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8 Inch Dual Brake Booster

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Specs
Material Type:
Steel
Sold in Quantity:
Each
Finish:
Zinc
Bolt Hole Pattern:
3.38" x 3.38"
Centerline of Holes:
3.38
Overall Thickness:
5.25
Outside Diameter:
8.00
Notes
Dual diaphragm booster.
8 Inch Dual Brake Booster

Click image to enlarge

Details

Reviews (9)

Q & A (8)

What's in the Box

Info

Compact, 8" diameter for installation under floor or on firewall of almost any vehicle. Zinc chromate finish.

Booster Tech Tip (GIF) 

Brake System Builder's Tip (Link)

Learn more about the proper uses of residual valves by reading our tech article. Brake System Selection

Specs

  • 8" O.D.
  • 5-1/8" main body length
  • 10-1/2" overall length
  • Back of the booster to the end of the threaded plunger rod is 4-1/8"
  • Firewall mounting studs are ¾" long at 3-3/8" center-to-center
  • Front master cylinder studs are 1-1/8" long at 3-3/8" center to center

Customer Reviews

Rated 4.8 out of 5 by 9 reviewers.
RATING BREAKDOWN
9 reviews
5 Stars
7
4 Stars
2
3 Stars
0
2 Stars
0
1 Star
0
RECOMMEND THIS PRODUCT:

OLD DOG
Verified Purchaser
Verified Reviewer
NORTH FLORIDA

GOOD PRODUCT, NOT QUITE UNIVERSAL.

March 20, 2016
MOUNTED TO '37 PLY FIRE WALL. LOOKS GOOD. WOULD NOT ACCEPT MY 1 1/8" BORE MASTER CYLINDER.
Pros:
  • Clean Finnish
Cons:
  • Not Universal Fit
  • Will Not Accept 1 18" Ma
Yes, I recommend this product.
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yahyabet
Verified Purchaser
Brandon SD

don't always go with suggestions

June 10, 2015
bought the 7 inch single cause was told it would work on drum/drum brakes and the customer said he was not going to add disc to the system. well it did not work. sent 7inch single back and installed the 8 inch dual and now I can stop that big old 59 Pontiac Bonneville.
Yes, I recommend this product.
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Bruce
Verified Purchaser
Kansas City, MO

10 times better than the 7" booster. 8" is awesome!

May 08, 2015
7" booster had terrible brake feel and after installing the 8" booster the 7" was a fail. I will only use the 8" booster from now on. Has 10 times the pedal feel and I can stop without a doubt in a close situation.
Yes, I recommend this product.
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SFCCTony
Verified Purchaser

Fixed my hard stopping issues

February 09, 2015
I had a 7 inch booster with a 1-1/8 master. It was really hard to stop the car. Swapped to this 8 inch booster and a 1 inch master now it stops easily with little effort. I might try my 1-1/8 master with this booster as its a real easy pedal with the 1 inch.
Yes, I recommend this product.
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Steve
York, PA

I have brakes now.

June 21, 2012
I needed a small dia. booster to clear my tall valve covers. I bought a 7" at a car show and it didn't work. I'm not sure if it was bad or just too small. I ordered this 8" and my brakes work like new.
Pros:
  • Easy To Install
  • Lightweight
Yes, I recommend this product.
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Steve
York, PA

I have brakes now.

June 21, 2012
I needed a small dia. booster to clear my tall valve covers. I bought a 7" at a car show and it didn't work. I'm not sure if it was bad or just too small. I ordered this 8" and my brakes work like new.
Pros:
  • Easy To Install
  • Lightweight
Yes, I recommend this product.
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Richard
Verified Purchaser
Mo

Thank you speedway

June 23, 2011
It is on my 57 chevy and now the brakes are as good as a new car.
Pros:
  • No Fade
  • Decreased Stopping Distance
  • Easy To Install
Yes, I recommend this product.
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Wiliweld
Verified Purchaser
San Francisco

8" Dual Brake Booster ROCKS!

April 07, 2011
I have a 1964 Chevy Fleetside (longbed) and already had a single 7" booster and I was worried that I may need to go to DISC brakes but after installing the 8" dual brake booster my truck stops on a dime and I'm glad the urgency for DISC brakes has been avoided. Having already had an after-market 7" unit in there, the installation was "plug-n-play"
Pros:
  • No Fade
  • Decreased Stopping Distance
  • Easy To Install
  • Lightweight
Yes, I recommend this product.
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Mark
Milw, Wisc

Good product

January 23, 2010
[...]
Yes, I recommend this product.
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Page 1 of 1

Product Q&A

8 questions : 8 answers

1 answers

Does this brake booster have a vacuum check valve built in? I have installed this unit and Not getting good brakes on my car. Has mid size chevy disc brake in front and 10" ford in the rear. I get hint of good brakes once in a while but peddle seems to firm up as it would if you ran out of vacuum

Mike1524
Tucson az
April 19, 2014

Does this brake booster have a vacuum check valve built in? I have installed this unit and Not getting good brakes on my car. Has mid size chevy disc brake in front and 10" ford in the rear. I get hint of good brakes once in a while but peddle seems to firm up as it would if you ran out of vacuum

Answers

April 21, 2014
EricM
Yes this booster has a built in one way check valve in the fitting that the vacuum hose hooks to. Check to see if you are getting sufficient vacuum to operate the vacuum booster. At least 17" of vacuum is needed for it to operate but 18" to 22" minimum is ideal.
1 answers

will the 8 inch booster directly mount to my 1968 camaro with wilwood master cylinder

shamu
Las Vegas, NV, USA
March 29, 2014

will the 8 inch booster directly mount to my 1968 camaro with wilwood master cylinder

Answers

March 31, 2014
EricM
If you plan to use a Wilwood master cylinder it must be compatible with a booster, however many of their master cylinders are not. A manual master has a deep bore piston to help keep the push rod in place and a power brake master has a slight dish in the piston. A booster has a four bolt mount instead of the two on a master cylinder and could use adapter plate number 91031402 to make the transition. Hook up of the booster to the pedal inside may take some additional parts if your existing will not cross over and you will need 18-20 inches of vacuum to get the full benefit of installing a booster.
1 answers

short or long pocket Brake Cylinder.? : Let me know if your booster works with both short and long pocket Brake Cylinder.?

denoisy
March 14, 2014

short or long pocket Brake Cylinder.? : Let me know if your booster works with both short and long pocket Brake Cylinder.?

Answers

March 17, 2014
EricM
All of our boosters work with master cylinders with a slight dish in the piston or as you described a "short pocket". We offer some master cylinders that come in a kit with the booster which have an adapter in the box that is inserted into the piston to convert the master cylinder from manual to power brakes. This is also true of others master cylinder that are stated to work for both manual or power applications.
1 answers

I have 1964 F-100 with 223 six...need to know if this booster will directly bolt on to firewall or if it need an adapter ?

slojet
austin, tx
February 03, 2011

I have 1964 F-100 with 223 six...need to know if this booster will directly bolt on to firewall or if it need an adapter ?

Answers

February 08, 2011
Jack
Our 8" dual brake booster has four equally spaced mounting bolts on the rear where it bolts to firewall or bracket , they are 3 3/8" spacing. If your truck has that bolt pattern spacing it should bolt up. We have an adaptor if going from manual brakes to power brakes, the specs are; 3 3/8" spacing of the four mounting bolts and the master cylinder side is 3 1/4" to 3 3/8". Good luck with your project and if you need any other help feel free to contact us for parts ordering or tech assistance.
1 answers

Hi can I use this brake booster too my master cylinder/pedal assembly for model T,A 1932 part nr 91631926 Best regards

December 04, 2011

Hi can I use this brake booster too my master cylinder/pedal assembly for model T,A 1932 part nr 91631926 Best regards

Answers

December 05, 2011
John
Part number 91031435 This booster would require an adapter plate number 91031402 to change from the two bolt to the four bolt. The master cylinder in your kit is not designed for a booster and would require a piece made by a machine shop to convert from the deep bore in the piston to a shallow dish. The other option would be a booster/master cylinder combo such as part number 91031413.
1 answers

How long is it from the face where it bolts to the MC to the opposite face excluding the studs? I have your 7" booster now and need to know how much longer an 8" dual will be so I'll know what mods to make. thanks

41 chevy
Whiteford, MD.
February 19, 2011

How long is it from the face where it bolts to the MC to the opposite face excluding the studs? I have your 7" booster now and need to know how much longer an 8" dual will be so I'll know what mods to make. thanks

Answers

February 23, 2011
Waymon
· 8" O.D. · 5-1/8" main body length · 10-1/2" overall length · Back of the booster to the end of the threaded plunger rod is 4-1/8" · Firewall mounting studs are ¾" long at 3-3/8" center-to-center · Front master cylinder studs are 1-1/8" long at 3-3/8" center to center
1 answers

I am replacing the booster and master cylinder on a 65 corvette and wanted to know if this booster would work

gabriel
Austin Texas
April 25, 2016

I am replacing the booster and master cylinder on a 65 corvette and wanted to know if this booster would work

Answers

April 27, 2016
Kevin
Expert
This booster would work if you have the clearance for the dimensions listed and the bolt pattern of 3 3/8" square works for you.
1 answers

I need to replace the booster on my 1960 Olds Dynamic. 371 ps/pb car with drums all around. What modifications are required to use this unit in my application.

LeadFreddie
Vernon, B.C. Canada
May 31, 2016

I need to replace the booster on my 1960 Olds Dynamic. 371 ps/pb car with drums all around. What modifications are required to use this unit in my application.

Answers

June 01, 2016
John
Expert
Booster 91031435 has a square 4 bolt pattern for mounting to your ride with centers on 3 3/8" both vertical and horizontal of which you will need to modify your mount surface to accept. The two bolt pattern for the master cylinder is 3.25", and when replacing the booster it is recommended to update the master as well to number 91031445 and install the included slug/cylinder in the box into the piston to work with the booster.
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