D30 Upgrade

I'd worry far less about driveshaft angle in the front and concentrate more on making sure it has proper caster. Unless the driveshaft angle ended up unworkable (unlikely) then Caster is the only number I'd be looking at up front. I think, (don't quote me) you want 5-7* at the knuckle.

 

I have not had a chance to measure but I don't think it is terribly bad. I think the shims were at most 2 degrees. I'll be back from a business trip on Weds and should be able to work on it again. I am running a very old 2 1/2" Rancho lift that has definitely lost some of it's lift in the last 21 years.

 

Caster affects the way the Jeep will handle going down the road. Too little and they get real squirrelly. You have hubs up front. 99 times out of 100 you've got the front locked in at slow speeds and driveshaft angle won't matter at all. But doing 60 down the road, you better have the caster right.

 

I have been researching what the caster should be. I have read 1 - 2 degrees negative. I have not had a chance to measure my Jeep yet. Anyone have the caster for a D30?

 

I believe it has been repeatedly stated at 5-7 degrees negative. Mine is set at 6 degrees and drives well.

Edit: I did say negative and meant to say positive caster as tarry pointed out. It does drive well at 6 degrees.

 

Jeff, You want Positive caster angle , not Negative...........as mentioned above 5 degrees should do , but a degree either side will work.




"Is it better to have the shock in front or behind the axle?"

The shocks on the D-30 were behind the axle due to the OEM sway bar that was up front............remove your old bracket or just replace it with this one ( available online everywhere just look under 1978-1980 CJ).............which is upside down in the picture but it fits nicely on the frame behind the axle...your bottom spring plates will either have to be modified for the rear mount or replaced..........

 

Thanks Tarry,
Once I get caught up on work I will try to get some time to work on this.
I can only find the 1 part number. Do you know if this fit both sides?

 

Yep fits both sides..........I may have a pair still around here somewhere let me look....

 

Cool, thanks!

 

OK, with the shims it was at 0 degrees. I took the shims out and it is between 5 and 6 degrees positive. The drive line angle is probably the same as it was with the D27. I'll get a pic later today.

 

Perfect..........5-6 degrees positive is about as good as it gets.......though remember you do need a happy balance between Caster and Pinion angle............as the front pinion unlike the rear will travel downward under acceleration and in doing so will increase the angle between there and the TC ............so if you have oversized tires you may think about correcting that 6 degrees to maybe 4 if that helps the pinion angle............

 

Got it Tarry.
Drive line angle does not appear to have changed much. I have a pic but need to resize it

 

You'll just have to measure it with an angle finder...........Jeep on level ground at ride height loaded like you drive it...........the front axle although not engaged all the time can be a little tricky angle wise on the U-joints life as the transfer case front yoke is tilting up beyond level ( zero) while the front pinion is tilting down...........If both slopes are in different directions (one up and one down), add the lesser number to the greater to obtain the operating angle..............both angles have to be calculated to get a true angle at the U-joint.............this is of course all about U-joint life.

 

I set the camber at a little less than 1/4". I will need to let it settle and roll it around a little and check it again.
I was playing with the shock location. If I move the top rearward about 1 inch but still in front of the axle they clear everything but the shocks are almost completely vertical. Any issues with that?

 

As long as the shock body won't contact the axle tube under compression. Unless you're running a shackle reversal, the axle will swing forward a hair under compression.

 

No problem being vertical ...........they are closer there to 1:1 ratio........I prefer to have them at a little angle but wherever they package up is where they can go...

 

Here is a pic of the driveline angle at ride height. Looks ok to me.

I think I am going to cut off the upper stock shock mounts and place them about here. Everything clears, I will need to tack or clamp it in the new location and try to cycle it to see if there are any issues.
Driver side

 

Driveline looks better than I thought it would.......................

On the shock..........hey if it fits there with adequate clearance for the tie rod and a little for the axle.........why not.......as mentioned above the axle will travel forward about .600-.700 under compression but do to the shock being mounted forward of the axle...........the clearance and shock just follows the axle fore & aft so it will not hit...

I would also check and see if at full droop your shock is not bottoming out...........which might change where and what shock & mount should go in there??

 

What about simply inverting the shock? The shock boot could be removed. Might depend on weather the shock is gas or hydraulic.

 

I'm not sure you can do that with a RS5000 shock. I thought I looked a while back but I cant remember. I'll do a little research.