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Brake Booster questions ...


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I would like to replace my Brake Booster and Master Cylinder on my 70 Monte.  I notice that there is an additional component on a 70 Monte booster that my 72 Monte booster does not have.  What is this extra device on a 70 Booster and what does it do?  Do I need to keep it or can I chuck it?  I only ask because my 72 Monte does not have one.  See pics below.

The first pic is from a 70 booster and the second from a 72 booster.

Also I see that I can purchase a 9" booster instead of the normal 11" booster.  Are there any pros and cons to going with the 9" one to gain some space?

Thanks!!
Mike

 

20200924_190443.jpg

20200924_190504.jpg

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Mike.

    That is a brake residual valve. For the Montes, only the 70 had it. 

    If I remember correctly, it slows the brake fluid pressure  as to not lock up the rear wheels during braking. 

Maybe if you swap out the proportioning valve from the 70 style to 71 style, you can remove the 70 valve under the master. I would check the wheel cylinder and master cylinder bore diameters before I swap it out. 

 

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1 hour ago, Mike Brichta said:

I would like to replace my Brake Booster and Master Cylinder on my 70 Monte.  I notice that there is an additional component on a 70 Monte booster that my 72 Monte booster does not have.  What is this extra device on a 70 Booster and what does it do?  Do I need to keep it or can I chuck it?  I only ask because my 72 Monte does not have one.  See pics below.

The first pic is from a 70 booster and the second from a 72 booster.

Also I see that I can purchase a 9" booster instead of the normal 11" booster.  Are there any pros and cons to going with the 9" one to gain some space?

Thanks!!
Mike

 

20200924_190443.jpg

20200924_190504.jpg

If you decide to replace the master cyl let me know because I think that is the correct one I need for my 71

Thanks Dennis

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Mike, unless you need clearance for big valve covers on a big block, you should stay with the original full sized booster.

As your master cylinder looks to be the correct original with bleeders, you should have a local shop rebuild it. Any traded in rebuilt unit won't have the bleeders.

There was a discussion a few months back about the valve you're asking about.

It's a residual pressure valve to keep a few PSI in the line to the rears to prevent the springs from fully retracting the shoes.

There's also a valve in the rear that slows the buildup of pressure which allows the front brakes to grab first.

All 1970 stuff, 71 & 72 didn't have either valve.

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Thanks guys for all of your input.  I am always impressed in how much your guys know about these little details.  I learn something new every day.

So I guess what I am hearing is all (3) of the 70 pieces (proportioning valve, residual pressure valve and rear pressure value) should all be used together and don't remove one without the others?  And they are only on 70 models.  71-72 do not use these extra pressure valves.  Does that sound about right?

Thanks!!
Mike

 

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  • 2 years later...

Do you need to remove both residual valves when converting to 4wh discs? I realize you need the correct master and distribution block. Do you know if you can removed the internals of the valve to maintain the stock appearance and lines?

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I think I would check with the brake manufacturer about that. Some 4 wheel disc set ups are designed to be stock swaps (leaving the original equipment in place) whereas others are a complete system replacement.  

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21 hours ago, riverdogs00 said:

Do you need to remove both residual valves when converting to 4wh discs? 

Yes, residual valves need to be removed for 4 wheel disc conversion.

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5 hours ago, jft69z said:

Yes, residual valves need to be removed for 4 wheel disc conversion.

Thank you much. Now contemplating just going manual.  I have to replumb the lines to eliminate the residual valves. If I stay power, I have to add a vacuum pump, or can just swap to manual and avoid that cost. 

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20 minutes ago, riverdogs00 said:

Thank you much. Now contemplating just going manual.  I have to replumb the lines to eliminate the residual valves. If I stay power, I have to add a vacuum pump, or can just swap to manual and avoid that cost. 

Why a vacuum pump, does the car have a healthy camshaft/low vacuum?

Manual brakes probably aren't going to give you satisfactory stopping performance, I'm thinking. Hydroboost is a popular option for power assist. Personally, I used a vacuum pump on my both Monte & Z/28 with great results and a factory booster.

Another option, though costly is the electric boosted brakes available from Jegs and Speedway:

https://www.jegs.com/i/JEGS/555/631250/10002/-1

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15 hours ago, jft69z said:

Why a vacuum pump, does the car have a healthy camshaft/low vacuum?

Manual brakes probably aren't going to give you satisfactory stopping performance, I'm thinking. Hydroboost is a popular option for power assist. Personally, I used a vacuum pump on my both Monte & Z/28 with great results and a factory booster.

Another option, though costly is the electric boosted brakes available from Jegs and Speedway:

https://www.jegs.com/i/JEGS/555/631250/10002/-1

I have 2 cars. This one is a mid 70s LS7 454 / 4 spd conversion. Its not going to be a daily driver, but rather a weekend cruiser / occasional strip car. I wanted to keep the underhood reasonably period correct.  

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17 minutes ago, riverdogs00 said:

I have 2 cars. This one is a mid 70s LS7 454 / 4 spd conversion. Its not going to be a daily driver, but rather a weekend cruiser / occasional strip car. I wanted to keep the underhood reasonably period correct.  

If you want to keep it 'period' correct, manual brakes without the booster won't really accomplish that. 

I buried the vacuum pump under the fender, completely out of view, looks stock & works really good (so far). I went with the Leeds brand pump, and pulled it out of it's plastic case. It can be ordered without the case, but was quicker to get it with, at the time (Amazon).

 

https://www.summitracing.com/search/part-type/vacuum-pumps-street/product-line/leed-brakes-bandit-electric-vacuum-pump-kits

https://www.amazon.com/LEED-Brakes-VP002-ELECTRIC-VACUUM/dp/B0789PGMZP/ref=psdc_15707041_t1_B0789PJWBN

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4 minutes ago, jft69z said:

If you want to keep it 'period' correct, manual brakes without the booster won't really accomplish that. 

I buried the vacuum pump under the fender, completely out of view, looks stock & works really good (so far). I went with the Leeds brand pump, and pulled it out of it's plastic case. It can be ordered without the case, but was quicker to get it with, at the time (Amazon).

 

https://www.summitracing.com/search/part-type/vacuum-pumps-street/product-line/leed-brakes-bandit-electric-vacuum-pump-kits

https://www.amazon.com/LEED-Brakes-VP002-ELECTRIC-VACUUM/dp/B0789PGMZP/ref=psdc_15707041_t1_B0789PJWBN

All good info - thank you :)

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16 hours ago, jft69z said:

Why a vacuum pump, does the car have a healthy camshaft/low vacuum?

Manual brakes probably aren't going to give you satisfactory stopping performance, I'm thinking. Hydroboost is a popular option for power assist. Personally, I used a vacuum pump on my both Monte & Z/28 with great results and a factory booster.

Another option, though costly is the electric boosted brakes available from Jegs and Speedway:

https://www.jegs.com/i/JEGS/555/631250/10002/-1

G.M. tried the electric booster pumps in the mid '80's on a lot of their turbo cars, ( GNs & T-Types) as well as the larger cars (Vista Cruisers & Deltas). 

They worked well, but like Joe mentioned, PRICEY when they break down. 

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8 minutes ago, Scott S. said:

G.M. tried the electric booster pumps in the mid '80's on a lot of their turbo cars, ( GNs & T-Types) as well as the larger cars (Vista Cruisers & Deltas). 

They worked well, but like Joe mentioned, PRICEY when they break down. 

I'm still vacillating.  The car is not a resto, just trying to keep it simple and something that does not have a lot of newer a/m parts on it. I need to look at my ss, and see what I have for valve cover clearance, as I have taller, old vintage cast covers on the new motor. If I have booster clearance, then maybe a vac pump. I know I could go to a newer dual diaphragm booster, but would rather not. Its all personal preference.  My SS I've left stock, and resisted adding any A/M parts to it. It runs and drives great. This one, is more of a toy - The kind of look I enjoyed as a kid.  We will see. On a positive note, I'm taking the engine to Westech in mid February and have Steve Brule dial in the carbs and tunnel ram, and put it on the dyno. Should be fun.

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2 hours ago, riverdogs00 said:

  We will see. On a positive note, I'm taking the engine to Westech in mid February and have Steve Brule dial in the carbs and tunnel ram, and put it on the dyno. Should be fun.

Cool, maybe someday we'll see it on their TV show getting set up!

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Like Joe, I also have a vacuum pump on "Big Red".  Located under the driver's side fender behind the windshield washer reservoir. 9" dual diaphragm booster and 3/4 spacers between the head and stock valve covers. At the time the "cheater" valve covers were not produced. 

IMG_20190928_174651.jpg

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18 hours ago, MC1of80 said:

Like Joe, I also have a vacuum pump on "Big Red".  Located under the driver's side fender behind the windshield washer reservoir. 9" dual diaphragm booster and 3/4 spacers between the head and stock valve covers. At the time the "cheater" valve covers were not produced. 

IMG_20190928_174651.jpg

I’m running a 9” booster with what I would assume is the “cheater” valve covers (3/4” taller) I could have got away with a standard booster but the extra room is nice. 

49003EC2-EC46-4EE1-808A-7C76AAB76337.jpeg

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My car has a dual diaphragm nine inch brake booster. It’s pretty much equal to the stock single diaphragm unit when it comes to adding “power” to your brake system.

My camshaft doesn’t produce much vacuum so I needed a fix. I would hate having all the extra hoses for a hydro-boost setup so I began studying electric pump systems.

As it turns out, many vehicles today have electric vacuum pumps, GM, Ford, Subaru...they’re pretty compact and are often used to help a car have better brakes. From what I can tell, almost all of them are supplied by Hella. Ford has they’re own designs and they’re pretty poor.

There’s four different Hella pumps, small to large. The largest one, the UP5.0 can provide vacuum for a brake system without any engine vacuum and usually come on trucks. This is the same pump that’s used in the very expensive Master Power Silent Drive vacuum pump.

The Hella UP5.0 is used in some Dodge pickup trucks, part number 68385753AB. Search this number on Ebay and you’ll find it for about $65.00.

The pre-made kits like from Master Power, Leed etc. are ready to go with a universal bracket, vacuum switch, relay and check valve. If you want to use the UP5.0 pump on it’s own, you’ll need to add these components.

Superior Transmissions makes an adjustable vacuum switch, K058 which is about $44.00 on Amazon. The relay is any standard 12 volt relay and nice aluminum inline vacuum check valves can be had on Ebay in a variety of hose sizes.

The Ebay Dodge pump comes on a bracket with rubbers between the pump and the bracket. You’ll probably make up some sort of bracket but you should still use the rubbers. I made up a bracket and it’s mounted in the fender behind the washer fluid jug, it’s out of sight.

I recommend the largest vacuum reservoir can you can find and fit in the fender-or several of them.

The system works pretty good on my car-and I have a large master cylinder with a 1-5/16" bore to move enough fluid for six piston front & four piston rear calipers. BTW, I’m thoroughly convinced that the engineers at Wilwood know nothing about brake hydraulics.

Pic is the Hella UP5.0 on the Dodge truck bracket.

158681245_HellaUP5.0.thumb.jpg.60b3abd5bf01f1c8ad0a01e4282d566c.jpg

 

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