Novak Conversions Jeep Wrangler TJ engine mounts

What are yall running for brake boosters?

D's Jeep Wrld

Do It for Dale & Be like Biff 🏁
Original poster
Supporting Member
Joined
Oct 28, 2022
Messages
1,288
Location
Planet Earf / DFW lol 😆
What brake booster would you guys recommend
After doing a bigger throttle body thinking that was the cause of my high idle issue (partially true) I discovered an intake leak fixed it and im idling around 1k RPM's
My booster has always made noise since I bought the jeep but it truly didn't bother me BUT after covering the vacuum hose from my intake to the booster when i plug it with my finger my idle goes down to where it needs to be (around 800) so that leads me to my next question
Have any of you guys got experience with the SKP Booster? Its cheap ,it has a heart so that tells me its good ?
Opinions?
Screenshot 2025-08-04 214634.png
 
Last month marked 5 years since I installed that exact booster in my TJ. It’s been fine.

I tried for months to get a Mopar booster. Spending well over $300 each. Kept getting my money refunded.

Then I tried a Crown booster. It was junk out of the box. Took it off 2 days later.

That’s what lead me to the SKP piece.
 
  • Like
Reactions: D's Jeep Wrld
First off...it sounds like your surgery was successful. Heal up quickly.

Second, and I am going to ramble because I have no proof to back it up. I believe there is more to a booster than two bolts and a pushrod. The value of a booster is to transfer your foot pressure to the pushrod to the master cylinder.

The effectiveness of said booster is what is important. To me, there is a balance between foot force applied and brake pressure applied at a given vacuum number. But good luck finding this information.

Using a far more diluted topic but has the same similarities - brake pads. Everyone claims this brand of that brand is best but not one of these companies produce data to support their claims. Even worse, the companies sending out the most "free pads" are going to get the most positive reviews.

However, I did find someone who did actually test them. If you care to watch an enlightening video.

Getting back to boosters. Let's say you need a stronger booster because you installed bigger tires and now you have more unsprung mass. Let's say the stock booster can produce 800 lb braking force with 18 psi of vacuum (I totally made up values because I have no idea what they really are). How would you ever find a booster that produces 900 lbs? The companies won't tell you because they are interested in telling you how great their product is and how shiny it is out of the box.

Itis not even possible to compare a single diaphragm with a double diaphragm with an electric system with hydro system. It stands to reason that each one of these would produce greater braking force but nobody produces actual data.

So, do your homework and make an educated purchase that fits your needs.
 
  • Like
Reactions: D's Jeep Wrld
Last month marked 5 years since I installed that exact booster in my TJ. It’s been fine.

I tried for months to get a Mopar booster. Spending well over $300 each. Kept getting my money refunded.

Then I tried a Crown booster. It was junk out of the box. Took it off 2 days later.

That’s what lead me to the SKP piece.

Wow really,that's awesome to hear cause as of today right as I posted this thread I bought the SKP Unit from rock auto😁
It's funny you mention that about getting a refund cause that happened to me months ago when I tried to buy a some grill isolator bushing and a mopar booster from my dealer.I was so happy but a month and a half later I saw a refund on my debit card....hours later I got a call from the dealer saying that they're discontinued 🙃
20250806_201531.jpg

High idle issue GONE! She idles right around 8/900 (but below 900) like I tuned it 😁
As of 30 minutes ago I drove the jeep with the new SKP booster and good lord what a difference,I can't believe I've been putting up with the vacuum noise and "poor" braking performance for these past 2 almost 3 years now😅 My 60-0 is alot faster than my 0-60 With this new booster 😆

Sipping on a slurpee from 7 eleven as I'm typing

Edit- slurpee is gone.....😆
What I really came on here to say is that 30 mins after posting the thread I bought the booster from Rock auto,Got it in today at 7pm,So they shipped it out quick 😁! Wasn't even expecting it today lol
 
Last edited:
First off...it sounds like your surgery was successful. Heal up quickly.
Yes, Thank God! Cause I'm healing up great man😁.....heck I'm even thinking of tackling my Savvy tummy tuck this week and order my drive shaft,I dont want too simply cause I got another week off and I've been driving my Lj for recreational use and for the sake of therapy, cause this thing makes me happy🙂

I'd rather not wait a week for a drive shaft or 4 days,Tom woods seems pretty quick but again I wanna drive my Jeep.
So, do your homework and make an educated purchase that fits your needs.
I didn't want an upgrade but a replacement! I knew my booster was bad and I knew (after diagnosis) that it was messing with my idle because of the vacuum leak within the booster.
Second, and I am going to ramble because I have no proof to back it up. I believe there is more to a booster than two bolts and a pushrod. The value of a booster is to transfer your foot pressure to the pushrod to the master cylinder.
With that said you weren't rambling,I learned something 😁 I often ramble alot too,without realizing until I look back at all I typed 😅
 
  • Like
Reactions: DuckNut
I'm working on installing an iBooster.

-Mac

What is that? A booster that has a integrated vacuum pump or something.....Something you control with your I-phone Hehe. I-Booster,I-Phone Get it 😆? .......Ok I'm done lol
My shitty jokes aside The "I" In I-booster makes me think its electronic
 
What is that?



-Mac
 
  • Like
Reactions: Tob
What is that? A booster that has a integrated vacuum pump or something.....Something you control with your I-phone Hehe. I-Booster,I-Phone Get it 😆? .......Ok I'm done lol
My shitty jokes aside The "I" In I-booster makes me think its electronic

It is. EV's don't have vacuum from an engine so they use an electric vacuum pump.

He's been getting ready for 6 months...but to his credit he has been picking junk up out of the forests.
 
He's been getting ready for 6 months...but to his credit he has been picking junk up out of the forests.

That and I just ripped my driver's rear shock off the upper mount on The Rubicon Trail. Ejected spring. After a few reinsertions I got lazy and left off the bump stop extension and the track bar came up and severed the fuel line and crushed both connectors. (Literally just wrote this in another thread.)

My fault...I screwed up my pinion angle and the clearancing on the rear spring perch was no longer sufficient.

This after a month of repeatedly taking apart my 231J trying to keep the red stuff inside.

I've got to stop breaking things so I can start braking things.

I've got it mostly ready for to install. I need to cut and fabricate an eye to interact with the factory pedal arm and drill four holes in the firewall. (I think.) Didn't want to risk missing my Rubicon Trail run.

IMG20250610171420.jpg
IMG20250610171412.jpg


-Mac
 
That and I just ripped my driver's rear shock off the upper mount on The Rubicon Trail. Ejected spring. After a few reinsertions I got lazy and left off the bump stop extension and the track bar came up and severed the fuel line and crushed both connectors. (Literally just wrote this in another thread.)

My fault...I screwed up my pinion angle and the clearancing on the rear spring perch was no longer sufficient.

This after a month of repeatedly taking apart my 231J trying to keep the red stuff inside.

I've got to stop breaking things so I can start braking things.

I've got it mostly ready for to install. I need to cut and fabricate an eye to interact with the factory pedal arm and drill four holes in the firewall. (I think.) Didn't want to risk missing my Rubicon Trail run.

View attachment 635284View attachment 635285

-Mac

Oh my you got alot on your plate man! Been there before too.....multiple times (not what happened to you but I mean in general)Edit- Now that I think about it,I almost really messed up my fuel line&wiring when I was setting up bump stops after doing my Jeeps west Geo. Correction brackets,The track bar bracket is up pretty high now so it comes by the fuel lines&such 😅it clears though

That looks cool! whats it out of?And do you have a thread on this ? EDIT- Dammit i cant read😅, I saw the link to your thread !
Gonna have to go with something like this myself one day if im serious about OM606 swapping my Lj,Got a ride along today in a 606 swapped Mercedes wagon after changing my booster😁 (longstory short went for a test drive in my Lj after changing the booster,went to a 7-eleven,Met a guy with a OM606 swapped wagon,Now my want for a OM606 is through the roof right now.....So is an AX15)
 
Last edited:
First off...it sounds like your surgery was successful. Heal up quickly.

Second, and I am going to ramble because I have no proof to back it up. I believe there is more to a booster than two bolts and a pushrod. The value of a booster is to transfer your foot pressure to the pushrod to the master cylinder.
Sorta, a booster is a direct connection between the brake pedal and the master. That means it will transfer foot pressure at any level of boost including engine off no vacuum.
The effectiveness of said booster is what is important. To me, there is a balance between foot force applied and brake pressure applied at a given vacuum number. But good luck finding this information.
Not a balance, it is a direct relationship based on number of diaphragms in the booster and surface area of each. Vacuum acts on the area in pounds per square in based on how much vacuum there is available. Max at high levels of vacuum is around 14 psi. Multiply that by the number of square inches of surface area the diaphragms have and that is your max available boost.
Getting back to boosters. Let's say you need a stronger booster because you installed bigger tires and now you have more unsprung mass. Let's say the stock booster can produce 800 lb braking force with 18 psi of vacuum (I totally made up values because I have no idea what they really are). How would you ever find a booster that produces 900 lbs? The companies won't tell you because they are interested in telling you how great their product is and how shiny it is out of the box.

Itis not even possible to compare a single diaphragm with a double diaphragm with an electric system with hydro system. It stands to reason that each one of these would produce greater braking force but nobody produces actual data.
Not one single aspect of that is true.
So, do your homework and make an educated purchase that fits your needs.
You just told everyone that there is no way to find the data to educate themselves but they should educate themselves and make an informed purchase. Do you even read what you write?

Back to the subject.
You're using the booster to define the rest of the system and it is only one part of the system that determines brake force. The booster size is determined by the master piston area into the caliper piston area versus pedal stroke.

I can take your stock TJ booster and drive the pressure into the calipers much higher simply by reducing the bore size in the master. That will come at the expense of adding pedal stroke until eventually the pedal will be on the floor. I can go the other way with a larger bore master and get you a high very hard pedal that only moves a couple of inches. The pressure into the calipers will be poor though.

I get contacted and see reference to near daily about a master cylinder "upgrade". There isn't one. The parts relationship as shown above have to be in that balance you were talking about, albeit poorly. Booster force versus bore size in master versus piston area in calipers versus pedal ratio.

You can increase the pressure out of the existing master a few ways. Hydroboost and a larger booster will both do that easily. The problem is the foundation of your system, the stock calipers, cast sliders, and the pad design won't live very long. Your premise of needing more brake force due to larger tires will quickly show the deficiencies in the stock foundation. You will get bent pad ears and bent sliders (cast reaction bars) when you start exceeding the design forces needed to stop big tires.

You're mixing up the forces in play and using that to try and find an answer that isn't able to be found.

You would benefit greatly by climbing down off of your high horse picking on companies that don't give you numbers you are not yet capable of understanding if they did. You want numbers, you have no clue how to even begin to apply them if they were given to you.
 
Ratios of hydraulic area , mechanical leverage ratios , booster area x vacuum " pressure " and input pressure from your fat leg all effect braking performance .
And that's before you take rotor diameter , drum diameter , caliper piston area , caliper type , type of friction material of pads/shoes , is the system hot or cold ,
tire size . What appears to be a simple brake system , has many factors that need to be combined to be a effective way to stop your vehicle . Thanks Blaine , for bringing some good brake options to the table for TJ's . I appreciate your big picture view of everything involved .
 
Thanks Blaine , for bringing some good brake options to the table for TJ's . I appreciate your big picture view of everything involved .
At least once a week and often more, I tell someone that if there was a master cylinder "upgrade", why wouldn't I just sell that rather than spending 100's of 1000's of dollars developing and building steering knuckles. Certainly be less painful, far less expensive, and a whole bunch more fun. I could store 2 years of inventory in the same space I keep one brake kit's worth of knuckles now that will last 6 months and there is 3 different versions of those.
 
Sorta, a booster is a direct connection between the brake pedal and the master. That means it will transfer foot pressure at any level of boost including engine off no vacuum.

Not a balance, it is a direct relationship based on number of diaphragms in the booster and surface area of each. Vacuum acts on the area in pounds per square in based on how much vacuum there is available. Max at high levels of vacuum is around 14 psi. Multiply that by the number of square inches of surface area the diaphragms have and that is your max available boost.



Not one single aspect of that is true.

You just told everyone that there is no way to find the data to educate themselves but they should educate themselves and make an informed purchase. Do you even read what you write?

Back to the subject.
You're using the booster to define the rest of the system and it is only one part of the system that determines brake force. The booster size is determined by the master piston area into the caliper piston area versus pedal stroke.

I can take your stock TJ booster and drive the pressure into the calipers much higher simply by reducing the bore size in the master. That will come at the expense of adding pedal stroke until eventually the pedal will be on the floor. I can go the other way with a larger bore master and get you a high very hard pedal that only moves a couple of inches. The pressure into the calipers will be poor though.

I get contacted and see reference to near daily about a master cylinder "upgrade". There isn't one. The parts relationship as shown above have to be in that balance you were talking about, albeit poorly. Booster force versus bore size in master versus piston area in calipers versus pedal ratio.

You can increase the pressure out of the existing master a few ways. Hydroboost and a larger booster will both do that easily. The problem is the foundation of your system, the stock calipers, cast sliders, and the pad design won't live very long. Your premise of needing more brake force due to larger tires will quickly show the deficiencies in the stock foundation. You will get bent pad ears and bent sliders (cast reaction bars) when you start exceeding the design forces needed to stop big tires.

You're mixing up the forces in play and using that to try and find an answer that isn't able to be found.

You would benefit greatly by climbing down off of your high horse picking on companies that don't give you numbers you are not yet capable of understanding if they did. You want numbers, you have no clue how to even begin to apply them if they were given to you.

Feel better?
 
  • Face Palm
Reactions: hosejockey61
Novak Conversions Jeep Wrangler TJ engine mounts