NO REASON NOT TO BUY FRONT SPRINGS

[PAULIBIKER]

Sonic carries springs for our 919 for $79.99.


SonicSprings.com

[rmb]

As much looking as I've done over the last few weeks I can't believe I didn't see them.

[mcromo44]

The advert suggests springs that are accurate, which is very necessary as crap springs can have actual rates as much as 10 % off the claimed rate.

The site has a decent looking spring selector.
I played with it a bit.
I used imaginary rider data.
A 235 # dressed rider on a 460 # wet 919.
Called it Standard/Sport Touring.
Did two useage scenarios, one for Normal Street the other Aggressive Street.
It called out 0.90 kg/mm for Normal and 0.95 for Aggressive.
I also played with the spring selector in an effort to find out if it will display what I'll call split rates, such as 0.925, where you are forced to use a 0.90 and a 0.95 to get the 0.925 and typically have to buy two sets of springs and only use one from each box. I could not spook the selector into any split rate selections. It turns out our Imaginary Rider is known to us, and we've had some back and forth on spring rates. I think he is going to end up trying 0.925s.

[Pvster]

each or for the pair?

[mcromo44]

Originally Posted by Pvster

each or for the pair?

for a pair

how are you doing these days ?

[nd4spdbh]

whats the spring rate of the stock springs?

[mcromo44]

Originally Posted by nd4spdbh

whats the spring rate of the stock springs?

They are dual rate.
I don't know the numbers, and they are not in the manual or any other for sure data I have seen.
BUT
Someone posted something a few years back. I seem to recollect a 0.75 or so with a 0.825 or so, in otherwords something like a .75/.825 dual rate or 0.775/.825 dual rate. I remember that when I looked at using 0.90s, those were about 15 % greater than the stiffer rate of the dual rate stocker. So, I think it is safe to say that the stockers are .75-.775 on the soft rating and .80 -.825 on the stiff rating. What remains is this, stockers are mush. Also, there are conflicting reports as to whether the fronts have been the same since day one or were softened in 04 when the softer rear spring was introduced. Personally, based on what I have seen so far, I think the springs stayed the same since day one.

[rob1100r]

919/CB-900 F ('04-'07) Fork Springs, RaceTech

[mcromo44]

Originally Posted by rob1100r

919/CB-900 F ('04-'07) Fork Springs, RaceTech

Meaning what ?
Do you accidentally leave out some intended text ?

[zaq123]

Originally Posted by PAULIBIKER

Sonic carries springs for our 919 for $79.99.


SonicSprings.com

wonder if spacers & washers are included. Are those their own springs? RT springs are made by eibach

[mcromo44]

Originally Posted by zaq123

wonder if spacers & washers are included. Are those their own springs? RT springs are made by eibach

Good point zaq123.
The springs are said to be made in the USA, and each one is said to checked (to be within tolerance I would assume being more correct). I suspect they are buyouts and could be Eibach.
RT does give a nice bundle of good quality spacer tubing and a handful of aluminum spacer adjustment washers.
If the Sonics are the same springs and come with the same type of kit, then why not.
IF that is.
No one has piped up yet re any experience with them though.

Have a nice evening.
Hey, is your suspension building assistant still working for you ?

[hornet919]

i thought the main upgrade for the front springs wasnt really the stiffness, but the fact the stockers were progressive and the aftermarkets were linear

[mcromo44]

Originally Posted by hornet919

i thought the main upgrade for the front springs wasnt really the stiffness, but the fact the stockers were progressive and the aftermarkets were linear

No.
The benefit is twofold.
Linear and stiffer.
The stockers are not progressives either, they are dual rate as best as I can tell by eyeballing them and doing some pitch measurements.

[brian]

anyone have a clue to the spring rate in f4i forks?

[mcromo44]

Originally Posted by brian

anyone have a clue to the spring rate in f4i forks?

Race Tech shows 0.751 kg/mm for the F4s and 0.66 for the F4is.
I don't believe it, in particular for the F4is.
The Race Tech spring calculator calls up a 0.90 for street riding and a 170 # rider before gear. That's a 36 % increase in rate, with 90s sounding reasonable and 66s sounding out to lunch low in any kind of context related to a street F4i.

[brian]

Well my front end could use some attention Im 250 and it feels like mud. Its not horrible but you get the idea.

[mcromo44]

Originally Posted by brian

Well my front end could use some attention Im 250 and it feels like mud. Its not horrible but you get the idea.

LOL

In car talk lingo of not so many years ago, you must have what is known as an LTS setup. As in Limited Travel Suspension. The F1 guys took that concept to the limit, basically creating solid setups once the downforce came in, the travel was all flex - no classic movement per se. I think the NASCAR guys run the front coils bound once the Gs kick in, but I'm not up on that at all.

[brian]

Yeah thats another world of aeropension, or suspynamics.... either way LTS is right.

[james_kraska]

someone in a warm place buy and install these. I want to see if I have a winter project. My front end bottoms out so bad on hard braking I get wheel hop. I'm only 200#.

[mcromo44]

Originally Posted by james_kraska

someone in a warm place buy and install these. I want to see if I have a winter project. My front end bottoms out so bad on hard braking I get wheel hop. I'm only 200#.

A stock front end 919 is the definitive bike in terms of diveyness.

[rmb]

Originally Posted by mcromo44

A stock front end 919 is the definitive bike in terms of diveyness.

+1! Soon to change...

[brian]

Originally Posted by james_kraska

someone in a warm place buy and install these. I want to see if I have a winter project. My front end bottoms out so bad on hard braking I get wheel hop. I'm only 200#.

really? I mean mine dove/dives with the stockers and the f4i set up but even on the stockers I could put it up on the front tire and not get any "hop"

Id shit myself if my front end started hoppin around.

[mcromo44]

Originally Posted by brian

really? I mean mine dove/dives with the stockers and the f4i set up but even on the stockers I could put it up on the front tire and not get any "hop"

Id shit myself if my front end started hoppin around.

Call is Wheel Hop, Slip Stick or Grip n Glide, it's the same thing in terms of what is happening.
Tire looses grip, and front end starts rebounding.
Tire gets grip back, and front end stops rebounding and recompresses.
It's on the ragged edge of wheel lock.
Probably so bottomed out during the grip phase that it's past the oil cushion and into full mechanical bottoming out, which in itself will cause loss of group as all compliance is gone except for what's in the tire sidewall.
Akin to a very low frequence ABS routine.
Ragged edge braking, that is for sure.

[det5lonewolf]

Lots of great info here:
http://www.wristtwisters.com/f94/to-...ack-25221.html


Also, the cheap way to get rid of wheel hop is to raise your fork oil level.

[07919Dave]

Originally Posted by james_kraska

someone in a warm place buy and install these. I want to see if I have a winter project. My front end bottoms out so bad on hard braking I get wheel hop. I'm only 200#.

I'm 200# before gear and I have never experanced this (knock on wood). I think maybe need to change your oil, add more and go to a racing type.

[mcromo44]

Originally Posted by det5lonewolf

Lots of great info here:
http://www.wristtwisters.com/f94/to-...ack-25221.html


Also, the cheap way to get rid of wheel hop is to raise your fork oil level.

To compensate for the mush OEM springs, oil level is not going to be enough of a factor under hard braking. Help some, yes. Cure, no.

[nd4spdbh]

Originally Posted by mcromo44

To compensate for the mush OEM springs, oil level is not going to be enough of a factor under hard braking. Help some, yes. Cure, no.

for sure... but i noticed a BIG difference at my weight (probably 170 fully geared up) by adding another 20mm of oil to the oil level of both forks, and switching to a good quality 10w synthetic fork oil... hell i was able to back off the preload by 3 notches in the front.

But i would like a lil stiffer spring.

[mcromo44]

Originally Posted by nd4spdbh

for sure... but i noticed a BIG difference at my weight (probably 170 fully geared up) by adding another 20mm of oil to the oil level of both forks, and switching to a good quality 10w synthetic fork oil... hell i was able to back off the preload by 3 notches in the front.

But i would like a lil stiffer spring.

My guess is that you experienced improvement by both the different oil and the change in level. 20 mm of top of the factory 155 is normally not going to make a huge difference, noticeable yes, mega - no. Interestingly enough, Race Tech calls up 140 mm as a starting point, and I ended at 125.

[nd4spdbh]

Originally Posted by mcromo44

My guess is that you experienced improvement by both the different oil and the change in level. 20 mm of top of the factory 155 is normally not going to make a huge difference, noticeable yes, mega - no. Interestingly enough, Race Tech calls up 140 mm as a starting point, and I ended at 125.

ya i mean it didnt make a HUGE diff, but it was noticible enough for me to put off changing fork springs. If i weighed any more than i do right now id have new springs in for sure.

[james_kraska]

Well, Mcromo seems to understand what I'm experiencing. I am due for a change w/ nearly 40k on the clock, but I was going to wait and change the springs at the same time.

[toys123]

About changing front springs on a 919 (a 2007) , I ordered a pair from Race Tech that I be installing soon. This was the only company I could find to order them from. Trying to keep my front end from diving under hard breaking. Almost got a deer late one night here in N.C. Front end dove so much the deer disappeared. New fork springs and higher wattage bulb for headlight might help see what I am about to hit (hopefully not). Also installed a Coerce countershaft sprocket guard (listing on E-bay was for 2002-2005 919 but the factory cover 2002-2007 were the same so it works). Dont think it will make the bike any faster, but it is a good looking piece. Price is high about $166 shipped fron Hong Kong.

[oak1971]

If I can find a job, I'll pick a set of those up.

[speedprotege]

Did anybody ever buy a set of these?

[PAULIBIKER]

Originally Posted by speedprotege

Did anybody ever buy a set of these?

Yup.............comes with spacers. No problems.

[velodesign]

I'm thinking of picking up a pair of 1kg racetechs (like to take the mrs. on rides and judging by the amount of beer I like, my 220# isn't going to go down too far).

I have the 2002 service manual in pdf format - same steps to replace the springs for an 07? Or is it a bit different due to different forks? Care to share if so?

[arctic954]

Only difference is the spring pre-load adjuster on the top...... I'm drawing a blank at the moment, but there is a sequence to putting the cap back on correctly so that the pre-load adjuster works properly. I searched, and found it easily here in the archives.

[jehicks87]

Just bought a pair of racetech .95s from a local store here. $89. He told me the price and then said, "You want em?" I said... "Um, yep."

[Ottawa919]

Any feedback on these Sonic Springs from those of you trying them? Thanks

[LeatherWings]

Originally Posted by Ottawa919

Any feedback on these Sonic Springs from those of you trying them? Thanks

like oak1971, I think once I find a new, better-paying job, I'll be trying out a pair of these springs.

A question for those of you who have replaced the OEM fork seals with aftermarket ones... the 919 forks seem to have a lot of stiction, so have any of you noticed any difference (i.e., less) stiction after replacing the OEM fork seals with aftermarket ones which claim to reduce stiction over OEM seals?

[mcromo44]

Originally Posted by LeatherWings

like oak1971

A question for those of you who have replaced the OEM fork seals with aftermarket ones... the 919 forks seem to have a lot of stiction, so have any of you noticed any difference (i.e., less) stiction after replacing the OEM fork seals with aftermarket ones which claim to reduce stiction over OEM seals?

The only thing I have heard is about tenth hand and that was they don't last as long and some start leaking early in life.

And 919s don't seem to have a lot of fork stiction, they have mega stiction. Personally, I think much of it is the seals, they are simply too good. My tubes are bone dry, meanwhile the tubes on our GSXRs have the appearance of an oil haze, but don't leak, and sure have less stiction. I think polishing makes it worse, as a bit of surface texture allows a place for minute amounts of oil to hide. Some builders polish, while some deliberately do some fine cross hatch.