[GS470]

I'm leaning towards installing an Astro van hydroboost unit and have been trying to figure out how to attach it to the firewall and have a couple questions.

How do you decide if you should mount it straight or angled? And if you angle it, what's the "correct" angle? The brackets from Pirate Jack look like a good starting point if angling is the way to go.

And how do you decide which hole in the brake pedal to use for the rod? Do you use the upper hole if you mount straight and the lower hole if you mount at an angle?

I assume the angle and brake pedal hole selection are related, but I'm not sure. For example, if I mount the hydroboost straight, can I use either hole? Does the rod need to go into the hydroboost straight, or can it be angled? Seems like it should go in straight, but I don't know.

[Old Goat 67]

If you mount it flat (straight), the upper hole is a direct shot, as manual brakes were.

If you mount it angled up, as the power brakes were (because of vacuum booster size), use the lower hole for a straighter shot.

[GS470]

Originally Posted by Old Goat 67

If you mount it flat (straight), the upper hole is a direct shot, as manual brakes were.

If you mount it angled up, as the power brakes were (because of vacuum booster size), use the lower hole for a straighter shot.

Thanks, Old Goat 67. So how do I decide which hole on the brake pedal is the better choice? It sounds like this decision will dictate how I mount the HB unit.

[Joel Koontz]

Which brake pedal hole you use will affect how much pedal presure you need to apply.

I explained (at least partially) how this will affect the function in post # 7.

Based upon my experience, I would think you would ALWAYS want to use the lower hole in the brake pedal, but others have apparently used the upper hole and are satisfied with how their brakes work.

IMO it would be BEST to have the rod line up directly with the brake pedal hole that you use, but it does not HAVE to be exactly in line. On the HB that I have the rod has a ball end and there is sort of a socket (as in ball and socket) on the rear of the HB that allows for some misalignment.

When my HB Rod was directly in line with the upper brake pedal hole, there was not enough flexibility to get it to work in the lower brake pedal hole. Had to tilt it more to get it to line up with the lower hole. Not sure how many degrees mine is tilted.

If you use Vac Booster Brackets, I would think they should point the rod toward the lower brake pedal hole since that is the hole that is normally used with OEM Power Brakes.

[Old Goat 67]

GS470,
In my mind, the BEST choice would be to have the rod on a flat plane to the master cylinder bore. This is the way they were engineered in the beginning. Surely there is a good reason, think about it.

Flat mount dictates going to top hole. If you are going to angle it, I would make sure the angle of the plate you use would be as close as possible to the angle of the brackets on the original vacuum booster.

How much pedal pressure you need to apply will be a function of how fast you want to stop. Each driver will do that differently. Believe me, the improvement of braking ability with hydroboost will demand that you forget about the previous characteristics of present braking system and learn how to brake as needed for what different situations in front of you dictate. The difference of fulcrum power between the two holes is not want your concern should be. Build it the same way it was engineered. Flat plane to master, and don't screw around with a rod that "COULD MAYBE" cause a problem in emergencies. Brakes are no place for "MAYBES". Make sure your rod is one piece, solid and the right length.

Charles

[Old Goat 67]

I opted to have mine flat for two reasons.

1) It would fit that way.
2) I hate to fill a master cylinder with an angle on it. Makes me think it could have been designed with a flat top on it instead.

[2SlowTA]

Originally Posted by Old Goat 67

GS470,
In my mind, the BEST choice would be to have the rod on a flat plane to the master cylinder bore. This is the way they were engineered in the beginning. Surely there is a good reason, think about it.

Flat mount dictates going to top hole. If you are going to angle it, I would make sure the angle of the plate you use would be as close as possible to the angle of the brackets on the original vacuum booster.

How much pedal pressure you need to apply will be a function of how fast you want to stop. Each driver will do that differently. Believe me, the improvement of braking ability with hydroboost will demand that you forget about the previous characteristics of present braking system and learn how to brake as needed for what different situations in front of you dictate. The difference of fulcrum power between the two holes is not want your concern should be. Build it the same way it was engineered. Flat plane to master, and don't screw around with a rod that "COULD MAYBE" cause a problem in emergencies. Brakes are no place for "MAYBES". Make sure your rod is one piece, solid and the right length.

Charles

Great post. Keeping it straight is the way to go.

I tried to get a shot of mine, but this was the best I could get. It needs to go straight in.



Your brakes are going to be so much better, you will not be worried about pedal pressure.

[Old Goat 67]

2SlowTA,

Am I correct in thinking that you put the hydroboost level on a Trans Am? I did not think it would fit that way. I guess I "assumed" the Camaro guys were doing it with the brackets because of clearance issues.... (darn I hate that word assumed). Boy, that's good news in my mind. There is no need to spend the extra dollars, if that's the case.

Can you post a picture of your install under the hood?

Thank you for the compliment,
Charles

[Joel Koontz]

I agree that you should try to keep the rod in a straight line with the brake pedal, but I definately do not agree that you should use the top hole of the brake pedal.

The Astro HB creates much more pressure than a normal Vacuum Booster (that also uses the lower hole) and using the upper brake pedal hole will increase the pressure even more. Thats why the upper hole is used with Manual Brakes.

Some seem to think that "the most powerful brakes, are the best brakes". More power is a good thing, up to a point, and then it is "too much of a good thing".

I would wager that the way I originally installed my HB I could have locked up the tires using just my big toe to apply the brake pedal. I want to be able to lock up the tires, but I would prefer it to take at least 100 pounds of force to do so.

If you elect to use the upper hole in the brake pedal, be prepared to have brakes that are very sensitive, and IMO, potentially dangerous in situations with limited traction, such as wet, or snow covered roads.

[2SlowTA]

Originally Posted by Old Goat 67

2SlowTA,

Am I correct in thinking that you put the hydroboost level on a Trans Am? I did not think it would fit that way. I guess I "assumed" the Camaro guys were doing it with the brackets because of clearance issues.... (darn I hate that word assumed). Boy, that's good news in my mind. There is no need to spend the extra dollars, if that's the case.

Can you post a picture of your install under the hood?

Thank you for the compliment,
Charles

Yes, I did mount it level on my 2nd gen Trans Am. Here are a couple of shots of it getting set up, is that what you wanted?

[Old Goat 67]

2SlowTA,

I had seen those you posted previously.
I was hoping you might have a shot from under hood showing the inner fender clearance.

Thanks,
Charles

[2SlowTA]

Oops, forgot I posted those. I am not presently using inner fenders, too heavy, so I can't help you in that area. If you want to run them and keep the HB level, you will need to clearance the drivers side one just a bit.

[Old Goat 67]

Thanks anyway. I sure would like to see someone with a level install in one of those. I just believe it would clear, but I may be wrong.

For you guys doubting the upper hole theory, here is more info you may not have seen. There are more out there who are putting them in flat and level. Be sure and watch Part 1 and then Part2.

http://v8tvshow.com/content/view/125/90/

Charles

[Socrates]

Great thread going here!

Just want to add one thing a lot of folks overlook: When upgrading to the hydroboost, replace your old rubber brake lines!!! If your hard lines are old/original replace them too!

When I put the HB on my Scout II the 37yr old rear rubber line ruptured the first time I hit the brakes in my shop!!! I'll be laying down new SS lines and braided soft lines when I put the HB in my 66 GTO. Rupturing a brake line over 100mph at the track just wouldn't be that much fun...

[Ollie]

Look what UPS delivered from Pirate Jack. The power brake brackets, extension rod, and clevis. Along with the rods that came with the Hydroboost I thank this is going to be a bolt in conversion. The bolts on the Hydroboost plate match the holes in the brackets exactly. the distance between the brackets at 2 1/4 inch is the same distance as the vacuum booster. The end of the Hydroboost is reght at the fire wall.

[Old Goat 67]

Looks like a shoe in, Ollie. How much did you have to give for all that?
How are you going to seal the firewall?
Is that a GM truck unit? What hoses will you use?

Charles

[Ollie]

Originally Posted by Old Goat 67

Looks like a shoe in, Ollie. How much did you have to give for all that?
How are you going to seal the firewall?
Is that a GM truck unit? What hoses will you use?

Charles

I paid a whopping $26.00 for the brackes, rod extension, and clevis, and another set of brackets. Plus free shipping but that was only good untill the end of March.

I am going to contact Pirate Jack's and see if I can purchase a boot/bellows from a power brake booster to seal the firewall hole.

I dont know what hoses I will end up using,as I plan on mounting the Hydroboost upside down. I will start with the part numbers of the hoses You have posted on Your web site.

I dont know what the Hydroboost was originally on, I got it from the same Ebay seller You got Your's from, Rafel 1769

[Old Goat 67]

I thought that unit looked the same. That's out of a mid 80's GM truck, that's what Rafel told me.

The hoses I used were for the same vehicle, but I don't know it you can make them fit if you turn it upside down. I didn't for two reasons, the built in drain passage in the booster and I had no clearance issues at all. In fact, with the deletion of the big old vacuum boost unit, clearance improved dramatically. Looks like stock when I compare it to my Tahoe unit.

Charles

[GS470]

Originally Posted by Ollie

Look what UPS delivered from Pirate Jack. The power brake brackets, extension rod, and clevis. Along with the rods that came with the Hydroboost I thank this is going to be a bolt in conversion. The bolts on the Hydroboost plate match the holes in the brackets exactly. the distance between the brackets at 2 1/4 inch is the same distance as the vacuum booster. The end of the Hydroboost is reght at the fire wall.

Looks like a nice fit, Ollie. Are those Pirate Jack's "650" booster brackets?

[Socrates]

Ollie,

Where did you find those adjustable booster rods with the ball socket end on the piratejack site? Product number? Thanks!