J10 vs J20 Frame ?

[jeephabit3]

In general are J10 and J20 Frames equal in strength? I am looking at doing a Truggy out of my 74 J20 but don't want the 130" wheelbase. It seems like a good option to just use a J10 Frame since the wheelbase is at 116" which is much more reasonable for a Truggy and not mess with cutting down the J20 frame. The J20 already has a newer front axle, 401/727/NP208 as it sits now which I would like to keep.

[HOOT]

Frames are the same as compared year to year.

keep the frames in the same general era and all should be fine. Or you can even find a wag or chero frame which again will be the same from the mid section up. That would give you a 109" wheel base vs. the 119" of a 7ft. J10.

[jaber]

If theres any doubt, you could finish boxing the frame on the 10 the rest of the way back.

[jeephabit3]

So would swapping the powertrain, axles, etc. out to a Waggy/J10 frame be easier than cutting the J20 frame to shorten it? I have not done a stretch/shrink before so I am trying to figure out which is less effort.

[Elliott]

No, just shorten the J20 frame, move the axles and be done with it. The waggy has too narrow of an axle and the Jtruck has a wider rear frame/spring pad distance.

[Tinkerjeep]

Okay...i'm way late weighing in here...but...

J20 frames have the 119" wheelbase boss stamped into the frame rails. What is this? its where the 119" WB front spring-eye bolt goes through the frame for the rear leaf-springs. it is about 12" forward of the 131" WB spring hanger for the front spring-eye of the rear leaf springs. This pic is of the shortened J20...131" WB down to 119" WB.




The spring shackles are stronger on the J20s than the J10s/Wag/Cherokees.

The frame wall thickness is about 40-50% thicker than the Cherokee/Wagoneer frame walls. Wag/Cherokee =.125".
J-trucks = approximately .188".

The J-truck Frame rails do "crank-out" behind the tranny crossmember so the J-truck rear axles have wider/more laterally stable spring mounting points than the Wag/Cherokees. You can inboard the rear springs and relocate the spring perches on the rear axle, but its more work.


The big killer is the 57" long rear leafspring packs...I think that's right...maybe 53"...anyway they're long. I chopped the frame off just behind the moved forward rear spring hangers, and chopped the bed...this is about as "bobbed" as you can go...


So, down-side:
The longer rear springs increase rear overhang, so you need to go BIG with tires and lift to compensate...or totally ditch the rear leafsprings and go 4-link and coil-overs.

Also: on J-trucks the width of tire is limited by the tire's inner sidewall proximity to the rear leafspring packs. It can be .25" with 4" backspacing on a 15x8" wheel and a 13.50x33 Swamper. This is max. Actually too close for my comfort.