First complication: the spring perches I ordered may not work out as well as I had hoped.
you will notice that they are quite a bit longer and "taller" than the originals. I think these would be just right for a SOA but that is not the plan. If I were to use them they will drop the rear axle 7/16" and I don't know what problems the added length will cause in spring stress in a SUA arrangement.
Other than that they are very well made and fit perfectly. Any thoughts?
IO,
I have the same
RuffStuff Specialties Replacment Spring Perches.... and I installed a
Dana 44 rear for my
CJ7 . I also saw some of the same points you did. I do have a few thoughts for you...
These are HD spring perches , lazer cut, no hesitation to say good stuff
Longer perches will lower and stiffen spring a bit, because its on the curved side of spring and with the U bolts will squeezed down the longer perch on the inside/top of the CJ spring. Mine rear end did get a bit stiffer..... a side affect did not need.... my CJ was very stiff already.
Dana 44 pumpkin has 1/2" more clearnace than the
AMC20 , I saw you mention the longer spring perch is also about 1/2 taller..... I noticed this and the perch height with a STD CJ spring mount will lower the rear end about 1/2" and will also flatten the spring curve a bit. So you gain 1/2" below the
Dana 44 pumpking vs the
AMC20 axle.... The CJ will squat a bit more with a flattened spring.
AXLE WRAP.... The longer spring perch will cut down axle wrap. As the rear will bit/traction and unload/spin the axle will/can put torque on the axle springs and allow the pinion to push up (forward launch) and can bind the drive shaft on high torque low gear situation.... SO the longer spring perch does have a benifit with high HP or high torque gears will control the rear end better...
Guys with high Hp engines may like the longer perches mech advantage to cut down on axle wrap. Axle wrap will hurt your traction and as the pinion moves up/down can also bind the drive shaft causing failures and vibrations...... This could be good solution for lots of CJs also...
Shorten Perch...... The longer perch can be cut down by inch or so on each side, remove 2" or so from each perch. This will cut down on the "flatening" of the spring arch. Will Allow for a softer spring and more arch. GUESS on my part but the more LIFT on the spring the more the longer preches will remove more of the arch. So I have a 2.5" spring lift and saw the spring was flattened a bit. 4" lift.... guess will have more spring flatening and thus more affect with the longer perch....
My suggestion and actions?
MY
CJ7 springs are very stiff..... I put in
Dana 44 rear HD, regeared, and locked front and rear. The CJ springs have been pushed more with the lockers/ flexed more and have loosened up compaired to the first 4 yrs of use. So, yes USE can soften up the spring ride... ON the rear now I have NO AXLE WRAP and a smooth double track when I try to break loose on gravel.... so doing its job. IF i do work back on axle for some reason I would remove about 1" from each end of the longer perches to maybe the stock
AMC20 lenght.... the
AMC20 was longer & wider than the
Dana 44 spring perches. I would use the old perches as a guide to lenght... EAsy to cut long perch shorter when in hand but harder once welded on axle. Also that
Dana 44 has 1/2 axle tubes.... will need a good welder to attach properly..... I paid ot have mine welded on since the welder I use is smaller.... cost me $20 bucks to do axle perches and few other pcs too.
The Three holes on replacement perch...
The extra holes can be used with lift to keep the stock drive shaft. Taller springs and can use the closer hole on perch and the drive shaft may stillhave the lenght to be used with the lift spring and still have a proper lenght.... Move it back to the furhter hole if lowering spring lift and drive shaft might be too long in that case....
During a wheeling 4 day wk end.... I collasped my
AMC20 rust spring perches.... Prev Owner put angle shims under the rear axle perches and they were a bit rusty after 35 yrs. From torque and the axle shims being a bit narrow.... the rear of perch collasped. My axle could now wrap and turn / rotate with the extra room on a damaged collasped NON flat perch.... When pushed up I had a drive shaft vibration... I was 220 miles from home and was able to drive it home.
Been there, saw many of the same considerations, thought this would help you.
If you want that 1/2 height back... could always have a machine shop take out the extra height.... Hard to do at home but a machine shop could do it for you. Just a thought.
I think they are the best spring perches on the market.