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Spring Over Axle for Wrangler YJ

Yet another view

by Chris Waterman

EB Swap

Main
Ford 9"
Dana 44
Spring Over
Final Notes

A spring over axle swap is a great way to get a lot of lift and get great articulation. The lift from a spring over axle swap comes from not changin springs, but by changing the way the axles mount on the springs. The CJs and Wrangler YJs have the axles mounted on top of the springs (spring under). If the axles are modified so they mount on the bottom of the springs (spring over), there will be at least 5" of lift.

Granted, it is easier to install a regular lift kit where everything is thought out for you, but the results won't be the same. The flat stock springs articulate better and there is plenty of room for big tires. The biggest obstacle to most people with the spring over is you need to be able to weld or know someone that can weld. If you can get over this hurdle, it is well worth the effort.

I did my spring over swap as part of an axle swap using early Bronco axles, so that complicated it to some degree. This article covers issues that would come up on any Wranlger spring over axle swap.

Springs

I already had a OME 2.5" lift springs before I did the spring over axle swap. I kept the rear set and I purchased a pair of rear YJ OME J1R springs I found at a wreckers (woohoo!) to replace my front ones. The rear springs have a higher spring rate and I wanted to use them in anticipation of the weight of a winch to come later this year. The higher spring rate will also help minimize spring wrap up front.

Spring Perches

Both front and rear I used adjustable spring perches to fine tune the pinion angles. Since I was swapping in an early Bronco Dana 44 up front, I did not have to deal with the problem of integrating the driver side spring perch into the differential housing. Because of the amount of lift with a spring over, constant velocity (aka CV joint or double cardon) drive shafts will most likely be necessary. This simplifies setting the pinion angle though because with a CV shaft, you just point the pinion to the transfer case yoke.

Rear shock bracket and driveshaft detail Since I got the pinion angles set right, I have had no driveline vibrations, which is a relief. The rear shaft is running at about a 21-degree angle relative to the t-case output shaft, which is steep even for a CV, but it doesn't bind when the rear axle is articulating, and I haven't worn out any u-joints yet...

The front D44 was (I think) set up with about 4-5 degrees of caster. When I had the brackets welded on, I positioned them such that I'd have around 8 degrees, which seemed to be the conventional-wisdom figure for springovers. That left the pinion pointing upwards about 4 degrees. Not great, but I figured the caster was more important than the front pinion angle. It turns out with this angle, the pinion is just about pointing at the transfer case yoke. The Jeep handles fine on the freeway - no wander at all. It might be hard to get the same results with the stock Dana 30 because YJ front axles come with more caster from the factory than an early Bronco. Setting caster requires cutting off the outer parts of the front axle.

U-Bolts and U-Bolt Plates

U-bolts I had made at a local spring shop for cheap, and I found spring plates at wrecking yards just by walking around until I found some with the right hole pattern. For the swaybar mounts on the front plates, I cut the heads off two 6" long 5/8" bolts and welded the stems (is that the right word?) onto the front spring plates. No problemo.

Drive Shafts

New (to me) Bronco shaft w/ Currie kit vs old POS YJ shaft What about the rear driveshaft, I hear you saying? Well, the YJ's notoriously short rear driveshaft was obviously a problem (especially with the low pinion on the Ford 9"). What I did to resolve the problem was purchase a used NP231 tailshaft shortening kit from Larry Soo. Larry didn't need the tail shaft shortening kit after he swapped a Dana 300 in his Wrangler YJ when he did a Scout Axle Swap.

For the rear shaft I used parts from a 80-something Monte Carlo and from a full size late 70s Bronco. This matched the hole pattern of the CV flange on the tailshaft kit. On the left is a CV joint shaft with the tailshaft eliminator kit on top and the original YJ drive shaft on the bottom.

Notch cut in skidplate for driveshaft clearance In the front, I used a the front CV drive shaft from a '97 Wrangler TJ that I happened to find in a junk yard. When I had the shaft lengthened, I had it done with a larger 2" 0.120" wall tubing. Note the scuff marks - a new exhaust pipe is a must I had to cut a notch in my skidplate (pictured to the right) to have clearance between the front shaft and the skid plate. There is still a slight conflict with the front shaft and the exhaust pipe between the manifold and cat. This probably wouldn't be an issue if you were not swapping in a front early Bronco Dana 44. In the picture on the left, you can see the scuff marks from the contact made by the drive shaft. I had a custom exhaust pipe bent from the manifold to the cat.

Shocks

Once the axles were in, I was able to measure the extended length of the shocks I'd need. My friend Larry gave me a set of stock rear shocks from an F250 or F350 that fit perfectly for my rear end, and I bought some nice long Rancho RS5012s for the front (34" extended!).

Steering

The track bar and drag link turned out close to parallel A dropped pitman arm was required with the drag link and tie rod configuration I used. I used a 4" drop pitman arm on the same trip. Even so the drag link is at a pretty severe angle, but it is parallel to the track bar which minimizes bump steer. The bump steer is real bad with no track bar up front. I've used a 7/16" clevis pin to connect the track bar to the axle bracket for a quick disconnect (thanks to Dave Gray for that idea).

Even with the drop pitman arm, the drag link angle is steep enough that the ends in the drag link rotate every time you change the direction of the steering wheel. The drag link pulls upwards and downwards at the same time it pulls left and right, respectively. The only fix I can see is a Z-bent drag link, which will also improve clearance between it and the right-side spring. Not sure if I might lose too much strength to be worth the improved steering though.

Brakes Lines

Custom brake lines I got some extended brake lines from Coast Industrial on Vancouver Island. I mailed them the necessary used YJ, Bronco, and Chevy brake line fittings, and they sent me a set of three lines made to order, with my fittings brazed onto their generic ones. They have a woven steel core coated in rubber, nice and strong. Thanks to Rob Bryce for this referral! Check locally for a shop that builds custom hyrdaulic lines to help you here.

For the the parking brake working using two long-side YJ cables and upgrading to the much-improved 90's type parking brake adjuster at the same time.

Axle Wrap

Surprisingly, axle wrap has not been a huge problem. It's there, and I do plan to fabricate and install a rear anti-wrap bar in the near future, but truth be told it's not as necessary as I thought it would be. Spring sag has also been very minimal; the progressive-rate OME springs have held up really well, but I'm careful not to bounce too hard on them, to avoid taking them into negative arch. Some extended bumpstops are in my plans for the near future as well, probably just some pieces of rectangular tubing bolted to the ends of my u-bolts on each spring plate.

Conclusion

Looks pretty good if I say so myself, and man oh man does it flex!

Flex

Last modified Wednesday, 01-Dec-2010 09:23:39 MST


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robert (3/21/2013)
have spring over lift but want it higher what should i do

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