Hydroboost Pedal feel. Bouncing feedback?

[jhenegh]

Quick question on how an F-Superduty hydroboost is supposed to feel. I recently installed an F-Super Pedal, used hydroboost and new master cylinder and the 2-port steering reservoir. If I hit the brakes quickly (like a yellow light or a quick stop), for a split second the pedal starts to depress, then I get a "feedback" pulse and the pedal firms up and feels like it pushes back slightly. It seems to operate and stop fine, and if I slowly get in the brakes (like a planned gradual approach to a stop sign) I don't get that "bounce" in the pedal.

If I'm actively steering and I go to hit the brakes, I can feel it in the steering too.

What is causing that pressure spike in the system? Is the used hydroboost unit on its way out?

Thanks

 

[OLDBULL8]

Could be the ABS reacting for a second. Is both rear wheel brakes adjusted the same?

 

[tbrumm]

Or is it the hydroboost entering "by-pass" mode for a split second?

 

[jhenegh]

Hey Bill,

ABS hydraulic unit is new, no ABS lights, and the rear and front brakes are new in their entirety. The rears were adjusted the same and have not heated up more on one side than the other (well I fixed that problem a before the hydroboost went on).

 

[cpdenton]

Not sure if it is supposed to do it or not, but mine acts the same way. It is a rebuilt booster.

I have always thought it had something to do with it taking a second for the fluid to redirect to the right spot.

 

[crash-harris]

Do you even have 4 wheel ABS? If not, then you wouldn't feel it in the front end.

 

[FORDF250HDXLT]

i get no such pushing back in either of my trucks.are you using a t or a dual return res?

 

[jhenegh]

Do you even have 4 wheel ABS? If not, then you wouldn't feel it in the front end.

I feel it in the steering as the pressure, since the same pressure pump powers both systems.

i get no such pushing back in either of my trucks.are you using a t or a dual return res?

Dual return reservoir

Not sure if it is supposed to do it or not, but mine acts the same way. It is a rebuilt booster.

I have always thought it had something to do with it taking a second for the fluid to redirect to the right spot.

Well at least I’m not alone!

 

[79jasper]

Could be something with the spool valve.

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[cpdenton]

Gentle even pressure never causes this to happen on mine.

Quick hard emergency stops are the only time it happens. When the pedal goes down quickly. Also, when it has been a while since I have adjusted my rear shoes up tight.

 

[jhenegh]

Gentle even pressure never causes this to happen on mine.

Quick hard emergency stops are the only time it happens. When the pedal goes down quickly. Also, when it has been a while since I have adjusted my rear shoes up tight.

Exactly what I've felt. But it hasn't been long enough for me to adjust the rear shoes again yet. I'm running DRW wheel cylinders on my SRW with the FSuper master cylinder, so we've got very similar/identical brake systems.