Brake bleeding and firmness

Hello all,

I am doing my first brake bleed on the dent style brake cylinder and I reviewed the wonderful Power Republic video.

Question 1: I always thought to bleed the brakes you would have the reservoir closed when the nipple is open or else it would pull in air but on the video that’s not the case….?

Question 2: I will be replacing the pads at the same time, will this help increase the firmness and stopping power?

Question 3: By getting out the air bubbles is this what increases the firmness and braking power?

Question 4: Are aftermarket pads ok or is it always worth it to use OEM?

Thank you

I think what happens is the air bubbles create slack in the brake system. The brake fluid compresses the brake clamping and if there are bubbles, you can imagine that that creates a point of no pressure. So the pedal has to travel past that point, lengthening the throw.

Unbled brakes feel soft. You have to push down a lot to get it to bite. Freshly bled brakes feel very sharp.

I think there’s two points: on the master cylinder is the thread you attach gravity feed. On the caliper is the cap you remove to bleed the brakes. This creates an open system where gravity is pushing the brake fluid downwards into the MC, thus pushing air out the caliper exit.

Really good explanation:

This makes sense, thank you

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  1. As long as the fluid level doesn’t get near the bottom of the reservoir, you won’t introduce air into the system. What you may have to watch for when bleeding with cap off is that when the brake pedal is depressed, you may have a small geyser of fluid shoot straight up. Just go slow and it shouldn’t be a problem. And be sure to close the nipple before releasing the brake.

  2. I would guess that this would just depend on the condition of the old pads. For cars anyway I find it takes a little bit before the pads bed in to the rotor

  3. IME for the most part yes. Comes down to the compression of air within the fluid causing the spongy feeling.

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ok great, will do. Thank you

1, 2 & 3 - what Mike said.
4 - It depends. I have heard some of the aftermarket pads are pretty decent and save you a few bucks. It really comes down to quality, durability and performance. Aftermarket pads can be capable of doing the job. Personally, the price difference was not enough for me to try them.

Many manufacturers will have different compounds available (soft, medium or hard). I used the OTK standard pad (soft) at first and they did well giving both good feel and stopping power, however they wore out quickly. I switched to the “hard sintered” pad and although I noticed a slight drop in initial bite when applying the pedal I gained a huge increase in lifespan. No real difference in stopping distance, just a little more force on the pedal. I suspect the aftermarket pads will yield similar results. You will just have to test them out and see.

I’ll have to try them both out. Thank you