Brake problems after axle swap.

[Joey7]

I have a m1009. I swapped in a 14 bolt in the rear and changed out front hubs on the front. Same calipers. Now I barely build any brake pressure. I changed the master which didn't help, and it seems like when I plug the rear line at the master it builds pressure just fine. I originally was thinking it might be the proportioning valve, but I'm seeing some people say you need a 1 ton master cylinder to accommodate the bigger wheel cylinders. Hopefully this is something common. Thanks,

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[Barrman]

Are the rear shoes adjusted properly? They set the pedal height.

 

[nyoffroad]

Barman's right, if those self-adjusters are screwed in all the way ( like when you assemble the brakes) then they will not contact the brake drum and will not adjust. All that will result in the brake pedal going almost to the floor. The adjusters should be screwed out until the drum lightly drags on the shoes and then backed off a couple clicks, get it close while assembly and then back up and hit the brakes, do that several times and the adjusters should finish tighten up to the proper spec.
This is assuming the brakes are bled of all air!

 

[gringeltaube]

........ but I'm seeing some people say you need a 1 ton master cylinder to accommodate the bigger wheel cylinders.

1st, do what nyoffroad suggested.
2nd, the stock rotors/calipers at front vs. the now bigger WCs (and drums) on the 14-bolt may cause a braking action imbalance, front/rear. That is, dragging your rear tires every time you need to stop fast...
In that case I would try to find WCs with a smaller I.D., or have the original parts sleeved and fitted with smaller pistons.

 

[ehuppert]

When you state "brake pressure" are you talking about low pedal, poor stopping, or spongy pedal? Actual hydraulic pressure to rear cylinders will be the same regardless of cylinder size. Braking "power" (stopping ability) may diminish due to wrong size, but hydraulic pressure in lines isn't affected....

Spongy pedal is air
Low firm pedal is adjustment


Do you get strong stream from rear bleeders when bleeding? If not it's air or something with MC. Proportioning valve off center would give firm pedal as would have no pressure to rear so probably not the problem...

Have seen rubber brake hoses collapse internally and cause no pressure, residual pressure, etc