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Workshop => Suspension and Chassis => Topic started by: zcarlson12 on April 13, 2022, 03:51:44 PM

Title: Crf450 rear master cylinder
Post by: zcarlson12 on April 13, 2022, 03:51:44 PM
I’m having trouble getting mine bled. It will not build pressure at all. New line, caliper rebuilt and brand new master cylinder. I’ve been wanting to use one to get rid of the hose and mounting to the air box. Has anyone who uses one had the same issue? Pedal throw too short? I didn’t see anything in a search on here. Thanks for any help.
Title: Re: Crf450 rear master cylinder
Post by: croat1 on April 13, 2022, 04:48:01 PM
I’m not running that setup but here’s a few questions for you….

Are you bleeding it on the quad? Bench bleeding the system?

Is the pushrod long enough?

Joe

Title: Re: Crf450 rear master cylinder
Post by: 2ndmoto on April 13, 2022, 05:14:45 PM
Air can get trapped behind the caliper pistons. Make sure to press them all the way in before bleeding your brakes
Title: Re: Crf450 rear master cylinder
Post by: gentner8 on April 15, 2022, 09:23:26 AM
I had a stubborn jeep clutch I couldn't bleed.  I ordered one of these, and I wish I would have done it sooner.  Hook it to a compressor, and pull the handle to bleed, and tighten the bleeder.  The other bottle is filled with fresh fluid, and self feed the reservoir until bled.  That was a small master cylinder, but I have never used it on a bike.  I will be swapping my brake lines soon enough, and will try it.  https://www.amazon.com/gp/product/B08GM9GSZ1/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
Title: Re: Crf450 rear master cylinder
Post by: zcarlson12 on April 18, 2022, 08:00:08 PM
Joe, bleeding it on the quad. Swingarm is relaxed without the shock on so it’s feeding it down to the caliper. I’m starting to think the pushrod is not long enough.

2ndmoto, I’ll check but I thought they were all the way in, thanks for the tip.

gentner8, I’m using something very similar hooked up to an air compressor. First time using it and it bled the fronts in less than a minute.
Title: Re: Crf450 rear master cylinder
Post by: broken1 on April 18, 2022, 11:21:43 PM
I read somewhere about pushing the fluid in from the caliper up to the MC but never tried that method. Could be worth a shot.
Title: Re: Crf450 rear master cylinder
Post by: croat1 on April 18, 2022, 11:56:32 PM
I still wonder about braking issues due to hard use when doing the CRF conversion.  Zak, I’m assuming this is what your setup looks like.

Joe
Title: Re: Crf450 rear master cylinder
Post by: croat1 on April 18, 2022, 11:58:03 PM
What I’m getting at as far as my “hard use” comment is the system capacity.

Joe
Title: Re: Crf450 rear master cylinder
Post by: zcarlson12 on April 19, 2022, 08:11:19 AM
broken1, worth a shot thanks for the tip

Joe yes that is it. I wanted to get rid of the hose so I thought it would be pretty easily swapped out. Turning out to be the other way around lol.
Title: Re: Crf450 rear master cylinder
Post by: zcarlson12 on April 19, 2022, 10:01:27 AM
Here’s a picture without the pedal on I’ll get one later today with it on.
Title: Re: Crf450 rear master cylinder
Post by: sameltoe on April 19, 2022, 06:38:20 PM
Mike's custom machine is who I had make that bracket in the above pic. Easy swap after that. They are a pain to bleed tho. Mike also made me a threaded washer that goes on plunger so you can have a return spring that's self contained.