New brake booster size ?

[Syclone3Mt]

I have a 72 C10 swb with disc/drum set up. I hate the current brake pedal. Seems I have to stand on it to get adequate brakes. I was looking at upgrading to a dual diaphram booster design. Would 7" or 8" be better? Any suggestions from anyone who has done this upgrade...? I was looking at a company called LEED Brakes. There pricing seems good and have great reviews. Anyone heard of them? Heres a link to the setup i was looking at. Thanks.

https://leedbrakes.com/i-23439481-co...ve-chrome.html

[Andy4639]

Go with the stock booster 11" and you will be much happier! I tried a 8" and hated it. I went back stock.

[Syclone3Mt]

Originally Posted by Andy4639

Go with the stock booster 11" and you will be much happier! I tried a 8" and hated it. I went back stock.

Was the 8" booster too touchy?

[Jason Banks]

I have seen Andy post about liking the 11 inch stock better but can't remember why exactly.

I have this set on one truck:
https://www.ebay.com/itm/1967-1972-C...m/330948170372

I like it so much I ordered another for my other truck.

[Mbeef61]

I used a booster for a c30. Love it

[HeavyHauler]

Will a bigger brake booster provide more power assist for the brakes so a person doesnt have to apply as much brake pedal pressure?

[Andy4639]

Originally Posted by Syclone3Mt

Was the 8" booster too touchy?

No , it just didn't seem to work as good as the original 11".
I had the stock booster in my 71 and thought the 8" chrome booster would be a little nicer to the eye under the hood. I never liked the way it stopped compared to the 11" for 30 some years. It may have been just me but i went back to the 11" after a year of hating the way it worked.

[Syclone3Mt]

Originally Posted by Jason Banks

I have seen Andy post about liking the 11 inch stock better but can't remember why exactly.

I have this set on one truck:
https://www.ebay.com/itm/1967-1972-C...m/330948170372

I like it so much I ordered another for my other truck.

Nice. Does your brake pedal feel really good now? Im just tired when I get to a stop light and having tho hold my foot on the brake so hard otherwise it wants to just take right off and leap through the red light. Im sure the LS swap and radical cam don't help either

[Syclone3Mt]

Originally Posted by Andy4639

Go with the stock booster 11" and you will be much happier! I tried a 8" and hated it. I went back stock.

Thanks for the advice.

[geezer#99]

Originally Posted by Syclone3Mt

Nice. Does your brake pedal feel really good now? Im just tired when I get to a stop light and having tho hold my foot on the brake so hard otherwise it wants to just take right off and leap through the red light. Im sure the LS swap and radical cam don't help either

How much vacuum does your motor have when you’re pushing so hard?

[Syclone3Mt]

Originally Posted by geezer#99

How much vacuum does your motor have when you’re pushing so hard?

Vacuum is good, put in a Texas Speed Low Lift 212/218, .550/.550 cam. Idles real nice with a slight lope. I think the current booster may have a diaphragm thats leaking or just old and worn. Just would like a softer pedal is all. So many choices out there for brake parts.

[RustyPile]

Originally Posted by Syclone3Mt

Nice. Does your brake pedal feel really good now? Im just tired when I get to a stop light and having tho hold my foot on the brake so hard otherwise it wants to just take right off and leap through the red light. Im sure the LS swap and radical cam don't help either

You have more at work here than what first meets the eyes.. Long duration cams develop lower manifold vacuum and require a higher engine idle speed. Without a torque convertor of a higher stall speed, the vehicle will, using your words, "just take right off and leap through the red light..." Lower vacuum means more pedal pressure to operate the brakes.

My 454 BBC develops only 15 - 16 inches of vacuum at idle.. The lopey cam won't allow the engine to idle much below 1,000 - 1,100 RPM, and the stall speed of the torque convertor matches the cam's requirements and specs.... Even through all this, the brake pedal pressure and overall stopping power is just fine..

I guess all that bling - bling on that $360.00 master cylinder/booster suits some people, but I installed this $170.00 unit on my truck.. https://www.summitracing.com/parts/sum-760197/overview/

[Syclone3Mt]

Originally Posted by RustyPile

You have more at work here than what first meets the eyes.. Long duration cams develop lower manifold vacuum and require a higher engine idle speed. Without a torque convertor of a higher stall speed, the vehicle will, using your words, "just take right off and leap through the red light..." Lower vacuum means more pedal pressure to operate the brakes.

My 454 BBC develops only 15 - 16 inches of vacuum at idle.. The lopey cam won't allow the engine to idle much below 1,000 - 1,100 RPM, and the stall speed of the torque convertor matches the cam's requirements and specs.... Even through all this, the brake pedal pressure and overall stopping power is just fine..

I guess all that bling - bling on that $360.00 master cylinder/booster suits some people, but I installed this $170.00 unit on my truck.. https://www.summitracing.com/parts/sum-760197/overview/

Thanks for all the great info. I’ll check vacuum tomorrow and report back with what I find. Even before the cam swap my brakes were the exact same.
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[dmjlambert]

Originally Posted by RustyPile

I installed this $170.00 unit on my truck.. https://www.summitracing.com/parts/sum-760197/overview/

I like the looks and idea of that kit. When you buy a kit like that, is there way to go into a car parts store and tell them a make/model/year and get a replacement master cylinder across the counter to replace the one in that kit? Or way to get a replacement booster? Or is it necessary to buy a new kit every time a part of it wears out or breaks and needs replaced?

[RustyPile]

Originally Posted by dmjlambert

I like the looks and idea of that kit. When you buy a kit like that, is there way to go into a car parts store and tell them a make/model/year and get a replacement master cylinder across the counter to replace the one in that kit? Or way to get a replacement booster? Or is it necessary to buy a new kit every time a part of it wears out or breaks and needs replaced?

Service parts are readily available from (among vendors/dealers) Summit Racing.. I believe the master cylinder is a Corvette item.. We also have this "kit" on a '57 Chevy Nomad that's in the care of my son.. He has told me the booster is a Toyota item..

[Syclone3Mt]

Well I decided to go with the ebay purchase and get the 8" dual diaphram booster with new proportioning valve. Bled the brakes and took it for a cruise last night. What a difference in braking performance. I measured vacuum to booster. In park idling, vacuum is 15.8" W.C. In gear idling its 18.2" W.C. The brake pedal is so much better, way more assist. Now to replacing the rear drums, shoes and wheel cylinders this weekend!

[dflarsen77]

It doesn’t seem popular but I looked at getting a dual diaphragm 9” booster. They come from 70s vettes I think. More power than a single 11” but not as wide. Less power than the big c30 dual 11”. Ultimately I went with the single 11” because it was the easiest and I have the vacuum.

https://www.jegs.com/i/Tuff+Stuff/90...xoCIDIQAvD_BwE

[RustyPile]

Originally Posted by dflarsen77

It doesn’t seem popular but I looked at getting a dual diaphragm 9” booster. They come from 70s vettes I think. More power than a single 11” but not as wide. Less power than the big c30 dual 11”. Ultimately I went with the single 11” because it was the easiest and I have the vacuum.

https://www.jegs.com/i/Tuff+Stuff/90...xoCIDIQAvD_BwE

The booster in your link is a dual diaphragm 9 inch unit.. Cost is two dollars less than the Summit complete booster, master cylinder, prorportioning valve, and mounting bracket assembly.. cheap, good, fast...….

[RustyPile]

Originally Posted by Syclone3Mt

Well I decided to go with the ebay purchase and get the 8" dual diaphram booster with new proportioning valve. Bled the brakes and took it for a cruise last night. What a difference in braking performance. I measured vacuum to booster. In park idling, vacuum is 15.8" W.C. In gear idling its 18.2" W.C. The brake pedal is so much better, way more assist. Now to replacing the rear drums, shoes and wheel cylinders this weekend!

Good job, syclone3... That booster/master cylinder assembly looks right at home...

[Syclone3Mt]

Originally Posted by RustyPile

Good job, syclone3... That booster/master cylinder assembly looks right at home...

Thanks Rusty, still waiting on parts for rear brakes.

[Larry S]

Originally Posted by Syclone3Mt

Well I decided to go with the ebay purchase and get the 8" dual diaphram booster with new proportioning valve. Bled the brakes and took it for a cruise last night. What a difference in braking performance. I measured vacuum to booster. In park idling, vacuum is 15.8" W.C. In gear idling its 18.2" W.C. The brake pedal is so much better, way more assist. Now to replacing the rear drums, shoes and wheel cylinders this weekend!

Is that a 6.0? Was your vacuum adequate?
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