stripped bleeder thread

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kwikasfakininja
Posts: 3
Joined: Sat Nov 05, 2016 4:01 pm
My Bike: '92 zxr400

stripped bleeder thread

Post by kwikasfakininja »

Hi guys,

stripped the thread for the bleeder bolt in one of my front calipers today, thinking about solutions...
I've read helicoils probably aren't a great idea as they possibly wont seal the fluid correctly. Apparently the stock bleed bolts are m7, would it be possible to tap a larger thread in the caliper and fit an m8 bolt? Anybody know where I might be able to find a larger nipple that would fit the zxr calipers?

Many thanks
Ewetea
zxr400 oc member
zxr400 oc member
Posts: 148
Joined: Mon Jan 12, 2009 12:04 pm
My Bike: ZXR400L5
Location: Newport Shropshire

Re: stripped bleeder thread

Post by Ewetea »

The bleed screw has a conical end. When it is screwed into the tapped hole, the cone meets a smaller plain hole further down and seats on it, much like a valve sealing the port in a cylinder head. You can't use a bolt because it wouldn't seal, and wouldn't have a hole in the side and up the middle to permit release of fluid when bleeding the system. Using a helicoil is acceptable as it just holds the bleed screw in place and secures it when the cone seats on the hole. There are probably larger bleed screws - try your local automotive spares shop, they are a common item. You will then need a tap of the appropriate size. Whichever method you use, drilling will be required, and it is essential that it is concentric with the existing hole. If it is off-set for any reason, or runs at an angle, the cone will not seat on the small hole. That's not to put you off, just make you aware of possible consequences. Ideally you need to use a pillar drill to be concentric and square, but even then you will have to be careful how you clamp the caliper to ensure success. An appeal for another caliper might be a better course of action.
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