Kawasaki Motorcycle Forums banner

Status
Not open for further replies.
1 - 20 of 35 Posts

·
Registered
Joined
·
178 Posts
Discussion Starter #1
I have an '05 ZX-6 and have completed 3 track days on it. This past Saturday, my front brakes started shaking pretty bad at the end of both straights (130-165 mph). The shaking would ease up once I slowed down a little and grabbed the brakes a little more.

I need to do whatever it takes to resolve this. With that said, I'm only looking to do what is needed and really nothing more. I was more than happy with the stopping power of the brakes on the first two track days.

Will installing steel braided brake lines resolve the matter?

Should I use different weight brake fluid?

Is it a MUST to upgrade the pads?

If so, what type and brands of pads do you recommend? What are the disadvantages?


Thanks in advance for all of your help
 

·
Registered
Joined
·
554 Posts
What track, what corner and how much do you weight? And if you know your lap times that will help.
 

·
Registered
Joined
·
2,752 Posts
If your brakes are "shaking", I would think you have a warped rotor, but you're not describing the problem with enough detail to tell for sure. You could have suspension issues, be weighting your bars too much (more likely), and/or tire issues. People tend to place blame on the bike a lot of times, when it's actually rider input/induced
 

·
Registered
Joined
·
178 Posts
Discussion Starter #5
The problem only occurs during high speed braking. Down the front straight at CA speedway I get up to 160-165 mph and on the back straight I get up to 130 mph. When I apply the brakes rather aggressively at this spped, I can feel the brakes pulsating. Once the bike has slowed a little and I grab more front brake it goes away. The pulsating does not occur at any other time on the track. I drove it today and no pulsating. That is why I believe that it is not the rotor.

Tires and pressure seem to be in very good working condition.

I weigh 185 lbs.

I do not know my lap times.

Again, I appreciate any help
 

·
Registered
Joined
·
295 Posts
Wait a little later and grab the brakes REAL hard. That way your turning better lap times and your not half assing the brakes which is when you say you feel the vibration. There, problem solved!:D
 

·
Registered
Joined
·
554 Posts
Its not brakes, its soft springs. You can make a short term fix by adding/firming compression. Your forks are bottoming and when they bottom you lose suspension. That causes the shake feeling. Also on the front straight don't brake so hard going into the chicane(turn one). Your on a 600 and even though it says 160 your only going 140 and you can take the turn at 120, so you want to ride the wall and start your dive with a slight trail brake as you enter the turn. Anyway back to the suspension, put a zip ty around your fork next time your there to check for bottoming. Your 185 with full gear 200-205. I'm also 185 (200 geared)and I use 1.0kg springs I tried .97 but wasn't enough. I think stock on a 6R its only .90kg or.92kg not sure though.
 

·
Registered
Joined
·
2,042 Posts
Stock on the zx6r is more like .88, while the zx6rr has .90. But both of those numbers are rated a little high afaik.

I'm 165lb "dry", and Ohlins .95 springs seem to work okay for me.
 

·
Registered
Joined
·
2,265 Posts
According to RaceTech, stock springs on the '05 6R and 6RR both measure .900 kg/mm. How accurate that is I don't know. I would have to agree that it is probably your suspension since you don't feel the problem at lower speeds. If it was warped rotors you would feel it regardless of the speed. Like heith said, firm up the compression damping. Changing out the springs for some heavier ones and going to a heavier weight oil will also help alot.
 

·
Registered
Joined
·
2,752 Posts
Originally posted by heith
Its not brakes, its soft springs. You can make a short term fix by adding/firming compression. Your forks are bottoming and when they bottom you lose suspension. quote]
I'm leaning towards this as well. Problem is, if you're hard bottoming you should feel it. Before you add compression, check your preload (sag), you should be around 32-35mm. Your preload sets where you ride in the stroke. If it's too soft, you'd be riding too far down, thus not giving yourself enough travel. Anyway, set your sag and go out again. If it doesn't work, like Heith wrote, add compression. In the end you'll probably want to go with .95's for your weight and track riding
 

·
Registered
Joined
·
2,042 Posts
xtremewlr,

Yeah, but my friend got both the zx6r and zx6rr springs measured before he exchanged them, and they are not .90, with the zx6r spring being further away. If you bounce the front end of both bikes you'll easily feel the much softer front end of the zx6r.
 

·
Registered
Joined
·
2,265 Posts
Well, like I said, I didn't know how accurate those specs are. I would pretty much expect the 6RR springs to be stiffer as the bike is meant to be more track oriented straight from the factory.

Back to the original question about brake specific upgrades, steel braided lines would be my first upgrade. They dont expand under pressure like the stock rubber ones do and you have one line going from the master cylinder to each caliper instead of the one line to the right caliper and then another from that crossing over to the left caliper. Better brake pads would help too. EBC HH pads or Vesrah pads would be next. My understanding is the Vesrah pads are the better ones but I have had good experience on my old bike with the EBC HH pads. Galfer wave rotors would be next but I really have no clue if they are any better than the stock wave rotors. Anyone know about that?
 

·
Registered
Joined
·
554 Posts
Better brake pads are the cheapest and most effective route. If you have a track only bike go with some race pads(EBC GFA369/HH) but if you do both track and street just get a good HH pad like EBC supersport HH(FA369/4HH. Race pads have to warm up and are really only good going fast. Stock lines are fine and only get out performed by stainless on the track under the hardest braking possible. While good pads outperform stock pads almost everywhere. Vesrah pads are the ish but cost to much for my blood, and ebc are very good and half the price. If you want EBC race pads make sure they have the "G" in front of the FA. Most people order FA369HH supersport/race pads and compare them to Vesrahs or Carbone Lorraine race pads and in fact its not a fair comparison. If they would order the GFA369HH race only pad they will find they are much closer in compitition.
 

·
Registered
Joined
·
554 Posts
Another thing about brake lines. Stock lines aren't rubber, they are high strength materials like kevlar. And you will here stories of people changing the lines and saying the brakes are way more firm. Well they don't take in account they just changed the fluid and probly had a air bubble. Or they say "I used to get brake fade at the end of a session and now its gone. But they don't think about how they also just switched there crappy old stock fluid for some RBF600 and bleed the lines doing it. Although I do have stainless lines I think if I were going on a cost route I would change pads and fluid before lines. Lines are more cosmetic.
 

·
Registered
Joined
·
178 Posts
Discussion Starter #17
First off, thanks to everyone for the insight.

It looks like two different schools of thought, its either the front suspension bottoming out or inadequate braking equipment.

To be honest, I don't understand how the forks bottoming out would cause pulsating. Furthermore, like I said, once I grab more brake, the pulsating stops.

Either way, I also have to be honest and say that I'm completely ignorant when it comes to the suspension and even remotely attempting to make the aforemetioned adjustments.

Does anyone know a mechanic or technician local to southern california that they could recommend that could take a look at my bike and make those types of adjustments? My local dealer are tools and I don't trust them as far as I can throw them.

The brake upgrades appear to be straight forward. Can one bleed bike brake lines similar to auto brake lines?

Again, thanks to everyone for your assistance on this matter.
 

·
Registered
Joined
·
2,265 Posts
If you were in the San Diego area, I would say take it to Lee's Cycle. Local bike shop down here owned by Jeremy Toye. Suspension setup runs $28. Worth every dime IMO.

Bleeding the brakes on a bike is just about the same as doing it on a car. Just don't forget that there is a bleeder valve located on the master cylinder too ;) Another trick that I have used before is after bleeding the brakes, tie the brake lever to the handle bar with the brakes on as far as you can squeeze them and leave it like that over night. Makes for nice and firm brakes come morning when you take the tie off :D
 

·
Registered
Joined
·
2,752 Posts
Originally posted by Hook
First off, thanks to everyone for the insight.

It looks like two different schools of thought, its either the front suspension bottoming out or inadequate braking equipment.

To be honest, I don't understand how the forks bottoming out would cause pulsating. Furthermore, like I said, once I grab more brake, the pulsating stops.

Either way, I also have to be honest and say that I'm completely ignorant when it comes to the suspension and even remotely attempting to make the aforemetioned adjustments.

Does anyone know a mechanic or technician local to southern california that they could recommend that could take a look at my bike and make those types of adjustments? My local dealer are tools and I don't trust them as far as I can throw them.

The brake upgrades appear to be straight forward. Can one bleed bike brake lines similar to auto brake lines?

Again, thanks to everyone for your assistance on this matter.
Uh, hello.. Buena Park here:D
BTW, people are theorizing it's you suspension because when it bottoms, you loose it, and your tire takes over. This will cause it to squirm and move around-more so over irregular pavement. You're saying that it goes away, but you've got to understand that you're also scrubbing speed and the amount of force that's being placed on your forks. We can check your entire braking system including your rotors, and get your suspension set up properly
 

·
Registered
Joined
·
554 Posts
When the suspesion bottoms you have no suspension. So the pulsating or wobble effect comes from the ground(bumps),tire slippage(skipping), and tire bounce. When you brake the front end dives and on long hard braking it dives alot. On short quik braking points it dives but not long enough to get through the compression stroke to bottom. When you release the brake the forks rebound(extend) then you apply brake again but not long & hard enough to bottom. Do this test. Take a zip ty rap it around your fork leg push it up. WARM UP TIRES, and find a good streight, go about 60mph and slam on your brakes. Take the bike back to the garage and measure how much stroke you had left. Now ad 3 or 4 clicks towards ->H of compression and repeat test. You should find about a half inch difference in you measurement. Why you ask. Because you slowing down the compression stroke.
 
1 - 20 of 35 Posts
Status
Not open for further replies.
Top