Novak Conversions Jeep Wrangler JK shifters

J8 booster talk

WSS

WSS

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Looking for some info on the J8 booster upgrade.

I bought a J8 booster from Jeephut. Full master cylinder and booster kits are hard to find, so i bought just the booster. Can I swap JUST the booster? or is the OE master cylinder different and will not work with the new J8 booster?

Thanks for any input!
 
I found all this reading:

Matching Components:
The Mopar J8 booster and master cylinder are designed as a pair, with specific dimensions and features that ensure proper functionality when used together.


  • Not Compatible with OEM:
    Attempting to use the J8 booster with an OEM master cylinder will likely lead to compatibility issues, improper brake performance, and potentially damage to the components.

    Heavy-Duty Application:
    The J8 booster and master cylinder are designed for heavy-duty applications like those found in Jeep models with larger brakes and/or one-ton axles, according to a Northridge4x4.com listing.


    Performance Upgrade:
    The J8 booster and master cylinder are considered a performance upgrade, providing better pedal feel, more brake bite, and improved braking performance, according to a Reddit post.




 
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Ok I read the questions. Can I buy a replacement master cylinder? Anyone have a breakdown of the parts that are included in the kit?
 
I found this part number for the master cylinder, the source is 50/50 reliable. My local auto supply cannot find the number.

68048757AA
 
WSS said:
I found this part number for the master cylinder, the source is 50/50 reliable. My local auto supply cannot find the number.
Click to expand...

This is the same part number I've found on a couple other forums. But there is a noticeable design difference in the 2009-2014 master cylinder and the one you need for your 2007. Check this link and look at the "other brands" section down the page. The W0133-2775579 specifically says it's not designed for heavy duty brakes.

https://www.partsgeek.com/htxk2t7-j...VjSsq1PhcNwvUlHQRLVjpJMvPow_fGHhoCXYEQAvD_BwE
 
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The bore you need for heavy duty brakes is 1 1/16" whereas most of the masters are a 1". I did find this on partsgeek:

https://www.partsgeek.com/hlpxwgp-jeep-wrangler-brake-master-cylinder.html

1747055646165.png
 
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Big difference! The bore sizes need to match. I did buy the quadratec kit over the weekend. I hope it ships soon, it says in stock. It has a 1.125" bore and designed for 60's. research is showing I will have to play with the pushrod adjustment, everything else should line up. It is crowded around my booster and master cylinder, should be fun.

Here is the quadratec kit:

https://www.quadratec.com/p/mopar/brake-master-cylinder-booster-jk-dana-60-axle-P5160050
 
This is from my kit I still have in the garage. I really do want to install it, but I have an underhood air compressor that I need to relocate or just put in a little tool bag.

The kit number is P5160050

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Last edited:
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I ordered the booster and master cylinder from jegs and the o ring/gasket from quadratec. Still need to find a reservoir. There are alternates to the kit res but still pricey.
 
Update. I have the booster, MC and "seal" (o-ring really) in hand. I just sprung for the very $$ 68048758AA reservoir from mopar parts giant. I confirmed it is in stock,so I should have it soon. Then, onto the install. Hopefully have it done before the coilover kit arrives.
 
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started the project this evening. Got the clip off of the pedal arm, air compressor removed and the pcm/abs tray loosened up.

Has anyone heard that it takes a scan tool to bleed the abs? I’ve heard it twice in videos today.

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