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Mopar J8 Master Cylinder and Brake Booster - JK Automatic Transmission

Drivetrain
Brakes
Brake Components >Mopar J8 Master Cylinder and Brake Booster - JK Automatic Transmission

Mopar J8 Master Cylinder and Brake Booster

JK Automatic Transmission

Read 11 Reviews | 13 Q&As

Part # P5160050

$449.00

msrp: $499.99

449 entries449 entries - 2025 Northridge4x4 Jeep Giveaway

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Product will ship from manufacturer, average time to ship: 120-150 business days

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Product Resources

Customer Reviews (11)

Questions (13) Answers (13)

Fitment Details

Features & Product Details

Have you swapped in the Mopar Big Brake kit (#77072434), one of those super trick TeraFlex Delta brake kits (#4403450) or some other brake kit needing more fluid? If so, the Mopar J8 Master Cylinder and Brake Booster kit is for you!

Jeep Jk Mopar J8 Master Cylinder & Brake Booster Features:

Performance brake booster

Big 1-1/8 inch master cylinder bore

Increases brake force

Designed for Heavy-duty axles

Straightforward installation

Boost the Performance of your Jeep's Brakes Mopar began as a family owned business that eventually transformed into a trusted brand to provide you with products that are 100% guaranteed authentic, brand new, and first quality. Their J8 Master Cylinder and Brake Booster is no exception to this as it features high-quality materials for long-lasting functionality. The purpose of this cylinder and brake booster is to make it easier for your Jeep to brake by increasing the force exerted without the need for additional force applied on the foot pedal. This keeps you safe during both daily driving and off-road applications, so you can stop your vehicle the way it was intended to stop.

Notes:

Same OEM parts included in Mopar's Big Brake Kit (P5160051).

Fits automatic transmission only

Does not fit with underhood ARB twin compressor mount

***THIS IS A MOPAR PERFORMANCE PART AND IS SOLD AS IS, THIS PART CARRIES NO WARRANTY FROM MOPAR

Product Resources

Customer Reviews (11)

Questions (13) Answers (13)

Fitment Details

Specifications

Brand: Mopar

Type: Master Cylinder

Mfgr. Warranty: No Warranty

Condition: New Product

Return Policy:

Standard

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REVIEWS & CUSTOMER MEDIA

11 Reviews

4.8 out of 5 Stars

5 Stars

(9)

4 Stars

(2)

3 Stars

(0)

2 Stars

(0)

1 Stars

(0)

Customer Photos and Videos

No user media. You can upload a photo or video of your install by posting a review.

J8 mc and booster 3 months ago

5out of 5stars

J8 booster and mc
Great product for my 1ton jk with 42s, it works just like stock bootee with stock axles, I got lucky to order this when in stock

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JK Big Booster and Cylinder 10 months ago

5out of 5stars

Anthony
Finally back in stock. This is the kit everyone says to get when getting bigger calipers. Install wasnt bad if you are handy. Make sure to bench bleed and watch install videos! This helped me a lot to make sure it all went together, and lined up right. The pedal feels shorter which is nice. I think im experiencing some other issues causing a slightly mushy feel still, but its not because of the kit.

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Almost perfect. 10 months ago

5out of 5stars

J8
I did a one ton axle swap into my JKU with 43” tires. I upgraded to a master cylinder with 1-1/16” bore, Brakes worked but were pretty soft. The J8 master cylinder is 1-1/8” bore. It firmed up the pedal quite a bit, feels like a JK with 35” tires. My only complaint is that I still go to the floor if I’m in low/low range with the Atlas on a down hill. Slide it in neutral and it immediately stops. If you’re running a Rubicon 4:1 transfer case, you should be able to stop anywhere with 43” tires. The installation is a pain due to the holes in the firewall. Also, you have to take extra care to make sure the master cylinder and the vacuum canister are perfectly aligned, don’t guess on the alignment.

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1 of 1 people found the following review helpful

Even these are on eBay 1 year ago

5out of 5stars

ca_14jk
Looks like all of these went to eBay for about $100 + more. They even copied Northridge 4X4’s description https://www.ebay.com/itm/326170816504?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=rfJKEi2XQpe&sssrc=4429486&ssuid=aB6iWWGaQ_m&var=&widget_ver=artemis&media=COPY

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1 of 2 people found the following review helpful

Needed for Teraflex Delta Kit Install 2 years ago

4out of 5stars

ARAYCPA
I foolishly ordered this from a lessor online vendor in hopes of saving ~$40. I was on back order for over a year before I decided to place a 2nd order with Northridge to see which order came in 1st. Northridge clearly stated the item was on backorder but I still received it in about 70 days. Never received the 1st order from other vendor and cancelled about 2 months ago. Still waiting on my refund check. Northridge is more transparent and treat's it's customers fairly. The product is what it is but Northridge is top notch.

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QUESTIONS & ANSWERS

Q: J8 gone the way of the dodo bird? JkRL2 years ago
Are these ever going to come back into stock or is heep just going to continue to yank our chain?
- 1 of 1 people found the following answer helpful
  A: We will see them again, just unsure as to when that will be.
  Northridge Chris @ Northridge4x4 2 years ago
  
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Q: MOPAR J8 MASTER CYLINDER AND BRAKE BOOSTER Josh3 years ago
Is there an alternative part that will work for a JK with a manual transmission?
- 1 of 1 people found the following answer helpful
  A: You can still use this with a manual transmission, you'll just need to source a reservoir for the clutch, such as a Wilwood one..
  Northridge Chris @ Northridge4x4 3 years ago
  
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Q: J8 booster and MC FIREBALL3 years ago
Will this fit a 2018 Wrangler JLU automatic?
- 0 of 0 people found the following answer helpful
  A: This is JK specific.
  Northridge Chris @ Northridge4x4 3 years ago
  
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Q: 2012 jk auto Blakebb23 years ago
Will this product fit my vehicle
- 0 of 0 people found the following answer helpful
  A: Yes, this will work for your 2012 JK auto, without issue.
  Northridge Chris @ Northridge4x4 3 years ago
  
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Q: Compatibility with 2014 JKU jespersen704 years ago
I have a 2014 JKU and I installed a Teraflex front big brake kit, I would like to install the Mopar J8 master cylinder and brake booster but it says it’s not compatible with 2014 only 2015 to 2018. Why is this kit not compatible with 2014? What is different and can I make it work? Thank you
- 0 of 0 people found the following answer helpful
  A: As long as you have an automatic, this will work for you without any issues.
  Northridge Chris @ Northridge4x4 4 years ago
  
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