'91+ 2wd knuckles on '88 2wd?

[Coyote]

Researching options for a future front brake project. My 88 Comanche 2wd has led a good life, but it's getting time to replace the original front rotors, ball joints and wheel bearings. The 88 2wd uses a weird hub and rotor design instead of the standard '91+ or 4wd set up. If I have to replace all of the worn parts anyways I was look at swapping it over to the newer design with standard/readily available rotors. I put drilled and slotted rotors on my 91 Cherokee and 03 Wrangler and absolutely loved them, but they are not available for the older designed 2wd front end. I'm not debating the stopping power. The original design was perfectly adequate, I just prefer the newer design. With that being said, will 91+ 2wd knuckles fit on an 88 2wd or do I need to swap the entire axle?

 

Coyote

[eaglescout526]

The older 84-86 2wd knuckles are the same as 4wd knuckles. You’d just need the spindle, hub and rotor. The later ones are smaller in terms of big brakes. 

[Coyote]

4 minutes ago, eaglescout526 said:

The older 84-86 2wd knuckles are the same as 4wd knuckles. You’d just need the spindle, hub and rotor. The later ones are smaller in terms of big brakes. 

So they only did that dumb design from '87 to '90? Figures Jeep would do something like that. Lol. Finding an '84 to '86 Jeep Comanche or Cherokee is almost impossible around here, but '91 and up are pretty plentiful. Is the '91 + knuckles the same as the pre '87 ones? I've seen the WJ knuckle swapps, but they require larger rims (16" or bigger). I'm trying to stay with the original Eliminator 15" rims. I can get/do the whole '91+ axle swap, was just hoping I could get away with just swapping the knuckles. 

 

Coyote

[eaglescout526]

Yeah it’s a weird thing AMC did but I’m sure it was a cost effective design for 2wd but they probably weren’t selling as many 2wd Jeeps as they were 4wd. If you think it’s genius to have the hub and rotor into on assembly but dumb when the entire thing has to be changed. But yeah I only recently discovered this with an 86 2wd axle I just got. 
later year knuckles will work, just if you’re after that big brake upgrade, I think the knuckle is completely different later than the early years. 

[SatiricalHen]

I have a pair of used unit bearing style knuckles. When using the unit bearing knuckles you need to put a “plug” in the unit bearing since the unit bearing preload is set with the axle shaft. I’ve used broken axle shafts when I couldn’t find the 2wd stub pieces.


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[Coyote]

44 minutes ago, SatiricalHen said:

I have a pair of used unit bearing style knuckles. When using the unit bearing knuckles you need to put a “plug” in the unit bearing since the unit bearing preload is set with the axle shaft. I’ve used broken axle shafts when I couldn’t find the 2wd stub pieces.


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Thanks for the tip. I've changed the unit hubs on my 91 Cherokee 4x4, but haven't had to do it on my 96 Cherokee 2x4 yet. I didn't realize that they take the same unit hub. Just crawled under the 96 and seen the plug you are talking about. Not sure how I feel about that, but at least it uses standardized parts so I should be able to get replacement hubs fairly easy. Just better make sure to get that plug when I get the axle/knuckles. 

 

[ghetdjc320]

Just a slight info adjustment here: 84-89 knuckles are the old style and 90+ are the new style. The old style used a bolt on caliper that housed the brake pads. The newer styles have a floating caliper design with cast in brake pad “wings”. It is this design that doesn’t allow for big brake setups on the newer style knuckles without serious mods. Wilwood makes a bolt on big brake kit for the pre-90 knuckles but you can also home brew one with parts store components. 

[eaglescout526]

Oh yeah that’s right. I forget late 89-90 was the change over to the HO stuff

[Coyote]

On 3/26/2021 at 5:34 PM, ghetdjc320 said:

Just a slight info adjustment here: 84-89 knuckles are the old style and 90+ are the new style. The old style used a bolt on caliper that housed the brake pads. The newer styles have a floating caliper design with cast in brake pad “wings”. It is this design that doesn’t allow for big brake setups on the newer style knuckles without serious mods. Wilwood makes a bolt on big brake kit for the pre-90 knuckles but you can also home brew one with parts store components. 

Thanks for the info. I'd like to have the big brake upgrade, but all of the stuff I've looked at (Wildwood, WJ knuck swap, Terraflex, etc) says they need 16" or larger rims. I'm trying to stick with the original 15" Eliminator rims so the big brake stuff is out for me. The newer style (91+) brakes with drilled and slotted rotors has done very well for me in the past. If I can get away with just swapping everything from the knuckles out I should be in pretty good shape. 😁

[ghetdjc320]

Only big brake setup for 15’s is the Vanco setup as far as I know. Blaine at black magic brakes sells them. He also sells the best stock brake components available for the 90+ knuckles. 

[Coyote]

I've heard good things about Black Magic brakes, but have never personally used them. I'll have to check them out. If I wasn't trying to keep the original rims I'd be all over one of the big brake packages. 

[ghetdjc320]

4 hours ago, Coyote said:

I've heard good things about Black Magic brakes, but have never personally used them. I'll have to check them out. If I wasn't trying to keep the original rims I'd be all over one of the big brake packages. 

Yeah check them out. Also keep in mind that drilled and slotted rotors offer less pad contact area and typically reduced stopping power. Conversely, they are superior in high performance applications where over heating is common. They can also combat brake fade. But if this is a normal daily driver, a good set of centric pads rotors, calipers and some black magic pads is the way to go.