A few questions about a disk brake job

[Buck]

I completed a brake job on my 88 Toyota 2WD truck today, installing new pads according to Eric’s wonderful video “Front Disc Brakes and How to Replace Them.” Thank you for the great advice. It was extremely valuable, as this was the first time I’ve done my own brakes. If a picture is worth a 1,000 words, then a video is worth a million. Overall the result was good, but not perfect, as I’ll explain.

First, Eric recommends silicone paste for the lubricant. I was at Advance Auto Parts and they did not have silicone paste, or know what it was. I ended up using Permatex Ultra Disc Brake Caliper Lube (#85188), and although it contains petroleum distillates, it states that it “protects rubber seals from drying out.” I hope using this stuff and not using silicone paste doesn’t doom me to replacing all the rubber boots, because I did not use silicone paste. Any opinions?

Next – while attempting to press the piston back on the first one I worked on, I first clamped the brake line as Eric suggests, then opened the bleeder, with tubing and receptacle attached. Using a big channel-lock, I tried to compress it, but it did not budge. Then tried using a C-clamp, and still no movement. No brake fluid was exiting the bleeder. Then I took the vice-grip off the brake line, and compressed the piston back with ease. Still no fluid exiting the bleeder, but at least I could continue with the remainder of that brake. On the other side, Eric’s procedure was textbook, working just as he explains it. Not sure if there is a problem with the first side (yet), but maybe some of you more experienced techs can advise me.

Last (and possibly related to the issue just discussed), and actually the bigger concern … before test driving, I pumped the brake pedal until it felt normal, then refilled the brake fluid reservoir. The braking is much improved, but the pedal is not smooth as it is pressed. It will start fine, and braking occurs. Resistance builds as one would expect, but then it lets up just a bit for a split second (almost like a bump) and then builds again. Braking is smooth, but the feel of the pedal is not. Is this possibly related to the absence of any fluid exiting the bleeder valve as earlier described?

Absent any other advice, my next step is to bleed the whole system, as the brake fluid needs to be entirely replaced. If I can’t get any fluid to come through the bleeder valve, then I have to assume there is some blockage in the line. Insights? Comments? Suggestions? Wisdom?

Thanks for the assistance.

Topic

[celticbhoy]

Did you gravity bleed the lines? No sure what could cause a rough pedal when depressing but I always gravity bleed the lines when replacing brake pads.

[Buck]

Thanks. First time doing a brake job, and the Eric video did not mention it, so I did not. However, that is the next thing I will do, and hopefully it will correct it. I am concerned that no fluid exited the bleeder valve as I was compressing the piston, so there’s a good chance a gravity bleed will tell the full story.

The truck is obviously older (223K), and the caliper, etc. isn’t pristine by any means. Hopefully changing the brake fluid and bleeding the system will do the trick.

[nicholas large]

a blockage is highly unlikely but have you checked that you have not twisted a brake flex i pipe by accident ? i done this a few times when i first started out doing brakes it is easy to miss when refitting caliper to disc ? also does the brakes feel like they momentarily let go when pressing the peddle specially on down hill slopes ?

[pilotvp]

Before bleeding the entire system, unclog the bleeders. :cheer:

[Buck]

[quote=”pilotvp” post=52858]Before bleeding the entire system, unclog the bleeders. :cheer:[/quote]

To unclog the bleeder, should I simply remove it and make sure the orifice doesn’t have anything blocking it? Do I need to look for a blockage anywhere else? Thanks for the help.

[scott37300]

Sounds like your bleeder is blocked. When you clamped off the brake line and opened the bleeder and couldn’t press the piston back in the caliper it was because with a blocked bleeder the fluid had no where to go. Once you took the clamp off the line the fluid was able to be pressed back towards the master and fluid resovoir.

I’m not sure about the soft spot in your brakes, might be air in the lines. In my opinion a good brake job includes a fluid flush which you can do yourself. Also many manufacturers are making changing the fluid part of recomended maintenance. Brake fluid is hydroscopic(SP) and absorbs water. If it’s left in for years moisture from hot/cold cycles will get in the fluid and start to break it down. You can do the two person method for brake bleeding to replace all the fluid but I use a vacuum bleeder. You might be able to clear up your blocked bleeder by having a helper sit in the vehicle and pump the brakes a couple times and hold it. While you loosen the bleeder, sometimes the pressure from the brake fluid will push the blockage out the bleeder. Then while they are still holding the pedal down tighten the bleeder and repeat as needed. But try and clean the bleeder first with a pick or small drill bit by hand, don’t use a drill! Then try to push the blockage out with the brake fluid. Put a 2×4 under the brake pedal so it’s not allowed to drop all the way to the floor while your helper is pumping it. Sometimes since the pedal isn’t used to going that far there is some build up of gunk on the master and you can ruin a seal if you let it go farther then it’s used to.

There should be some videos on youtube about bleeding brakes and I think Eric even has one.

[Buck]

[quote=”scott37300″ post=52862]Sounds like your bleeder is blocked. When you clamped off the brake line and opened the bleeder and couldn’t press the piston back in the caliper it was because with a blocked bleeder the fluid had no where to go. Once you took the clamp off the line the fluid was able to be pressed back towards the master and fluid resovoir. [/quote]

That’s exactly what I was thinking. Planning to test the theory tonight.

[quote=”scott37300″ post=52862]I’m not sure about the soft spot in your brakes, might be air in the lines. In my opinion a good brake job includes a fluid flush which you can do yourself. Also many manufacturers are making changing the fluid part of recomended maintenance. Brake fluid is hydroscopic(SP) and absorbs water. If it’s left in for years moisture from hot/cold cycles will get in the fluid and start to break it down. You can do the two person method for brake bleeding to replace all the fluid but I use a vacuum bleeder. You might be able to clear up your blocked bleeder by having a helper sit in the vehicle and pump the brakes a couple times and hold it. While you loosen the bleeder, sometimes the pressure from the brake fluid will push the blockage out the bleeder. Then while they are still holding the pedal down tighten the bleeder and repeat as needed. But try and clean the bleeder first with a pick or small drill bit by hand, don’t use a drill! Then try to push the blockage out with the brake fluid. Put a 2×4 under the brake pedal so it’s not allowed to drop all the way to the floor while your helper is pumping it. Sometimes since the pedal isn’t used to going that far there is some build up of gunk on the master and you can ruin a seal if you let it go farther then it’s used to.

There should be some videos on youtube about bleeding brakes and I think Eric even has one.[/quote]

Thanks for the tips. Never would have thought to place a 2×4 under the pedal. After getting the blockage resolved (if that is the problem), I did plan on doing a brake fluid flush. The fluid in there is definitely more than a few years old, and pretty dark. There are 2 other vehicles in our household that will be getting the same treatment.

Eric’s videos were the impetus for me to do the brake job. Seeing was believing – that it was not as difficult as I had perceived it to be. Having a resource like this forum is great too.

[Dustin Hicks]

[quote=”Canoe” post=53004]Sounds like your bleeder is blocked. ….The fluid in there is definitely more than a few years old, and pretty dark. There are 2 other vehicles in our household that will be getting the same treatment.

Eric’s videos were the impetus for me to do the brake job. Seeing was believing – that it was not as difficult as I had perceived it to be. Having a resource like this forum is great too.[/quote]

+1 on the blocked bleeder. Just clean it out, or replace it. ‘Pretty dark’ brake fluid is a classic sign the system needs to be flushed. Brake fluid is usually a fairly clear light amber color.

[EricTheCarGuy]

As pointed out the bleeders can get rusty and blocked. If I encounter that issue I just remove the bleeder entirely and then try to compress the piston. If it compresses then, the bleeder is blocked. I normally clean up rusty bleeders with a wire wheel and then use a pick to get the rest of the rust out. Then I finish with a little compressed air and I’m good to go. Once you reinstall the bleeder it should work normally.

I don’t think using the disc brake lube was a good idea. Mixing lubricants in a caliper can cause issues. Mainly seizing of the pins. I would recommend that you look for silicone paste online and use that in the future. It has a lot more uses than just brakes.

As for how the brakes are feeling it’s hard to say. Go back and check your work to see if there is anything out of the ordinary. Also while you’re at it try using silicone paste instead of that brake lube. I wish they’d stop selling that stuff or just switch their formula to a silicone base to avoid issues.

[Author]

Replies