Power booster Question.... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Longhorn Man · 04-03-2002, 10:15 PM

I know it's been gone over before...but is there a diferance between the drum/drum booster, and the drum/disc booster?
I have 2 extra disc ones, and a drum/drum one on the other side of town still mounted to my old cab.

------------------
'69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man
I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it.
FINALLY got the HORNIAC...a '70 one ton Longhorn with a Pontiac 350/350 and lots of 'personality'. Check out The Longhorn Webite.
If you need a pic posted, E-mail me at longhornmail@yahoo.com
Andy, in Columbus Ohio

69 longhorn · 04-03-2002, 11:32 PM

Chevy duty lists....71-291 (67-72) 1/2 ton bendix....same # (67-70) 3/4 ton bendix. 71-291A (71-72)3/4 ton bendix,& 71-291B (67-72) 1/2 to delco-moraine. Other than the size, I think you can interchange them,but may have a different brake feel due to size(not 100 % sure though)......69 longhorn.

[This message has been edited by 69 longhorn (edited April 03, 2002).]

barn9 · 04-03-2002, 11:51 PM

This could really be a dumb question (I haven't pulled mine out yet), but are the #'s stamped on them somewhere, or do you have to rely on the parts books?

------------------[*]'71 Cheyenne, 402BB[*]Winfield, KS[*] http://barn9.freeservers.com[*] steer50@hotmail.com

Longhorn Man · 04-04-2002, 12:06 AM

hmmm, good Q. And if they are on there...where at?

------------------
'69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man
I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it.
FINALLY got the HORNIAC...a '70 one ton Longhorn with a Pontiac 350/350 and lots of 'personality'. Check out The Longhorn Webite.
If you need a pic posted, E-mail me at longhornmail@yahoo.com
Andy, in Columbus Ohio

JimKshortstep4x4 · 04-04-2002, 09:27 AM

The only difference that I have been able to come up with where I could recognize the difference is on the single to double boosters. The doubles are considerably longer than the singles. There is a site with the common boosters pictured on it and it does not distinguish between drum and disc brakes.

I used the drum brake booster on disc brake truck and I cannot tell any difference between the way that truck stops and how a truck with the original disc brake's booster
stops.

The web site for pictures of the boosters is as follows:
www.brakebooster.com/booster.htm

Jim

[This message has been edited by JimKshortstep4x4 (edited April 04, 2002).]

Beast388 · 04-04-2002, 10:07 AM

I have a booster off a 68 GMC C10 on my 71 GMC K10. I noticed no difference in pedal feel or braking ability. The swap was 100% bolt in.

------------------
71 GMC Suburban 4X4
The "Beast"
388 CID Stroker, Scat crank, H-beam steel rods, KB Pistons, Speed-Pro Moly Rings, Clevite bearings, Speed-Pro High Volume oil-pump, Comp Cams 254H 4X4 Xtreme cam, SR Torquer 2.02/1.60 heads, Comp springs, Trick Flow pushrods, Comp Roller Rockers, Edelbrock Performer RPM intake, 3310 750cfm Holley, Summit HEI, MSD 6AL, Built TH350 Transcat Supper II shift kit 2000 RPM Stall, 4" Rough Country Lift....etc.

dmec · 04-05-2002, 03:24 AM

the difference i have noticed is in the master cylinders. moraine boosters use a master cylinder with a shallow indentation in the piston. bendix uses a deep indentation in the piston. i just went through this. i needed to replace my master cyliner on my 71. went to parts store and asked for master for 71 with disc brakes. would not work with my moraine booster. took it back and after trying different years found master from 73 worked with moraine.

04-03-2002, 10:15 PM	#1
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Power booster Question.... I know it's been gone over before...but is there a diferance between the drum/drum booster, and the drum/disc booster? I have 2 extra disc ones, and a drum/drum one on the other side of town still mounted to my old cab. ------------------ '69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it. FINALLY got the HORNIAC...a '70 one ton Longhorn with a Pontiac 350/350 and lots of 'personality'. Check out The Longhorn Webite. If you need a pic posted, E-mail me at longhornmail@yahoo.com Andy, in Columbus Ohio

04-03-2002, 11:32 PM	#2
69 longhorn Registered User Join Date: Aug 2001 Location: rock island,il,usa Posts: 5,382	Chevy duty lists....71-291 (67-72) 1/2 ton bendix....same # (67-70) 3/4 ton bendix. 71-291A (71-72)3/4 ton bendix,& 71-291B (67-72) 1/2 to delco-moraine. Other than the size, I think you can interchange them,but may have a different brake feel due to size(not 100 % sure though)......69 longhorn. [This message has been edited by 69 longhorn (edited April 03, 2002).] __________________ http://community.webshots.com/user/hotrodhorn

04-03-2002, 11:51 PM	#3
barn9 Half a bubble off! Join Date: Jun 2000 Location: Winfield, Ks, USA Posts: 5,588	This could really be a dumb question (I haven't pulled mine out yet), but are the #'s stamped on them somewhere, or do you have to rely on the parts books? ------------------[]'71 Cheyenne, 402BB[]Winfield, KS[] http://barn9.freeservers.com[] steer50@hotmail.com __________________ Just call me LB. '71 Cheyenne, 402BB, hauls blondes, brunettes, or redheads.

04-04-2002, 09:27 AM	#5
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	The only difference that I have been able to come up with where I could recognize the difference is on the single to double boosters. The doubles are considerably longer than the singles. There is a site with the common boosters pictured on it and it does not distinguish between drum and disc brakes. I used the drum brake booster on disc brake truck and I cannot tell any difference between the way that truck stops and how a truck with the original disc brake's booster stops. The web site for pictures of the boosters is as follows: www.brakebooster.com/booster.htm Jim [This message has been edited by JimKshortstep4x4 (edited April 04, 2002).] __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

04-04-2002, 10:07 AM	#6
Beast388 Suburbans RULE! Join Date: Jan 2000 Location: Clinton, IA 52732 Posts: 689	I have a booster off a 68 GMC C10 on my 71 GMC K10. I noticed no difference in pedal feel or braking ability. The swap was 100% bolt in. ------------------ 71 GMC Suburban 4X4 The "Beast" 388 CID Stroker, Scat crank, H-beam steel rods, KB Pistons, Speed-Pro Moly Rings, Clevite bearings, Speed-Pro High Volume oil-pump, Comp Cams 254H 4X4 Xtreme cam, SR Torquer 2.02/1.60 heads, Comp springs, Trick Flow pushrods, Comp Roller Rockers, Edelbrock Performer RPM intake, 3310 750cfm Holley, Summit HEI, MSD 6AL, Built TH350 Transcat Supper II shift kit 2000 RPM Stall, 4" Rough Country Lift....etc. __________________ --Ben 71 GMC Suburban 4X4 The "Beast" 388 CID Stroker, TH350, NP205, 8-lug D44, 14BFF w/ Detroit, 4.10:1 gears, 4-Wheel Disks 4" Lift, 35" MT/R's.

04-04-2002, 12:06 AM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	hmmm, good Q. And if they are on there...where at? ------------------ '69 G.M.C. 350/350. Trying to clean up the left over damage from the Dope-Smokin-Old-Man I've been dubbed the Longhorn Freak/Fanatic/Expert, I just hope I can live up to it. FINALLY got the HORNIAC...a '70 one ton Longhorn with a Pontiac 350/350 and lots of 'personality'. Check out The Longhorn Webite. If you need a pic posted, E-mail me at longhornmail@yahoo.com Andy, in Columbus Ohio

04-05-2002, 03:24 AM	#7
dmec Senior Member Join Date: Jun 2000 Location: yucaipa ca Posts: 580	the difference i have noticed is in the master cylinders. moraine boosters use a master cylinder with a shallow indentation in the piston. bendix uses a deep indentation in the piston. i just went through this. i needed to replace my master cyliner on my 71. went to parts store and asked for master for 71 with disc brakes. would not work with my moraine booster. took it back and after trying different years found master from 73 worked with moraine.



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