Jump to content

Rear Rotor Clearance/Air in Brake Lines


Recommended Posts

I just finished installing new rotors and when I put them on there isn’t even space on both sides. The side closest to the bracket has less than a dime width vs the outside which has allot.

Short of it being normal to sometimes have an uneven gap so long as it doesn’t touch, I am going to have to assume a manufacturing problem with the rotors.

The fronts look good and are the same manufacturer.

Attached are picture of the old and the new which makes me think quality control on the rotors.

it also looks like my brake reservoir emptied while I was changing brake lines. Am in for trouble with the ABS system or will a simple bleed for all 4 calipers still be ok?

Anyone have any thoughts or experience with this.




Link to comment
Share on other sites

Have not put the tire on yet to get the rotor tight. But press fitting it seems to have clearance.


thing just got a whole lot more fun now too as I can’t fully compress the front calipers to get them over the new brakes and rotor.

tried everything but I think they are hanging up with rust on the piston for the last couple of mm’s I need.

Edited by Syd146
Link to comment
Share on other sites

I ended up pulling the calipers off to heat one of the bleeders anyway.

there is putting at the top end. Not ideal but don’t have options right now so I put them together after cleaning them off. They are fully retracted and move smoothly best of all they got around the brakes.

How would I know if the master cylinder did get air in it/ is having issues? The reservoir was empty but it filled up fairly quick.


also so many options for bleeding. Gravity or pressure. Some are saying never pressure as you push the master cylinder into an area it doesn’t normally get pressed into. Then others say you can’t gravity bleed air out. Very confusing.



Link to comment
Share on other sites

We always used pressure at my shop.  Never had any damage caused by the tools. 


If the res went dry, but the system was sealed and no one depressed the brake pedal, you are probably good.  If the res went dry while the system was open you have air.  If the res was dry and the system was sealed and you depressed the brake pedal, you have air.   You will most likely not be able to bleed the air using conventional methods.  You will have to bench bleed the master cylinder.  I have accomplished this "in car" many times on Subies.  But it is not fun, it is a practice session in extreme frustration. 

Link to comment
Share on other sites

Just bled them was pretty spongy at start. When I finally got to the front left there was allot of air and foam, then seemed to run clear no bubbles. Hardly any air from others though. Bleed about 500 ml.


So close to the finish line yet so far……

Put rear tires on and the wheels wouldn’t spin. Really starting to think the rear rotors aren’t to spec. They aren’t in the middle of the bracket and the pin against the top bolt on the tires are mounted. The top bolt on both brackets protrudes (it has a washer on it as well). The original rotors seem to be more in the center.

Going to check to see if both top and bottom bolts are the same length tomorrow.



Link to comment
Share on other sites

The Subaru won in the end swapped the brackets and thought I had enough clearance but when I mounted the tires they bound up and wouldn’t budge.

I did eventually get them to move with allot of force from both hands. Tried to run the car on 4 Jacks and they grind in the back. Worse though is the brake pedal shudders then compresses when the wheels stop. I am completely lost. Bench bled the master cylinder and then ran almost a liter of brake fluid bleeding the rest starting RR, LR, FR, FL. What can cause the pedal to shake like that.

I think I’m going to buy a different brand of rotors and hopefully they get the proper clearance. Otherwise the other option is new calipers and brackets.


Either way I wont be able to do anything to it for 3 weeks now as I have to travel for work. I was so hoping to be done with this. It all started with a fuel tank change and became way to much more. Feel defeated with all the money and effort I dropped into it. Well we will see when I get back. Last option is I might just give in and take it to a shop. Out of my depth now with clearance issue and brake shudder.

Link to comment
Share on other sites

I was just thinking the same last night. Would the rotors dragging be messing with the ABS.

rotors diameter is the same as the originals parking brake is perfect inside the rotor. Just feel like the rotor is milled a little to close to the hub.

ordering a different brand of rotors today. Will post when I get back from my trip.


fingers crossed that’s it.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Create New...

Important Information

Terms of Use