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Bill Smith
Founder, 1929-2014
Speedy Bill
Since 1952
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America's Oldest Speed Shop ®

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8 Inch Dual Brake Booster

Specs
Centerline of Holes:
3.38
Material Type:
Steel
Sold in Quantity:
Each
Overall Thickness:
5.25
Finish:
Zinc
Outside Diameter:
8.00
Bolt Hole Pattern:
3.38" x 3.38"
Garage Sale:
No
Notes
Dual diaphragm booster.
8 Inch Dual Brake Booster

Click image to enlarge

Details

Reviews

Q & A

What's in the Box

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 5 reviewers.
RATING BREAKDOWN
5 reviews
5 Stars
4
4 Stars
1
3 Stars
0
2 Stars
0
1 Star
0
RECOMMEND THIS PRODUCT:

Mark
Milw, Wisc
Product Rating

Good product

January 23, 2010
[...]
Yes, I recommend this product.
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Wiliweld
Verified Purchaser
San Francisco
Product Rating

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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Richard
Verified Purchaser
Mo
Product Rating

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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Steve
York, PA
Product Rating

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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SFCCTony
Verified Purchaser
Product Rating

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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Page 1 of 1

Product Q&A

6 questions : 6 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

1 answers
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.

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

1 answers
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.

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

1 answers
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.

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 ?

1 answers
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.

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

1 answers
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.

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

1 answers
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
Page 1 of 1

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Learn more about selecting the proper master cylinder for your vehicle by reading our tech article. Brake System Selection. 

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Booster Tech Tip (GIF)

Learn more about selecting the proper brake booster for your vehicle by reading our tech article. Brake System Selection.  

Wilwood 261-13270 Aluminum Tandem Master Cylinder Kit with Bracket and Valve
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The combination proportioning valve substantially simplifies wiring and brake proportioning adjustments on vehicles with custom brake systems. The combination block maintains full isolation between front and rear fluid circuits and is specifically designed to accompany the Tandem Chamber Master Cylinder. The combo valve and bracket are black E-coated for a performance look and long lasting durability. Stainless steel fluid tubes are precision bent with preinstalled stainless tube nuts for a simple bolt-on installation between the Combination Proportioning Valve and the Wilwood Tandem Master Cylinder. Stainless steel button head fasteners thread into the bracket for a simple installation and years of durable, rust-free performance. Simply connect the fluid lines, bleed the system, and you're finished.

  • Bore size: 1-1/8"
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Wilwood Tandem Master Cylinder Kit Product Data Sheet (PDF)

New Product Release (PDF) 

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These high-tech corvette-style master cylinders were designed using OE specifications and 100% tested.  They have a 1" bore and are suited for disc/drum combinations. Each master cylinder is ported on both the left and right sides, allowing for installation in many different applications. This exclusive design features a mating flange that works with applications requiring 3-1/8” through 3-3/8” bolt patterns.  These master cylinders will work with manual or power brake systems and can be quickly changed with the included adapter pin to plug the deep well.  The wide body and low profile gives this master cylinder the clearance you need when installing in tight areas and yet it maintains a large volume of fluid necessary for 2 and 4 wheel disc brake applications.

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Brake System Builder's Tip (Link)

Learn more about selecting the proper master cylinder for your vehicle by reading our tech article. Brake System Selection. 

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Brake System Builder's Tip (Link)

Note: Customers intending to use this as a manual brake pedal assembly should note that the pushrod and boot are not included.

Learn more about selecting the proper master cylinder for your vehicle by reading our tech article. Brake System Selection

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