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Old 01-11-2008, 08:25 PM
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djmac djmac is offline
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Planning an axle project

Well I am preparing for my axle replacement and I want to do this right the first time so I am calling in everyone’s help and experience. I am going to remove my amc 20 and d44 axles from my 82 J10 and replace them with a 79 ford d60 high pinion/ kingpin front axle and a d70 at the rear. Both have 4:88 gears. Currently I have a 4”DPA with a BJ’s 6 inch spring lift and extended spring shackles for my front lift and the rear has BJ’s 6 inch spring lift with 3” blocks. My plan is to go from the 35” TSL’s to around 38” or so I need about 10” or more inches of lift. I would prefer not to do a body lift. If possible I would like to salvage the front or rear springs as they only have about 5000 miles on them but I am interested in improving my flex so I am open on what to do with the springs. I am pretty good under the hood but when it comes to axles and stuff I am pretty green so I am open to all opinions. I have a lot of questions so for the sake of clarity I am going to list them below:
  • What is the best way to center an axle under a body? With so many unequal dimensions under the body what do you measure from and to when centering an axle?
  • I have an astro hydroboost and astro master cylinder. These axles have huge brakes what should I use to for a proportioning valve and the M\C replacement?
  • What would the best way to achieve the amount of lift I need to clear the 38” tires? I do not want to cut the flares or lift the body.
  • I am unclear as to what parts I am going to need to install the hi-steer. I think I need a new drag link, 2 knuckles, and 2 arms. Anything else? My front axle came with the tie rod and ends intact
  • I assume the existing shock mount will not work. Where would I get J10 shock mount brackets to weld on?
  • What would be the minimum rim size and recommended offset for the wheels for these axles?
  • If my rear axle yoke is slightly offset from the center will that create enough angle distortion to create a driveline vibration? Will CV joint take care of the vibration?
I don’t expect anybody to answer all this stuff but chime in on what you do know. And thanks for the helping me stay out of trouble!
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82 J10 SOA 6" SPRINGS D60-D70 W/DETROIT LOCKERS 38x15.5 TSL'S on 12" M/T CLASSICS 460 V-8 C-6 CUSTOM EFIS EFI AND HYDROBOOST
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Old 01-11-2008, 09:53 PM
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Unless you run discs in back the Astro MC should have adequate reservoir capacity, if you need more you can pop the reservoir off and replace it with one off a similar Jeep aluminum MC or a GM MC.
If you are still disc/drum your proportioning valve will be adequate.
For the lift, move your springs under the frame (requires a shackle inversion and re-evaluate height which should be about 10" lift (swap in GM 63" springs for better articulation at about the same height, maybe +1" with the shackle).

For the high steer, you can leave your tie rod low and just use a single hole high steer arm on the knuckle and run a drop pitman/drag link to that. There's a couple versions to do this, but that is the cheapest.
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  #3  
Old 01-12-2008, 08:06 AM
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Quote:
Originally Posted by Elliott
Unless you run discs in back the Astro MC should have adequate reservoir capacity, if you need more you can pop the reservoir off and replace it with one off a similar Jeep aluminum MC or a GM MC.
If you are still disc/drum your proportioning valve will be adequate.
For the lift, move your springs under the frame (requires a shackle inversion and re-evaluate height which should be about 10" lift (swap in GM 63" springs for better articulation at about the same height, maybe +1" with the shackle).

For the high steer, you can leave your tie rod low and just use a single hole high steer arm on the knuckle and run a drop pitman/drag link to that. There's a couple versions to do this, but that is the cheapest.
Elliott
Great news on the brakes. The shackle inversion and the 63" spring , is that for the rear axle? Is there a particular year chevy I need to specify to get the right part? Can I use my existing 4" DPA?
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  #4  
Old 01-13-2008, 03:49 PM
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I did some checking and for $225 I can get the steering arm, stud kit, custom length drag link and modify my dpa. For the lift I am thinking of going SOA and a 3" or 4" spring lift. This is not my DD but I do have to get to the hole and back...do I have to keep the torsion bar? On rear lift I am hoping to keep my rear springs which have a 6" lift. If I keep the 3" blocks and the 6" spring should I expect clearance problems by not inboarding them?
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82 J10 SOA 6" SPRINGS D60-D70 W/DETROIT LOCKERS 38x15.5 TSL'S on 12" M/T CLASSICS 460 V-8 C-6 CUSTOM EFIS EFI AND HYDROBOOST

Last edited by djmac : 01-15-2008 at 10:14 PM.
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  #5  
Old 01-16-2008, 08:52 PM
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82 J10 SOA 6" SPRINGS D60-D70 W/DETROIT LOCKERS 38x15.5 TSL'S on 12" M/T CLASSICS 460 V-8 C-6 CUSTOM EFIS EFI AND HYDROBOOST
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  #6  
Old 01-16-2008, 09:04 PM
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j20brett j20brett is offline
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you are looking for rear springs form an '88 to '98 chevy 1/2 ton for the 63". when inboarding springs you will have to move the perches

For your 10" lift, soa will give you 6-7 in, so either a 4" lift spring or rancho 2.5" springs. Brutus has the same amount of lift on his, you could ask him what he is running in the front.

you can make your own shock brackets, or a generic set from any offroad site. heres one set
http://rustysoffroad.com/mm5/merchant.mvc?Screen=PROD&Store_Code=rustys&Product _Code=RX-SM1&Category_Code=cus

you shouldnt have any vibe issues if you setup the rear axle with the correct pinion angle (pinion should be parallel to tcase, ie same angle)
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  #7  
Old 01-16-2008, 10:27 PM
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djmac djmac is offline
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Quote:
Originally Posted by j20brett
you are looking for rear springs form an '88 to '98 chevy 1/2 ton for the 63". when inboarding springs you will have to move the perches

For your 10" lift, soa will give you 6-7 in, so either a 4" lift spring or rancho 2.5" springs. Brutus has the same amount of lift on his, you could ask him what he is running in the front.

you can make your own shock brackets, or a generic set from any offroad site. heres one set
http://rustysoffroad.com/mm5/merchant.mvc?Screen=PROD&Store_Code=rustys&Product _Code=RX-SM1&Category_Code=cus

you shouldnt have any vibe issues if you setup the rear axle with the correct pinion angle (pinion should be parallel to tcase, ie same angle)

Thanks for your input. What do you think would be the consequences of keeping my 6" rear springs in their stock locations" I know I would have to relocate the perches on the axle but would I have clearance problems else where? If I go with the chevy springs I still need 3" or so of lift to match the front. Are they available in a 3 or 4" lift?
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Old 01-16-2008, 10:33 PM
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On the reservoirs, just look for one that is on an aluminum MC and has the stepped sections where it attaches, either the FSJ '81+ or GM will do. They can be brittle sometimes and can shatter when popping them off if they've had too much heat over the years. On the install, put the grommets in the MC first and then push the reservoir on. Best to do all this in a vise if possible.
BTW, I just set up an M715 and a Commando so we'll see how the fit goes on those two rigs Also, did a Toyota FJ40 and working on an AMC Eagle as well as a CJ7.
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Last edited by Elliott : 01-16-2008 at 10:35 PM.
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  #9  
Old 01-16-2008, 10:57 PM
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j20brett j20brett is offline
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ive never done the 63" springs conversion, so i really couldnt tell you how much lift it gives. PM brutus as he moved his springs under the frame when he did his axle swap...dont know what leafs he went with though.

and im sure you could order a set of 63" lift springs from any suspension company
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  #10  
Old 01-16-2008, 11:07 PM
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djmac djmac is offline
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Quote:
Originally Posted by j20brett
ive never done the 63" springs conversion, so i really couldnt tell you how much lift it gives. PM brutus as he moved his springs under the frame when he did his axle swap...dont know what leafs he went with though.

and im sure you could order a set of 63" lift springs from any suspension company

For some reason it did not occur to me that the 63" spring is what give the lift. Elliott mentioned them in an earlier post but I did not realize they would provide lift beyond stock.

Thanks
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Old 01-16-2008, 11:41 PM
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It gives you lift for at least two reasons, the hangers are now under the frame and the shackle will need to be inverted to put the hangers under the frame.
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***I can set you up with hydroboost for your brakes: http://www.ifsja.org/forums/vb/showthread.php?t=106056
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Old 01-17-2008, 05:54 AM
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I'll try to answer a couple of questions based on how mine worked out.
63" Springs:
Eye to eye distance for the hangers when complete came in at roughly 62 3/8"
The lift gained came in about 2 1/2" more than stock 56" springs with the big overload removed from the 63's.
Combined with the shackle flip and slightly taller Tad-Perch on the 14-Bolt I'd say I got 9" of lift.

I'm going to guess here and say that if you inboard the springs under the frame you will get about 1" more than that above.

I'm not sure what your clearance numbers are for the D70 but it should be easy enough for you to calculate.
Measure the distance between the calipers/backing plates (doesn't matter what axle really) subtract about another 1.5" per side for U-bolt clearance, then compare to your outside rear spring distance.

My guess is that unless that axle is very wide you will be inboarding under the frame just to keep things simple.

Also:
I have sent a few sets of 14-Bolt perches out to D70 owners but never heard back if they are a exact fit, my guess is they do but will need a bit of clearancing with an angle grinder.
The RB kit in it's standard form will not inboard under the frame without mods. So I have started offering these for the inboarding folks:



or



Brutus has some great tech pic's on his site also for the JTruck folks.
http://fsjbrutus.com/jeep/lift/
http://fsjbrutus.com/jeep/lift/images/rearlift1.jpg
http://fsjbrutus.com/jeep/lift/images/rearlift2.jpg
http://fsjbrutus.com/jeep/lift/images/fulllift4.jpg
http://fsjbrutus.com/jeep/lift/image...riverlift4.jpg
http://fsjbrutus.com/jeep/lift/image...iverlift11.jpg
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Last edited by Tad : 01-17-2008 at 06:10 AM.
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  #13  
Old 01-18-2008, 04:36 AM
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Well it looks like I got enough info to be dangerous! Thanks alot everybody for the tips. Now I have to get the parts together so I can get started.
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