05 V70 spongy pedal after front brake job

[850 LPT]

Hi guys,

This one really stumps me. I have done brake jobs dozens of times on P80 cars and I was expecting the same routine on the o5'.

All I did was replace the rotors and pads. And as always I carefully pushed back the caliper pistons after sucking some brake fluid out of the reservoir.
Now the brake pedal feels very spongy, more so with the engine running.

What could be wrong?

There are no external leaks by the way, that was the first thing checked. Is there something going on because this is a 5-speed? Did I somehow manage to kill the master cylinder?

Any idea would be appreciated.

Thanks, Dirk

[JRL]

Bed in the brake pads and bleed again.
You need to get the glaze off the rotors

[850 LPT]

Thanks Jim, I never had the brake lines off, so I see no reason to bleed the brakes. At least I never had to in the past.

The way it worked for me in the past is that after installing the pads I would have to pump 3-4 times until the pedal got firm again. This is because of the extra travel in the piston which was all the way pushed back.

But not this time, I'm not getting a firm pedal. And I checked, the pads are pressing against the rotors as they should.

[Steve H]

You have installed the anti rattle springs wrong. I have done it on Saabs and a Volvo. If they are not correct the peddle will be spongy. Look at your rear caliper to see that you have the spring on the wrong side of the caliper bracket flange.

[850 LPT]

You saved my day, Steve.

I just checked and sure enough, I messed up the springs. Fixed them and the pedal feels much better. I will test drive in the morning.

Thanks!!!

[Steve H]

I have done this too many times on Saabs and now I did it on my Son's Volvo S60. As soon as I hit the peddle I know what I did. I just do not do it often enough to remember the orientation of the spring. Lets face it it looks and installs just fine when you do it wrong and that does not help. I am glad I could help.

[abscate]

Nice. Btdt and got the Tshirt on VW, Dirk.

By the way, even if you don't open the hydraulics, I've found sometimes bleeding is required after compressing Pistons.

Logical? No. Observed? Yes.

[850 LPT]

This actually crossed my mind, but I dismissed it because I realized that I was starting to overthink things as usual. But I had left the reservoir cap only lightly screwed on for a few days. Actually I kind of forgot about it because I did a lot of other stuff on the car, tune up, new thermostat etc. So I thought could the fluid have drawn enough moisture to......nah, that's crazy.

Anyway, I drove the car all day yesterday and the brakes are fine of course. Next job is replacing the front struts...

[Steve H]

I found when replacing the front strut to do this helps. Put your jack stands in alignment with the ball joints on the lower control arms with the jack stands supporting the car on the subframe. With the weight of the car on the jack stands run a ratchet strap under the jack stands and secure the hook to side you are not working on to the far jack stand and then secure the ratchet side of the hook to the control arm you want to pull down. You can pull down the control arm and keep it down with the ratchet strap using the car's weight on the jack stands and the low point of going under the jack stand with the strap to actually pull the pressure off the bushings that is trying to pull up on the control arms. Don't get happy with pulling them down enough to damage your control arm bushings just enough to not fight with the struts and the control arms that will return to a position that is actually higher than they are now when the strut is removed due to the bushings. Above all remember struts/springs can kill you and know what you are doing.

[abscate]

Ive got the cross strut tool if you/me are driving by something this fall...