[vertigto]

Long story short, the shop installed a Right Stuff 4 disc big brake conversion kit on my 70 GTO that will not adequately stop the car (will not lock up). Right Stuff sent a 7/8" bore master cylinder and installed performance pads that helped a little in stopping distance, but didn't solve the problem. FWIW...original 400 newly rebuilt (30 over) with mild cam pulling 15' at idle. Should have enough vacuum, but whatever.

Last resort is to try http://"https://rpui.com/-The-Right-... kit (HBUK001).

Unfortunately, the hoses included in the kit are backordered and they can't provide an accurate date. This is the last part/issue to complete the restoration, so a little impatient and not wantingto wait indefinitely.

So...looking for recommendations/other hydroboost kits to use with the rest of my Right Stuff brake kit/installation. I see CPP sells their own version and even sells two hose kits separately (braided or rubber), but not sure if compatible with what I already have from Right Stuff.

Any experience with other hydroboost kits that you would recommend? Any help/advice would be greatly appreciated. FWIW...not interested in trying vacuum cans or pumps, just want to do this right and finish/drive the car.

<Frustrated in NC>

[Lemans64]

I used Hydratech booster, they sell a hose kit that is braided, But I made my own with kits from Russell Hose.
Also used their fittings. Isn't the power system supposed to use a 1 1/8th master? My 64 stops on a dime, stock 69-72 GM disc in front
and stock 64 drum in rear. Make sure you wear your seat belt the first time you drive it. I am using a 1- 1/8th wilwood master.

http://www.hydratechbraking.com/GM_A_Body.html

[TinInjun]

If you’re not building enough brake system pressure, a hydro boost system will not help. You may need to to change to a 3/4 inch bore master cylinder to fix your issue.

[chuckies76ta]

Originally Posted by TinInjun

If you’re not building enough brake system pressure, a hydro boost system will not help. You may need to to change to a 3/4 inch bore master cylinder to fix your issue.

Hmmm, Can you elaborate on your statement?

[chuckies76ta]

Originally Posted by Lemans64

I used Hydratech booster, they sell a hose kit that is braided, But I made my own with kits from Russell Hose.
Also used their fittings. Isn't the power system supposed to use a 1 1/8th master? My 64 stops on a dime, stock 69-72 GM disc in front
and stock 64 drum in rear. Make sure you wear your seat belt the first time you drive it. I am using a 1- 1/8th wilwood master.

http://www.hydratechbraking.com/GM_A_Body.html

This^^^^. Need a 1-1/8" Master Cylinder with disc brakes from what I know and used.

The Hydro boost works very well with this M/C. You have to make sure the Power steering pump has the higher pressure valve. I believe somewhere around 1300 psi. I like the power steering pumps with the fitting for the return bleed line from the hydraboost. If not I weld my own own.

[chuckies76ta]

Pic of pump for demo only.

[Scott65]

I don't have anything to add to the hydro boost subject. But I'm curious about the original iteration. Were you using power assist, or manual braking to begin with? The 7/8" bore makes sense for manual, and no sense for power. You could be dealing with a proportioning issue or something of that nature that won't be resolved by hydro boost. If it were me, I'd want the current system working properly before I decided I didn't like it...

[Lemans64]

Originally Posted by chuckies76ta

Pic of pump for demo only.

Currently using the T in return line, no issues. But I do like the reservoir with 2 returns. Just not sure if all reservoirs use the same size hole for the pump to mount into? Have a Chrome one now so no welding in fitting. Also using Sepentine drive so must use current pump, keyed shaft.

[Scarebird]

What exact kit did you get?

Is your pedal hard or soft?

Some of these kits do not match OEM masters at all.

[vertigto]

Car was originally power front disc and rear drum before the restoration and stopped fine. With the frame off, 18" wheels and desire for improved braking, I opted for the Right Stuff big brake kit (apparently 1" bore MC). Also got their stainless brake lines, so everything new through Right Stuff.

Here is the link.

The Right Stuff kit did not adequately stop the car/lock up the brakes. Their tech(s) did some troubleshooting with the shop and stated to try the 7/8" bore MC (increase line pressure?) and upgraded pads, which decreased the stopping distance some, but will not lock up. Pedal before and after new MC/pads was hard...you could stand on it and not lock them up. No discernible fade after successive hard stops.

Right Stuff has not offered any additional solutions, except to try their hydroboost on my dime with no guarantees. I would love to know why their original kit with 1" or 7/8" bore MC cylinders did not work, but they/the shop are out of ideas. I'm all ears for additional thoughts and/or troubleshooting measures. FWIW...My power steering pump is a stock replacement.

Here is the link to their hydroboost kit, which incidentally is NOT in stock and no idea of fulfillment date (they said it could be 4/8/12 weeks). They said this was all I needed to work with the original big brake kit. I believe the shop still has the original 1" MC and the 7/8". Is everyone saying it is not compatible with the hydroboost kit, as RIght Stuff has stated?

FWIW...here is the link to the complete Right Stuff hydroboost 4 wheel disc conversion kits. for comparison. I only see a difference of rotor size (11" instead of 12"/13" on the original kit).

Right Stuff will not stand behind the failure of their original big brake kit, since the completion of the restoration took much longer than anticipated to find this out. I truly don't understand why the original kit doesn't work.

Thoughts? I just want to get this finished right and am out of ideas. I really don't want to have to rip the entire kit out and start over. Not sure I have the $$ or time. Open to suggestions. Could this be as easy as replacing the proportioning valve (not sure how)?

[Scott65]

A couple of observations: typically I think a 1 1/8" bore is typical with power discs. Is the brake rod linkage in the correct hole on the pedal. (Correct pedal leverage) If it had the 1 1/8" bore master cylinder and had high pedal effort, I think I'd suspect a booster issue. Did they give good instructions on verifying all the linkage connections? Is it possible the booster is bound up, or unable to apply all it's assist?

[Scott65]

Another option is to remove the booster and try the 7/8 bore master, with the brake pedal linkage in the correct hole for manual brakes. This will at least offer an idea as to where the issue stems from. Correctly set up manual brakes systems will stop perfectly well, an some like the input feel. Either way, at this point it seems the hydro boost would be money not well spent until the underlying issue is determined.

[Scarebird]

Background: About a decade ago Right Stuff wanted to sell our products; they did not have much in brake product other than steel lines, which is their main business. They flew us out to visit them and we examined their operation. Excellent distribution but no real research or developement for brake things, hence their interest in ours. It was in the end doomed as the owner at the time did NOT disclose the fact he was well into negotiations with Trim Parts who bought them out, stopped all contracts and fired upper management. So I am not too impressed with them as they don't know about what they sell.

That said, your issue:

The master is the garden-variety Corvette setup, either 1.00 or 1.25" bore. The booster is a piece of shiat that no knowledgeable vendor should sell - way too small. Your main issue here is the master bore is too big for those Ford Mustang calipers IF used with a GM 6:1 pedal - the stock Mustang bore is also 1" but I suspect higher mechanical leverage.

This is the animal we recommend: GM's dual 9" - works down to 9 inHg.

the 1981 301T came with these among other cars. I have a used one if interested; I converted my Lemans to manual 4 disc and it is surplus (master may need rebuilding). You may still need to go to a smaller bore master.

[Tom Vaught]

Ford has had Hydra-boost on Mustangs and Trucks since 1996.

The pedal will put your face into the windshield with a conventional Brake Stop (That the previous GM vacuum booster will not do).

I use a 1" bore Corvette 4 wheel disc Master Cylinder without any issues.

Tom V.

[TinInjun]

Originally Posted by chuckies76ta

Hmmm, Can you elaborate on your statement?

See Scarebird’s response above. 3rd paragraph.

[Lemans64]

Just another question here, Why is it that some people opt for the improved Bigger braking system when the original system is very good?
Was there a Problem with the original system or just figured the upgrade would be nice? As noted above my 64 has 69-72 GM factory calipers and drums
and stops very well, if not wearing seat one could hurt themselves. Sounds as though Right Stuff my have got it WRONG in the development part??

[65madgoat]

7/8" master is for manual brakes. Period. Also check hose used to vacuum booster - often wrong hose installed will collapse and braking experience will be how you describe.

[FrankieT/A]

I converted my car to hydro boost...no issue.
I used the hydroboost unit from an Astro van. Hoses??? Way simpler than people think. If your ok with regular stock looking hoses then use hydro hoses from a '78 Cadillac Seville if your fittings are standard and an '81 Seville if metric. Bolt on...

[400 4spd.]

[Tom Vaught]

Originally Posted by FrankieT/A

I converted my car to hydro boost...no issue.
I used the hydroboost unit from an Astro van. Hoses??? Way simpler than people think. If your ok with regular stock looking hoses then use hydro hoses from a '78 Cadillac Seville if your fittings are standard and an '81 Seville if metric. Bolt on...

Good Job FrankieT/A.

The Astro Van is one of the best units to use.

I run Stock Looking hoses vs aeroquip and it works fine. OEM quality engineering

Instead of using a tee and one return back into the reservoir, I had 2 nipples added on my PS reservoir. One for the Hydraboost and one for the Power Steering Return.

This stuff is NOT HARD.

Tom V.