[///ASN]

Hi, came across something today and wonder if anyone knows what causing that.

Story:
My friend replacing brake rotor & pads today, eventually it's night time and he started and moved the car to get more lights.
*But he didn't put the brake pads back on the car while moving it.

Then he found that he could no longer push the caliper piston back.
My brake pads spreader tool also broke when he forced it. Used whatever tools available still couldn't push it back.
Then tried releasing the brake fluid from the valve and thought the piston can be pushed back, no luck.

Took the whole caliper off the car and no matter how much force and tools used, no luck. The piston is just not wanting to go back anymore.

Planning to get the car towed to a workshop tomorrow.

I am guessing the piston is stuck since he drove the car and used the brake without the pads on?
If so, why the piston will get stuck if the pads aren't there?
Just want to know the theory behind it.

[vtl]

What kind of car is it? Front or rear? Rear could have a self adjusting handbrake in the caliper which might require you to use a different tool to retract it.

[juld0zer]

Post up a photo. Vtl is probably on the right track but being on the E90 forum, i've never seen an E90 with a caliper handbrake.

Other possibility is the piston has popped out all the way and you guys are trying to drive it in wonky or it is sitting on the edge of the bore. But that is a bit farfetched.

Even if it has popped out, just buy a rebuild kit and take the caliper off to a brake shop and get them to rebuild it for you. Push down and hold the brake pedal down with some wood or a jack stand to avoid emptying the fluid reservoir and causing more problems

[///ASN]

Originally Posted by vtl

What kind of car is it? Front or rear? Rear could have a self adjusting handbrake in the caliper which might require you to use a different tool to retract it.

It's a 1994 integra vti R
The brake is for the front, and pretty sure they are the floating caliper as I helped him did the right front and the piston went back nice and easy with the brake pad spreader tool.
It's just the piston on the left front that didn't go back.

But again, I am guessing if it is due to the brake pads on the left were not there when he moved the car and causing the piston pushing out from the caliper too much?

*read from the internet last night, if it is the rear brake, some people saying turning while pushing.

[///ASN]

Originally Posted by juld0zer

Post up a photo. Vtl is probably on the right track but being on the E90 forum, i've never seen an E90 with a caliper handbrake.

Other possibility is the piston has popped out all the way and you guys are trying to drive it in wonky or it is sitting on the edge of the bore. But that is a bit farfetched.

Even if it has popped out, just buy a rebuild kit and take the caliper off to a brake shop and get them to rebuild it for you. Push down and hold the brake pedal down with some wood or a jack stand to avoid emptying the fluid reservoir and causing more problems

My guess is the piston has popped out way too much since the brake pads were not there when he pressed the brake pedal.

but why can't a piston be popped out too much? And what if the brake pads are totally worn, will that make the piston extended too much as well?

Why pressing & hold the brake pedal will avoid emptying the reservior?
I thought pressing the pedal will only "push" the fluid to the wheel instead?
Just out of curiosity, what could happen if all brake fluid is drained out?

[insanesam]

As I recall for Honda's the piston looks like a big screw head. You need to push and turn it at the same time

[vtl]

I could be wrong but isn't an Integra is a Honda and not a BMW?

[///ASN]

Originally Posted by insanesam

As I recall for Honda's the piston looks like a big screw head. You need to push and turn it at the same time

But with the right front, the piston can simply be pushed back to the housing?

[///ASN]

Originally Posted by vtl

I could be wrong but isn't an Integra is a Honda and not a BMW?

Yes, it is a Honda, it's not a BMW but just thought if anyone might know about the mechanism of the piston.

I thought if the BMW piston will have the same problem and if so, what causing that

[insanesam]

Originally Posted by ///ASN

But with the right front, the piston can simply be pushed back to the housing?

The front is different to the rear. I think the parking brake is built into the calliper for hondas

[juld0zer]

By pushing the brake pedal down and holding it down, you close the port in the master cylinder that allows fluid to leave/return to the reservoir. If you don't, then you'll get air in the ABS module if the Honda is ABS equipped. Either way, you'll be up for a full bleed if the reservoir empties. You will lose some fluid when you disconnect the caliper but it will be very marginal - just enough to relieve the pressure and whatever dribbles from the hose

You will need to strip back the piston boot to see what's going on. Part of rebuilding a caliper involves sliding the new boot onto the piston then refitting the piston - this allows you to see where you are going.

Usually brake designers stipulate a minimum pad thickness to account for the potential of the piston popping out if both pads on a caliper were to be worn to metal - which for some cars is a real possibility. BMW specifies 3mm as minimum pad thickness but IMO that is a bit generous.

So stepping on the brake pedal with no pads in place and popping out the piston, especially on the front is a real possibility. However it is usually accompanied by a loss of fluid. Try twisting the piston and pushing gently but squarely at the same time.

[Hoper]

Originally Posted by juld0zer

By pushing the brake pedal down and holding it down, you close the port in the master cylinder that allows fluid to leave/return to the reservoir. If you don't, then you'll get air in the ABS module if the Honda is ABS equipped. Either way, you'll be up for a full bleed if the reservoir empties. You will lose some fluid when you disconnect the caliper but it will be very marginal - just enough to relieve the pressure and whatever dribbles from the hose

You will need to strip back the piston boot to see what's going on. Part of rebuilding a caliper involves sliding the new boot onto the piston then refitting the piston - this allows you to see where you are going.

Usually brake designers stipulate a minimum pad thickness to account for the potential of the piston popping out if both pads on a caliper were to be worn to metal - which for some cars is a real possibility. BMW specifies 3mm as minimum pad thickness but IMO that is a bit generous.

So stepping on the brake pedal with no pads in place and popping out the piston, especially on the front is a real possibility. However it is usually accompanied by a loss of fluid. Try twisting the piston and pushing gently but squarely at the same time.

If you've broken the brake retractor tool its likely that the piston wasn't square, and if it's partly in it could be really jammed now depending on how much force the tool put on it

follow the advice you've been given, buy the rebuild kit, pull the caliper apart, you should be able to see what's happening, if you're lucky the piston won't be jammed in on an angle...good luck

[Socket]

I have nothing constructive to contribute to this thread

[_ink]

Originally Posted by Socket

I have nothing constructive to contribute to this thread

Haha.. Honda DIY advice in a bimmer forum.. first for everything!

[juld0zer]

I guess we're a bit more sensible here.
At least our suggestions didn't involve cable ties, duct tape, Plastidip, stickerbombing and some spacers.

[///Mposter]

There are tons of 1994 integras around. Might be better if you could salvage one from a used car. Pinch the soft line, remove the caliper, replace with used one, remove clamp, bleed that one side .

Or take a C -clamp, preferably a 4" to 5" , and tighten the clamp until the Piston goes back in. I'd use the old brake pads as a flat surface since the integra pistons are concave like a cup.
Good luck!

[///ASN]

Thanks for everyone comments.

I posted it only because I was trying to help my friend out, I did some research online before I posted it here and thought people here may have been DIYing their cars for years who may have extensive knowledge or came across something similar with this before (regardless of what make or model).

Again, I apologize for posting something that is not BMW related on this BMW forum.

[juld0zer]

I personally dont have an issue with people asking general questions even if we are a BMW forum. Most of the technically minded folks hang here and not in the pub sections anyway haha

How did you go? Rip it apart yet?