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86MJ lift & Exploder 8.8 axle swap, finally...


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So I finally had the time to start the mods on the 'manche today, and spent a few hours prepping the 8.8 diff. I removed the perches and welded the tubes to the pumpkin, then the rain ended all operations since I am working outdoors. The diff is equipped with a sway bar and I intend to connect the links to the frame of the truck, anyone done this? Is there an ideal measurement for perch placement on the axle tube from the brake backing plates or does this require temporary installation on the leaf springs to dial it in? I'd like to keep the rear brake load sensing valve but am unsure it will work correctly still with the rear disc setup. A disc/disc master cylinder swap may be in order because of this I reckon...thoughts?

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5 hours ago, zomeizter said:

So I finally had the time to start the mods on the 'manche today, and spent a few hours prepping the 8.8 diff. I removed the perches and welded the tubes to the pumpkin, then the rain ended all operations since I am working outdoors. The diff is equipped with a sway bar and I intend to connect the links to the frame of the truck, anyone done this? Is there an ideal measurement for perch placement on the axle tube from the brake backing plates or does this require temporary installation on the leaf springs to dial it in? I'd like to keep the rear brake load sensing valve but am unsure it will work correctly still with the rear disc setup. A disc/disc master cylinder swap may be in order because of this I reckon...thoughts?


In regards to the brakes, you will need significantly more pressure to drive rear disks. Despite assumptions to the contrary, stock drums actually have more stopping power than stock disks. However, there are many other reasons to swap. Self adjusting, easier maintenance and better performance (cooling and self cleaning) are at the top of my list. Plus a parking brake that works in both directions.

The load sensing valve may work in a pinch if you lengthen the rod to sit higher than normal when level. I deleted mine along with the distribution block a long time ago. Ran all new lines, rear disks, Wilwood prop valve, 2000 XJ booster and MC. Never looked back. But going to add some Wilwood fronts eventually. 
 

in regards to the sway bar, I haven’t seen one retained from an 8.8 but adco makes a rear MJ sway bar that some hear have used. 
 

For the perches, it’s best to install the axle and get all your measurements just right. Pinion angle is critical plus centering the axle to the truck. Once you have that setup just hit it with a few tack welds then take it out and burn it in

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if I remember right, it's 42" center of perch to center of perch.  a little time with the tape measure should get this centered between the backing plates. :L:  (just don't measure off the diff for anything since some axles aren't 100% centered)

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15 hours ago, ghetdjc320 said:


In regards to the brakes, you will need significantly more pressure to drive rear disks. Despite assumptions to the contrary, stock drums actually have more stopping power than stock disks. However, there are many other reasons to swap. Self adjusting, easier maintenance and better performance (cooling and self cleaning) are at the top of my list. Plus a parking brake that works in both directions.

The load sensing valve may work in a pinch if you lengthen the rod to sit higher than normal when level. I deleted mine along with the distribution block a long time ago. Ran all new lines, rear disks, Wilwood prop valve, 2000 XJ booster and MC. Never looked back. But going to add some Wilwood fronts eventually. 
 

in regards to the sway bar, I haven’t seen one retained from an 8.8 but adco makes a rear MJ sway bar that some hear have used. 
 

For the perches, it’s best to install the axle and get all your measurements just right. Pinion angle is critical plus centering the axle to the truck. Once you have that setup just hit it with a few tack welds then take it out and burn it in

 

6 hours ago, Pete M said:

if I remember right, it's 42" center of perch to center of perch.  a little time with the tape measure should get this centered between the backing plates. :L:  (just don't measure off the diff for anything since some axles aren't 100% centered)

Thanks dudes, I will begin with the teardown of the axle on the 'manche once the weather improves and mock up the replacement onto the springs to dial in the perches. I went out and measured the perches on the stock axle and 42" is what I got, as Pete mentions. 

 

 

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  • 4 weeks later...

Pulled the AMC 20 axle today, hopefully I get the 8.8 under the 'manche tomorrow, shooting for at least getting the perches tacked for final welding.

 

 

 

 

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Axles next to each other for comparison, the Furd one sure looks stout...

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I'm gonna run these GM shackles (right) recommended by someone on the forum here, should help with the sag of the original leaf springs. I reckon I should get about 6-7 inches of lift with SOA and these shackles, we'll see...

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6 minutes ago, zomeizter said:

Pulled the AMC 20 axle today, hopefully I get the 8.8 under the 'manche tomorrow, shooting for at least getting the perches tacked for final welding.

 

 

 

that's a dana 35 :L: 

 

you'll love the 8.8  :D 

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5 minutes ago, ghetdjc320 said:

Yikes, tough working conditions! Try to get some longer spring perches for soa to prevent axle wrap. Especially if your springs are sagging

Haha! It was pleasant actually...I did get them perches from Barnes.

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10 hours ago, Pete M said:

the AMC 20 has a perfectly round diff cover. :L:    like basketball levels of round. 

 

 

Rebel_Machine_166.jpg

I see now...I reckon the D35 I pulled will go under a utility trailer, unless one of y'all need a 4.10 axle...

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1 hour ago, zomeizter said:

I see now...I reckon the D35 I pulled will go under a utility trailer, unless one of y'all need a 4.10 axle...

 

even being a dana 35, the 4.10s is a great upgrade over 3.07 or 3.55.  I'm sure someone would love to have it. :L: 

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19 hours ago, Pete M said:

the AMC 20 has a perfectly round diff cover. :L:    like basketball levels of round. 

I always thought of it as Charlie Brown head round.

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Mocking up the 8.8...

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Not liking the full droop shackle angle...

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Gets a little better with the weight of the empty bed, I am considering a dual shackle set up but I'm going to run this and see how it behaves.

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I'm going to use the Ranchos (in great shape) I took from the donor Exploder, one of the original Bilsteins is defective, which explains the weird ride once in a while (both fully extended)...

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I did not have time yesterday to tack the perches' final position due to not having the combination u-joint for the d-shaft, hopefully I get this done this morning and burn the perches on as well.

I'm using the original spring plates (flip-flopped) so I can retain the lower shock mounts and so far looks like they'll work, once it all fits right I'll grab some new u-bolts for final quench.

So far it looks like the d-shaft length is adequate too and I noticed that the leaf springs are very flexy.

More pix and stuff later...

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On 2/21/2021 at 9:38 AM, Pete M said:

shackle angles look normal to me.  :dunno:  what angles are you looking to achieve?

I reckon slightly less than 90 degrees but if they look alright I'll run with it for now. I measured the springs eye-to-eye unloaded and got 53", I was hoping to swap in some Silverado ones I scored but them are 62" eye-to-eye and super stiff compared to the flexy stockers. I was able to complete the mods to fit the 8.8 last Sunday, all I got left is the parking brake shoe replacement and cable retrofit on the pawls/actuator thing-a-majigs. 

 

 

D-shaft angle at the pinion matched to the T-case output, new flange and combo U-joint...

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Perches welded to the axle tubes

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Lovin that high AF rear on the 'manche, looking aight with the 31" mudder on steel...

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Had to leave town for work this week but ima hit the 'manche's front end this coming weekend, more to come...

 

 

 

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Looked up some suspension torque specs online, found some for cherokees, can someone confirm these also apply to an MJ?

 

Item ........................................ Ft. lbs. ................... Nm

Lug nuts (1/2 X 20 w/ 60* cone) .... 85-115 .............. 115-150
All tie rod ends .....................…..... 55 ...................….. 74
Steering (both ends) ..............…..... 55 ................….... 74
Shock absorber upper nut .............. 16 ................….... 22
Shock absorber lower nuts ............. 17 ................….... 23
UCA frame end .....................…...... 66 ..............…..... 89
UCA axle end .........................….... 55 ................….... 74
LCA frame end ......................…..... 85 ...................... 115
LCA axle end .........................….... 85 ...................... 115
Track bar frame end ..............…..... 60 .................…... 81
Track bar axle end .................….... 40 ..................…... 54
Track bar bracket bolts ..........…..... 92 ...................... 125
Track bar bracket nut .............….... 74 ....................... 100
Track bar bracket support bolts ...... 31 ....................... 42
Hub bolts (3) ............................…. 75 ....................... 102
Hub- axle bolt ..........................….. 175 ..................... 237

 

Main eye: 115 lbft (21mm)
shackle eye and shackle bolt: 80 lbft (21mm)
U-bolt nuts: 55lbft (18mm)

Alingment specs (stock):

Angle ............. Preferred ........... Range ............. Max R/L diff.

Caster ............ +7.0* ........ +5.25* to +8.5* ......... 1.25*
Camber ........... -0.25* ....... -0.75* to +0.5 ........... 1.0*
Total Toe-in .... +0.25* ....... 0* to +0.45* ............. .05*
Thrust angle .... 0* to ± 0.15* 

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Front lift went in today, coil springs are 5.5" RE which I thought would be inadequate to match the rear SOA but looks like they're ok, we'll check later on once they settle some, I do have a set of 2" spacers for the coils if the rake is excessive. The control arms are Core 4x4 Tier III with the Johnny joints, the installation was easy except at first I guess I made them too long by centering the adjustment on the tubes, had to adjust them in a lot to get the front wheels sort of centered. RC drop brackets went in quick too, I had to "massage" the caster adjuster holes to accept the slightly thicker hardware, and I guess the upper control arm in an XJ mounts differently because the instructions wanted me to use a thicker bolt on the frame arm pocket. As you can see in the pics, the driveshaft will need extended and I'll need longer shocks since I can't even bolt them on with full weight on the axle. I am really happy with the sexiness so far, can't wait to finish it and wheel it at the woods nearby. Gonna be a few weeks since I have to go out of town for work again for a couple weeks. More progress pics later on, critique is welcome, cheers.

 

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20 hours ago, Pete M said:

makin' good progress :L:  would you like me to move this over to the Projects section? 

Thanks man, if y'all think it would be better to move it there, go right ahead, all good with this here hippie...

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  • 1 month later...

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