4th gen brake pedal going to the floor

Jack · Post by **Jack** » Mon Feb 29, 2016 12:50 am

Now I haven't driven my Prelude since it threw its cambelt in August last year but I'll do my best to describe the issue I was having.

It stopped fine, ABS worked spot on etc. But if I was braking for a few seconds (say coming to a complete stop rather than just slowing for a corner) the pedal would start to go to the floor. Releasing it and pressing it again would get me an extra few seconds of braking.

It never actually struggled to stop, just isn't a nice feeling as the pedal goes to the floor if you stay on it long enough!

Braking system is standard as far as I know, except some braided lines. Will be running 5th gen 5 stud hubs and ATR calipers when its running again. I suspect the issue is to do with the master cylinder or servo? The car has always had a vacuum leak in my ownership, could this be contributing?

Someone mentioned to me that there was a recall years ago for this but I can't find anything online. If that's the case and mine hasn't had it done, should I just get the H22A7 up and running and take it in to Honda and let them deal with it?

YouTube · Post by **Sailor** » Mon Feb 29, 2016 12:55 am

It sounds as if there's air in the system. This is unlikely to be related to the vacuum leak.
First check for obvious leaks. Then try bleeding it at the slave cylinder.
The steps after that are to do with checking the seals.

I wouldn't be surprised if the brake fluid needs changing as well if it hasn't been done for a long while.

Post by **JEBB4** » Mon Feb 29, 2016 7:29 am

Sounds like the master cylinder to me.. I'm not sure if there the same but maybe try the master off the ATR.. Or a second hand Lude one of someone on here if there different be easier to change when the engines out too..

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Mon Feb 29, 2016 7:56 am

I would try bleeding the system properly first off.
If still no good and no sign of leaks from anywhere else on the system then master cylinder would be prime suspect indeed.
I have read on here people have had master cylinder seals turn inside out due to incorrect bleeding process, though I've not experienced that myself.

Post by **vanzep** » Mon Feb 29, 2016 10:31 am

I think there are two seals in the brake master cylinder and it sounds as if one of the seals is on its way out.
I had brake pedal creep like you describe and over time it got worse - replaced the master cylinder and all was good

Jack · Post by **Jack** » Mon Feb 29, 2016 11:52 pm

I'm pretty certain it isn't air in the system or a leak. It never got worse in the 8-9k I did before the engine went bang. The pedal is initially hard but goes soft after a few seconds - not what you'd expect from air in the system afaik?

I'll offer the ATR M/C up and see if it's compatible. I've also got a BB8 one that I can use if need be - I believe that will be a stright fit?

Bludge · Post by **Bludge** » Mon Mar 14, 2016 9:55 pm

Sounds like a leaking master cylinder. check the fluid level, if it looks like you are losing fluid even though there isnt an obvious leak it could be leaking back into the servo.

maybe look at the fluid and then sit and put the pedal to the floor repeatedly for a while (while stationary

) and see if the fluid level drops.