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C8.25 disc swap ?s

4x4JeePmaNthINg

NAXJA Forum User
Location
Colorado
Hey all,
Wanted to get my wits about me before delving further into this venture. I know there are many options for donor disc swaps, a loads of how to threads.


One question that popped into my head was: are there any size differences to these zj,kj.... options, so far as do any have a bigger pad that may bite better?

Anyone have any preference for E brake set up?
 
It does not matter for backing plate or rotor, but if you get pads and calipers for a late model TJ or TJ Rubicon you will get a 40% or so bigger pad. There won't really be more clamping force on it but it will last longer and displace heat better.
 
I used the Dana 35 backing plates and rotors/calipers.

Absolutely put on longer studs. Who knows when you might have to put on an aluminum wheel in a pinch.


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What size stud for the 8.25 for the backing plate, doesn't seem safe for reusing the donor axles plate studs.

Cal, Ide love to use tj parts but good luck finding that around here, zj/liberty can be found.

Does any thickness of the backing plate change for so v8 vs anything else.

The biggest reason for this upgrade is about the only option there is to hold onto axles enough to hopefully pull a vehicle over if needed, I the event of an axle break.
 
I had no need for longer backing plate studs. The KJ is the only one that's a direct fit for a 8.25". For the best pad get the EBC Truck Yellow's.
 
The biggest reason for this upgrade is about the only option there is to hold onto axles enough to hopefully pull a vehicle over if needed, I the event of an axle break.

Btw, 8.25 axles are pretty strong so if you haven't done anything with your d30 it would be more likely to break first. I ran mine pretty hard for 16yrs before I decided on a brake upgrade so I did everything at one time hoping that would last for my lifetime! Yukon for the rear and Ten factory for the front.
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I was kinda wondering how somebody would be breaking an almost Dana 44 strength Chry 8.25 axle shaft while on pavement ?
 
I was kinda wondering how somebody would be breaking an almost Dana 44 strength Chry 8.25 axle shaft while on pavement ?

4.56 ARB locked on nitto 33s soon 35s. Who's saying I plan on breaking on pavement? I hope nothing breaks, but a 44 vs 8.25 have limits and very different outcomes if a shaft goes......;)
 
Btw, 8.25 axles are pretty strong so if you haven't done anything with your d30 it would be more likely to break first. I ran mine pretty hard for 16yrs before I decided on a brake upgrade so I did everything at one time hoping that would last for my lifetime! Yukon for the rear and Ten factory for the front.
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Yeah, I want all of that, especially the front break upgrade. At least I can wish.
 
It may look like a lot of parts and work but each axle only was a days work. They were about the same amount of work and cost's.
 
What size stud for the 8.25 for the backing plate, doesn't seem safe for reusing the donor axles plate studs.

Cal, Ide love to use tj parts but good luck finding that around here, zj/liberty can be found.

Does any thickness of the backing plate change for so v8 vs anything else.

The biggest reason for this upgrade is about the only option there is to hold onto axles enough to hopefully pull a vehicle over if needed, I the event of an axle break.

You should not be buying used pads or calipers.

Every parts house has them.
 
It does not matter for backing plate or rotor, but if you get pads and calipers for a late model TJ or TJ Rubicon you will get a 40% or so bigger pad. There won't really be more clamping force on it but it will last longer and displace heat better.

In gathering parts for a disc brake swap, I've determined to a fair degree of certainty that pads and calipers for any 2003-2006 TJ Wrangler (Rubicon, SE, Sport, etc.) and any 2003-2007 KJ Liberty are all the same. Just an FYI for anyone doing similar research. And if I'm wrong about this, I'd sure appreciate it if someone would set me straight.
 
I just did mine on Friday. I saw a parting ad on the CL for a same year Grand Cherokee as my XJ. I told the guy what I wanted, he insisted that I take the whole rear end not just the brake parts for $150. He let me have the prop valve too. I told him to pass my number to anyone looking for the axle in case they wanted both axles or didn't need the brakes and a week later my phone rings, this guy had ZJ with a growl. Sold what I didn't need to him for $100.
Swapped the backing plate studs for grade8 fine thread bolts and loctite. This worked well for me because I couldn't locate studs and the welds on my rear end were clean and tight enough to not require any shaving of the heads.
I told the guy at the parts store I needed longer wheel studs (I'm running alloy wheels) and of course being only capable of finding what his computer told him I just said they were for a '94 F-150, just right to compensate for the rotor thickness but I could have used longer.
 
I just did mine on Friday. I saw a parting ad on the CL for a same year Grand Cherokee as my XJ. I told the guy what I wanted, he insisted that I take the whole rear end not just the brake parts for $150. He let me have the prop valve too. I told him to pass my number to anyone looking for the axle in case they wanted both axles or didn't need the brakes and a week later my phone rings, this guy had ZJ with a growl. Sold what I didn't need to him for $100.
Swapped the backing plate studs for grade8 fine thread bolts and loctite. This worked well for me because I couldn't locate studs and the welds on my rear end were clean and tight enough to not require any shaving of the heads.
I told the guy at the parts store I needed longer wheel studs (I'm running alloy wheels) and of course being only capable of finding what his computer told him I just said they were for a '94 F-150, just right to compensate for the rotor thickness but I could have used longer.

Just curious, any pics of brake lines/ e brake set up?

I'll have to get the right knurl stud for my yukon axles, my current I don't think are long enough if I need to add space.

What welds are you referring to, I'm a bit unclear here?
 
Just remember that whatever axles you buy to do your homework on studs. When I bought my Yukon axles, their website listed the wrong studs. My Yukon's take .618" studs so I used Dorman #610-260.

This is from your other thread.
 
I just did mine on Friday. I saw a parting ad on the CL for a same year Grand Cherokee as my XJ. I told the guy what I wanted, he insisted that I take the whole rear end not just the brake parts for $150. He let me have the prop valve too. I told him to pass my number to anyone looking for the axle in case they wanted both axles or didn't need the brakes and a week later my phone rings, this guy had ZJ with a growl. Sold what I didn't need to him for $100.
Swapped the backing plate studs for grade8 fine thread bolts and loctite. This worked well for me because I couldn't locate studs and the welds on my rear end were clean and tight enough to not require any shaving of the heads.
I told the guy at the parts store I needed longer wheel studs (I'm running alloy wheels) and of course being only capable of finding what his computer told him I just said they were for a '94 F-150, just right to compensate for the rotor thickness but I could have used longer.

You must have a D35 axle though, only the KJ has backing plates that fit unless you modify them.
 
Just curious, any pics of brake lines/ e brake set up?

I'll have to get the right knurl stud for my yukon axles, my current I don't think are long enough if I need to add space.

What welds are you referring to, I'm a bit unclear here?


Didn't take any pics but the brake lines were easy enough to just bend by hand where I needed them to point. I cut the mounting tabs off of the stock ZJ soft lines to free up some room.


The welds i was referring to are the ones that join the backing plate flange to the axle tube or bearing housing on the end of the tube. I imagine that they are done by machine so they are more than likely pretty consistent throughout production of these axles. Anywho, you will notice that your studs are clearanced or the head of them is not round. They do this to avoid contacting that weld throwing the stud off square when it is tightened. You can still avoid this if you have a fat weld in the way using bolts by just shaving one of the hex corners off.




I do have a Chrysler 8.25 axle and I did have to work on the holes in the backing plates to get them on.
 
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