Brake pedal bottoming out after Hydroboost install

[guidoverduci]

Ok, up next… just installed Hydroboost kit with wildwood MC. I have the rod that connects the Hydroboost to the brake pedal extended all the way, It’s barely threaded on. Problem is the brake pedal still hits the floor. I’d say it’s about 5 1/2” from the floor and that’s as far as I can get it. Any thoughts?

 

[lars]

Have you bled the brakes and tried driving it? I can easily push my pedal all the way to the floor when sitting still. If I do that when I'm driving I'd be skidding down the road. That's a quirk of hydroboost that, in my experience, transcends which master cylinder and/or booster you use. I've had a few of each, that's one thing they all have in common- at idle, not moving, they all went to the floor if I pushed. And not a panic stomp. Just a solid push. But when moving, long before that, brakes are locked up.

 

[guidoverduci]

Have you bled the brakes and tried driving it? I can easily push my pedal all the way to the floor when sitting still. If I do that when I'm driving I'd be skidding down the road. That's a quirk of hydroboost that, in my experience, transcends which master cylinder and/or booster you use. I've had a few of each, that's one thing they all have in common- at idle, not moving, they all went to the floor if I pushed. And not a panic stomp. Just a solid push. But when moving, long before that, brakes are locked up.

The bronco is all torn apart at the moment, won’t be driving it for awhile. I think I just got caught up in the instructions mentioning that in order to properly operate (and bleed correctly) the pedal shouldn’t hit the floor. As far as bleeding, I installed the Hydroboost, MC, and prop valve, then all I’ve done is “bench“ bleed the MC while installed. Everything is pretty level and the instructions suggested it’s ok to do it that way. I haven’t attached brake lines yet… I was just under the assumption that the unit would reach full travel before the pedal hit the floor. It’s probably just my lack of understanding.

 

[toddz69]

You don't want the brake pedal to 'bottom out' in the master cylinder before it hits the floor, if I'm understanding what you're saying. If it does, you could damage the master cylinder, blow out seals, etc. by stomping on the pedal during a panic stop.

Todd Z.

 

[guidoverduci]

You don't want the brake pedal to 'bottom out' in the master cylinder before it hits the floor, if I'm understanding what you're saying. If it does, you could damage the master cylinder, blow out seals, etc. by stomping on the pedal during a panic stop.

Todd Z.

I’m referring to the warning that says the MC push rod must bottom out in the bore before pedal hits floor board. It’s on my wildwood MC instructions. I just assumed that while bleeding the installed MC via brake pedal, I’d hit a force before the floor. But I don’t have the rest of the system hooked up, and I haven’t / can’t start the motor.

 

[BOBS 2 68S]

Did you install the "bullet". Wild Horses instructions say to install the bullet first.
I was able to bleed my brakes with the WH hydroboost kit with out the engine running

 

[guidoverduci]

Did you install the "bullet". Wild Horses instructions say to install the bullet first.
I was able to bleed my brakes with the WH hydroboost kit with out the engine running

Yep. Kit came with it installed and I just bolted it all up.

 

[00gyrhed]

Hydroboost or not the pedal must not hit the floor before the MC bottoms out. If your pedal goes to the floor ever, you have a serious problem. The HB is a booster, the pedal to MC is a hard compression connection all the way through, so the brakes still work if the HB dies, or engine dies, or you throw the belt etc. There should be approx. 3/4 of dead travel at the top and about the same before the floor. If a panic stop takes you to the bottom of the MC, the MC has already failed or the something else has blown!! The wildwood warning is correct. No MC should be installed in such a way for the pedal to bottom out on the floor before the MC does.

All these lengths are adjusted by the little piece of steel that goes in between the HB and the MC, and to some extent the connection of the pedal to the HB rod. They can be fine tuned to give you optimum pedal travel. It kind of sounds like the metal rod is too short or not installed.

 

[guidoverduci]

Hydroboost or not the pedal must not hit the floor before the MC bottoms out. If your pedal goes to the floor ever, you have a serious problem. The HB is a booster, the pedal to MC is a hard compression connection all the way through, so the brakes still work if the HB dies, or engine dies, or you throw the belt etc. There should be approx. 3/4 of dead travel at the top and about the same before the floor. If a panic stop takes you to the bottom of the MC, the MC has already failed or the something else has blown!! The wildwood warning is correct. No MC should be installed in such a way for the pedal to bottom out on the floor before the MC does.

All these lengths are adjusted by the little piece of steel that goes in between the HB and the MC, and to some extent the connection of the pedal to the HB rod. They can be fine tuned to give you optimum pedal travel. It kind of sounds like the metal rod is too short or not installed.

That all makes sense to me. Here’s a question… does/can the pedal still travel if the MC bottoms out first? Maybe I’m reaching the bottom of travel in the MC and not realizing it??

 

[guidoverduci]

That all makes sense to me. Here’s a question… does/can the pedal still travel if the MC bottoms out first? Maybe I’m reaching the bottom of travel in the MC and not realizing it??

And as I read that… it mechanically doesn’t seem plausible.. so something is missing.

 

[00gyrhed]

I made my entire HB set up from a 78 mercury marquis made the adapter plate and used the stock bronco with disc brakes MC. But i was very careful in setting up the rod length and pedal connx. the rod is a direct connx to the pedal all the parts stackup under compression, that way you still have brakes even when the power is lost. No automobile I have ever owned hits the floor before bottoming out the MC, it is not safe. If the brake goes to the floor something is wrong. the first choice is the rod in between the HB and MC is missing.

I would just unbolt the MC from the HB and look. I left mine out one time nd swore I had put it in.

 

[guidoverduci]

I would just unbolt the MC from the HB and look. I left mine out one time nd swore I had put it in.

Bump. Pedal still hits the floor, pill is in, Hydroboost is bolted up to firewall correctly, rod is fully extended, pedal travels 5.5” before hitting floor. Does anyone know if there is still the ability for the pedal to move AFTER the MC cylinder bottoms out??

 

[00gyrhed]

At this point your are going to need to get someone that actually understands and is familiar with your specific system. Nobody here wants to tell you something and then somehow be blamed if you loose your brakes and hurt someone because they were misunderstood. Including me. If the rod is the right length then there just isn't much way to screw this up. At least from what I found when I made my system. I cobbled mine together from an EB MC, a 78 Mercury Marquis HB, Made the adapter plate, rod, and pedal linkage myself. You should be asking Wild Horses these questions since they sold it to you. Maybe something isn't right? Maybe the WHs set up is for early bronco MC and the wildwood MC is different and required a different rod? In any case you need to get someone that is familiar with the parts you are using. I have no idea what the HB WHs uses is or what a WW MC looks like. It could be the locator hole in the MC piston is drilled deeper than what WH expected. Could be you have parts missing, or improperly installed.

I imagine WHs will bend over backward to help get this fixed as the last thing they want to do is end up in court over the length of a steel rod.

 

[4x4man514]

i recently installed the same kit and had the same issue. the instructions explain to adjust the rod on one side of the threaded adjustment and leave the other side be. (the other side is loctited). i had to break the loctited side loose to get just a little more adjustment and was able to get the pedal to bottom out just b4 it hit the floor. but barely. it was close.

i have my whole brake system together now and have bled the brakes, have a good solid pedal. what im a little worried about is now my front brakes seem to be locked up. like you im still building mine so it isnt running and i dont know if they will release once the hb has fluid flowing through it .

 

[DirtDonk]

Sorry to hear you guys are having a hassle.
I’m not an expert here so just throwing this out there, but did either of you hook up the Hydro boost to the firewall and push on the pedal without the master cylinder installed?
I don’t know what the symptoms are of this, but I’ve heard that if you make that mistake the Hydro boost unit is done for and needs to be reset or rebuilt.
So the general rule of hydro-boost is never ever push on the pedal without the master cylinder installed.

4x4man, I suppose it’s possible that once fluid is applied it could release, but I’ve never heard of that characteristic in a hydraulic system. Usually the opposite in fact.
To me if your front brakes are locked up the booster to master rod is adjusted too far out.
That, or the pedal is somehow putting some initial pressure on it.

But curious, how are you testing for a pedal action and feel without hydraulic fluid running through the pump and booster system?
I thought that would completely change between the two modes?

 

[DirtDonk]

On that same line of thinking, without power steering fluid in the booster maybe you are never going to get a pedal.
Perhaps it relies on the fluid for part of it’s ability to even push the master.

And hopefully it does not do the same damage by pushing the booster all the way through it’s stroke without fluid, that it does when you push it through it stroke without a master installed.

 

[4x4man514]

I did read the instructions and it does clearly stare not to push pedal without mc attached. So I made sure not to do that. After everything was installed I did bleed the brakes and was able to get a full pedal just like any other time. Im sure the brake system should function whether it has assist or not. Right now I have the pedal rod disconnected trying to figure out how the switch and bushing go on there. ( I don't know what I'm doing wrong but for some reason I can't get it to fit. The bushing fits fine with ought the switch and the switch fits fine without the bushing but I cant get them both to fit on the stud of the pedal). Anyways maybe when I get it hooked back up and can push the pedal again it will release.

Sorry Guido I didn't mean to hijack your thread Hopefully some of this will help you to.

 

[DirtDonk]

Both seem to be such similar conditions that I think it’s good you posted here.
An answer for one may very well help answer the other.

 

[guidoverduci]

I did read the instructions and it does clearly stare not to push pedal without mc attached. So I made sure not to do that. After everything was installed I did bleed the brakes and was able to get a full pedal just like any other time. Im sure the brake system should function whether it has assist or not. Right now I have the pedal rod disconnected trying to figure out how the switch and bushing go on there. ( I don't know what I'm doing wrong but for some reason I can't get it to fit. The bushing fits fine with ought the switch and the switch fits fine without the bushing but I cant get them both to fit on the stud of the pedal). Anyways maybe when I get it hooked back up and can push the pedal again it will release.

Sorry Guido I didn't mean to hijack your thread Hopefully some of this will help you to.

No problem. We are In similar situations. I also made sure I attached the pedal last. I’ve put a pic up in case it helps you get the pedal hooked up.

As of now, I hooked up the rest of the system, bled all the brakes, and it feels as I would expect for a correct install. But again, engine hasn’t been started. I did bleed the power steering per instructions by jacking up the front and rotating wheel lock to lock before I ran into the pedal to floor issue.

 

[4x4man514]

No problem. We are In similar situations. I also made sure I attached the pedal last. I’ve put a pic up in case it helps you get the pedal hooked up.

As of now, I hooked up the rest of the system, bled all the brakes, and it feels as I would expect for a correct install. But again, engine hasn’t been started. I did bleed the power steering per instructions by jacking up the front and rotating wheel lock to lock before I ran into the pedal to floor issue.

Guido do you have a plastic bushing on your pedal? I cant really see one in your pic.

My brakes felt right too after bleeding it wasn't until I tried to roll the bronco that I realized they were stuck. Maybe nothing. I need to get a cooler and get that last line on bleed it and then try it.