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Discussion Starter · #1 ·
I have an 08 450xc. After a couple of yrs of it basically just sitting in garage I took it to a shop to get some work done. During first big outing the brakes kinda seemed to lock up. The rear brake became super pressurized and you could not push the brake. With that the rear brake got super hot and when attempting to bleed to take some pressure away it was boiling. Fast forward I took it to shop and they rebuild entire rear caliper(thought that was issue) took it out this week to just ride around the yard and it is still doing it after only 5-10 mins of riding. When it does it it shows the rear brake light on even when off the bike. You can let the bike sit and cool and the issue goes away. Super long post and hopefully for those that have read can give me some guidance鈥 just wanna ride. 馃槖馃槙
 

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Never experienced issues on the quads, but have read about this on a KTM bike forum. Make sure there is a little play in the brake pedal linkage. If it's tight from the start it leaves no room for expansion once you start using it and things heat up.
 

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Discussion Starter · #3 ·
Never experienced issues on the quads, but have read about this on a KTM bike forum. Make sure there is a little play in the brake pedal linkage. If it's tight from the start it leaves no room for expansion once you start using it and things heat up.
thanks for the info I鈥檒l take a look. I鈥檝e already had master cylinder rebuilt and didn鈥檛 fix problem on to brake lines next if i can鈥檛 find a 鈥渟imple鈥 fix.
 

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So A few things to note here:
As I push things harder and harder, the less and less crazy I am about the magura stuff for basically everything on the quad besides the front brakes, Which are awesome. The clutch, and the rear brake, are honestly just not great in my opinion.
I think your issue is one of two things:
The rear master cylinder has this coating on it that flakes and keeps the seals from working right. I鈥檝e trashed them in very little time. They show failure just like you鈥檙e describing. The coating flaking seems to lock them up.
The Brembo dirt bike ones fit right up, you have the grind the contact pin down, but other than that it bolts right up and is MILES better. No issues whatsoever with it after a couple seasons now.
And then Quad 97 makes a great point. The brake lever needs more slack than you think. I鈥檝e had this get me before, too.
Some additional info: It鈥檚 Probly worth throwing a new seal and piston in them while you can still buy the parts (especially if it鈥檚 been overheated) . It鈥檚 a super simple job.
Lift the rear end of the quad up, spin the axle, watch the brake rotor itself. If It is visibly warped, that could be a problem as well.
There is also a guy on FB that makes a conversion kit to a Brembo dual piston caliper and brake stay, which is my next plan of action.
As of now, I鈥檝e just had to back off using my rear brakes as much as I would like to.
 
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