[steve25]

Just run bigger motor so ya have more vacuum!

[HWYSTR455]

The issues with hydra boost is that you loose a lot of pedal 'feel', and pedal granularity. In a lot of cases it 'over boosts' too.

There's a cost association with using one too, not to mention additional troubleshooting overhead, cost, and increased potential of failures. (more moving parts)

The only reason to use a hydra boost is if you have no other choice, like with boost. That's why the Buick GNs got them.

You're far from no other choice, and a dual 9" booster is your best bet. Don't throw stuff on there 'just because'. A dual 9" works to almost 9-10" of vacuum, and I suspect you will be well above that.

My daughter's 442 has like 12-13" at best, and the assist from a dual 9" is almost too much. It's like a Caddy from the early 70s, will throw you through the windshield if you're not expecting it.

.

[mgarblik]

There is a thread in this section about aftermarket cruise control. Take a look at that. One of the posters has several pics of a 67 GTO with hydroboost installed and he seems to really like it. Don't know what the rest of his braking system consists of. I have worked on many hydroboost systems. In general, they are used on trucks and heavy cars that require lots of boost or diesels that don't run a vacuum pump. Agree they provide little pedal feedback and provide tremendous boost pressures. When I worked on Ford cop cars with the system, we had numerous situations where we had to replace rotors because the cops would sit in the median after a little pursuit and kind of massage the brake pedal while they were waiting to jump out on the road again. The system put out so much pressure they would bend and sometimes crack the rotors from sitting still and putting heavy foot pressure on the pedal. On a 4-wheel drum brake system, I would think the self-energizing action of the shoes would make for a very touchy brake pedal combined with the super boost provided. Disc/drum would probably work better. Concerning Buick Grand National brakes: I am pretty sure all years came with the GM PowerMaster brake booster. That was a sort of self-contained electric hydroboost that used an electric pump and not power steering pump pressure. Sort of like an integral ABS system. They had all kinds of service problems and some GN's were converted to true hydroboost like the OP is asking about.

[MD79TA]

It was 12 months ago but that's fine thing change I guess.

[Lemans64]

I used a Hydratech Booster, works very well. I only had 8 niches of vacuum and had tried a vacuum pump. Yes the vacuum pump worked, but it was noisy and you could feel the vibration when it came on. Also had relay problems which you would not know until trying to stop with no vacuum.
http://www.hydratechbraking.com
I went for the full show option. Looks and performs very nice. It can be done a lot cheaper but I did not want a used one.

[mgarblik]

Originally Posted by Lemans64

I used a Hydratech Booster, works very well. I only had 8 niches of vacuum and had tried a vacuum pump. Yes the vacuum pump worked, but it was noisy and you could feel the vibration when it came on. Also had relay problems which you would not know until trying to stop with no vacuum.
http://www.hydratechbraking.com
I went for the full show option. Looks and performs very nice. It can be done a lot cheaper but I did not want a used one.

I went to their web site and looked around. Looks very nice and a nice web site. I found in their FAQ's my exact question. They DO NOT recommend using a hydroboost, (at least their's), on a 4 wheel drum brake application. They say it will be grabby in the front and pull left and right. So that answers my question concerning my 62. Since I am married to the 8 lugs, I guess a new vacuum booster/master cylinder is my only option for a dual system. That's unfortunate.

[waterdog]

Look into Astro Van hydro boost. Have one on 65 GTO with front disc. Works great and not to hard to install. You need power steering and bend or modify the brake line.