Axle/suspension upgrade early FSJ

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Phils67
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Axle/suspension upgrade early FSJ

Post by Phils67 » Tue Mar 10, 2020 1:36 pm

This will be a minor thread mostly for my own record keeping. It will cover swapping j20 axles, spring under frame front conversion with FSSR, and using GM style 52" spring and mounting conversion for the rear in a post mount style 1967 J2000. I've been very slowly building these axles over about 2 years as time money, and motivation allowed. I will try to post pics, measurements and part numbers as I go so anyone interested can learn from my experience and failures during this process. These axles are near ready to go under and today I started with the removal of the front differential this afternoon which went surprisingly smooth. So, FINALLY, here we go!
NOTE: SOME PARTS ORDERED DID NOT WORK SO READ THROUGH THE THREAD IF YOU WANT TO BE SURE TO ORDER THE CORRECT PARTS FOR THIS SWAP
Last edited by Phils67 on Tue Mar 31, 2020 2:11 pm, edited 1 time in total.
1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Phils67
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Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Tue Mar 10, 2020 1:40 pm

First two pics are the front differential removed. It came out extremely smoothly. Definitely not intimidating so far... and with the diff out I found the source of my death wobble issues. The front springs and posts are worn out badly and with the diff installed it didn't seem as bad. Now that it is out it is blatantly obvious where a major part of the issue was. Video link of the springs so you can see how badly they are worn ImageImage//cloud.tapatalk.com/s/5e67fadc1e1 ... 161909.mp4

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1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Phils67
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Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Tue Mar 10, 2020 3:18 pm

Looking at the disc brackets on the rear I am starting to think it's going to be an issue how they are clocked. I think the calipers are going to interfere with the springs. At least the upper bolt. Maybe I'll get lucky. DoubtfulImage

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1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Phils67
Posts: 823
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Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Tue Mar 10, 2020 4:16 pm

Just ordered these brackets for the rearward front mounts. Taking measurements off of my father in laws CJ7 I believe they will work and are very close to the proper distance off of the frame to a stock j10/j20. They will about 1/4" or so lower than stock mounts but if anything it will give me slightly more castor which shouldn't be an issue. The goal is to keep the front fairly close to stock geometry to maintain proper castor. Should have them this weekend hopefully. Ordering the rest when my tax returns hits tomorrow then there is no turning back! Ultimately all of the spring mounts will be bolt-on style with grade 8 hardware, leaving me room to adjust if needed and also easy to replace someday if they ever break or rot.

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Last edited by Phils67 on Wed Mar 11, 2020 11:38 am, edited 1 time in total.
1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Phils67
Posts: 823
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Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Wed Mar 11, 2020 11:23 am

Just spent the last 2 hours measuring, searching and ordering parts. Hopefully I ordered everything correct and it is going to be basically everything to get the wheels back on the ground soon. Shocks, wheels and tires will have to wait for now until I free up more money. Ordered the j20 front springs (7 leaf), GM 52" rear springs (5/1), both u-bolt kits, rear calipers, 2 sets of brake pads, stainless hoses for all 4 corners, the rocklaurence FSSR kit, oem front shackles. and forward rear spring hangers for a GM truck. The rear spring hangers are going to have to sit a little lower than the stock post mounts but since the rear hanger is below the frame currently it should be ok I think. Time will tell. Now for the worst part... waiting.
1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Stuka
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Re: Axle/suspension upgrade early FSJ

Post by Stuka » Wed Mar 11, 2020 12:21 pm

The spring mounts should work fine provided they are 2.5" wide.

Also fixed your post for you so the image would show up, one of the brackets got left off.
1981 J10 AMC 258 with HEI and Weber 32/36 DGEV Carb, T176, NP208, D44/M23 with 4.56 gears and Detroit Locker, 6" lift, 33x12.50 Cooper STT's, BJ's Offroad Rear Dozer Bumper.
2017 JKU Rubicon Lifted and stuff
Pevious Jeeps: 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

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Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Wed Mar 11, 2020 12:57 pm

Stuka wrote:
Wed Mar 11, 2020 12:21 pm
The spring mounts should work fine provided they are 2.5" wide.

Also fixed your post for you so the image would show up, one of the brackets got left off.
Which pic?
1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Re: Axle/suspension upgrade early FSJ

Post by Stuka » Wed Mar 11, 2020 2:22 pm

Phils67 wrote:
Wed Mar 11, 2020 12:57 pm
Stuka wrote:
Wed Mar 11, 2020 12:21 pm
The spring mounts should work fine provided they are 2.5" wide.

Also fixed your post for you so the image would show up, one of the brackets got left off.
Which pic?
The screenshot of amazon for the spring hanger.
1981 J10 AMC 258 with HEI and Weber 32/36 DGEV Carb, T176, NP208, D44/M23 with 4.56 gears and Detroit Locker, 6" lift, 33x12.50 Cooper STT's, BJ's Offroad Rear Dozer Bumper.
2017 JKU Rubicon Lifted and stuff
Pevious Jeeps: 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

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Phils67
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Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Wed Mar 11, 2020 2:57 pm

Oh. It showed the whole thing on my screen. Didn't even know lol
1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Phils67
Posts: 823
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Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Wed Mar 11, 2020 2:58 pm

Well good. Here is the one I ordered for the forward rear mountImage

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1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Phils67
Posts: 823
Joined: Sat Mar 24, 2018 3:11 pm

Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Thu Mar 12, 2020 10:31 am

Front springs showed up today from General Spring, part number 97-400, which is fast since I only ordered them yesterday. The arch is pretty big, almost as much as the Hell Creek 4" springs currently on it. It's going SUA like the front axle was intended to be so it should be about 3" lower than it currently sits with the old diffs if I estimate correctly. I will post a pic of them side by side later. If I get the ambition to pop the old fronts off before work.
Last edited by Phils67 on Thu Mar 12, 2020 4:31 pm, edited 1 time in total.
1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Phils67
Posts: 823
Joined: Sat Mar 24, 2018 3:11 pm

Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Thu Mar 12, 2020 12:56 pm

Comparison of the new stock height 2.5" J20 springs vs. the 4" Hell Creek 2" wide first gen lift springs. I think with the new springs, FSSR and new mounts all around I will end up about 2.5-3" over stock height, which is ok by me since I hope to clear 34x9.5 tires comfortably. Waiting on spring mounts now to get the front portion started ImageImageImageImage

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1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Topic author
Phils67
Posts: 823
Joined: Sat Mar 24, 2018 3:11 pm

Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Thu Mar 12, 2020 1:08 pm

Not to get ahead of myself here but what size dog dish caps fit 16" steel wheels? I want to go white steel 4 slot ford style wheels with babymoons since the 15" dog dish won't fit. Figure I can add red/gold Jeep decals to the center's to make them look the part. They are like 11.5" caps for 16" right?
1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Stuka
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Re: Axle/suspension upgrade early FSJ

Post by Stuka » Fri Mar 13, 2020 6:22 am

A lot of times a 15" wheel dog dish will fit on a 16" wheel. But that is often only for 5 lug 16" wheels, not 8 luggers.
1981 J10 AMC 258 with HEI and Weber 32/36 DGEV Carb, T176, NP208, D44/M23 with 4.56 gears and Detroit Locker, 6" lift, 33x12.50 Cooper STT's, BJ's Offroad Rear Dozer Bumper.
2017 JKU Rubicon Lifted and stuff
Pevious Jeeps: 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

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Phils67
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Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Fri Mar 13, 2020 9:16 am

Correct. I have seen people weld bumps on them and also drill in VW style clips to use the 10" on a 16" 8 lug. I keep toying with the aftermarket smoothie wheels with caps but I dont think they would look right, and it isnt a cheap guess.
1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Phils67
Posts: 823
Joined: Sat Mar 24, 2018 3:11 pm

Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Fri Mar 13, 2020 5:35 pm

:) :) Update. I has front shackles
1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Phils67
Posts: 823
Joined: Sat Mar 24, 2018 3:11 pm

Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Sat Mar 14, 2020 8:52 am

Ordered Wagner TQ ceramic pads for a 78 K10 with 13" brakes and they will work it looks like for the front and rear. So the rear calipers should also be correct when they arrive. That's good. One less thing. So far so good on parts accuracy it seems. I've been trying to figure out the correct stuff for a few years now. Image

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1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Phils67
Posts: 823
Joined: Sat Mar 24, 2018 3:11 pm

Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Sun Mar 15, 2020 12:55 pm

First snag. The caliper brackets on the rear are clocked wrong. I'll never clear the springs or be able to remove the upper bolt to change the pads. So looks like I have to pull the shafts and hubs off and rotate the brackets down some. Also noticed the calipers ordered for the rear have a 3" diameter piston. The ones used on the front disc conversion a while back have a 2.75" piston. The caliper with the 3" doesn't work on the front axle so hopefully the ones already in the truck will work with the front. They should. I believe they were for a J10 but cant recall,its been a while and I dont remember the part number on the front. Big reason I am doing this post and making notes for this project as I go now. Oh the joy of building stuff..Image

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1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Phils67
Posts: 823
Joined: Sat Mar 24, 2018 3:11 pm

Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Mon Mar 16, 2020 9:07 am

Parts are starting to flow in pretty regularly today. By the end of this weekend everything should be here. Pics and updates coming soon
1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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Phils67
Posts: 823
Joined: Sat Mar 24, 2018 3:11 pm

Re: Axle/suspension upgrade early FSJ

Post by Phils67 » Mon Mar 16, 2020 10:02 am

So far today the Stainless brake hoses came from CutThroat 4x4, the rear GM springs from General Spring, the rear forward GM mounts and the front rearward CJ7 mounts. Posting pics of the mounts against the frame, unmounted for now just to get an idea. If the CJ7 brackets dont pull in a little I may have to shim the bushing with a washer on each side but that's the least of my concerns. So far it looks like it will all work out pretty good!ImageImageImageImageImageImage

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1967 Gladiator J2000, currently under the knife getting J20 axles, late model spring-under-frame frontwith FSSR, 52" GM springs with ranger brackets in the rear, 3.73 with Detroit's, 4 corner disc, 235/85R16's on white steelies.

1990 Comanche MJ/ 2.5TBI Renix/AX4/2wd SporTruck base model shortbed/main Jeep/daily driver

2001 Cherokee XJ/ 4.0/AW4/NP231/D30-35/backup Jeep/daily driver

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