Slightly softer and longer pedal after caliper replacement- normal?

Mhc04

Mhc04

Member
 Berkshire
Hi all,

I recently replaced both front calipers on my 3.0i after they started sticking and overheating (first the right, then the left a couple of days later when i noticed it also starting to stick.

The replacements themselves went smoothly, but I'm second guessing the pedal feel afterwards and wanted to sanity check with people more knowledgeable.

What I did:
-Replaced both front calipers with new febi units
-Cleaned and greased slider pins
-Bled the system using a pressure bleeder at 10psi
-Fluid reservoir never dropped below min
-Continued bleeding until bubbles stopped, then flushed ~200ml of fresh dot 4 through each front corner

One thing to note is that I didn't use a hose clamp when removing the old calipers, as I was worried I'd damage the hose.

-Pedal doesn't need to be "pumped" to gain stiffness
-No visible leaks and fluid level hasn't decreased
-Car brakes fairly strongly when pedal is pressed firmly, I do trust the brakes

However, the pedal now feels slightly longer and softer before the brakes really bite compared to before. Maybe slightly "springy" would be an appropriate description, although I'm inexperienced with cars so find it difficult to judge what's normal.

It could be possible I've gotten used to driving with the knackered calipers, where the pad clearance would have been a lot smaller than with the new calipers. Maybe now I have to press the pedal more to compensate for the bigger gap between the pad and disc?

A few questions:
-Is a small change in feel normal after replacing calipers?
-Could air realistically still be trapped somewhere after flushing 200ml of fluid through each front corner?
-Was it a mistake to not clamp the brake hose?
-Anything specific I should double check?

For context I'm planning on replacing all pads and discs as well as a full system flush, so this current set up is temporary until then.

Thanks in advance.
 
Mhc04 said:
It could be possible I've gotten used to driving with the knackered calipers, where the pad clearance would have been a lot smaller than with the new calipers. Maybe now I have to press the pedal more to compensate for the bigger gap between the pad and disc?
Click to expand...
That would be my guess.
 
Chippie said:
That would be my guess.
Click to expand...
Nope. Once the pads are clamped back on the disc the only thing that pushes them back when you release the pedal is the spinning disc. So irrespective of pad wear you only have to move the pad the same amount.
However, if your old callipers were seizing then the pedal may have felt harder as it would have taken more effort to shift the pistons.
 
enuff_zed said:
Nope. Once the pads are clamped back on the disc the only thing that pushes them back when you release the pedal is the spinning disc. So irrespective of pad wear you only have to move the pad the same amount.
However, if your old callipers were seizing then the pedal may have felt harder as it would have taken more effort to shift the pistons.
Click to expand...
Yeah my old calipers had a lot of corrosion on the pistons so it makes sense they'd be harder to move. Slider pins were also quite dirty so maybe that also contributed?

When I do a full system flush along with doing the pads and discs, ill see if the feeling changes, if not I'll have to accept it as normal.

Thanks.
 
If its while driving and you replaced the pads, it could be due to the new pad compound having a different biting point (and if you didn't replace/sand the rotors could be due to different friction compounds on the same rotor).
 
I’m doing the same job on mine this weekend so I’ll let you know how it feels.
 
That ‘feeling’ is technically referred to as ‘compliance’….compliance in a braking system is a ‘softness’ or ‘travel’ not associated with air in the system..

So..for example…sliding caliper brakes always more compliant vs opposed piston due to their design, rubber hoses are more composing than braided versions etc..

So..it appears you’ve introduced more compliance…maybe the new calipers design is just not as good..bushes / pins etc…maybe you pit so much grease in the caliper sliding pin hole it’s pushing the caliper back?
 
After breaking into the ABS / Caliper braking system it is best to carry out a maintenance bleed that activates the ABS/DSC Pump motor block.
I Used INPA to carry out the bleed service programme, effectively this activates the abs pump whilst you bleed and ensures thatvtere is zero air in the system.
 
So i changed both front callipers today. The left one was seized sufficiently so that I burnt my finger on the disk! The pedal feels exactly the same now as it always did.
 
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