Brake Issue
 

So a little history 2000 Boxster S brakes are about three years replaced rotors and pads .I do a brake flush every year.
Driving home from work a couple of weeks ago the rear brakes develop some issue . I'm on the free way doing 80 ish within a few miles I pull off because I feel the cars brakes dragging . Both rotors are blue they got so hot the brakes were locked up. I get the car home and try to bleed some fluid off .No way I cant get any fluid through the system by pressing the brake peddle. I have replace both rear calipers and rotors and pads .Put in a new master cylinder .Vacuum bleed the system at all 4 corners . I go for a test drive and passenger rear rotor is noticeably hotter than driver side .Assume I got a bad caliper .exchange it for another do another bleed and same issue . I have checked the parking brake and its not the problem .S.O.S. Cant afford to take to dealer. I'm at a loss and would really appreciate some of your thoughts as to what the problem could be .Thank you guys .JEFFPA What do you think?

Gabe, I am not an expert by any means but ran into a similar situation many years ago.., where the rear calipers were locking up after the brake fluid expanded by heat.

Because after replacing the master cylinder, I over adjusted the pedal travel and the solution was to loose a bit the adjustment between the pedal and the master cylinder (allowing a bit of extra play on the pedal).

Something to check anyway, Good Luck!

When was the last time the rubber lines we changed? As they age they have a tendency to swell and restrict flow.

I have not replaced the rubber lines .But today did buy some stainless lines from Pellicans they will be here next week . Really hope that's the problem as I am baffled by this .

Have the front wheel bearings been changed recently? The ABS system have any fault codes? Have you checked that the wheel speed sensors are clean and in place, wiring good? If the ABS gets incorrect wheel speed data from the front wheels it will apply rear brakes to attempt to control wheel speed difference.

2ooo boxster s No traction control . No abs codes .Looks like theirs is only one hydraulic line from the ABS pump to a Tee on driver side rear .Both rear brakes controlled from one line .If it is an ABS should it not cause both rear calipers to stick?

Just going by the info you posted above in red. Traction control is not necessary for ABS to control wheel lock up. The 2000 has 3 channel ABS, so yes only one brake line to rear.

What tire sizes are you running front and rear?

with everything you've done trying to sort out the problem, it would be cheaper just to take it to a shop for repair. you don't need to pay dealership rates; there's lots of independent shops in Houston

i am having the same issue with my 1998 Boxster. we replaced brake lines, calipers rotors and the master cylinder. Today all 4 wheels locked up on me just barely made it home. Only thing we haven’t replaced is the brake booster. Did you find a solution your problem?

Replacing master cylinder , rear calipers , rotors and all brake lines , pads pulled all the lines off abs pump blew compressed air thru all the lines , vacuum bled system fixed my problem .

did the op of this thread find the solution to his brake system issues?

I'm having same issues of rear brakes locking up and cannot bleed the system,

thinking to replace the original rubber brake lines... then look at abs pump, then maybe booster though it's acting properly..

my test for the booster? turn off car, pump the brake and it would go from 3/4 travel, second pump 1/2 the travel, third pump of the brakes 1/3 travel.... suspect it's not the booster

i have 2000 boxster S with 65,000 miles on it

blow out abs pump is the next step

I replaced the rubber lines with stainless .Replaced both rear calipers .Replaced the master cylinder . I removed all the hard line from from the ABS Pump and with the lines disconnected at the rear blew compressed air thru all the lines . Put everything back together and my brakes have been fine ever since doing this.

I've had a '99 and '04 that had corrosion in the brake booster. The brakes would stick and drag, but also the pedal would stay part way down. It sounds like your pedal is working normally, so I'm thinking ABS unit as well. Probably no help, but here's the Booster replacement.
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super advice... after checking fluid at the master cylinder, abs unit and rear calipers, i found the front caliper is working as expected. pump and hold the brake and the juice flows out of both sides of the front calipers.

pump and hold the rears and i get some fluid like a trickle to the passenger side rear outside bleeder only and none on the inside, and on the driver's side rear bleeder absolutely none...

so thinking i'll blow out the lines - following advice from above posting reply and blow out the lines all the way to rear and rebuild the rear calipers - fresh piston seal and dust cover, silicon grease so as to not damage the rubber seals

if that's doesn't get the brake juice flowing, i'll look at abs unit... cracked all the six lines on the abs unit - 2 x 13mm and 4 x 11mm and all six had good flow from the master cylinder, i didn't crack the four 11mm that feed the four calipers yet...

I did have good flow from the rear rubber lines (one each side) with rear calipers disconnected and used a m10x1.0 pitch bolt and chunk of rubber so i'd have brakes enough to safely drive the boxster around the corner to my storage - running no rear brakes and only the fronts... spongy as it's difficult to fully bleed the system with this set up!! And actually had decent braking from the front brakes only... must be the four pistons fronts!!

so good to hear your fix worked out and still going strong after four/five months... i had same/similar symptoms to the point my brakes were glowing red hot and rear brake wear indicator(s) were on fire... shopping for a used abs unit... what dies on these units? looking through the schematics, they seem very simple. rigging up a micro computer to open and close the valves to clear out any gunk... and my unit looks like it came out of the showroom. unlike the rest of the car!!

Gents,
I ordered the URO brake master cylinder from ******************************** and installed last week.

prior to the install i could not push any fluid to the rear brakes. fronts oddly were fine.

once new m/c installed, i was able to pump the fluid through, then bleed with motul 5.1

all good so far.

i was going on a bit of a wild goose chase with new abs units, brake booster upgrade (which my 2000 boxster S was built in late 1999 and was on the cusp of gen 1 986 vs gen 2 986.

hammered the brakes a bunch of times in the dry and rain this past weeks to activate the abs. I hadn't really got the abs to work in months, maybe years... and last major drive was in a snow storm in Feb so when i pulled it out in the spring and the rear brakes seized, i was somewhat baffled esp with a 60,000 mile boxster

fixed for now!!