Weak Brakes

[silverbullet]

All,

I have tried to ensure that if one thing works well on the Bronco it will be the Brakes. Ive dumped money in all the parts I thought were necessary to make this happen, I think. They still dont seem very strong. Here's a list of new parts:

SS lines hard and braided: JBG
Master/Vac assist: JD
Caliper/rotors/pads up front ('76)
Disk upgrade rear: WH

The only thing that is not new is the H-block, original. Whether I step on them light or stomp there is not much difference is braking power??? I cant get anything to lock up even on gravel. What the heck? I do have a vac canister for vac reserve. Are they not bled correct?

I just want to be able to stop the thing quick if necessary. Any suggestions would be greatly appreciated.

Dave

 

[Dsquared]

I'm having the same problem. Just put new discs up front and vaccum assist, new master cyclinder. I bleed and bleed and bleed, and never got any better. I finally gave up and took to a local mechanic. Should get back in couple of days, will up date at that time.

 

[silverbullet]

I think it must be something with the original distribution block down on the frame rail. Havnt tried it without the Vac. Canister either.

 

[76Broncofromhell]

You really need to be more specific on what "Doesn't stop the thing quickly" means. Is the pedal too stiff? Is it too soft? What are you trying to accomplish?

Brakes aren't that complicated. It's mechanical advantage times hydraulic advantage = pressure at the wheel.

 

[silverbullet]

If I step supper light on the pedal approaching a stop light the brakes seem to hold fine and will bring you to a stop like normal. If I step hard on the brakes in one hard press the pedel seem to hit a hard stoping point and will not slow the vehicle any slower. And will not lock up any of the tires even at 20 on gravel.

As with the general feel of the brakes it doesnt feel as the thing bows forward, as if most of the stoping power is not coming from the front. It seems there is something keeping the pressure from building in the correct places.

It would seem that if you had to stop quick on pavement it would lock the tires up right?

Dave

 

[silverbullet]

My bukin bronc will be out of commision for a while during the trans rebuild. Is there anyone who has had this problem and been able to remedy it. Any help would be great!

 

[lars]

hydroboost

I'm surprised no one beat me to this...

You must have an early Bronco, probably with rock-hard (firictionless) crappy parts store brake pads or shoes, and possibly big tires. Set aside about 2 days, then do a search on "hydroboost". You'll need that much time and more to read all the results. I would explain myself but there is so much that has already been written that there's no point. I can say that if you learn how it works, then dump your vacuum stuff in favor of a hydroboost system you'll understand why everyone raves about it the first time you step on the brakes. It works so well that even with the aforementioned rock hard crappy frictionless pads & shoes that many parts stores sell, you'll *still* have good brakes.

 

[Skuzzlebutt]

How many miles do have on the new brakes. They'll work alot better after a few hundred miles. The pads & rotors new to get broken in to reach they're best performance.

 

[BG's 68 Bronco]

It sounds like no matter how hard you step on the brakes you have the same amount of braking force.

Two thing pop out at me, but I don't knowthe answer... hopefully it will trigger someone else experience/knowlege.

1st the amount of vacuum assist is affected if you're running a (i don't know correct technical term) aggressive cam

2nd I don't know if the h-block can have a negative affect on the braking system, but my guess is it may.

I am stabbing in the dark a bit here, but for someone who knows more about the h-block and amount of vacuum please set my questions straight.

Thank you ;D

 

[Cooter_76]

Quick question about terminology: Would a 76 have come with a proportioning valve with the factory disc/drum instead of an "h-block"?

 

[Hazegray]

I have the same problem, but with the Chebby conversion. First portion of brake travel provides good braking power, but hits a brick wall when firmly pressed down. I'm going to upgrade my front brake pads soon...

 

[lars]

Quick question about terminology: Would a 76 have come with a proportioning valve with the factory disc/drum instead of an "h-block"?

Yes it did.

 

[DanWheeler]

so you have discs all around then?

How was your braking before you installed all these new parts? Better/worse?

What size tires do you have?

Which master cylinder do you have?

I have HEARD that disc brakes dont lock as well as drums. I have drums all around w/ 32" tires and no hydroboost/vacuum assist and I can almost lock them up on pavement going 20-30. No problem on wet pavement.

I wouldn't think the H-block would have much effect.

 

[DanWheeler]

this thread has some info about H-blocks / proportioning valve. Sounds like there are a few guys running 4 wheel discs with H-blocks no problemo.

http://www.classicbroncos.com/forums/showthread.php?t=80260

 

[Broncobowsher]

I have only a few things to consider.

I once drove a friends F150 that had an el-cheapo brake job. Brakes felt exactly like what you describe. Put good pads on it and it was back to OK.

Other then that, I wonder if the booster pushrods are adjusted correctly? If it bottoms out then bedal will feel hard, not travel and braking action will not increase with additional pedal pressure.

 

[DanWheeler]

I have to at least ask... the pedal isn't hitting the floor is it? or the leverage binding on something else? Have you visually confirmed that you have good travel of the rod going into the vacuum assist? Could you try removing the vacuum assist and connecting the master cylinder directly to the brake pedal?

just throwing out ideas here

 

[silverbullet]

The pedal is not hitting the floor but is bottoming out on something. I must have the linkage to the Vac booster adjusted wrong, dont know the correct method. Both the booster and MC are from JD. And all parts have been installed with less than 1000 miles on them. And I it has a proportoning valve not h-block.

I combined a chassis and body baught seperatly to make one so I did not have the chance to drive it before the upgrades. Is there a method to adjusting the 'pushrod?' for the MC? I will do a search.

Thanks again, oh I have 33's.

Dave

 

[lars]

The pedal is not hitting the floor but is bottoming out on something. I must have the linkage to the Vac booster adjusted wrong, dont know the correct method. Both the booster and MC are from JD. And all parts have been installed with less than 1000 miles on them. And I it has a proportoning valve not h-block.

I combined a chassis and body baught seperatly to make one so I did not have the chance to drive it before the upgrades. Is there a method to adjusting the 'pushrod?' for the MC? I will do a search.

Thanks again, oh I have 33's.

Dave

Have someone step on the brake while you watch the bellcrank in the booster bracket. Make sure it's not interfering with anything through its range of motion. Better yet, pull the booster and bracket, sell it on Ebay (or this site) and install a hydroboost. Seriously. Vacuum boosters are ok with 31" tires. 33" they are marginal. Plenty of people on this board including myself have been totally skeptical until they tried driving with it. I was converted the first time I hit the brake. It's hard to imagine that your brakes can be so strong.

 

[raharr3]

I had brand new vacuum power brake set up from one of the Bronco parts houses and couldnt hold a candle to the stopping power of the Hydro assist. Just do it...it will make you feel safer ;D needless to say the vacuum crap on the floor in the garage now.

 

[silverbullet]

I nearly went this rute during inital purchase and was hesitant for double the price. I should have gone this rote to begin with I bet. What is the best path to follow for this upgrade? Parts house, salvage? Should I ditch the proportoning valve and just go with an adjustable?

Anyone what to purchase a nearly new vac booster and MC. Less than 1k miles.

Dave