mytc05

Rear brake pistons won't compress for brake replacement

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Hey all,

I'm replacing my rear brakes, and the pistons won't compress down for my to fit it over the new brakes and rotor. With the Teves ABS system, is there something special I need to do to allow the pistons to compress down? I saw something where people were talking about bleeding the system. Do I have to open the bleeders as part of this process? Most cars you can just manually push the pistons down with the right tools, but these puppies aren't budging. Would definitely appreciate some guidance. Thanks!

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You should get yourself a service manual. I don't have one in front of me, but there is an access plug at the back of the caliper that you need to remove. There is an allen head adjuster that you will need to turn to retract the piston. Other members should be able to add more detailed guidance.

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I do know that when you flush the brake system, the front brakes will drain like traditional brakes on cars but the rear brakes have to have the ignition switch to the 'ON' position for them to drain.  When the ignition is in the 'ON' position the teves system is activated.

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Hey Garnet & Gold. So, to depress the piston in order to put the caliper back on, are you saying I need to have the key in the "on" position? 

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Posted (edited)

I'm out of my element here, but in my experience rear disc caliper pistons frequently need to be screwed back into the caliper, not merely pushed. You can usually tell if this is the case because the piston has notches on it designed for a tool, which you can buy cheaply at any auto parts store and attach to your 3/8 socket wrench. For example:

 

 

48249d1277592425-how-to-r56-rear-brake-pad-replacement-piston-compressed-jpg.60797

25961363_lis_28600_pri_larg.jpg

 

Again, sorry if this doesn't apply to the TC, I'm not familiar with them, but I do recall spending a particularly frustrating Saturday afternoon with a C-clamp trying to retract the rear calipers on my mother's Taurus SHO with no success. A neighbor spotted me losing my temper and showed me the way.

Edited by Matt Harwood (see edit history)

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Posted (edited)
8 hours ago, mytc05 said:

Hey Garnet & Gold. So, to depress the piston in order to put the caliper back on, are you saying I need to have the key in the "on" position? 

!!!!!!!! DISREGARD THE 2 “foreigners” that replied above. THEY DO NOT UNDERSTAND THE BRAKE CALIPERS ON OUR ‘TC by MASERATI’ automobiles!!!!!!


OK pal, here’s the scoop. At this point you will want the KEY OFF!

In order to RETRACT the piston into the caliper, you remove the aforementioned PLUG in the center, backside of the caliper, then insert a correct size ‘metric’ Allen wrench. I think it is 4mm or 5mm. Once the proper Allen wrench is inserted and engaged inside the the caliper, rotate the Allen wrench in a counter-clockwise direction until the piston is fully retracted.

Now you can finish the brake pad replacement and caliper installation.
Once assembled, you MUST adjust the brake pads. BEFORE anything else, loosen the tension on the parking brake cable by backing off on the 13mm adjustment nut for the cable adjustment. THEN be sure the parking brake arm on the caliper is fully released and able to move freely! ADJUST the brake pad clearance by rotating the Allen wrench clockwise until all clearance is taken up and the brake rotor is unmovable. NOW rotate the Allen wrench counter-clockwise until the rotor rotates with just a little drag. Remove the  Allen wrench and reinstall the plug securely. Repeat the entire process on the other rear caliper. WHEN BOTH CALIPERS ARE ADJUSTED, you may bleed the brake fluid if you plan to. When you are done, check brake pedal to verify you have a good pedal, this with the ABS pressure pumped up, KEY ON. If it feels good, it’s time to adjust the parking brake cable. You can snug up on the 13mm nut until the drag on the rotors increases, check parking brake pedal from time to time. It should lock the rear brakes at about the midpoint of its travel. One more time, VERIFY that there is not excessive drag on the rear brakes. FINALLY, you should be done. Lower the car to the ground and road test it CAREFULLY. Be sure the brake fluid is at the proper level, that there are no leaks.
HOPEFULLY YOU ARE THROUGH!

Edited by Hemi Dude
Misspelled word (see edit history)
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50 minutes ago, Hemi Dude said:

!!!!!!!! DISREGARD THE 2 “foreigners” that replied above. THEY DO NOT UNDERSTAND THE BRAKE CALIPERS ON OUR ‘TC by MASERATI’ automobiles!!!!!!


OK pal, here’s the scoop. At this point you will want the KEY OFF!

In order to RETRACT the piston into the caliper, you remove the aforementioned PLUG in the center, backside of the caliper, then insert a correct size ‘metric’ Allen wrench. I think it is 4mm or 5mm. Once the proper Allen wrench is inserted and engaged inside the the caliper, rotate the Allen wrench in a counter-clockwise direction until the piston is fully retracted.

Now you can finish the brake pad replacement and caliper installation.
Once assembled, you MUST adjust the brake pads. BEFORE anything else, loosen the tension on the parking brake cable by backing off on the 13mm adjustment nut for the cable adjustment. THEN be sure the parking brake arm on the caliper is fully released and able to move freely! ADJUST the brake pad clearance by rotating the Allen wrench clockwise until all clearance is taken up and the brake rotor is unmovable. NOW rotate the Allen wrench counter-clockwise until the rotor rotates with just a little drag. Remove the  Allen wrench and reinstall the plug securely. Repeat the entire process on the other rear caliper. WHEN BOTH CALIPERS ARE ADJUSTED, you may bleed the brake fluid if you plan to. When you are done, check brake pedal to verify you have a good pedal, this with the ABS pressure pumped up, KEY ON. If it feels good, it’s time to adjust the parking brake cable. You can snug up on the 13mm nut until the drag on the rotors increases, check parking brake pedal from time to time. It should lock the rear brakes at about the midpoint of its travel. One more time, VERIFY that there is not excessive drag on the rear brakes. FINALLY, you should be done. Lower the car to the ground and road test it CAREFULLY. Be sure the brake fluid is at the proper level, that there are no leaks.
HOPEFULLY YOU ARE THROUGH!

 

Thanks Hemi. Always impressed with your knowledge of our TC's! I am not the most mechanically advanced when it comes to work on cars, though I have okay knowledge and can often get by with some guidance. Usually, when I'm posting, it's to run things by you all for your guidance, and if I get in over my head, my dad helps me with these "projects". He was a Chrysler mechanic for years and then a service manager before he owned his own dealership. My grandfather has owned a Chrysler dealership for most of his life as well. That's why sometimes my verbiage might not be the best when I'm explaining an issue I'm having. I often am trying to relay what my dad has told me for y'all's input. I do have a TC service manual, but my dad and I didn't have it handy earlier when we were working on this, and I know our TC's have lots of unique little quirks. I figured there was something else up with this system (like the plug and Allen wrench adjustment), but just didn't know what. I knew we couldn't screw it in from the front. So, that's why I was confused. Thanks for pointing us in the right direction! Made quick work of it once I knew about the plug and Allen wrench adjustment on the back of the caliper. I just did a brake job on my newer vehicle myself about two weeks ago, and the piston pushed in pretty easily without any separate adjustments. So, that also was throwing me for a loop. Always appreciated Hemi! You save a lot of us many stressful hours of confusion and yanked out hairs! 🤪

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Just one short question here; Are you the writer of the articles on Allpar.com who tells the stories about his grandfather that had a Chrysler dealership back in the 1950 - 60's?

I sure enjoy reading them as I began as a mechanic in a DeSoto - Plymouth dealer in 1959.  I have owned MOPARS all my life starting with a 1948 Dodge 4 door sedan.

This car is one I use to service for its owner, John Schneider.

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To bleed the rear brakes the key must be on, and the brake pedal partially depressed to turn the pump on with the bleeder open on the rear caliper. Once no air is coming out (make sure that it doesn't suck the reservoir dry!), snug the bleed screw and let the pedal go. Don't let the pump run for more than about 60 seconds as it can overheat the circuit.

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