag to 30 mm (the lowest I could achieve) set front damping so that as you bounce on the forks with the brake on they rebound once and then settle. (Easier to demonstrate than explain) Now the fork action under heavy braking was progressive without any sign of lockup but I could get the forks to bottom out very very easily.

Next Reduce air gap in 10mm increments, progressively reducing the air gap bought improvements to fork travel under braking but still the chance of bottoming the forks until the air gap was 120mm then the fork action was harsh at the end of its travel although the forks didn't bottom out.
Next Change Oil for 7.5wt with standard air gap, now the fork action under heavy braking was harsher and I could just get the forks to bottom out. Reduce air gap in 10 mm increments. Progressively reducing the air gap didn't improve feel under braking when the air gap was 120mm then the forks would again go solid under hard braking

Next Install WP progressive fork springs, change Oil for 5wt with standard air gap, wind in preload and set static sag to 25mm.
The fork action under heavy braking was much more progressive without any sign of lockup and I couldn't get the forks to bottom out my zip tie on the fork leg showed that I was pretty close though, continue to reduce air gap in 10mm increments.
Progressively reducing the air gap brought slight improvements to fork travel under braking, I stopped adding oil at 130mm as I knew that any less gap caused a problem I was now using about 85% to 90% of travel.

Finally I ended up with WP fork springs (these are progressively wound springs slightly longer than standard),5wt oil, 130mm air gap,.
A can’t remember and my notes don’t show the exact set up I ended up with (ironic now I’m trying to recreate it) but it was a massive improvement over std, for very little cost and as I said before at the time there were very limited aftermarket options so to me the improvement from the set of springs and oil were a great result.

To recap std the fork springs are to soft, and the compression damping to harsh fitting progressive springs and tweaking the oil wt and levels brings massive improvements over the frankly dangerous stock setup.
Unfortunately that’s as far as I got with the first bike before it ,,,, well before I crashed it, ironically I lost the front at about 50 and while I was unscathed the bike faired less well and was beyond repair.

So that’s where I’m now with the ‘new’ one, well a 20K ’97 example which is stock so I’ve got all the same issues I had 14yrs ago.

The first time I didn’t get around to addressing the rear end issues choosing to try to remedy a more obvious front end problems, and in a way I’m doing the same again by opting for just a rear spring, but the std spring is way to stiff and it’s impossible to get the correct static sag, I’m 6’0 200 pounds and if I have the per load set more than the second notch it’s bouncing me in the air, my thought is if I fit a slightly softer spring (matched to my weight and to the fronts) the overall balance of the bike will be substantially improved allowing me to tweak is a bit with ride heights and basic damper settings.This is where I’m at currently and I think all in all my course of action makes sense, dealing with the problems presented and spring rates are one of the VTRs problems.

Now just let me have a look at some of your comments (well meaning they may be) and I do appreciate your time, but firstly yes it does matter if the springs are progressive as opposed to linear (straight???) a progressive spring allows it to react quicker and move to it’s stiffer rating in a progressive manner (hence it’s name) couple this with a suitable wt fork oil and the low speed damping should improve and as the loads increase the heavier second winding of the prevents the forks bottoming out.

You state that ‘The VTR is according to most people that know about suspension light on the spring already’ this is plainly ridiculous if referring to the rear spring, maybe the ‘most people’ you were referring to aren't as well informed has you thought or were reffering the fork springs (which are under sprung)and you got confused, the fact is the std rear spring in over sprung, it’s almost impossible to get any static sag in the rear with the OE rear spring, I think the absolute opposite of what you said would be true, I think maybe the rear shock is over sprung and under damped , in this case fitting a lighter progressive spring would help the limited damping and make any range of adjustment useful.

The fact is that from the factory the VTR suspension left a lot to be desired, it was imbalanced with adjustments that were pretty much useless, the only way to redress the balance is to look at what’s wrong, which basically is: front to soft and rear to hard, now correct me if I’m wrong how can addressing these obvious no fundamental faults be what you’d call a ‘bad idea’ ???getting the front and rear spring rates in the same ball park as got to be good no???
I respect your views but you could try to be little less pious in making them.

budd

Thanks for that

Tweety

Agreed... You go build your bike the way you like it... I'll refrain from helping you...

Glad you think my thinking is interesting... Yes, the front is horribly undersprung, the rear is infact also that for a 200 pound rider... It's the valving thats way off in the rear, so a new spring doesn't help as much as you think, but yeah it will make the bike feel a bit more balanced as both ends are soft...

FYI I know very well the difference between progressive or not progressive springs (you call them linear, I'll call them "straight" as in straight rate, unless that confuses you?), you completely missed the point of that sentence (I'm thinking on purpose?) So a single last question...

You are 200 pounds... The front is originally sprung for around 100 pounds... And yes, it's overdamped in comparasion to that, but you are honestly convinced that it's 100% overdamped? Because that is what you are saying, add on another 100% in terms of spring, and it balances out?

You say my thinking is interesting? Well, that makes two of us then... Because it's simply not that much overdamped...

8541Hawk

Well I have to agree with Tweety on this one.
I also bought my SH in '97 and still have it.

First of all I stay away from progressive springs, as how do you set the damping? If you set it for the soft part of the spring, then you have too little when you get to the hard part. If you set it for the hard part, then you have too much in the soft part but that is a different discussion.

What you are doing is a band aid fix for the suspension. Sure it "might" work better than stock but why not doing it right and set the valving for the springs you are running? With your method, you are just setting yourself up to wad another bike.

Oh and for suspension swaps, they have been around from day one. The 900rr front end was the set up in '97 -'98.

So while it does sound like you have taken the time to make your set up work pretty good, you would be much better off going the few steps farther to make it right.

budd

Tweety
no matter how you look at it the std bike is under sprung at the front and over sprung at the back with inconsistent damping, simply fitting better matched springs as got to improve balance, tweaking the fork oil and air gaps creates a much more usable machine for minimal cost and an afternoon in the garage. And while I freely admit it’s not the most complete solution it does work, and by ‘work’ I mean it makes the dire std suspension tolerable and at this moment in time that’s all I need.
The problem with the rear spring is it doesn’t give you any worth while set up options, fitting a lighter rear spring should allow the static sag to be set correctly (which is a start) and I wouldn’t call it ‘soft’ I’d call it compliant and therefore better able to deal with the potholed things that masquerade as roads over here.

Hawk
I agree progressive springs are a compromise, but at present I’ve no intention of changing the valving on the std forks so this compromise actually works quite well, admittedly masking rather than curing the problems, and believe me there is no ‘might’ about it does absolutely improve things, anything that stops the front from simultaneously bottoming out due to lack of spring wt and locking solid due to dodgy damping as got to be seen as an improvement.
And of course front end swops have been around since day one, but in reality how many owners strip out the forks on a brand new bike? They may decide on this course of action eventually but it’s usually after tinkering with the existing forks as failed to yield the desired results and the only option remaining is to fit some forks with a better fundamental design.
At what point did you fit 900rr forks to yours? I’d be surprised if the bike was less than a year old.

I doubt I’d go down that route myself as I can’t justify the financial out lay, when you look at what’s required (used CBR 900 forks, these forks need to be sprung and valved to suit the VTR, a set of yokes (triple trees to you), brakes, wheel, bars etc) you have to question if it’s worth it and that’s ignoring the rear damper which at the very least would need a custom rebuild, at the end of the day all I bought this VTR because it was cheap, in good condition for it’s age and I liked the easy going nature of my old one, I don’t would want to end up spending a load of cash only spoil this easy to live with character trying to create a razor sharp hypersports bike, I have a pal with a Aprilla RSV-R and it’s in a different league to the Honda, much faster, has Ohlins suspension that simply works out of the box, if I decide I want a proper sports twin I’ll buy one of those rather than try to make the VTR something it’s not.

But in the mean time I’ll seek to improve the Honda’s pleasant demeanour with minor mods that build on it’s character rather than eroding it.

Tweety

I will fully agree that the damping is wildly inconsistant with the springs, front and back... I also "agree" that by fitting heavier progressive spring in the front and a lighter progressive spring in the rear you are moving the bike as a whole towards being more balanced... I never disputed that for one moment...

But for a 200 pound rider, you have now moved the bike from being dangerously undersprung and underdamped in the front (compared to your weight, but still overdamped compared to the springs) and relatively decently sprung and horribly overdamped in the rear, to being uniformly undersprung both front and rear... Ie soft... Not compliant, since that implies you have both spring action, and damping action in sync to deal with the bumps... And at that point your front is horribly and possibly dangerously underdamped (something I doubt you could test fully with the rear left unchanged), and the rear is still overdamped, now even more so compared to the spring, so still somewhat erratic but less jumping around and snatching...

I fully agree that the bike in this condition is easier to deal with than stock, since it behaves less erraticly than with the front and rear being opposite ends of the spectrum... But I still think it's very, very far from optimal...

And I think once you have ridden that bike a short while, you will find it very easy to overwhealm that front suspension since the rear isn't hopping around on it's own anymore... I tried the exact thing you did, with progressive springs and lighter fluids in the forks... Then I tried linear springswith valves for my weight, and it was a night and day difference...

Now I'm running the bike with CBR 1000RR forks with springs and valves fitted for my weight and honestly the difference in damping isn't much... The main difference to the stock fork is the fact that it doesn't flex like that did... (Plus the brakes and adjustability, which is a definite gain...)

Now, if you do the front like you imagine it, and change the rear to a F4i shock with a spring and valving suited to your weight, the cost will most likely be roughly the same as taking the stock shock with your new spring, rebuilding it with fresh fluids and gas (it's from 98 fer christsake!) and it will give you 90% of what an Öhlins rear shock will give you, since it has the setup options... And it will be stupendeously cheap compared to the Öhlins or the likes...

That's why I suggest skipping the step of "patching" the stock shock and then potentiallymaking an expensive upgrade as you mentioned... Make a cheap upgrade in the first place that blows the patch-job away and is nearly as good as the expensive one... Less money spent, more value gained... Go read up on it on the forum... I'm not the only one happy with mine...

BTW... The reason I don't like going to very much lighter fork fluid is that then the valves are more or less free-flowing with a 200 pound rider, making the spring the deciding factor... It won't "lock-up" but I highly doubt the valving make any difference what-so-ever to the characteritics, besides in your mind... And since the adjustability of the VTR forks is limited, it makes it impossible to adjust away...

thetophatflash

I've had good luck with HyperPro progressive springs front and rear with RT gold valves in front. Not as good as a swap, but a vast improvement.

cliby

HH pads work very well, I love mine.

budd

First let me clarify something, my weight, I know I said 200lbs in a previous post but truth be told it’s so long since I weighed myself I had absolutely no idea how much I actually weighed, I vaguely remember been around 85kg some years ago and that’s where the 200lbs figure came from although 85kg is still short of 200lbs at 187.
So because I was going to be ordering some springs I thought it wise to find out exactly how much I weighed, and I got a pleasant surprise weighing at a svelte 73kg or around 160lbs and I’d not realised I’d been on a diet!!!
So now that’s corrected, I think it will ease spring situation somewhat, and I agree with what your saying and I fully understand that the correct way to approach it is to take it as an whole, either fix the forks with linear springs and damping match to my new lightweight frame (ie me) or replace with RR items and at the same time sort the rear damper with a rebuilt F4i item but at th moment the bike isn’t a priority (I’m currently building an Impreza race car so that is rapidly absorbing all my time and money) so I can only really allow myself the absolute minimum in terms of spending on the bike, so I’ve allowed myself £250 to sort it out as best I can.
This is to include new brake pads, oil and filter and getting the Diablo Corsas fitted and balanced, I already had the tyres, so the cost breakdown is roughly as follows Oil + filter £35, 2x sets of EBC HH pads £45, £20 for mounting and balancing the tyres, the leaves approx £150 for the springs which isn’t quite enough but I’m sure I find the little extra.(I’d also quite like a 43T rear sprocket but that may have to wait till next month)
Once the Impreza is finished (well as much as these things ever are finished) I should be able to look again at the Honda but chances are if it’s something like I’ll end up running it the way it is all summer and parking it in the shed all winter only to once again have a mad dash to get it ready of Apr (exactly the same as this year) I really need to be more organised.

Quick question re the rear shock, who does the conversion and where are they based, this been a largely US based site I assumed it would involve shipping the damper to and from the States.

budd

I'm not going for the valves but I'm hoping just the springs and some tweaking of the front oil wt and levels will bring a worthwhile improvemnt, it's good to know you've had success with it, I must be on the right track.

Yeh I'm pretty much sold on the HH pads now

8541Hawk

Well I guess I have really buggered mine up then.......

I ran modified stock stuff for a while but now have a Ohlins valved RC 51 front end with a Ohlins shock in the back.

So run whatever you like and believe it or not we are actually trying to look out for you as poorly set up suspension can get you into a position to wad another bike.

Also make sure you run a fork brace with the stock front end as it does make a big difference.

Tweety

Well, your new and improved weight does change things a little, but not entirely... Congratz BTW...

At 73 Kg or 160 pounds still puts you in the category way above what the stock forks are capable of handling without help... But yeah, it changes the feasibility of keeping the stock valving a bit... I'd say horribly or dangerously mismatched just barely changes to really mis-matched, but probably OK for a "Budget Type" fix... I still think 5 wt is to thin... If you could make it work with 7.5 wt instead you might have decent damping left, and no lock-ups... Seems a worth while experiment at least with better rear grip...

I'm myself at an all-time low for the last ten years at almost dead even 200 pounds, on a 6'4" frame... And I quite easily overpowered the progressive Öhlins springs and stock valving... But yeah, I was riding pretty aggressively...

Yeah, the F4i conversion takes some finesse, but it's not that hard... Jamie Daugherty is the man to talk too... He helped me out (I'm in Sweden) by letting me buy it on eBay, have it shipped directly too him in the US from the seller and then he sent it too me once rebuilt... Saves on shipping, a lot...

I can't tell you his current price, but for me the $20 something shock plus parts and work turned out ridiculously cheap, and even with the stupid fee's and shipping, it was less than a 1/4 of the price a new Öhlins cost at the time... Not free, but most definetly bargain basement price tag with top notch performance... And that's hard to beat...

budd

it's a very cheap fix I'm after, I've allocated as much I can to it for the moment, which I suppose is the problem really I’ve failed to heed the advice I often give in relation to cars, these type of things need to be thought out, designed, parts located and acquired then everything fitted at the same, with hindsight I should’ve done the research and planning back in Oct when I took the bike off the road for the winter and ended up with a bespoke solution on a budget.
Are well hindsight is a wonderful thing, the fact is I didn’t do that so I’m back to the progressive springs, re the fork oil I might be mistaken when I said I ended up with 5wt in with the WP springs it was a long time ago and my records are little more than bits of paper with notes scribbled on them, so it could well of been 7.5wt, either way the Hyperpro kit comes with the oil supplied so I guess I’ll just use that, see how it goes, also I’ve solved the potential spring fitting issue, the suspension company who are supplying the kit are going to fit it for free so it saves me the trouble of messing about with it.

budd

LOL yeh it does , but seriously it sounds like a labour of love, and sometimes to get exactly what you want you have to create it yourself, good luck to you and keep up the good work

speedkelly@aol.com