Brake pedal still soft after replacing everything

Post by **FireFox31** » 11 Jun 2025, 10:59

My brake pedal is soft and braking performance is weak even with new pads, rotors, calipers, and fluid. This is on Geronimo, my 2000 V70 with 394k miles and a rough life before my ownership. How can I get the brake pedal to be firm and deliver stronger braking performance?

Are there any tests I can do to locate the problem? I will try my pressure tester which screws into caliper bleed valves. Can other components be tested, such as the brake booster or master cylinder? Thanks.

Vova585 · Post by **Vova585** » 11 Jun 2025, 11:13

I would suspect problems with main brake cylinder at those miles. It is not cost prohibitive item and decently easy to replace. At the time of cylinder replacement you can check if the pushrod from brake booster is at correct length(I might be wrong here, but think they are adjustable). Then I would focus on proper brake bleeding procedure including abs valves(hope you have Vida to tell you correct procedure and ability to cycle the abs unit).
Also simple things like: if the caliper is stalled correctly with bleeder screw up, any old rubber hoses that are pinched or overstretched.

Post by **abscate** » 11 Jun 2025, 11:38

I probably have extra master cylinders from this vintage if needed

MC swap us surprisingingly easy on these cars

Post by **wizechatmgr** » 11 Jun 2025, 17:44

When you bled it did the MC go dry at any point?

Post by **FireFox31** » 11 Jun 2025, 19:38

Thanks for the advice. Yes, the braking system ran completely dry when I first replaced all the components in 2021. Once everything new was installed, the brake pedal was soft, just like now. I bought a small tool to bleed the master cylinder but have not done it yet.

Also, thanks for the reminder about VIDA telling me how to bleed the ABS unit. It may also have drained in 2021, and it was horribly failed before I got the car. A rebuilt unit from Matty Moo helped but it still triggers ABS randomly at times, so I leave it disconnected. I will review that bleed process. Thanks again.

Post by **abscate** » 12 Jun 2025, 03:58

The master cylinders on these cars have impressive track records , there are so few failures here on30 year old cars.

Post by **scot850** » 12 Jun 2025, 10:28

It can be 'fun' to get air out of the ABS pump. A 'push' pressure system is what I find most effective, but I'm sure others will say they have had success with pull systems too.

Good luck!

Neil.

Post by **MoVolvos** » 12 Jun 2025, 17:23

scot850 wrote: ↑12 Jun 2025, 10:28 It can be 'fun' to get air out of the ABS pump. A 'push' pressure system is what I find most effective, but I'm sure others will say they have had success with pull systems too.

Good luck!

Neil.

.
Have done push pedal with the car running on the last few cars. Requires two persons however. Once the pedal is all the way down the 2nd person at the bleeder closes the screw before releasing pedal and pushing again. Start bleeding at the farthest from the MC.

Rebuilt the MC on the 05 GS430 and pedal was rock hard solid. Bench bleed the unit before attaching the lines to make sure no bubbles are in the MC. I had to do mine in car pushing the brake pedal as I don't have a vise.
.

.

yanga001 · Post by **yanga001** » 13 Jun 2025, 08:23

Check your brake lines. I have a 99t5 where the lines broke down and expanded. Makes braking extremely hard and in my case it would seize up the calipers. My mechanic just fixed another 98 v70 with this issue.

Post by **FireFox31** » 01 Jul 2025, 13:37

yanga001 wrote: ↑13 Jun 2025, 08:23 Check your brake lines. I have a 99t5 where the lines broke down and expanded. Makes braking extremely hard and in my case it would seize up the calipers. My mechanic just fixed another 98 v70 with this issue.

Good tip, thanks. I've replaced one front hose and will do the other soon. But the rear rubber hoses are discontinued, at last check.

How did this cause your calipers to seize? My pistons seize constantly but I assume it's rust from poor quality metal or moisture in the fluid that I don't change often enough.