New Brakes, Brake pedal soft sometimes

Troymclure

Troymclure

New member
Hi all,

Last weekend I found some stuck pistons in my front calipers, so I decided to replace them and take the time to swap to braided stainless lines up front. I also threw in a set of new front pads.

After installing I went through and bled the brakes, including the rear and put everything back together. Went for a drive, and the pedal felt nice and firm, but randomly will have a really long throw. It feels like the pedal goes to the floor and then catches and brakes normally after. If the pedal starts going to the floor and I quickly tap the brakes, the pressure comes back and I get a firm pedal again.

So I go home and bleed the brakes another time or two, and same issue. From what Ive researched, this sounds like a master cylinder failure, but Im skeptical since I just replaced so much. Is it possible theres still air in there or something else going on? Really hoping its not the master, since I know thats an expensive part that needs to be put in at the dealer due to the damn abs scan tool needed to bleed the new master.
 
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Troymclure said:
Hi all,

Last weekend I found some stuck pistons in my front calipers, so I decided to replace them and take the time to swap to braided stainless lines up front. I also threw in a set of new front pads.

After installing I went through and bled the brakes, including the rear and put everything back together. Went for a drive, and the pedal felt nice and firm, but randomly will have a really long throw. It feels like the pedal goes to the floor and then catches and brakes normally after. If the pedal starts going to the floor and I quickly tap the brakes, the pressure comes back and I get a firm pedal again.

So I go home and bleed the brakes another time or two, and same issue. From what Ive researched, this sounds like a master cylinder failure, but Im skeptical since I just replaced so much. Is it possible theres still air in there or something else going on? Really hoping its not the master, since I know thats an expensive part that needs to be put in at the dealer due to the damn abs scan tool needed to bleed the new master.
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Did you let the master get empty when you bled the brakes? Sounds like air trapped in the MC to me
 
I had same issue a few years ago. Went thru several big cans of brake fluid. No joy. No one on here ever had this issue. Frigged around with it for 2 weeks. No luck and no one had any idea. Finally took it to a dealer and he bled it in 15 minutes at master cylinder. They were way better with his special bleeding tool.
All i can say is maybe give em a try.
I have had 4 fourth gens and this one is the worst on brakes. Softest i mean. Service guy tried saying these electric assisted brake are all soft feeling.
Its a pain. Hope this helps in your search.
 
Had the same issue. Dealer had to bail me out after 2 weeks every night bleeding the brakes and using gallons of fluid.
Dealer bled em at master cylinder. 15 min. 30 bucks.
I have owned 4 fourth gens and this one i have now has the worst softest brakes. Oh and pistons that sieze every year.
 
Champ306 said:
Had the same issue. Dealer had to bail me out after 2 weeks every night bleeding the brakes and using gallons of fluid.
Dealer bled em at master cylinder. 15 min. 30 bucks.
I have owned 4 fourth gens and this one i have now has the worst softest brakes. Oh and pistons that sieze every year.
Click to expand...

Yeah that makes sense, thanks. Ill take it in to the dealer this weekend hopefully and get it fixed. At least I can drive it in though, and dont have to get a tow truck
 
I have bled dozens of different vehicles' brake lines in my 45 years on this Earth and I can honestly say that the 4th gen T4R is the most "finicky" of ALL OF them! If you get air in the lines, you really have to bleed each wheel a MINIMUM of 10 pumps per wheel to be absolutely sure you get all of the air out. Just do a thorough bleeding on all 4 wheels and it should resolve your problem.
 
preacher35 said:
I have bled dozens of different vehicles' brake lines in my 45 years on this Earth and I can honestly say that the 4th gen T4R is the most "finicky" of ALL OF them! If you get air in the lines, you really have to bleed each wheel a MINIMUM of 10 pumps per wheel to be absolutely sure you get all of the air out. Just do a thorough bleeding on all 4 wheels and it should resolve your problem.
Click to expand...

I cant even count how many pumps Ive done on each wheel already over the course of a few days. I also feel like if it was air in the lines, the pedal would be soft all the time not just sometimes.
 
I had a similar issue after replacing my two front calipers.

Did you use Cardone reman calipers? If so, I have another theory. I think since these calipers have so many issues, they have a huge demand for remans and therefore continue to remanufacture calipers to the point where some of the ones can't be machined any more before going out of spec. I had two calipers that leaked from the seam between the two halves (very slight leak). I did some measuring and sure enough they were at the minimum thickness to allow for the rotor and new pads. Its possible that they have been machined too many times already to really have a good mating surface/seal between the two caliper halves.

After a third caliper I finally got a decent one. I had an intermittent soft pedal after installing the first two calipers. To check and see if you got any bad ones, have someone pump the brakes and watch the seam for any tiny tiny bubbles or fluid.
 
chitown40 said:
I had a similar issue after replacing my two front calipers.

Did you use Cardone reman calipers? If so, I have another theory. I think since these calipers have so many issues, they have a huge demand for remans and therefore continue to remanufacture calipers to the point where some of the ones can't be machined any more before going out of spec. I had two calipers that leaked from the seam between the two halves (very slight leak). I did some measuring and sure enough they were at the minimum thickness to allow for the rotor and new pads. Its possible that they have been machined too many times already to really have a good mating surface/seal between the two caliper halves.

After a third caliper I finally got a decent one. I had an intermittent soft pedal after installing the first two calipers. To check and see if you got any bad ones, have someone pump the brakes and watch the seam for any tiny tiny bubbles or fluid.
Click to expand...

Hmm interesting. I think I did use the cardone calipers. Are they the ones remanufactured by napa? Ill look into that before going to my appointment at the dealer to check. Thanks for the tip

EDIT: Just went and checked, didnt find any leakage from the caliper or any of the lines
 
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Update: dropped it off at the dealer today, and they bled the system including the master cylinder, and the problem persisted. So looking like the master cylinder may have failed. Theyre gonna have a specialist diagnose it tomorrow morning. Crossing my fingers its not, but theres not many options left at this point.
 
Troymclure said:
Update: dropped it off at the dealer today, and they bled the system including the master cylinder, and the problem persisted. So looking like the master cylinder may have failed. Theyre gonna have a specialist diagnose it tomorrow morning. Crossing my fingers its not, but theres not many options left at this point.
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Man, that sucks. If it is the master cylinder, that part is over $1k. Keep us posted.
 
They were way better with his special bleeding tool.
11i.jpg
AVe201
 
So Toyota wants to pull everything apart and check the whole brake system, since this is a safety issue. But they want to do the diagnosis to the tune of $800, which doesn't even include fixing anything they find wrong. So I basically told them to f off, Ill take it somewhere else. Now just to find a place that can figure it out.
 
Ok so my truck needs a new master cylinder. Planning to swap it myself, then get a tow to toyota to get it bled. Any idea on where to get a new master cylinder? Been having a hard time finding one. Local parts stores near me are asking close to $2000 so trying to get a bit cheaper online.
 
Troymclure said:
Ok so my truck needs a new master cylinder. Planning to swap it myself, then get a tow to toyota to get it bled. Any idea on where to get a new master cylinder? Been having a hard time finding one. Local parts stores near me are asking close to $2000 so trying to get a bit cheaper online.
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[MENTION=95421]Troymclure[/MENTION], the cheapest places to find a new, OEM brake MC (part#47201, which does NOT include the brake booster) that I could find are 1)Village Toyota Parts in Florida (they do mail order) for $1,016.00: BRAKE MASTER CYLINDER. Fits: 2004 TOYOTA 4Runner SR-5 4000CC 24-VALVE DOHC EFI, AUTOMATIC 5-SPEED | Village Toyota Parts

And OEMPARTS123.com for $1,014.00. Sorry, I do not have a link directly to the part page as, for some odd reason, their site will not allow me to cut/paste a specific link to their site. I have ordered from them in the past. Excellent service and prices. Anyway, I hope that helps you out!
 
preacher35 said:
[MENTION=95421]Troymclure[/MENTION], the cheapest places to find a new, OEM brake MC (part#47201, which does NOT include the brake booster) that I could find are 1)Village Toyota Parts in Florida (they do mail order) for $1,016.00: BRAKE MASTER CYLINDER. Fits: 2004 TOYOTA 4Runner SR-5 4000CC 24-VALVE DOHC EFI, AUTOMATIC 5-SPEED | Village Toyota Parts

And OEMPARTS123.com for $1,014.00. Sorry, I do not have a link directly to the part page as, for some odd reason, their site will not allow me to cut/paste a specific link to their site. I have ordered from them in the past. Excellent service and prices. Anyway, I hope that helps you out!
Click to expand...

Thank you very much, probably go with one of those. With those, I have to swap the electronics and hydraboost assembly on to the new master cylinder right? Im actually worried that theres an issue there too as my abs has been acting up, so I might try to buy the whole assembly. But that also looks like it adds $1000 so I dont know. Ugh, decisions, decisions.
 
So I decided to check out my brakes again, and went for a quick test drive. As soon as I started moving theres a terrible clanking noise. Turned around, and went home, put the truck up on a jack and had about a inch of play in the wheel. Turns out the wheel bearing exploded itself. So got it changed out today and went for another test drive. Turns out that was the issue the whole time.

The bearing had so much play, it would move the rotor around as I drove and would push the pistons back into the caliper as I drove. So then randomly I would get a soft pedal, and by tapping on the brakes I would re-seat the pistons against the pads and it would stop normally. So looks like its fixed. Definitely gonna keep an eye on it though.
 
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