replacing brake calipers - pinch line or not?

[Alow]

I am going to replace the calipers in my 1. As so, I have to disconnect the brake line. Should I pinch it before I do so or not?

I've read that if you don't pinch it, you may get air in the line and have to bleed it. The other side of the argument is that even if you pinch it, you have to bleed it, as air may still get in there.. Plus you may damage the brake line when pinching it..

So if you are going to bleed anyway, why pinch it? I am thinking I won't, and I'll just bleed the entire system when I am done.

Can anyone comment?

[bluemoon]

Not, instead of pinching the line wedge a stick against the brake pedal and the seat frame. You don't have to depress the pedal all the way down. Just enough to prevent brake fluid from leaking from the lines when you disconnect them from the calipers. It will also keep air from entering the lines as well. Use a small catch bowl to collect the few drops that will leak out. You should bleed the brakes after the lines are reconnected.

[Dackelone]

Hydraulic brake lines might be have rubber O.D. hoses... but inisde (I.D.) they have a hardend inner hose linning. There is no way you can crimp that hose shut to prevent fluid from leaking out. Best thing would be to use a (some sort of)rubber cap on the hose/line ends.

I would highly reccomend you using a pressure bleeder. Like the Motive(euro) one. Best $50 I ever spent! You will need about 2 liters of super DOT-4 brake fluid. It is better to have more on hand than less. Trust me!

SO... I guess you are putting on some Performance (yellow) calipers?

[dread1]

just bleeding the thing you lazy person.

[moveswiftly]

Originally Posted by dread1

just bleeding the thing you lazy person.

[BrokenVert]

+1 on the motive pressure bleeder. I've got one and it's amazingly easy.

But maybe it's because I've never done a brake job on a bimmer but why would you need to diconnect the brake line while changing pads? I Always just wedge some 1/4 inch pieces of wood so that the pistons can't compress while I'm changing the pads on the other side of the car.

[moveswiftly]

Originally Posted by BrokenVert

+1 on the motive pressure bleeder. I've got one and it's amazingly easy.

But maybe it's because I've never done a brake job on a bimmer but why would you need to diconnect the brake line while changing pads? I Always just wedge some 1/4 inch pieces of wood so that the pistons can't compress while I'm changing the pads on the other side of the car.

There's no reason for the pistons to compress unless you have your foot on the brake lol... are you bleeding brakes and changing pads at the same time

[BrokenVert]

Originally Posted by chesterfan1230

There's no reason for the pistons to compress unless you have your foot on the brake lol... are you bleeding brakes and changing pads at the same time

On all of the fords I've worked on you need to recompress the piston inorder to fit the new caliper. When you push back one set of pistons you damn well better make sure that the other set cant move.

[moveswiftly]

Originally Posted by BrokenVert

On all of the fords I've worked on you need to recompress the piston inorder to fit the new caliper. When you push back one set of pistons you damn well better make sure that the other set cant move.

oo i see...on our cars u just need to use a clamp to expand the pistons the new pad will fit.

[Alow]

Originally Posted by Dackelone

Hydraulic brake lines might be have rubber O.D. hoses... but inisde (I.D.) they have a hardend inner hose linning. There is no way you can crimp that hose shut to prevent fluid from leaking out. Best thing would be to use a (some sort of)rubber cap on the hose/line ends.

I would highly reccomend you using a pressure bleeder. Like the Motive(euro) one. Best $50 I ever spent! You will need about 2 liters of super DOT-4 brake fluid. It is better to have more on hand than less. Trust me!SO... I guess you are putting on some Performance (yellow) calipers?

Yes, putting on performance brakes Yep, have a Motive pressure bleeder. I haven't used it on the BMW yet, but have used it extensively on my VW. I just need to go get the brake fluid for the BMW. I only have Motul and I don't think I want to use it on this car since its a daily driver for now.

Originally Posted by BrokenVert

But maybe it's because I've never done a brake job on a bimmer but why would you need to diconnect the brake line while changing pads? I Always just wedge some 1/4 inch pieces of wood so that the pistons can't compress while I'm changing the pads on the other side of the car.

I am not just changing pads, changing everything: pads, rotors and calipers.

Thanks for your comments. I've decided to not try to pinch it. I'm however stuck on fitting the brake pad sensor. Can't figure out how it goes. I also got a new clip with the kit that I am supposed to use for it and of course I don't know where it goes :-/

Could anyone please upload a pic of their 135i front brakes with the wheel off? or better yet, the performance brakes? Also, if you can turn the wheel toward the inside of the car so I can see where the brake pad sensor fits/routes that'd be extremely helpful!

[BrokenVert]

Originally Posted by chesterfan1230

oo i see...on our cars u just need to use a clamp to expand the pistons the new pad will fit.

more special tools to buy and fill the garage with I guess... I have tools in my garage that go to cars that family members sold 20 years ago...it's aweful

still wondering why the op needs to pull and then seal the brake line while doing a brake job tho

[Alow]

Originally Posted by BrokenVert

still wondering why the op needs to pull and then seal the brake line while doing a brake job tho

Must've posted while I was posting. I am changing calipers too

I think I figured my issue thanks to the photos on this thread:

http://www.1addicts.com/forums/showthread.php?t=212459

On the stock 128i, the brake pad sensor is routed like this:
Little black box -> hook up nearby in the chassis -> strut -> cap of caliper bleeder screw -> pads.

On the performance brakes (and 135i) it looks to be routed this way:
Little black box -> hook up nearby in the chassis -> strut -> pads. The clip is then used to hook the wire with the brake line (as per 3rd and 4th picture in thread I mentioned above).

[Evice]

I'd rather not take chance and bleed it no matter what. It is something you can't be cheap or lazy about. It is your stopping here you are wagering

You should also take alot of pictures!! I am going to do this brake job pretty soon as well

[moveswiftly]

Originally Posted by BrokenVert

more special tools to buy and fill the garage with I guess... I have tools in my garage that go to cars that family members sold 20 years ago...it's aweful

still wondering why the op needs to pull and then seal the brake line while doing a brake job tho

He's replacing rotors which requires removal of stock line. So either he caps the line or plugs it somehow or pinch it. Either ways dude just bleed the brakes when your done.

[AussieRacer]

OMG, pulling apart the lines and considering not to bleed?!?!? Crazy thoughts!

[Alow]

Originally Posted by AussieRacer

OMG, pulling apart the lines and considering not to bleed?!?!? Crazy thoughts!

Where did I say I was not going to bleed? I said I was going to bleed regardless of whether I plugged/pinched line or not

Originally Posted by Evice

You should also take alot of pictures!! I am going to do this brake job pretty soon as well

Okay, will do. I was thinking bout putting together a DIY. I think I might. It really is pretty easy once I figured some things out.

[Alow]

Originally Posted by chesterfan1230

He's replacing rotors which requires removal of stock line.....

Incorrect. replacing rotors does not require removal of brake line. Only when replacing the caliper.

If you are going to replace a rotor you can just take the caliper off (with the brake line attached) and support it on something while you change the rotor.