I need help...brake help

[Fourpoint282]

So a few months ago I upgraded my brakes:
- switched out OEM calipers with a set of Bren I calipers from the 3.0TQ5
- JHM LW rotors all 4 corners
- JHM ss brake lines
- hawk pads (rear) red stuff (fronts)

After all this, the braking was responsive, but my pedal is softer than used to be. I did 2 full flushes and an abs cycle to ensure air in lines was not the issue. Still same soft feel. Then took the car to Audi to have them flush and cycle ABS. Still same soft feel.

What in the heck am I missing?

I know the pedal feel could be stiffer. I know this bc if I pump the brake once and then brake, braking is much more stiff.

What else do you guys think I am missing to make the pedal not as soft?

Here’s a before/ after pic because, well pics are more fun

IMG_6455.JPG


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[allroadmark]

bigger master cylinder.

[roboto_1337]

Also I think that even with a proper bleed you can't really get all the air out without a proper vacuum/power bleeder.

[Fourpoint282]

bigger master cylinder.

I’ve heard this might be the case. Do you know if I can Simply buy a MC from an RS4. I think they are same size as S4?

If I get a bigger MC, are there any other parts I would need to replace or upgrade?


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[allroadmark]

I would assume but cannot be sure that rs variant would be 27mm as opposed to 25mm a4 s4. Being the same platform it should be plug and play but get clarification from someone before you buy a master cylinder.

[SprintBlueWorld]

Just did front brakes myself, Hawk pads with JHM lightweight rotors SS lines, and had the same concern, bled them twice. The pedal seemed to travel further before engaging. It could be all in my head, but I found that after bedding in the brakes and driving it for a week, it seemed to improve. Just drive it.

[Fourpoint282]

I’ve got a couple thousand miles on car since upgrade...brakes need something more to stiffen up the pedal. Initially the pads help but over time they wonk bite quite as wel


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[allroadmark]

search online for break in procedure, makes a huge difference to pad bite when bedded correctly.

[Fourpoint282]

search online for break in procedure, makes a huge difference to pad bite when bedded correctly.

Thanks, well aware of break in procedure and agree. My calipers have larger volume, thus more fluid to push, thus larger MC (I would assume)


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[roboto_1337]

Thanks, well aware of break in procedure and agree. My calipers have larger volume, thus more fluid to push, thus larger MC (I would assume)


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I still don't think that there would be enough compression of the brake fluid to equate to the spongy feeling in the brake pedal. I'm running brembo 18Z calipers which have greater volume than the stock S4 calipers, yet once I got all of the air from the system and the pads bedded it actually seemed that my brakes were stiffer. I would check for leaks, then bleed them again as per the procedure.

It could actually be signs that your master cylinder is failing if you're unable to get the stiffness back.

If you're really concerned about the pressure you're generating, see below

https://www.joesracing.com/rt-4172-m...nder-math.html