[BILTIT]

Originally Posted by takid455

I'll answer some of the repetatory unanswered questions here. Look at the other HB post a few topics down to see pictures of my setup.

the adaptor plates on the HB units have diiferent bolt patterns than a 2nd gen. get the straight one. no need to the angled one. I'm sure you could modify the brake pedal support to use the HB bracket. I was able to one of Nicks and it made life easy. Stay away from truck units as the valving is internally different. Astro/ Safari ones are optimum. 94+up. mustang ones will work but have less pressure. You will need to modify the eyelet on the HB unit, no if ands or buts. brake pedal to rod ratio should be 1:7 IIRC. My 78 brake pedal had a 2nd hole on it that I used and matematically worked out very close to the proper ratio.

I am guessing this to mean that it will put out too much pressure for the lighter vehicle such as a car VS a truck?

[Murf'sDad]

Originally Posted by takid455

I'll answer some of the repetatory unanswered questions here. Look at the other HB post a few topics down to see pictures of my setup.

the adaptor plates on the HB units have diiferent bolt patterns than a 2nd gen. get the straight one. no need to the angled one. I'm sure you could modify the brake pedal support to use the HB bracket. I was able to one of Nicks and it made life easy. Stay away from truck units as the valving is internally different. Astro/ Safari ones are optimum. 94+up. mustang ones will work but have less pressure. You will need to modify the eyelet on the HB unit, no if ands or buts. brake pedal to rod ratio should be 1:7 IIRC. My 78 brake pedal had a 2nd hole on it that I used and matematically worked out very close to the proper ratio.

Thanx for the followup Kid. I'm tracking a HB unit from a '95 Safari right now.

The second hole you refer to; is it the one about 1" above the stock hole and has the bolt holding on the bracket for the brake light?

Also did you use the rod from the old booster or the one that came with the HB unit, or something else?

Thanx, Stewart

[Ollie]

Originally Posted by Murf'sDad

Thanx for the followup Kid. I'm tracking a HB unit from a '95 Safari right now.

The second hole you refer to; is it the one about 1" above the stock hole and has the bolt holding on the bracket for the brake light?

Also did you use the rod from the old booster or the one that came with the HB unit, or something else?

Thanx, Stewart

Yes the second hole about 1 inch above the stock hole. the push rod needs to be as straight as possible. The upper hole is for manual brakes. The brake lite switch can be mounted in the lower holes.

The HB push rod is too short and needs to be modified by cutting off the end and threading a hemi joint. The attached photo is of the HB I bought off Ebay. You can see the threaded end with the hemi joint. This is from the same Ebay seller Old Goat 67 bought his from

[Murf'sDad]

Originally Posted by Ollie

Yes the second hole about 1 inch above the stock hole. the push rod needs to be as straight as possible. The upper hole is for manual brakes. The brake lite switch can be mounted in the lower holes.

The HB push rod is too short and needs to be modified by cutting off the end and threading a hemi joint. The attached photo is of the HB I bought off Ebay. You can see the threaded end with the hemi joint. This is from the same Ebay seller Old Goat 67 bought his from

I figured that had to be the one. Just was never sure what it was for. Never seen a 2nd Gen with manual brakes.

Is the rod about the same length as the original?

Stewart

[Old Goat 67]

Ollie,

The one I got from NOVO came with two rods. One about 3" long (which I used), and one about 6" long. Put it in top hole which made a perfect fit using the original clevis and a straight and level hook up going out to the booster. Spaced the Hydroboost unit to the firewall with some 3/8" flat stock, so I didn't have to grind out the firewall hole. PERFECT fit.

Link here for one on eBay now; only one rod. Mine came with two.
http://cgi.ebay.com/ebaymotors/power...4114QQtcZphoto

If yours came with only one rod, mount the unit with 3/8" spacers and cut the rod to the needed lenght and thread it to fit the original clevis.

Charles

[Ollie]

Murf's Dad

I have never seen a FB without PB either, maybe the peddle is used on other models.
The stock HB rod is about 1 inch short and the eye is not corret size.

Old Goat 67

Yes that is the same Ebay seller I got my HB from. I did not notice they only offer one rod now, oh well, looks like I will have to shorten the rod. What is thread size of the rod?

[Old Goat 67]

Going out to shop to check the unused rod thread and length. I'll get right back to you Ollie.

Charles

[Old Goat 67]

Ollie,
Long rod is 3/8 X 24, 5 3/16" long.
Short rod I used was same thread, but only about 3" long.

Also, Ollie I used the original vacuum booster bracket to determine where to drill the plate at the rear of the Hydroboost to fit the four studs sticking out of the firewall. No modifications to the car done at all, with the 3/8 spacers.

Charles

[Ollie]

Thanks OG67,

The HB should be showing up any day now. I wounder if I Emailed them if I could get a short rod.

[Old Goat 67]

Ollie,
I went back and checked my ebay bid and it said the same thing as the new one does, but I recieved two rods in box.....

Charles

[takid455]

Originally Posted by BILTIT

I am guessing this to mean that it will put out too much pressure for the lighter vehicle such as a car VS a truck?

In simple terms, yes. A quick physics lesson here. The HB units are designed to safely stop the mass (vehicle) they are installed upon. Keep this in mind. A 250 or 3500 series truck is design to have relatively high GVW (vehicle plus pay/ tow load) compared to lest say a car or light utility van. Putting a high mass unit on a low mass application will yield much quicker braking torque at the expense of unpredictable or non linear braking force.

Simple terms. Installing 14" Z06 brakes on a VW bug. It will be over braked and hard to control and manipulate. I drove a Porsche speedster kit car with Porsche brakes once. I honestly felt the 1965 Imperial I had at the time stopped better.


Looks like most of the questions have been answered. no need to reiterate.

[Old Goat 67]

I used the above reasoning when deciding to go with the truck unit. Replacing GVW or "tow load" with "speed" and or "boat trailer", (which are in the planned use) and the fact that the brakes were never ever adequate before, I deduced that having too much braking ability (if in fact it is), would be FAR better than not enough again or still.

From the test runs I made with a couple of extreme stops thrown in, I must say that the results bear out my expectations and reasoning. For once in this car's life, it feels to have truly adequate and manageable braking.

Charles

[Joel Koontz]

I am using a HB and MC (1 1/4" bore) from a 92 Astro Van on my 68 LeMans(GTO CLONE) Convertible.

I installed it last fall and the brakes seem to work great except IMO they are now TOO POWERFUL.

I considered what takid455 said in post 53 and specifically chose the Astro HB as I thought it would be closer to the GVW of my car than most of the units that are available.

Not sure if the HB is any different than what they put on HD Pickups, etc. Based upon the minimal amount of pedal force it takes to lock up the brakes, I suspect that the HB units themselves are the same.

I just put the HB on last Fall and have not driven the car a lot since I put it on. I think I could adapt to the feeling and it would be OK on dry roads, but I would be concerned about it on wet/snow covered roads. I seldom drive it on wet roads, and virtually never in the snow, but I would prefer it to take more pedal effort, even in the dry.

I am now trying to find a MC with a larger bore to see it that will make the pedal feel more to my liking.

These are links to some posts I have started:

http://forums.maxperformanceinc.com/...aster+cylinder

http://www.camaros.net/forums/showth...65#post1169565

[Ollie]

Joel,

Just finished reading your post in the two links above. In post #9 on the Team Camaro Tech. You stated "I don't have any special pads or shoes on the car, just what ever they had cheap at Auto Zone."
Maybe that is the problem, the pad material is too soft in these cheap pads, causing the brakes to grab. If you changed the pads to a better quality, the material would be harder and would not be as sensitive. Just a thought.

[Old Goat 67]

Very interesting and consuming reading, Joel. In fact, I am waiting on my printer to get done with the 10 pages of Diagnostic Process, so I can sit in the Lazy Boy and digest it all.

I'm still digesting this, but I'm thinking in my head that the change from vacuum assist to hydroboost assist is somewhat parallel to what we as new young drivers had to learn when power brakes first started appearing in abundance on the braking scene. NOT to hit that pedal as aggressively as we had with manual brakes.

A lot of this has to do with realizing we are the human with the brain, but the vehicle is a machine doing what you tell it. Case in point, NEVER hit the brakes hard in a spin or slide, because the first wheel to lock up IS GOING TO BE the one that leads the vehicle to it's final resting place. To prove this, take a toy car and drill a small hole through a wheel and into the body. Insert a small nail and try to send the car across the floor in a straight line. Watch what happens.

I have had thoughts of adding brake anti lock functions to our cars to computerize this system like the newer cars, but then I start talking to myself and saying "Hey, you are the computer".

At any rate, I salute you, thanks for the brain energy you generated. Keeps the cells from dying off, and I will be watching this whole thought process proceed (here and on the other forum). After all, Columbus took a chance, right?

Charles

[Joel Koontz]

What brake pads might work better?

I have stock rear drum brakes and an F-body spindle/brake conversion on the front.

I suspect that SPECIAL brake pads/shoes may cost quite a bit more than a larger MC.


I fully realize that I want to avoid hitting the brakes too hard and I might learn how to apply them more "smoothly", especially if it was the only vehicle I drove, but I frequently drive 4 or 5 other vehicles in addition to the Pontiac. Of course the brakes on the other vehicles all feel somewhat different, but I have no problem switching between them. Getting out of one of them and into the Pontiac is significantly different and if faced with a "Panic Stop" situation, I think it would be too easy to accidentally lock the brakes up.

[Socrates]

Joel,

I've read your posts here and elsewhere and wanted to comment before though got tied up.

I think we'd both agree that locking up the tires is the worst thing you can do for stopping a car. Best braking/stopping performance occurs with just enough brake pressure to fall just short of locking up the tires. Clearly, there is a very delicate balance here between the brakes system, the suspension, the weight balance and weight transfer of the car, and particularly the tires' ability to grip and not slip on the road while braking, which is a lot to work with here. The answer you're seeking may not be a simple one, though a MC swap is the obvious first step.

I see you're running drums out back. Do the discs or drums lock up first, or do they lock together?

What tires are you running? When I had new POS BGF TA's on my GTO I could lock them up with ease with just factory disc brakes. Now with new sticky Nitto's on the they take a whole lot more effort to lock up, and the car seems to stop faster in a hard stop.

Any chance you have worn out shocks or springs on any corner?

Which MC are you running again, and are you running an external pressure valve to the back? Are you running factory size brake hard lines, too?

I think pads could help, though of course they generally are not a cheap option. I love performance friction Z pads. I think a good ceramic may work for you too, as they don't get super gripy/touchy unless really hot, so the would take more pedal to lock in normal driving for sure. You might loose a little modulation for stoplight driving with ceramics, however, though the modern Vettes seem to do ok with them on the street.

Ultimately, the MC is where I'd personally start as well, though there are other factors to think about. I'm not savvy on your brake combo to suggest a good MC, though if you want to put discs out back I have a few suggestions. I have a Safari hydroboost with the Safari high fluid capacity disc/drum MC for my Scout II and it's a great, tested combo that many folks have ran to satisfying results, though the International is clearly not a Pontiac, with an extra ton of weight and foot of tires to deal with, so that MC may not work as well for you...

Hope you find the answer, and be sure to share what it is when you find it!

[Joel Koontz]

The shocks and springs are good. The tires are not super sticky, but good radials that grip fairly well. I am using the 1 1/4" MC that was on the 92 Astro Van with the HB.

The car stopped/braked very well with the stock booster and MC prior to the HB installation. I COULD lock the brakes up with heavy, but not extreme pedal pressure.
I never had any concern about locking the tires up too easily.

I am not suggesting that I can't stop the car without sliding the tires, but if I was driving on damp/wet roads and a deer ran out in front of me I think it would be all too easy to lock up the tires.

My stock system worked well, but required a bit(but not a lot) more pedal effort than I would consider ideal. The HB works well, but requires significantly less pedal effort than I think would be ideal. I would like a pedal effort about 1/2 way in between.

I think the right MC will get the pedal pressure where I want it to be, but it may be a trial and error process to get it right. I am discovering that there are not a lot of options for MCs with over 1 1/4" bores (the ones I have found are from trucks with HB) and most or all appear to have fairly tall reservoirs and I am concerned I may have a hood clearance issue with some or all of the ones that are available.

[BILTIT]

You could put in adjustable proportioning valves.

[Socrates]

Originally Posted by Joel Koontz

I am discovering that there are not a lot of options for MCs with over 1 1/4" bores (the ones I have found are from trucks with HB) and most or all appear to have fairly tall reservoirs and I am concerned I may have a hood clearance issue with some or all of the ones that are available.

Joel, The rez pops right off and can easily be swapped from a tall to a short rez in about a minutes time. Just put a big screwdriver under the rez and pry it out gently. Really easy to do and commonly done with h-boost swaps in the 4x4 world (we want/need the bigger rez on trucks). There are big rubber seals in the MC to keep the leaks away.

Hope a new larger bore MC works out. Let me know what application you're trying for my notes!

Worst case why not just go back to a vac booster or manual brakes? Seems like you might not really NEED superduty brakes and the h-boost may be overkill for your current brake/tire setup and your type of driving, maybe? You can have too much of a good thing. I'm actually worried about the h-boost being too much with C5 13" brakes I'm putting on my 66 along with LS1 rear discs and sticky Nitto's. I have a manual brake MC on hand to put in just in case I can't find the perfect, magic MC to tie it all together with the h-boost!