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MTB Dirt Mountain Bike Forums forum - Topic - Rear brake shudder

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Noob
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Jindalee
Forum posts: 17

Rear brake shudder

February 21, 2012 07:23pm

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Ok so i've been on the new bike for about 2 weeks now. I have noticed that the rear disc brake is shuddering and getting progessively worse. Noticeable at speed and especially when cornering under brakes. I've tried different bias ratios with the front and rear brakes with no difference. There seems to be more brake dust/dirt around the rear brake housing comparing to the front brakes. The disc is running absolutely true and straight. The brake unit is a Shimano M575.....should I have concerns and be talking to the bike shop as the bike is only 2 weeks old? Even had a rider pass me by today and comment on the awful noise coming from the bike so it doesn't sound good.

ozynigma

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Grim Ripper
46 yrs
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Underwood
Forum posts: 1311

Rear brake shudder

February 21, 2012 07:47pm

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Yes your bike shop should be fixing that, it is not normal. It could be something really simple.

dean0

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Knob Scrubber
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Southside
Forum posts: 322

Rear brake shudder

February 21, 2012 08:16pm

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It's probably a Giant hardtail judging by the type of brakes and noise you're describing. The shop can try things... but it's a very common problem. Try searching on the forums for this problem, some common fixes are;

- Change of brake pads

- Change of brake rotors

- Big clean of brake rotors

- Change brake brands altogether (the shimano's are crap anyway)

I have the same brakes on my Giant 29er and it makes a horrible noise. The brakes are terrible too but I live with it

troikken

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Rear brake shudder

February 21, 2012 08:29pm

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I'll take the bike into the shop before I mess with it and see what they think. The front brakes are sweet....it's just the rear that is being a drama. It's got to be something with the pads or brake unit itself as like I say...the disc is perfect...well from the eye anyway...I havent set up a dial indicator on it

onyx

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Gumby
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Brisbane Northside
Forum posts: 89

Rear brake shudder

February 21, 2012 08:45pm

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I had a similar issue and it was caused by one of the rotor bolts being loose.

troikken

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Rear brake shudder

February 21, 2012 09:10pm

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I just checked the brake mount bolts and they are fine. The rotor doesnt seem to be bolted to the hub...just flush mounted pins by the looks....are these removable? There is even gap between the pads and the disc and they mount up evenly when the brakes are applied. It's got me beat so hopefully the bike shop can pin the problem.

Mikka

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Knob Scrubber
25 yrs
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Location:
Brisbane
Forum posts: 254

Rear brake shudder

February 21, 2012 10:23pm Updated 21-02-2012 10:24 pm by Mikka

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It sounds like it will be a Shimano "Centrelock" rotor, which connects to the hub with a splined fit and a lockring. It does have what appears like studs between the centrelock section and the rotor proper.

I'm guessing it looks something close to this: http://www.chainreactioncycles.com/Models.aspx?ModelID=28025

ruzzelz

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Gumby
54 yrs
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Location:
Brisbane Nth
Forum posts: 62

Rear brake shudder

February 22, 2012 08:11am Updated 22-02-2012 08:12 am by ruzzelz

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Try taking the bike on the road and do serval sequences of hard downhill braking to full stop from a speed in excess of 25-30 km. This seems to work for me when I have a similar problem.

I just love a little hill climb

Slow pom

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Knob Scrubber
37 yrs
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Forum posts: 497

Rear brake shudder

February 22, 2012 12:49pm

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Same thing happened with a set of xt brakes I bought, but I was using Aligator starlight rotors.

I swapped the stock pads for some Kevlar compound ones, and they've been sweet since. In my experience our dusty conditions don't play well with stock sintered pads - they're better in wet muddy pad destroying conditions.

Thats just my opinion though.

troikken

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Forum posts: 17

Rear brake shudder

February 22, 2012 04:46pm

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Russelz - Thats how I noticed the problem on the road and bike paths. On the downhill at speed and trying to brake. More noticeable when downhill cornering.

Slow Pom - The rotors say to use resin pads only...can the kevlar compound pads be used anyway?

Shrek !!!

Member
Mad Skillz
Forum posts: 778

Rear brake shudder

February 22, 2012 06:34pm

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You never confirmed the bike make.

I had a beautiful XTC alliance (half carbon half alloy) which had a huge rear shudder and graunch noise

It was great for racing and such because as you touch the rear brakes it scared the bloke in front into moving over.. very useful but embarrassing onn the next climb..

Bike shop looked after me well, VERY wel.. tried all the required changes then Giant replaced the frame. No more alliance frames so they gave me the FULL carbon XTC.

Shop was Tom Wallace at Lutwyche, Ben's and John's ( there is a few of them) were super helpful about it all.

Talk to the shop, it COULD be in the frame.

troikken

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Rear brake shudder

February 22, 2012 06:48pm

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PtZell - The bike make is a Merida One Twenty 1500D. Shudder and graunch is definately the sound it's making.

ozynigma

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Grim Ripper
46 yrs
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Underwood
Forum posts: 1311

Rear brake shudder

February 22, 2012 07:01pm

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Quote: troikken

The rotors say to use resin pads only...can the kevlar compound pads be used anyway?

I think these are the cheapest and least durable Shimano rotors.

A rotor upgrade wouldn't hurt in any case and maybe you will get it free or heavily discounted if its a warranty issue. If you are southside I probably have an XT centrelock rotor you could try to see if it fixes the problem.

Another thing to check is if they centrelock spline lock nut is on tightly.

ruzzelz

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Gumby
54 yrs
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Location:
Brisbane Nth
Forum posts: 62

Rear brake shudder

February 22, 2012 07:58pm

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Quote: troikken

PtZell - The bike make is a Merida One Twenty 1500D. Shudder and graunch is definately the sound it's making.

If it is new form 99 Bikes just take it back - they will look after you. They changed the pads twice for me and then gave me some advice about not feathering the brakes, braking harder while MTB riding and also the downhill hard braking to clear the problem if it returns.

Doughnuts

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Albany Creek QLD
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Rear brake shudder

February 22, 2012 09:09pm

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I had exactly the same problem with my old Specialized FSR. It was also fitted out with Shimano disk brakes (Deore). When braking the rear would make an awfull noise (squeal & vibration) and at the same time would lose braking power. I tried different pads, then a different rotor but the problem still existed, eventually bought a new caliper and that solved the problem.

In hindsight a full re-bleeding of the hydraulic line may have fixed it as there may have been air trapped in the caliper/piston area?? If so I don't know where it came from as the brakes where fine for some time before it started.

In your case, I would definately take the bike back to the shop to get it tested and fixed!

troikken

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Rear brake shudder

February 23, 2012 05:15pm

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Yes I think the general feeling is not to mess with anything at this stage and take the bike back to the shop and get them to check it out! Still under warranty so hopefully they should be able to sort me out.

troikken

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Jindalee
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Rear brake shudder

February 29, 2012 05:07pm

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I dropped the bike into the bike shop and the mechanic filed the front lip on the rear pads and problem solved. The shudder is gone! I've only just taken the bike for a quick scoot up and down the street and so far the brakes are smooth. A little less "grippy" than before but they are running good.

Zadam

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Grim Ripper
Forum posts: 1410

Rear brake shudder

March 01, 2012 04:38pm

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They can put a man on the moon, you would think they could make brakes that don't have all these issues.

troikken

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Jindalee
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Rear brake shudder

March 11, 2012 01:56pm

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Ok...rear brake shudder drama continues an it's doing my head in!! First time at the bike shop....the brakes felt good but after some speed and a few minutes the shudder returned. I took it back to the bike shop....new pads fitted....they said it test rode fine. After a short ride by myself the brake shudder returned.

A mate suggested a few tips so I took to the garage and this is what I did. I checked out the mount surface between the caliper mount, mount spacer and the frame. The frame face was pretty shocking....uneven...and rough like a cheese grater. So I re-faced the frame face and caliper spacer on both sides so they are now flat, even and smooth. The actual caliper face looked pretty good so I didn't touch it. Next I pulled the rotor off the hub and deglazed it with 320 grit paper using a circle motion to get a nice cross-hatch on the rotor face on each side. I did notice the circle vent holes along the rotor face were slightly raised as the 320 grit paper showed quite easily they were higher than the rest of the face. I cleaned the rotor face down with Isopropyl Alcohol to make sure it's as clean as. Refitted the rotor to the hub and checked the tightness of the spline fitting on the cassette side too....so all good. I checked all the rear frame suspension joints to make sure nothing was slightly loose. I took the bike for a quick ride down the hill out the front of my house and so far 150% better....so far!! Good grip, smooth braking action and no shudder!! thankfully!! Fingers crossed this has fixed the problem....if not I'm not sure where else to go from here.....the only way to tell is next time i'm on the trails. Hopefully it's all good!