[97dirtybird]

I sent dymag an email, ill see what they have to say. That would be that would be very helpful. Thanks.

 

[beestoys]

Ok Bear came back first.
Have him check with any carbon frame repair shops for bikes, they should be able to inspect it
Leni is going to ask around and get back to me.

 

[beestoys]

In the meantime I'd try what Fizzy suggested with the chase car and phone recording.
If that caliper was mounted on the pull side I'd be less inclined to suspect the mounting. But it's on the push side so loading forces may be wreaking havoc on the whole system.
Also I can't be 100 % because of the camera angles but are the calipers in the same plane. IE directly across from each other. If not you could be inducing a wobble when the calipers close down on the discs. Because they aren't actually grabbing at the same location in relation to each other in the wheel. This could be compressing/twisting/loading the forks differently enough to induce the shake.

 

[TheDuck]

I sent dymag an email, ill see what they have to say.

Lets see what you get back but if needed I can call into their HQ which is only 10 miles from me. FWIW I did a small amount of work for Dymag something like 20 years ago (Finite Element analysis of carbon fibre wheels and designed a carbon fibre single sided swing arm). Their chief designer then was Mike Wilson, I think he is still there .....

On the problem itself, are the discs OE Bird items? (they look like it but in far better condition than I have ever seen), I'm thinking bobbins.

 

[iXXion]

Appears to be stock forks and stock axle. I see no reason to think that any of the important contact points have changed.

I suspect a complete front wheel assembly could be swapped in. If this was my bike, I think I would do the following:

*Pull the calipers. Obviously they are delinked so no problem. Zip tie them up with a block between the pads and go for a ride. All you have it back brake. See if there is any problem. If not...
*Put one caliper back on. Go for a ride. See if there is a problem. If there is, take the caliper off, zip tie it up, and put the other one back on. See if there is a problem. If there is....
*Replace the calipers with stock calipers. You don't need to be fancy, just make them work. Connect your one brake line and plug the other hole. See if there is. If not, you're looking at the fancy brake calipers as the culprit. If not, its probably the wheel. Replace it with a stock wheel and try again.

Other less likely culprits could be tight or sticking rotor bobbins, bent rotors, steering head bearings, or something really bizarre in the master cylinder.

You told me once, where are you?

 

[97dirtybird]

Okay, all suggestions for the stock wheel swap have been considered, as well as isolating each caliper while riding. Dymag wants the serial number which im going to give to them this morning. Spoke with previous owner and he did say that these rotors were from China. Thats a huge red flag for me. Looking online I think I actually found the same rotors. In the back of my head im really wondering if this is the issue. Good point on them not being installed directly across from each other. Im in Ohio.

 

[iXXion]

Worst case is get out here with it and we'll swap parts until we figure it out. Or come out, pick up spares, and bring them back when you're done.
Im in PA 18810. Not close but not half a world away.

 

[TheDuck]

Spoke with previous owner and he did say that these rotors were from China. Thats a huge red flag for me

Have you got a dial gauge that you can mount perpendicular to the discs? If you have you could quickly check the disc run out. Those calipers should generate a lot of stopping power and heat. Couple that with Chinese discs and you have a perfect recipe for warped disc(s).

 

[97dirtybird]

In my old automotive mechanic days we never used any Chinese brake parts because the cheap steel used and manufacturing quality. Guaranteed come back. I don't have a dial guage but having them checked would save me alot of hassle switching wheels and calipers between my birds. The rotors appear to have the same wear pattern in them but ive noticed that not quite half way around them the wear groove is flush with the rest of the rotor width and the rest is thinner than the rotor width so you can feel a lip if you move your fingers up and down on the rotor. Seems enough of a sign that its warped. I bet I could just purchase new rotors and be happy with my new bird.

 

[fizzy]

Did you say the rotors were already checked and were fine.? Just randomly throwing new parts at the problem could be costly until you get lucky. If there is anyone in your neck of the woods that is willing to temporarily swap out parts, I would do that. You need to announce the model year as the front end went thru some changes....

Also, back to my earlier question, are you certain the wheel spacers are correct?

 

[beestoys]

Well you can always old school it too. Piece of heavy wire taped to the fork leg. Bent to just touch the rotor and then give it a spin. If they are warped it'll show up.

 

[97dirtybird]

Its a 97 but was made in 96. Im not sure about wheel spacers on it. I was given Stock calipers for the new bike. I have another 97, but didn't want to treat it as a parts bike because it is not but it has stock wheels and calipers. I could take those rotors and put on the new bikes wheels to try. I looked for the serial number on the wheel and didn't see one. Wonder if the tire needs to be off and its on the inside. I think the dial measure may be the first thing to do. I want to start with the less involved stuff first. Anyone know where i can get a cheap front fork stand? This bike does not have center stand.

 

[fizzy]

Looking at the pics you posted, I see another problem. The wear pattern on the discs goes thru the middle of the inner vent holes. Never seen that before. The wear pattern normally begins much closer to the inner edge of the disc. In other words, these callipers seem to be too far from the axle by about 3/8".
Or your discs are too small. Compare diameters with your "parts" bike.

 

[97dirtybird]

Good eye fizzy! Ok from center of axle to outside of rotor is 6" on both bikes. New bike is showing 1" 1/8" of actual wear pattern on rotor. (Inside of pad wear starts halfway through the inside vent hole like you spotted)
Old bike is showing 1" 3/16" of actual wear pattern on rotor. (Entire pad is contacting through all vent holes) I bet that helps keep the heat down!
Both pads are contacting the entire rotor.
Stock setup is putting a wider contact point on rotor than the aftermarket setup. Not sure if the contact point is the same length though between setups.

 

[97dirtybird]

Good eye fizzy! Ok from center of axle to outside of rotor is 6" on both bikes. New bike is showing 1" 1/8" of actual wear pattern on rotor. (Inside of pad wear starts halfway through the inside vent hole like you spotted)
Old bike is showing 1" 3/16" of actual wear pattern on rotor. (Entire pad is contacting through all vent holes) I bet that helps keep the heat down!
Both pads are contacting the entire rotor.
Stock setup is putting a wider contact point on rotor than the aftermarket setup. Not sure if the contact point is the same length though between setups.

 

[Skaircro]

I'd be checking if the disc diameter is the same as OEM. You say you have another 97 bike, I'd be temporarily swapping the complete front wheel off your other 97 with this one (if discs are the same size).

Make sure everything in the front end is aligned. There is a procedure where you loosen all fasteners except upper triple(?), give it some downward force on the front and tighten everything back up. Never done it myself but seen it mentioned here.

 

[macka20]

Just looks poorly designed to me only having two mounting bolts way up high, and none down low. Lots of torque on the calipers.

to me the two mounting bolts up high looks un functional less and stable than most brake designs

 

[97dirtybird]

Yeah thats what my original thought was also Macka20. I think it should also have a mounting arm that goes to the bottom of the fork from the caliper that possibly uses longer pinch bolts at the bottom of the fork. That way the bottom of the calipers is also stabilized. I have ordered new brake rotors and pads. Should be a few weeks yet. Hoping that fixes it.

 

[97dirtybird]

Moment of truth this week, bike goes in for new galfer rotors and ebc pads thursday. I'm going to have them check for runout before they remove the wheel. Instructions say to use correct offset with the waves from side to side and lightly sand the rotors before install.

 

[97dirtybird]

You know when you just can't win? My new rotors are too big. Guess ill have to pull the tire and get the rim specs so I can relay that to dymag.