Brake time! Part questions - JeepForum.com
 
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post #1 of 12 Old 07-30-2021, 10:06 PM Thread Starter
Mr. Puddles
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Brake time! Part questions

Its finally time to look at the brake system. Sadly I dont have the funds to do a WJ knickle swap fo O gotta make the best of the turd I have. I am replacing everything except the hard lines so heres my first issue


Booster
Will the WJ booster fit the ZJ? Id much rather install a brand new unit vs a reman and I cant get a new ZJ booster.


Calipers
Plastic or steel? Ive read the plastic pistons dont transfer heat to the fluid like the metal ones do but being its not a race car Im not that worried about it. Is there a functional difference between the 2? Ive searched and found bief mention of calipers but no real piston material discussion.


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post #2 of 12 Old 07-30-2021, 10:26 PM
PolkaPower
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Brake time! Part questions

Quote:
Originally Posted by Mr. Puddles View Post
Its finally time to look at the brake system. Sadly I dont have the funds to do a WJ knickle swap fo O gotta make the best of the turd I have. I am replacing everything except the hard lines so heres my first issue


Booster
Will the WJ booster fit the ZJ? Id much rather install a brand new unit vs a reman and I cant get a new ZJ booster.


Calipers
Plastic or steel? Ive read the plastic pistons dont transfer heat to the fluid like the metal ones do but being its not a race car Im not that worried about it. Is there a functional difference between the 2? Ive searched and found bief mention of calipers but no real piston material discussion.

http://www.safebraking.com/tech-why-...nolic-plastic/
ZJ brakes are pretty undersized so they probably make a good deal of heat.

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post #3 of 12 Old 07-31-2021, 09:10 AM
zjosh93
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In my opinion...

Phenolic is a cost saving measure. If you look at vehicles that have a police or severe service option, they usually have steel pistons where the civilian versions are phenolic. To me, that means the OEMs have done the math and steel is better if you really use the brakes.

Phenolic may insulate better but the pistons swell over time and start to move unevenly in the bores. If you've ever bought a pair of new calipers and had the brakes pull to the side that's the phenolic.

Cardone steel piston calipers are available on RockAuto for almost the same price as phenolic. I bought mine locally since most places sell Cardone parts.
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post #4 of 12 Old 08-01-2021, 05:17 PM
PolkaPower
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Brake time! Part questions

Phenolic composite today is much better than it used to be and it's used on virtually every modern vehicle. Where it really shines is in applications that see very high heat build up such as racing. Nascar, Formula 1, police interceptors, ect all use brake calipers(Brembo, ect.)with phenolic pistons because they are light weight and don't transfer heat to the brake fluid.
Steel pistons transfer heat and boil brake fluid at much lower temperature and weigh more.


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post #5 of 12 Old 08-01-2021, 06:22 PM
zjosh93
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I have nothing but respect for you Polka but I'm going to need to see some documentation for your NASCAR and police claims. Looks like the Ford Interceptor sedan and suv and the Charger Pursuit used steel pistons through at least 2019 (the civilian cars got phenolic). NASCAR switched to AP Racing as the sole caliper supplier, and AP lists only billet aluminum and stainless pistons as far as I can tell. The old NASCAR Brembos on eBay are all stainless or billet aluminum as well.

As for F1, well I assumed they were all carbon/carbon brakes at this point. In any case a 2021 F1 car is about as far from a 90s ZJ as you can get.
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post #6 of 12 Old 08-01-2021, 08:03 PM
PolkaPower
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I can't remember where I read it but I thought they used a combination of phenolic pistons with stainless caps to reduce the weight and heat but still have better durability but it could be incorrect. I'm definitely not going to debate with someone more knowledgeable about it.


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post #7 of 12 Old 08-01-2021, 08:32 PM
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Interesting, I had never thought to check for nascar calipers on ebay, those things are huge! And it does appear they all have steel pistons.

I will say, Ive had a terrible time with calipers seizing on my 94 ZJ. Lost count of how many times I've used the napa lifetime warranty. Fluid stays fresh since Im constantly replacing calipers, so moisture shouldnt be the issue. Always wondered if those rebuilt calipers get new pistons.

If I had it to do over, I would've bought new calipers with steel pistons.

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post #8 of 12 Old 08-02-2021, 07:21 AM
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Quote:
Originally Posted by jeepjeepster View Post
Interesting, I had never thought to check for nascar calipers on ebay, those things are huge! And it does appear they all have steel pistons.

I will say, Ive had a terrible time with calipers seizing on my 94 ZJ. Lost count of how many times I've used the napa lifetime warranty. Fluid stays fresh since Im constantly replacing calipers, so moisture shouldnt be the issue. Always wondered if those rebuilt calipers get new pistons.

If I had it to do over, I would've bought new calipers with steel pistons.
That was my experience also with Autozone calipers. I think I went through 3 sets before getting a pair that were reasonably matched. If I hit the brakes slowly, they were fine, but if I hit the brakes fast, they would pull to the side. I returned them and had them credit me the core charge so I could get the steel piston versions on RockAuto. Those were great.
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post #9 of 12 Old 08-02-2021, 07:43 AM Thread Starter
Mr. Puddles
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Quote:
Originally Posted by jeepjeepster View Post
I will say, Ive had a terrible time with calipers seizing on my 94 ZJ. Lost count of how many times I've used the napa lifetime warranty. Fluid stays fresh since Im constantly replacing calipers, so moisture shouldnt be the issue. Always wondered if those rebuilt calipers get new pistons.

Were you using the Phenolic?

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Quote:
Originally Posted by kg6mov View Post
The 4.0 is dumb old tractor motor, itís too stupid to know itís supposed to die.
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post #10 of 12 Old 08-02-2021, 07:44 AM Thread Starter
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Any input on the booster compatibility?

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2002 Dakota aka Winnie aka Mad Max
1996 Grand Cherokee aka Puddles aka Pikey Life
Quote:
Originally Posted by kg6mov View Post
The 4.0 is dumb old tractor motor, itís too stupid to know itís supposed to die.
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post #11 of 12 Old 08-02-2021, 08:10 AM
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I think your first question should be, "how do my knuckles look on the axles?" Unless you've addressed that already then they probably have grooves worn into them over the years. I am going to have to address this exact issue soon. WJ swap or Vanco are the 2 easiest things to do beside welding the knuckles.

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post #12 of 12 Old 08-02-2021, 08:40 AM Thread Starter
Mr. Puddles
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Quote:
Originally Posted by Boone96ZJ View Post
I think your first question should be, "how do my knuckles look on the axles?" Unless you've addressed that already then they probably have grooves worn into them over the years. I am going to have to address this exact issue soon. WJ swap or Vanco are the 2 easiest things to do beside welding the knuckles.
When i did ball joints 2 years ago there were no grooves that I could see. She say for almost a year after that so I doubt they have worn in

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2002 Dakota aka Winnie aka Mad Max
1996 Grand Cherokee aka Puddles aka Pikey Life
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Originally Posted by kg6mov View Post
The 4.0 is dumb old tractor motor, itís too stupid to know itís supposed to die.
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