Bent/warped rotor signs?

油井緋色

油井緋色

Well-known member
Site Supporter
So I hit a pinecone the other day and I noticed the following issues after the tiny lowside/drop:

Applying front brakes at low speeds causes, what feels like, the front suspensions to compress at a pulsating rate. This symptom goes away at higher speeds.

Rear brake or engine braking does not cause this. Could this be a warped rotor? =(
 
Can you get the front wheel off the ground, if so a simple spin will tell you if it is warped.
 
Guessing you may have knocked the wheel out of alignment a bit. This can cause the fork to twist in or out and increase friction quite a bit. Suggest you loosed off the front axle pinch bolts. Push down on the front to move the forks up and down, without hitting the brakes. This should align the forks again and you can tighten the pinch bolt. Simply relying on the spacers is not good enough to stop the fork from rotating out or in a bit.
 
Thank you bot. I will attempt both tonight and see what happens...though this weather is kinda ******.
 
in cars at least, warped rotor problems are worse at higher speeds, or the faster the wheel and rotor has to spin.
 
brucewayne said:
in cars at least, warped rotor problems are worse at higher speeds, or the faster the wheel and rotor has to spin.
Click to expand...

Perhaps I don't have bent rotors then as I travel above err...average on the highway. I noticed no high speed instabilities on the way home.
 
Really stupid question but what do I look for when I spin the wheel freely?
 
You hit a pine cone and crashed?


Excuse me while I LOL.

Anyhoo...I'm not sure how you could have damaged the rotor on a drop but I'm sure you cocked it up good some how. Better replace both rotors & pads just to be on the safe side.
 
Spin the wheel and see if the rotor comes into contact with the pads.
Or visually inspect the rotor to see if it wobbles.
 
killerkeith said:
You hit a pine cone and crashed?


Excuse me while I LOL.

Anyhoo...I'm not sure how you could have damaged the rotor on a drop but I'm sure you cocked it up good some how. Better replace both rotors & pads just to be on the safe side.
Click to expand...

Yeah I'm planning to do all if I find out they are bent. And yes, low speed turn + pine cone. I thought they would be soft and squishy, instead it got caught under my front wheel and down I went....this is gonna end up being one expensive ****ing pine cone.

Mina said:
Spin the wheel and see if the rotor comes into contact with the pads.
Or visually inspect the rotor to see if it wobbles.
Click to expand...

Thank you. Will do in an hour or two.
 
Wheel spins freely for maybe 3/4ths of it, there is a certain section that gets stuck. I also notice the pads getting closer to the rotor at one point but I'm not 100% sure as it's really hard to see.

.............=(
 
If your rotor is warped, you don't have to ball out and buy new rotors.
Just look for used OEM ones, they aren't expensive.
I don't see why you have to change the pads though, unless they're worn out, I would just leave them as is.
 
A warped rotor will cause the lever to pulsate when braking and my push the pads apart so that you lose the ability to brake. To check, loosen pinch bolt(s), axle, lower triple clamps and compress the front forks, then re-tighten everything and spin the wheel with a dial indicator on the rotors. Anything more then 10 thou is too much. You can straighten them with an adjustable wrench if they're not completely out to lunch.

OR................Take it to a shop.
 
phil_si said:
A warped rotor will cause the lever to pulsate when braking and my push the pads apart so that you lose the ability to brake. To check, loosen pinch bolt(s), axle, lower triple clamps and compress the front forks, then re-tighten everything and spin the wheel with a dial indicator on the rotors. Anything more then 10 thou is too much. You can straighten them with an adjustable wrench if they're not completely out to lunch.

OR................Take it to a shop.
Click to expand...

Shop it is later today.

Mina said:
If your rotor is warped, you don't have to ball out and buy new rotors.
Just look for used OEM ones, they aren't expensive.
I don't see why you have to change the pads though, unless they're worn out, I would just leave them as is.
Click to expand...

Do you know of anyone that makes colored rotors (gold)? I was looking into Brembo but I've heard race rotors don't last as long and I do quite a bit of commuting.
 
Last edited:
phil_si said:
A warped rotor will cause the lever to pulsate when braking and my push the pads apart so that you lose the ability to brake. To check, loosen pinch bolt(s), axle, lower triple clamps and compress the front forks, then re-tighten everything and spin the wheel with a dial indicator on the rotors. Anything more then 10 thou is too much. You can straighten them with an adjustable wrench if they're not completely out to lunch.

OR................Take it to a shop.
Click to expand...

This. Its a very noticeable pulsating, you can also run your nail along the rotor and you'll clearly feel the uneven ridges.
 
油井緋色;2012510 said:
Wheel spins freely for maybe 3/4ths of it, there is a certain section that gets stuck. I also notice the pads getting closer to the rotor at one point but I'm not 100% sure as it's really hard to see.

.............=(
Click to expand...

There is a runout spec in the service manual, if your rotors have more runout then the spec they are considered warped and should be replaced. Eyeing it out if its bad is possible, but I use a digital dial gauge to check this accurately.

If you want pas by when you have time and I can measure it for you... Only takes 1 minute

As someone said if your rotor or rotors are warped, you will be able to pump up the front brake lever firm when standing still. As you start to move the bike the lever will pulsate and your brake pressure will drop, then again when you stop you will be able to pump it firm again, and it will go soft as you move again. This happens as the warped rotor pushes your pads and pistons back into the calipers, requiring you to pump them back out to get pressure...
 
JohnnyP636 said:
There is a runout spec in the service manual, if your rotors have more runout then the spec they are considered warped and should be replaced. Eyeing it out if its bad is possible, but I use a digital dial gauge to check this accurately.

If you want pas by when you have time and I can measure it for you... Only takes 1 minute

As someone said if your rotor or rotors are warped, you will be able to pump up the front brake lever firm when standing still. As you start to move the bike the lever will pulsate and your brake pressure will drop, then again when you stop you will be able to pump it firm again, and it will go soft as you move again. This happens as the warped rotor pushes your pads and pistons back into the calipers, requiring you to pump them back out to get pressure...
Click to expand...

Thanks for the offer but I got it done already. One was off by 8, other was off by 12 and the bounciness was making me paranoid.

Ended up replacing them with Braking Strada Batflies since OEMs were around the same price and gold rotors from EBC would take a month to come in :(
 
DVS said:
I hope you kept the warped rotors, you can have them straightened. It's a freaking art form but it comes back true.
Click to expand...

Where? My dad's Burgman 650 front rotors might be warped. For the first km or 2 of riding they feel fine even under hard braking. After that they have a really odd feeling, sort of like stepping down stairs.

Sent from my SH-02E using Tapatalk 2
 
You must log in or register to reply here.
Back
Top Bottom