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Brake Calipers inquiry

972 Views 21 Replies 6 Participants Last post by  93celicaconv
I am writing this because I am unsure if there are any differences between the brake calipers between the USDM and JDM 6th gen celica.
The issue that I am having is that when you let off the brakes the calipers dont release/relieve pressure on the brakes causing friction that results in loss of efficiency and takes more power to move the car while generating excess heat, so I am looking to replace all 4 on my ST202.
in a bit of an extension I also am curious about stuff like the Super Strut Suspension if that is the same as the USDM struts that are available.
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· One with the farce
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The only way your calipers won’t release is if they are seized. Otherwise, it’s completely normal for the pads to be in slight contact during driving. You don’t want the pads to “pull away” from the rotors, otherwise there would be excessive pedal travel before the brakes would apply.
mad for the super strut suspension, it’s not just a different strut…it’s a different suspension and very expensive. Apparently people with super strut suspension convert theirs to normal style because of the replacement cost
 

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Discussion Starter · #3 ·
I have an issue where i am losing about 30 percent of the fuel efficiency i should be getting because two of them will not release pressure at all and those 2 wheels are next to impossible to rotate when the car is on a lift and in neutral, whereas the other 2 wheels will spin freely
In regards to the super strut suspension I am trying to keep the car as OEM as possible so I bit the bullet on a pair of front struts
 

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Discussion Starter · #5 ·
what i did to determine the calipers are most likely the problem was putting the car on a lift, releasing the hand brake, putting it in neutral, and noticing 2 of my wheels will spin freely (the ones on the left side) but the ones on the right side are locked up and require my full body weight to try to even budge the wheel. After taking a flat head screwdriver and manually relieving the pressure on the 2 problem calipers the wheels would spin freely.
After seeing that the wheel would spin freely after relieving the pressure, i engaged the brakes only to find the same wheels have the same issue again while the others didnt
Some symptoms are, loss of power and fuel efficiency, affected wheels got to 250 degrees F after about an hour of stop and go driving
 

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After taking a flat head screwdriver and manually relieving the pressure on the 2 problem calipers the wheels would spin freely.
Sorry, but I have to understand you better. How did using a flat head screwdriver relieve pressure? What are you doing with the screwdriver?

The way to relieve brake fluid pressure at a suspect caliper is to open the bleeder on that caliper a bit (best to put a clear tube over the nipple of the bleeder and have that tube go up vertically, so as not to allow air to enter the caliper). That will relieve pressure. Does the wheel turn freely then? If not, you don't have a problem with locally blocked brake fluid pressure on certain calipers. You most likely have corrosion in the cylinder of the caliper that prevents the piston from retracting once brake fluid pressure is relieved.

If you provide me your Celica's VIN (or frame number), I can look up your specific Celica and compare it to USDM models regarding brake caliper commonality.
 

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Discussion Starter · #9 ·
Its too late to take my own pictures but the way my coworker who used to be a mechanic showed me is the technique displayed at 58 seconds in this video
, simply using a flathead screwdriver as a lever to slowly retract the caliper a bit, and as I said, doing so releases the pressure allowing the wheel to spin freely until i hit the brakes again and they get stuck again.
In the morning I'll grab the body code as it's late at night for me here
 

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If for some reason, the brake line feeding that caliper wasn't dropping pressure after the brake foot pedal is released, the method shown does nothing to relieve that brake fluid pressure. It simply would be a way to force the piston back against that pressure. It does relieve the force the piston had against the caliper though, as the piston is sticking inside the caliper (due to corrosion from neglected brake fluid changes), and it needs a lot of force to move the piston in the caliper cylinder that has corrosion.

Looking forward to seeing your VIN or frame number to see if I can help you with the caliper options for you.
 

· One with the farce
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If for some reason, the brake line feeding that caliper wasn't dropping pressure after the brake foot pedal is released, the method shown does nothing to relieve that brake fluid pressure. It simply would be a way to force the piston back against that pressure. It does relieve the force the piston had against the caliper though, as the piston is sticking inside the caliper (due to corrosion from neglected brake fluid changes), and it needs a lot of force to move the piston in the caliper cylinder that has corrosion.

Looking forward to seeing your VIN or frame number to see if I can help you with the caliper options for you.
Actually there is no built up pressure in the line between the piston and the master cylinder, other than when brake pedal pressure is applied. The caliper does not release because either the piston(s) or the slide pin(s, if so equipped) are seized. Using a screwdriver to retract the piston slightly is better than opening up the bleed screw, as doing that doesn’t retract the piston.
 

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Actually there is no built up pressure in the line between the piston and the master cylinder, other than when brake pedal pressure is applied.
Generally, this is true. But I've seen this condition - with the cause being very neglected brake fluid that caused enough corrosion that the proportioning valve for the rear brakes, on one side, was plugged up enough with corrosion that it acted as a pretty darn good check valve. So this can't be ruled out. I would say rare, but still possible.
 

· One with the farce
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That would be an extremely rare instance for sure, and would be prudent to include that in the list of causes.
 

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Discussion Starter · #14 · (Edited)
If for some reason, the brake line feeding that caliper wasn't dropping pressure after the brake foot pedal is released, the method shown does nothing to relieve that brake fluid pressure. It simply would be a way to force the piston back against that pressure. It does relieve the force the piston had against the caliper though, as the piston is sticking inside the caliper (due to corrosion from neglected brake fluid changes), and it needs a lot of force to move the piston in the caliper cylinder that has corrosion.

Looking forward to seeing your VIN or frame number to see if I can help you with the caliper options for you.
The model number is going to be: E-ST202-BLPZF if thats enough information, a little reluctant sharing the actual frame number at the moment. The year for the vehicle is going to be 1997
 

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Lets ASSume the flex lines are plugged internally. Release the pressure due to the lines acting like a check valve and the calipers free up. Try releasing the lines where they come from the master cylinder, not the other end. If the pressure does NOT release then it's the lines.
 

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Your Front RH Caliper is Toyota P/N: 47730-20530
Your Front LH Caliper is Toyota P/N: 47750-20530
Your Rear RH Caliper is Toyota P/N: 47730-20540
Your Rear LH Caliper is Toyota P/N: 47750-20540

Both your rear caliper part numbers are consistent with the USDM 6th Gen Toyota Celia ST & GT models.

Both your front caliper part numbers are not used on any USDM Toyota models. USDM 6th Gen Toyota Celica ST & GT models used Toyota P/N's: RH: 47730-20520 / LH: 47750-20520. The pistons used in these calipers also differ in part numbers, as do the brackets that hold the caliper to the front hub knuckles. The front brake pads also differ in part numbers.

Note sure if this helps you or not. But, to be honest, I would think you would be able to purchase aftermarket refurbished calipers through an automotive parts store in Japan for the front right anyway. Amayama.com (out of Japan) has a new OEM front RH caliper assembly but is very expensive ($469.25 USD w/o shipping).

Rectangle Font Parallel Screenshot Number
 

· just a nobody
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Its too late to take my own pictures but the way my coworker who used to be a mechanic showed me is the technique displayed at 58 seconds in this video
, simply using a flathead screwdriver as a lever to slowly retract the caliper a bit, and as I said, doing so releases the pressure allowing the wheel to spin freely until i hit the brakes again and they get stuck again.
In the morning I'll grab the body code as it's late at night for me here
In other words, you haven't really done anything to determine why the brakes are dragging; the video is only about pushing the pads and piston back, nothing to do with diagnosing the issue you have!
Your problem might be as simple as the slider pins are sticking, but you do need to take things apart to determine that!

Just saying!
 

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Discussion Starter · #18 ·
Your Front RH Caliper is Toyota P/N: 47730-20530
Your Front LH Caliper is Toyota P/N: 47750-20530
Your Rear RH Caliper is Toyota P/N: 47730-20540
Your Rear LH Caliper is Toyota P/N: 47750-20540

Both your rear caliper part numbers are consistent with the USDM 6th Gen Toyota Celia ST & GT models.

Both your front caliper part numbers are not used on any USDM Toyota models. USDM 6th Gen Toyota Celica ST & GT models used Toyota P/N's: RH: 47730-20520 / LH: 47750-20520. The pistons used in these calipers also differ in part numbers, as do the brackets that hold the caliper to the front hub knuckles. The front brake pads also differ in part numbers.

Note sure if this helps you or not. But, to be honest, I would think you would be able to purchase aftermarket refurbished calipers through an automotive parts store in Japan for the front right anyway. Amayama.com (out of Japan) has a new OEM front RH caliper assembly but is very expensive ($469.25 USD w/o shipping).

View attachment 404511
The part numbers are going to be a life saver however that one listing is extreme as I was able to find a pair of new old stock of compatible calipers that I could get shipped from Europe for about 330 total
Thanks for the assistance , I'll look into some of the other theories that were brought up before ordering calipers but I feel somewhat confident that is the issue.
 

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Discussion Starter · #19 ·
F it I'm gonna try my hand at the local dealership see what they are capable of and if it would be any cheaper then finding a bizarre import somewhere. Worst case scenario they look at me like I am speaking in tongues, best case scenario i get oem hardware which would be nice for my goal with the car
 

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what i did to determine the calipers are most likely the problem was putting the car on a lift, releasing the hand brake, putting it in neutral, and noticing 2 of my wheels will spin freely (the ones on the left side) but the ones on the right side are locked up and require my full body weight to try to even budge the wheel. After taking a flat head screwdriver and manually relieving the pressure on the 2 problem calipers the wheels would spin freely.
After seeing that the wheel would spin freely after relieving the pressure, i engaged the brakes only to find the same wheels have the same issue again while the others didnt
Some symptoms are, loss of power and fuel efficiency, affected wheels got to 250 degrees F after about an hour of stop and go driving
Could this be a master cylinder issue? Or possibly ABS?
 
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