#757283 - 01/17/10 08:36 AM
B-Body Dual Diaphram Brake Booster Upgrade
|
Joined: Dec 1999
Posts: 6,890
Z65_Paul
Administrator 20+ Year
|
Administrator 20+ Year
Member

Joined: Dec 1999
Posts: 6,890
McDade, TX
|
If you're like me, you've hated the feel of your stock brakes from day one. In my case, it literally was on day one, driving the SS right off the dealer lot in 1986. I even returned the car and complained, but was told "it's normal". The pedal has an extremely soft feeling, and hits the floor during panic stops. Even then, the SS barely stops, resulting in many unwanted close encounters with disaster. After a bit of research here on good ol MonteCarloSS.com, I found that GM used a puney 12" single diaphram (aka pancake style) brake booster on all 1986 model Montes.. and on some other years. Later year (87-88) as well as some earlier year Montes got the 9" dual diaphram brake booster, which provides better performance and brake pedal feel. While I still plan on upgrading the remainder of the brake system, I decided to start with a swap out of the single diaphram with a 12" dual diaphram from a B-Body (1990 Caprice). You can use this same procedure to swap in a G-Body 9" Dual Diaphram. Before we get started, a note about engine vacuum. For the brake booster to operate at peak performance, engine vacuum should be ideally at 18 inches. Booster performance drops off as engine vacuum drops. And typically, engine vacuum can drop off with engine performance upgrades. Use of a vacuum reservoir, or an auxillary vacuum pump can help recover brake booster performance. Tools required: 15mm deep socket, at least a 12" extension, universal joint, ratchet, needle nose plyers, philips screwdriver, wrench to remove battery cable and an assistant. ProcedureDisconnect the negative terminal of the battery. You'll be working under the dash, with wrenches in close proximity to the fuse panel and other wireing. Better safe than sorry later. Take note of the location and configuration of all items in the vicinity of the brake booster. Here, a photo showing the 12" single diaphram booster as installed from the factory.  Next order of business is to remove the dash panel just below the steering column. 4 screws required to remove. This allows access to the pin at the top of the brake pedal.  Using the 15mm socket/ratchet, remove the self locking bolts holding the master cylinder to the brake booster. (Note the orientation of two brackets being held in place by each bolt, one holds the speedometer cable, the other holds a wire harness.) Remove the master cylinder from the booster and let it float, held up by the brake lines. Next remove the vacuum line from the check valve on the brake booster. Also route the various wire harnesses, vacuum and window washer lines to the rear of the brake booster.  The plunger of the brake booster is held in place at the top of the brake pedal by a washer and R-Clip shown below. The round part of the R-Clip should be pointed down. Using a pair of needle nose, grasp the rounded tip of the R-Clip and pull. The clip should easily come off.  Next, using the 15mm deep socket, extensions, universal joint and ratchet, remove the 4 self locking bolts under the dash holding the brake booster in place. Once removed, have an assistant help in the removal of the brake booster, rocking it back and forth while you remove the plunger from the pin at the top of the brake pedal. Care should be taken in the initial separation of the brake booster from the fire wall. There is a thin gasket which can be reused if not mangled during removal. I'm told these gaskets are available from a few vendors. I do not have further information however.  Once removed and placed next to the B-Body dual diaphram brake booster, you can see the obvious difference. Note the pin shown removed from the booter below. This pin is matched to the booster and is placed between the booster and master cylinder. Do not reuse the old pin. You must use the pin which came with the new booster. Below, the original 'pancake style' G-Body 12" single diaphram booster on the left, the new B-Body 12" dual diaphram on the right.  Below, the new B-Body 12" dual diaphram booster on the left, the original 'pancake style' G-Body 12" single diaphram booster on the right.  Reinstallation, like many things, is just the reverse order. Place the gasket on the new booster, insert it into the fire wall. Using an assistant to move the booster back and forth, place the booster plunger back onto the pin at the top of the brake pedal. Once on the pin, place the washer on the pin, and reinsert the R-Clip into the hole in the pin. Then secure the booster to the fire wall using the original 15 mm self locking nuts. Replace the dash panel with the 4 screws. Make sure the booster unique pin is placed in the hole in front of the booster, then position the master cylinder in place. Ensure the two original brackets holding the speedometer cable and wire harness are in place before tightening the two 15 mm self locking nuts for the master cylinder. Re-route the various wire harnesses, vacuum and window wash lines through the clip at the top of the booster.  Secure the vacuum line from the power booster filter to the booster check valve. While you're at it, I recommend replacing that power booster filter. If you're like me, you've not touched it in 25 years. It's about time for a new one. At under $7 a piece from AutoZone (HELP! section P/N 80195), there's no good reason not to replace the filter. For this swap, I chose to purchase a remanufactured brake booster for a 1990 Chevy Caprice. The Cardone part number (used by most local auto parts stores) is P/N 54-71040. At AutoZone, this lists for $92.99 with a $10 core. Since you're not replacing a like item, the core doesn't apply, so a total of $102.99 for the item, with lifetime warranty. You can also purchase this booster paired with a B-Body Master Cylinder (P/N 50-1040) for $122.99 plus $20 core, or $142.99 total. I don't reocmmend using the B-Body master cylinder with the stock brake system, but this may be a viable option if you've already upgraded. Or, you certainly can go to your local bone yard and find a late 80's B-Body and pull this item. Also note: If you purchase a remanufactured unit, it will come in a rather unattractive gray tone. I spray painted mine with satin finish black Rustoleum. While I haven't yet had the opportunity to go on a long drive with the new b-body booster, I can tell you the drive way pedal feel is dramatically better. The pedal responds with a firm feel that does not bottom out. I'll report back when I've had a chance to go on a drive. I think no matter what, it's a good first step (of many) in upgrading the stock brake system. Special thanks to Bob (mmc427ss), PaulB (PB86SS/87LS), and Steve (TPI Monte SS) for their additional guidance prior to this swap. I hope this helps. It is certainly a good upgrade to consider if you have a single diaphram (pancake style) booster. Good luck!
|
|
|
#757322 - 01/17/10 03:07 PM
Re: B-Body Dual Diaphram Brake Booster Upgrade
[Re: Z65_Paul]
|
Joined: May 2004
Posts: 983
BladeOfAnduril27
15+ Year
|
15+ Year
Member
Joined: May 2004
Posts: 983
Doylestown, PA
|
Is this a worthwhile upgrade for those of us who have the stock G-Body dual-diaphram boosters?
~ Matt H.
1988 Monte Carlo SS w/ T-tops, White with gray int, 350, Summit cam, World Torquer S/R heads, Holley St. Dominator intake, Edelbrock 600cfm carb, Champion 3-row alum radiator, ramchargers, 200-r4 with CK Shift Kit, billet servo, 2200 stall, Afterburner headers, Pypes 2.5" with x-pipe, Violator mufflers (stock exit), S10 front brake swap.
|
|
|
#757323 - 01/17/10 03:14 PM
Re: B-Body Dual Diaphram Brake Booster Upgrade
[Re: BladeOfAnduril27]
|
Joined: Aug 2001
Posts: 14,862
Gruvin
Moderator 15+ Year
|
Moderator 15+ Year
Member

Joined: Aug 2001
Posts: 14,862
Texas
|
Is this a worthwhile upgrade for those of us who have the stock G-Body dual-diaphram boosters? with a 3" bigger diaphragm, i think it would be a good upgrade, especially if you are going to further upgrade the brakes now or in the future
My first SS! Sold Jan 2004 ![[Linked Image]](http://www.MonteCarloSS.com/images/Gruvin_84SS_sig.jpg) 87 SS bought 9-5-04: Sold 6-18-2010 - project 87 finds a new home with another undisclosed MonteCarloSS.com member!
|
|
|
#757362 - 01/17/10 05:12 PM
Re: B-Body Dual Diaphram Brake Booster Upgrade
[Re: Monte_ExpreSS]
|
Joined: Dec 1999
Posts: 12,379
PB86SS/87LS
Administrator 20+ Year
|
Administrator 20+ Year
Member

Joined: Dec 1999
Posts: 12,379
New Berlin, WI
|
I think the b-body booster is a "must have" for any car with brake upgrades, especially if your car has the stock single diaphram unit. As for if it is an improvement over the dual g-body booster, I'm not sure how much, but surely it is. Maybe someone who has done that can share. I think if your brake system is stock with the dual g-body unit, it might not be that noticeable going with the b-body unit. As far as years for the b-body booster, the late 80's style generation worked for a few of us, not sure on specific year ranges unfortunately. I got mine off a junkyard Caprice with the composite headlights, so 88-90'ish I believe. I can concur with Paul C. with what a difference in brake feel it made  .
- 86'SS 383 CCC QJet- BRF 2004r-8.5" 3.42 - 87'LS 350 MAF/SD TPI- CRF 2004r-7.5" 3.42 - 81'Grand LeMans Safari Wagon 350 CCC Q-Jet/CZF 2004-r/8.5" 3.73 - 07'TBSS Stockish daily driver
|
|
|
#766005 - 02/16/10 03:55 AM
Re: B-Body Dual Diaphram Brake Booster Upgrade
[Re: Z65_Paul]
|
Joined: Oct 2008
Posts: 571
AndreB
Member
|
Member

Joined: Oct 2008
Posts: 571
Milwaukee, Wi
|
I would caution against using a later model B-Body (post 1990) booster only because I have not seen it used on a 4th Gen G-Body. Perhaps someone has definite experience one way or another. Since the B-Body went through a generational change in 1991, the configuration may not be compatable. When u say may not be compatible, u mean the 4 bolts lining up to fit and also the 2 bolts to fit the master cylinder? We are sorta stripping a 95 blazer. Im gonna see of the if the booster from it fits, maybe tomorrow if i get to it.
85SS 350v8, 200-4r, bodywork and H4 upgrade coming soon dreday1062000@yahoo.com
|
|
|
#766026 - 02/16/10 05:46 AM
Re: B-Body Dual Diaphram Brake Booster Upgrade
[Re: AndreB]
|
Joined: Dec 1999
Posts: 12,379
PB86SS/87LS
Administrator 20+ Year
|
Administrator 20+ Year
Member

Joined: Dec 1999
Posts: 12,379
New Berlin, WI
|
I bought a brand new GM MC for a early to mid 90's b-body and it was definitely different in how it mounted and/or the lines. I didn't keep details but I want to say the line fittings were different sizes, not sure on the physical mounting of it.
- 86'SS 383 CCC QJet- BRF 2004r-8.5" 3.42 - 87'LS 350 MAF/SD TPI- CRF 2004r-7.5" 3.42 - 81'Grand LeMans Safari Wagon 350 CCC Q-Jet/CZF 2004-r/8.5" 3.73 - 07'TBSS Stockish daily driver
|
|
|
#860604 - 03/16/11 07:02 AM
Re: B-Body Dual Diaphram Brake Booster Upgrade
[Re: kubihibi]
|
Joined: Nov 2006
Posts: 160
Big Reazon
Member
|
Member
Joined: Nov 2006
Posts: 160
Seattle, Wa
|
Why is it not recommended to use the b body master cylinder on stock brakes?
I eat rice and buid muscle. You add body kits I add racing slicks. My car is fast your car pretends to be fast. I step on the gas you hear my rumble. You step on the gas and it sounds like a bee is near my ear. Just know this you pull up to my car you might as well catch you own car on fire, because they call me the rice burner.
|
|
|
#984171 - 09/26/13 04:10 PM
Re: B-Body Dual Diaphram Brake Booster Upgrade
[Re: Z65_Paul]
|
Joined: Oct 2008
Posts: 184
tall t-top
Member
|
Member

Joined: Oct 2008
Posts: 184
San Antonio, Texas
|
any tips on how to pick a good booster at the boneyard.
Andrew
86 MC SS t-top, 305 with port and polish, Edlebrock Performer Intake, Flowtech Afterburner headers, duals to Jeg's chambered mufflers, Jeep steering shaft, Turbo Eclipse seats (Weekend toy but a project at the moment) 91 C1500 extended cab, TBI 350, 2in suspension lift, Jeep steering shaft. (Daily driver) 2012 Mitsu Outlander Sport (wife's car)
|
|
|
#984212 - 09/27/13 01:14 AM
Re: B-Body Dual Diaphram Brake Booster Upgrade
[Re: Z65_Paul]
|
Joined: Dec 1999
Posts: 12,379
PB86SS/87LS
Administrator 20+ Year
|
Administrator 20+ Year
Member

Joined: Dec 1999
Posts: 12,379
New Berlin, WI
|
I looked for a composite headlamp older Caprice (late 80's). I forget the exact rationale, besides being the "newest" version that would work.
- 86'SS 383 CCC QJet- BRF 2004r-8.5" 3.42 - 87'LS 350 MAF/SD TPI- CRF 2004r-7.5" 3.42 - 81'Grand LeMans Safari Wagon 350 CCC Q-Jet/CZF 2004-r/8.5" 3.73 - 07'TBSS Stockish daily driver
|
|
|
#984220 - 09/27/13 02:35 AM
Re: B-Body Dual Diaphram Brake Booster Upgrade
[Re: Z65_Paul]
|
Joined: Jan 2000
Posts: 5,652
mmc427ss
20+ Year
|
20+ Year
Member
Joined: Jan 2000
Posts: 5,652
Pottstown, Pa
|
Several other vehicles use the 12" dual booster, Blazers, fully equipped S10 Blasers and pickups, vans and trucks.
Criteria for the choice of vehicle is: Looking for a donor vehicle with a curb weight of about 4200-4400. Montes weighs about 3400-3600, booster from say a 5K lb truck may have to much assist. Also the inlet for vacuum should be about the 10 o'clock location. Inlets can vary depending on vehicle . Always use the booster pushrod that comes with the donor, it's length is gauged to the booster. Bob
Late 80's to mid 90 Caprice is always a good donor, try to get one with as low mileage as possible. My donor was an 87 loaded Caprice, garage kept, some Grandma totaled the front end, very low mileage. Of couse I did the swap 12 years ago, picking was much easier then. Bob
|
|
|
#996467 - 03/03/14 07:33 PM
Re: B-Body Dual Diaphram Brake Booster Upgrade
[Re: rhalpin]
|
Joined: Oct 2006
Posts: 1,799
JAWSS
Member
|
Member

Joined: Oct 2006
Posts: 1,799
Ft. Hood, TX
|
Cant figure out how to subscribe to a thread Go to the top left of the thread and click the thread options button, on that menu it will say thread notifications. Click that. HTH J
 86 Monte Carlo SS T-top 69 Cutlass S Convertible 70 Chevelle Malibu (Second owner, grandma car) 12 Cadillac CTS-V Wagon
|
|
|
Moderated by 345HP87SSAC, 85_SS, Dalt10, Gruvin, mannblk, MC87SS, mcss383, MY FYN 79, PB86SS/87LS, Phil87SS, Russ, ss4ever, TPI Monte SS, Z65_Paul
|
|
by clyde
|
by Ted88SS
|
by FuzzyDnkn
|
by ls1_monte
|
by montess406
|
|
Recent Contributors
kevins88ss
|
|
|