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Bent rear disc

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I just bent my rear disc brake and am wondering what I shoud do about it? Do I have to purchase a new one replace it? CanI bend it out to save some $$$? Are rear disc guards worth the money ($130)? Are front disc guards also worth it.

I am also wondering if anyone can post a pic of the rear brake set up on their back tire. It feels pretty loose on there and doesn't feel tight. There is an empty threaded slot at the top terminal end of the brake setup and I am feeling that it shouldn't be empty like that. It looks clean, like a bolt use to be there, but now isn't. Does anyone know what could have happened. It was a pretty bad wreck.

Thanks

CER

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Buy a new disc.....the bent one is FINISHED....no hope...kaput...toast...sorry for the bad news, but that is the way it is.

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I've straightened a few of them over the years. If you have have a knack for this type of thing, you can do it. Clamp a reference guide, of some sort, to the swing arm. Spin the wheel slowly and use a marker to help locate the center of the bend so you don't end up with an "S" curve. Use a large Crescent wrench, adjusted snuggly, on the disc. Take your time and don't over shoot center. If you miss the mark, you will feel pulsations in the pedal. You've got nothing to loose in trying. :)

PS: Buy a shop manual.

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Replace it immediately and probably your disc brake pads too. Stick a Scotts read disc protector on there. I have one and in all the rocks that bike has been through it never has had any trouble since I did that. They are expensive but worth it. prairiedawg :D:):):p

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Holy cow! You guys must all have money to burn! :) You can also take your front tire off and then remove the disc and with a non metal mallot(wide faced hammer) lay your disc on a hard flat surface and work the area in need of repair with firm, but not to aggro, hits. You can check the trueness of your work by putting your disc back on the wheel and give 'er a spin. Use your caliper as your trueing guide. Mark the still untrue area with a marker and repeat your handyman skills.

Of course it all depends on how badly you bent the disc.

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Holy cow! You guys must all have money to burn! :) You can also take your front tire off and then remove the disc and with a non metal mallot(wide faced hammer) lay your disc on a hard flat surface and work the area in need of repair with firm, but not to aggro, hits. You can check the trueness of your work by putting your disc back on the wheel and give 'er a spin. Use your caliper as your trueing guide. Mark the still untrue area with a marker and repeat your handyman skills.

Of course it all depends on how badly you bent the disc.

Perhaps some of of us (most of us) realize the differenc between repairing a part with that potential,, and replacing a part it is unwise to attempt repair of. :D

I saw in a move once where I guy trapped on an island did his own dentist work with an ice skate... :) Sounds to me right up the ally for those wishing to beat on a brake rotor to straighten it :p

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buy a new disc. i have seen titax brand as cheap as $50.00 bucks. if your brakes end up throwing you off the bike or not making you stop i bet it will cost you more than a new rotor does. :)

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Anyone who is so poor to even try to staighten a disc should not be riding a motorcycle in the first place. A disc is not made out of a soft and malliable material that will bend easily and freely. All you are doing by staightening one is making it even weaker. Not a piece I would want to fail on me.

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Why not try to straighten it? You've got nothing to lose. It would be different if it was the front disc, but it's only your rear. What does straightening your rear disc have to do with how much money you have or don't have? $50 bucks is $50 bucks.

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Straightening a brake disc should be an emergency procedure only in my opinion, something to get you out of trouble.

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Why not try to straighten it? You've got nothing to lose. It would be different if it was the front disc, but it's only your rear. What does straightening your rear disc have to do with how much money you have or don't have? $50 bucks is $50 bucks.

It's your bike,, and I don't ride with you.. Do what ya want :)

My recommendation to those still listening... Is replace a damaged rotor. Service limit is 0.3mm run out. Your not going to beat a rotor back in to shape and maintain that limit.. Additionally... the work hardening done to the metal which could cause other issues makes this whole discussion.. rather silly,,...

But,,, makes no difference to me,,,, :D Harbor Freight makes a nice hammer (the only tool I would own from them) that would be perfect for beating on a bent rotor :) (you'll never get it right,, but might make for some entertainment......for those of us watching :p )

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I am married with a couple of children and am always looking to save a buck. I even cut my own hair. I rode an XR that had more zip ties and hose clamps that it should have, but none of the patch work was on systems that affected my safety.

I don't try to save money by letting my car tires go until the metal bands show even though I may be OK. Get a new disc, they cost less than a tire and less than a trip to the hospital when it fails to work on a steep hill.

A bent my front disc once when I was going down an un-marked trail and ran head first into another rider going pretty fast. He hit my front disc and bent it completely around into the spokes (90 degree bend). Had to take the wheel off and remove the disc to get back to the car.

Good luck

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This thread is starting to get down right hilarious! :) If an OEM rotor can be straightened back into spec, it is not going to fail! Who has ever seen one fail? You guys sound more nervous than my Mother! To have a rotor on the back of a dirt bike "break" from braking ... Think about it! If you HAVE to stop the rear tire is probably not even touching the ground because the front is doing all of the work... Think how much it expands and contracts from the thermal shocks it goes through all of the time. The rotor could be close to red hot and then get dosed in a 50 degree water crossing.

...but it's for safety... sounds so sweet, don't it... I'm going to search for a "What's the best oil thread"... I need to vent... It needs to stop snowing... what am I doing in Minnesota anyway??? ... damn cabin fever... should have bought that snowmobile...aaauuuggghhh! :)

Sorry guys... just havin' a little fun...

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If OEM handlebars can be bent back to spec, are they "good as new"? :)

If the master link on a chain bends, is beating on it with a hammer going to "fix" it? Maybe a paper clip will hold it together. :)

If you're tire or tube gets cut, will duct tape make it all better? :p

If you're out of Brake Fluid, will vegetable oil work for a while? :D

If you're that destitute that you can't afford a new rotor, I'll check my supply of spare parts, I think I've got one. I can use the tax deduction for another "charitable donation"! :D

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:) If an OEM rotor can be straightened back into spec, it is not going to fail! Who has ever seen one fail? QUOTE]

I have.

The rider is notoriously cheap. Bent rear rotor. Beat it back with a hammer. All seemed fine at room temperature. Until he needed the brakes. Got some heat into the rotor. Huge chunk of the rotor broke off. Trashed rear caliper and the rear hub, and the rest of my afternoon dragging his bike outta the woods.

Could have been way ugly had we been hauling ass when it went.

Find other places to save money besides brake parts.

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This thread is funny. :)

I'm not poor, been riding dirt for about 30 years - and I will straighten a rotor IF it is only slightly bent. Some desert guys would lose their homes if they replaced every slightly bent rotor.

If it is slight you can use a soft-faced mallet and tap it right while its still on the wheel. I have also taken them off and used a press to get back into spec. (I've even turned rotors on a lathe/tp grinder when I was really into it - but too much work IMO compared to the cost of a new one) The critical thing is to make sure you get it right so no wobble exists or the brake will overheat easily and possibly cause problems at an inopportune time. Like any other fairly critical repair, take the bike for a ride and check it out before you go for longer rides.

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:) If an OEM rotor can be straightened back into spec, it is not going to fail! Who has ever seen one fail? QUOTE]

I have.

The rider is notoriously cheap. Bent rear rotor. Beat it back with a hammer. All seemed fine at room temperature. Until he needed the brakes. Got some heat into the rotor. Huge chunk of the rotor broke off. Trashed rear caliper and the rear hub, and the rest of my afternoon dragging his bike outta the woods.

Could have been way ugly had we been hauling ass when it went.

Find other places to save money besides brake parts.

I would never use a hammer to straighten a bent rotor. My method is to use a crescent wrench. This way minimizes bend hardening. Thanks for the story though! Now I can't say I have never heard of a brake rotor failing.

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I say just leave it off! You save a ton of weight without the rear brake system. You still have the front brake which is more effective anyway! how much do you really use your rear brake? :)

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