YJ leafs

[DADSOLDCJ]

I'm building a '76 CJ5 that dad left me a couple years ago. right now I'm in the deconstruction stage and looking into buying a new frame. While looking at frame options on Throttle Down Kustoms and see that with shackle reversal, i can put YJ springs on for a better ride. i've read that the YJ springs are straighter for this reason. My ??? is, does that affect the ride height, goin from CJ to YJ leafs? Since they don't have the curve the CJ's do. Also, are the rear springs the same? I can rock stock CJ rears with front YJ'S, right? Thanks.

 

[Torxhead]

For some time now, the spring shackle reversal is not really an improvement as it was once thought it was:Pros and Cons of Shackle Reversal
Installing the longer spring up front should give a softer ride as it is the same as the longer and wider rear spring.

 

[DADSOLDCJ]

ok thanks, that link is great. It's going to be mostly street, some mud, so it sounds like the shackle forward is the way to go. But your saying to still swap out for the YJ springs for the smoother ride?

 

[Peanut Butter]

Yes, but that's not the only factor, shocks, tires all play a part.

 

[DADSOLDCJ]

So back the original question.. Since the YJ leafs are straighter, does the front ride height lower? Should I buy a lifted YJ set to match height of rear CJ's?

 

[Lumpy Grits]

If you plan to run a winch. I would consider that weight also.
FWIW: After I installed my Warn 8274 winch. I installed a 'add-a-leaf' helper spring to my front OEM springs.
LG

 

[007]

When you buy a YJ conversion kit, the standard springs give the equivalent of a standard stance on a CJ. A 2 or 2.5 inch lift kit gives 2 or 2.5 inches of lift, so don't be confused by the flatter spring comments.

As stated, you can buy a nice YJ spring kit and ruin your ride with pickup truck shocks and tires. Everything between the ground and the chassis makes a difference.

So yes, a YJ spring conversion kit will offer a smoother ride, even with 2-2.5 lift. I'd do the back as well as the front, no need to have a rough ride in back. Also, make sure you get shocks that are for a CJ and/or are adjustable so you can maintain the improvement you purchased in springs. If you plan to do a winch or something up front, discuss that with your vendor or have some custom made by a company like Alcan.

 

[tarry99]

So back the original question.. Since the YJ leafs are straighter, does the front ride height lower? Should I buy a lifted YJ set to match height of rear CJ's?

Lots of confusion on the YJ springs and flatter is better if your looking for ride quality.

The first thing that anyone should do in order to understand how to obtain the best ride is to weigh each corner of your vehicle first with all the weight onboard. Springs are all about supporting weight at a given height and spring frequency. With that information it's much easier to then put the right spring under the vehicle.

Ride quality and Lift don't normally travel the same path when just changing a spring within the same OEM mounting space unless that space was previously engineered for the spring.

Buying a 2 or 3 inch lift is at best a guess as to how well it will fit your needs.
Bump Steering, Pinion and Castor angle all have to be considered.

When a spring is arched up for lift , three things happen. First the spring has to be re-arched up which adds to a stiffer spring needed to hold the weight up at your new ride height. The physical length of the spring now becomes longer but yet is still asked to fit & work within the original eye to eye spring space.......unless you move the fixed end of the frame spring bracket the shackle angle which plays a major part of ride quality will move. Add the fact that the spring will not have the same bending frequency will all add up to a rougher but higher ride height...........just can't have them all.

I like a wider ( 3" +/-) and thinner leave package, but also a few inch longer than CJ spring that is specified by weight to do the work as you require.

If you want the ride quality & height of a much more compliant , flatter & longer spring that has to be built into the mounting of said spring first...........don't ask the spring to change.

If your going to build or buy a new chassis that all can be engineered between the chassis & spring builder..........Bill at Alcan in Colorado or Jeff at Deaver springs in California can assist you in getting exactly what you want the first time.

 

[PistolDave]

Just saw this thread and thought I would add this visual aid. This is my 86 sitting on BDS 2" lift SOA wrangler springs. They are obviously being used in spring under configuration. I believe the shackles are 0.75" longer than stock. Tires are 31x10.50x15. All 4 springs are the same part number.

Also, if I remember correctly, the Wrangler spring by virtue of being longer moves the axle forward a small amount, which can be helpful in keeping larger tires out of the back of the fender. Sorry if this has been stated already.
Dave