Front forks diving under braking

[michael-james]

I got a 07 FZ6-S2 and am experiencing a tendancy for the forks to dive a lot under braking especially when stopping. Seems like the front end wants to eat the tarmac. I'm not braking excessivly hard or anything and had a kawa before with adjustable front forks which seemed fine. As this bike has no adjustability to the front end is this normal and if so it sucks. Should be able to brake hard without feeing like your going over the bars.
Any thoughts remedies??

 

[DefyInertia]

Measure your sag and report back.

You can increase your preload by removing the caps and adding washers or spacers. You can increase damping with heavier oil. Won't be race ready but if you're under sprung and damped you'll be moving in the right direction.

You could also replace the springs, add emulators, or do the R6 fork swap. Or buy a different bike.

 

[malicious439]

Or buy a different bike.

Always helpful remedy for new FZ6 owners:BLAA: I've always felt that the front suspension on our FZ6 is a bit weak. It may depend on your riding/stopping style if you put more weight up front by leaning a lot and so on.:thumbup:

 

[PhotoAl]

Know what your talking about! My 04 had lots of dive on braking. A month ago I changed the fluid to 10 weight (used Honda oil cause thats what the dealer I stopped by had). Big difference front is much firmer and the dive under breaking is much less. It's not perfect and changing springs and putting cartridge emulators in would have been better, there on my wish list.

 

[FAZR6]

It is the way these forks are. The whole reason why I first did the R6 fork mod and many others have followed. The more practical fix is to have the cartridge emulator mod done because it's more plug and play, so to speak but if you aren't happy with the way the stock forks feel, IMO you won't be happy with them with heavier oil either. It is a cheap improvement however.

I would also like to say that I feel like dollar for dollar, the FZ6 is one of the best all around bikes ever made but It's always bugged me that the forks, of all things are the only real weakness in the package. I never understood why the yzf600r forks, which were in production for 10 hundred years or so, where not a viable option. You telling me that they couldnt add $100 to the price of the bike to put a real set of forks under it?

 

[malicious439]

It is the way these forks are. The whole reason why I first did the R6 fork mod and many others have followed. The more practical fix is to have the cartridge emulator mod done because it's more plug and play, so to speak but if you aren't happy with the way the stock forks feel, IMO you won't be happy with them with heavier oil either. It is a cheap improvement however.

I would also like to say that I feel like dollar for dollar, the FZ6 is one of the best all around bikes ever made but It's always bugged me that the forks, of all things are the only real weakness in the package. I never understood why the yzf600r forks, which were in production for 10 hundred years or so, where not a viable option. You telling me that they couldnt add $100 to the price of the bike to put a real set of forks under it?

+1 for Truth:cheer:

 

[FinalImpact]

As mentioned measure the sag but even at that, it could be the springs are fatigued. Not every spring set is equal and some go bust sooner than others regardless of how they are used.

Either way:
How many miles
how much do you weigh
do you ride over rough conditions as the norm
are your rear brakes working
does your bike have extras loaded maybe ride 2 up often or anything like that?

As the fluid breaks down it becomes less effective at damping so at a minimum it seems worthy to replace the fluid and establish a new base line.

 

[michael-james]

My bike is almost brand new 07 model out the crate 2010. Only done just over 1000kms. So not at all worn, check my new thread on break in feel.
As stated i had an FZ8-N as loan bike when mine was in for service. It doesnt have adjustable forks either and costs almost twice as much. What is it with yamaha that 8 costs plenty and still no adjustment. They were no better than the 6's. My brakes have more bite though which surprised me. I think i just have to live with the forks issue and judge my braking distance better.

 

[RJ2112]

My bike is almost brand new 07 model out the crate 2010. Only done just over 1000kms. So not at all worn, check my new thread on break in feel.
As stated i had an FZ8-N as loan bike when mine was in for service. It doesnt have adjustable forks either and costs almost twice as much. What is it with yamaha that 8 costs plenty and still no adjustment. They were no better than the 6's. My brakes have more bite though which surprised me. I think i just have to live with the forks issue and judge my braking distance better.

New springs. .9 Kg single rate will make a tremendous difference in brake dive. The suspension on the FZ6 is it's greatest short coming.

 

[greg]

does the suspension problem depend on the rider weight?

do heavier riders have more problems?

when i did the fork seals on mine i put in a 10W oil, and it seemed to improve the handling quite a bit

 

[RJ2112]

does the suspension problem depend on the rider weight?

do heavier riders have more problems?

when i did the fork seals on mine i put in a 10W oil, and it seemed to improve the handling quite a bit

The OEM springs are dual rate. Don't know what the initial rate is, but the idea is that the 'soft' first part of the spring will give a smooth ride in 'typical' riding conditions for the 'typical' weight rider. You're supposed to use the stiffer part of the spring in braking conditions, etc.

When you put a heavier rider on the bike, they consume most or all of that soft section of the springs. This is okay, if you don't consume all of the stiffer section of the springs in normal riding.

I suspect the target weight the designers used was around 150 lbs, rather than the more typical 200+ rider weight in gear we see in the US. Even the stiffer section of the spring is really too light.

My personal preference is to use a single rate spring that is going to give control through the entire suspension motion. I want as much of the suspension travel as possible to be available, so I want the sag to keep the bike near the top of the suspension stroke with me on the bike at rest.

Uniform motion, rather than soft followed by slightly stiffer travel. (And still, in my opinion, too soft.)

 

[rjo3491]

Sorry, I replied to the wrong thread, my bad!

 

[g8anos]

I had the same problem too... the springs where just too soft for optimal riding and braking conditions.

The solution for me was to upgrade the bike with stiffer WP springs and thicker WP oil (I thing 15), it was optimal for riding conditions here in Greece.

Total cost 130e, but money well spend. It was a great improvement, concerning faster driving stability, sharp turns and braking.

 

[tedrogers]

I just checked and I have Racetech springs installed and 20wt Silkolene oil...and it still dives like a submarine. What else can I do? Is there enough oil in there? Do I need spacers, washers, shims? With only one spacer in there I could barely get the shock tops back on last time!

I think I may have to go the expensive route and put the R6 mod forks on, although it will set me back near 300 GBP (UK). I've just purchased a front fork stand, and I'll use that again, but 2nd hand R6 forks go for silly money here, and I'll have to buy the additional mod parts from one of the forum members who holds them in stock (in the US). I expect it will work out about the same as getting the parts machined over here in the UK though.

 

[hk_fz6_05]

dude don't know if you've seen this, but txinfidel is selling a complete r6 fork set
http://www.600riders.com/forum/bikes-parts-sale/47970-r1-r6-fz1-fz6-parts.html

nothing to do with me, just thought I'd give you a heads up. good luck, I'm going for the hyperpro springs and then we shall see what that does for me.

 

[Northern Rider]

Originally Posted by Northern Rider
It's great you guys are talking about this issue. I have a 07-FZ6 been riding for about four years now. I love the bike but hate the front end. After reading the June 2011 Cycle World Magazine, I started looking into some changes. For those that don't know Cycle World bought a 2005-FZ6 and turned it into a streetfighter(Page 63). They did some body work, ergos, and drivetrain but what I was interested in was the suspension. Thus after reading the article and some research I decided find the local Race Tech dealer near Toronto and have them do some work, just because I really don't trust my mechanical expertise.

1) Cartridge Emulator Kit (Race Tech): suppose to give you the benefits of a deflection disk damper

2)Front Spring: Stock 0.77kg/mm race tech numbers for 200lb = 0.968kg/mm so I opted to put a 1.0kg/mm

3) Rear Shock Springs: Stock 12.5 kg/mm Race Tech numbers 200lb =13kg/mm, decided to stick with the stock spring.

since I had the girl in the shop decided to put on the new pair of boots, Metzeler roadtec Z8 interact, I have never ridden a Metzeler was on BT-21 which I found to be a great tire, but wanted a change.

So took the bike in today, getting it back friday and I wil let you know the outcome. If anyone has any comments on the Metzelers it would be great to hear. Also please comment on the suspension upgrades, I hope I get some good feedback because I am sick of the front end but LOVE MY FZ6.

 

[MrMogensen]

+1 for new springs...

 

[FinalImpact]

I just checked and I have Racetech springs installed and 20wt Silkolene oil...and it still dives like a submarine. What else can I do? Is there enough oil in there? Do I need spacers, washers, shims? With only one spacer in there I could barely get the shock tops back on last time!

I think I may have to go the expensive route and put the R6 mod forks on, although it will set me back near 300 GBP (UK). I've just purchased a front fork stand, and I'll use that again, but 2nd hand R6 forks go for silly money here, and I'll have to buy the additional mod parts from one of the forum members who holds them in stock (in the US). I expect it will work out about the same as getting the parts machined over here in the UK though.

You're on the right path - you need to control the compression rate and rebound rate. Oil alone will not do that no matter the weight. So emulators or forks. Forks are Great I did the R6 and couldn't be happier!!

Get a few to chime in on the emulator setup and maybe they can help you dial that in.

Also - if someone needs some stock 08 Forks, look me up!

 

[Dennis in NH]

Back when I had my 08 FZ6, I solved this problem by adding the Hyper Pro progressive springs up front along with the thicker fork oil that came with it. It helped a good amount.

Another thing that will help is to lean back a little if you need to slam the front brakes.

Eventually, I got a rear Hyper Pro spring -- that was perhaps a tiny bit better but not as big an improvement as the Hyper Pros up front.

Dennis