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Buell Forum » 1125R Superbike Board » Archives 001 » Archive through September 04, 2010 » Shuddering Front Brake When Trail Braking: What's the Fix? « Previous Next »

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Mountainstorm
Posted on Saturday, August 28, 2010 - 02:18 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

17K on the bike, new OEM pads, original rotor. The brakes feel like they have little bumps on them : p If I brake hard in a straight line they are just kind of annoying, making the front wheel feel square, but when braking entering a corner with some lean angle it really upsets the front end and makes the bike shudder.

So what's the fix? Can I just sand or otherwise resurface/renew the rotor? Should I just replace it? Is there some setting for the suspension to minimize that shuddering?

It's not exactly a new issue...but it's becoming a problem ad I want to correct it.

Thanks in advance.
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Ccryder
Posted on Saturday, August 28, 2010 - 03:26 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

If you brake hard 2-5 times it usually scrubs off the built up pad material. You can also use a Bear-Tex pad on a 4.5" grinder. I do it that way when I change tires.

I try and do the hard braking 2-3 times a week. Just do it at a speed of 50mph or so and watch out for gravel or bumps. I am talking about some real hard braking to scrub the rotor.

Later
Neil S.
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Mountainstorm
Posted on Saturday, August 28, 2010 - 06:31 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thanks pard. I'll probably pull the rotor and try and get it down to metal.
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Dannybuell
Posted on Saturday, August 28, 2010 - 07:22 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

The bumps may be warpage, my S1 experience suggests a better rotor. IDK whats out there for the 1125's the S1 has had Ferodo pads on EBC rotors for 60Kmi, like night and day for the street. They warm up quickly and stop smoothly with no fade or pulsation.
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Anonymous
Posted on Saturday, August 28, 2010 - 10:58 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Not warpage. Pad material deposit. The Erik Buell Racing rotors, pads and mount system reduce this dramatically.
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Jgarner99
Posted on Sunday, August 29, 2010 - 12:22 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thanks, Anonymous.
However, I have a question about the EB&R rotors. One is thicker and one thinner, but what other advantage do these rotors have?
Specifically, are they a different material?
I ask because I once replaced SS rotors with cast iron ones, and the feel was 100% better. Then again, that was 20 years ago (an eon in brake technology), so I may be barking at the moon.
Also, (for 90% street) which EB&R rotor is better? Thick or thin?
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Smoke4ndmears
Posted on Sunday, August 29, 2010 - 12:35 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I picked up, from the guys in wisconsin, the uprated mounting hardware and the performance friction pads. great pad feel though not the intial bite you get from the streeters. very linear though, and no deposits on the rotor either.
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Mountainstorm
Posted on Sunday, August 29, 2010 - 11:19 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thanks for the advice. Too broke to replace anything right now, but it's on the list.
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Terp_bueller
Posted on Sunday, August 29, 2010 - 07:58 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I also have pulsing front brake...08 1125R. Deposits or not...H-D Service plans to replace the rotor as a warranty item. I have been trying a few of the remedies on this and other threads...just can't get the pulse eliminated.

Anonymous,
Can I bring the bike by the paddock, this Saturday, for "field test" rotors and pads? : )
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Blower1
Posted on Monday, August 30, 2010 - 02:51 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I had a pulsating front brake in my -08 1125R and get a new front disc as warranty, no pulsating then.

(Message edited by Blower1 on August 30, 2010)
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Jdugger
Posted on Monday, August 30, 2010 - 09:06 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I'm not sure I agree with anonymous.

The Erik Buell Racing rotor mounting system is designed to draw heat out of the rotor and into the wheel from heavy braking. If you aren't using the brakes hard enough to scrub the deposits, I don't see when benefit the Erik Buell Racing mounting kit will provide.

Yes, it's better. But, I don't believe it's the fix to this problem. Using the brakes HARD or getting softer "street" pads is the fix to this problem.
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Mountainstorm
Posted on Monday, August 30, 2010 - 09:16 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I definitely use the brakes hard. I think the irregular surface of the rotor is beyond a 60-0 scrub with the calipers. I've only used the OEM brake pads. I'm open to trying something different, but I was not impressed with the EBC rear pads. They squeal and have worn out rapidly.

I'll start by removing the rotor and blocking it down with sandpaper. I'm a carpenter...it's the best I could come up with : p

Once the rotor is all shiny and flat according to my steel straight edge I'll see if that cured the problem. If not I'll have the dealer look it over and maybe I'll get lucky and they'll replace it. I am outside the 2 year factor warranty, and I am not sure the ESP I purchased will cover wear items like rotors.
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Froggy
Posted on Monday, August 30, 2010 - 09:19 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Using the rear brake to hold the bike when stopped will significantly decrease the chance of this affecting you. But yes the problem is a result of pad material leaving deposits on the rotor or sometimes in the rotor mounting springs.
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Mountainstorm
Posted on Monday, August 30, 2010 - 09:23 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

When I have problems they fall 99% of the time into the "sometimes" category.

I would not be surprised if there is something off about the rotor mount because the pulsing became more pronounced after my latest front tire change.

Considering that every time I get tires mounted they damage something I should probably inspect those mounting parts.
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Jdugger
Posted on Monday, August 30, 2010 - 10:20 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

> I definitely use the brakes hard. [...]
> I was not impressed with the EBC rear pads.

These two statements are quite contradictory, honestly.

Please post a picture of your rotor. I'll have a good idea of what's going on just looking at it.

> I should probably inspect those mounting parts.

The drive bushings *are* wear parts. Can you get a close up picture of the tire kinda "radially" so I can see the drive bushings inside the rotor's mounting flanges? I'll need to see the bushing -- not just the bolt head, hence the "radially" comment.

Finally, do this check for me -- you are using 2008/2009 OEM rotor mount hardware, right?

Put your hand through the wheel so that the palm pad of your hand is resting on the rotor and your fingers are able to reach around the backside of the spokes. Now, attempt to make a fist, and note the play in the rotor -- should be about 1/8" of an inch. Do this around the wheel, and tell me what you find.
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Jdugger
Posted on Monday, August 30, 2010 - 10:23 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

> Once the rotor is all shiny and flat according to my steel straight edge

Go to a good machine shop supply and buy a dial indicator. Use that along with your static balancer to check rotor run out.
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Dannybuell
Posted on Monday, August 30, 2010 - 12:32 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Mountainstorm - "would not be surprised if there is something off about the rotor mount because the pulsing became more pronounced after my latest front tire change."

Why not check the run out now, perhaps somebody may have bent your rotor with the tire change?

(Message edited by dannybuell on August 30, 2010)
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Mountainstorm
Posted on Monday, August 30, 2010 - 01:35 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thanks I'll take some pics and do the suggested checks.
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Fresnobuell
Posted on Monday, August 30, 2010 - 01:44 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Also, the bolts for the rotor are supposed to be a one use and replace...not sure if this is something like the gaskets and washers which are supposed to be changed everytime, but are usually okay to be re-used.
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Mountainstorm
Posted on Monday, August 30, 2010 - 02:22 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I hope not eek

The play on the rotor seems consistent. It's about a 1/16"







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Jdugger
Posted on Monday, August 30, 2010 - 05:04 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Well, here's my opinion from the pictures:

1. Your rotor mounting hardware is fine. As long as the rotor has the play I've described it's healthy. You can start to tell when the rotor mounting kit is going out (well, the rotor, too) when the bushings are no longer perfectly square in the rotor flanges. Yes, they actually twist! And, that's the indication the rotor is shot because the load on the drive bushings has actually dug them into the stainless rotor stretching out the flanges!

2. You do have some oxidation around the mount bolts which isn't ideal, but if it easily comes off with a brass brush, don't worry about it. Just make sure you have that play I described in the rotor when you grab it with your palm and the rotor isn't fused to the mounting bolts.

3. The color of your rotor suggests you are using it well, but not *that* hard. I look for the edges to be at least a deep golden/straw color to indicate the rotor getting hot. (racers get it DARK blue, purple and even a bit charcoal sometimes.) There's some indication of deposits in the 2nd picture and on the backside of the rotor, so I'm inclined to suggest you try a less aggressive pad than the OEM pad. Something like the EBC HH (*NOT* Extreme Pro) or other "street" pad. Avoid racing pads. The OEM pad is actually a rather aggressive pad, and honestly wants a track day or spirited canyon ride to not cause the pulsing problems. I think a softer, less aggressive pad is more suitable for most riders, honestly.

4. The comments about getting the run-out checked are spot on. If you are in D/FW Texas and want to make a ride out to the track, I'll do it for you -- doesn't take 20 minutes to pull the wheel and put it on the balancer.

5. Re-using the hardware is a 50/50. The main thing to look for is uneven wear on the shoulder of the bolts. If there is noticeable wear, go ahead and discard the bolt. If it's OK, clean the bolt's threads with a brass brush, blow out the hole in the wheel, and use loctite red (normally) or blue (generously -- this is what I do) to secure the fastener. Torque is 25lbs. Always use new/fresh drive bushings, and always inspect the rotor's flanges, in particular where the drive bushings wear as those tend to go. I have a set of Titanium bolts on my superbike wheels, and at $20 a bolt I assure you I re-use them. I also put a dab of anti-seize on the shoulder of the bolt, but I see that as completely unnecessary on the ordinary or Erik Buell Racing mounting hardware as it's cheap enough to pull and replace every few front tires.
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Mountainstorm
Posted on Tuesday, August 31, 2010 - 07:51 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Excellent post sir.

I will replace the pads and bushings as soon as I can.
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Motorhead102482
Posted on Wednesday, September 01, 2010 - 03:52 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I would like to add, that with new pads, I've noticed shudder when repeatedly braking hard (as in a MSF course) before the pads are all of the way bedded. Just my cent and a half.
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