I wanted to get stuck in and get the Jeep completed so that i can test drive for a few weeks before getting the re-gear.
Last night i dropped under the old girl with a digital protractor and took all the angles. Everything had been thrown about a bit over time and with all the tire and suspension mods in the last few years.
Front: My diff angle was 82.5* (1.5* true castor). This put me well out and was why my steering was so light and wandering. For a 5" lift it needs to be about 86* (5* true castor).
Rear: I have a double cardon drive shaft in the rear. Relative to the diff, my pinion was pointing down about 4.5*. This could get vibey at speed. Your supposed to have about 1.5* to allow for axle wrap.
I wrote everything down and worked out a plan for the next morning.
Well, this morning i got out all the tools, jacks, jack stands, rattle gun, etc.. I knew the rear would be a bit of a hassle.
I tackled the front first. This part was easy. Undo the upper double adjustable control arms and twist them 1 revolution at a time until i had the correct angle. I brought it into spec, locked the lock nuts and took it for a test drive. As suspected, by adjusting the rear of the diff down, it alters the pinion angle for the worse. Its always a compromise. Steering felt great and no wander, but a small vibe was introduced at higher speeds. Also, the pull to the left is more pronounced.
The rear was a pain. I have a 12mm lift block under the springs. My idea was to convert it to a shim. I decided on 2* first. Jack car, remove wheel, remove U bolts, jack leaf springs, lower diff and get block out. Machine block to get desired angle. Reinstall and do the other side.
I did this and got my shaft/diff angle down to 3*. So i did the whole thing again taking the blocks/shims another degree to 3*. This put the diff/drive shaft arrangement to within 1.5*.
Packed everything away and took it for a test spin. Jeep feels much better. Rear end doesn't feel tight. Might be my imagination, but she feels looser and more powerful.
Anyway, that's all the major projects finished (i think).
Now its time to fill the tank, and drive, drive, drive.. and keep ironing out wrinkles and bugs.
The regear will slow the rotation of the drive shafts and helps eliminate vibes, as well as set it back in the correct powerband.
I might be getting the offset ball joints to alleviate the left pull. I think this is mainly an Australian feature.
Cheers,
Pic below showing the control arms and pinion angle and castor. Lower adjustable control arms used to centre wheel in wheel arch when lifted. Upper double adjustable control arms used to set castor. Very easy with these, as just undo the nuts and twist arms.
Pic below of the lift block/shim. Easy to do. I used an online trigonometry calculator to punch in length of plate and angle required. It then tells you how big a wedge you need to remove. In my case for 2*, i had to remove 4mm at one end. Sliced it and diced it with a grinder. Only problem was that i had to redo them and make them 3*.
Pic below showing drive line angle. With the lift block/shim, the pinion angle came back at a nice 1.5*. Pic also shows the Brown Davys long range fuel tank (125 litre), airbag suspension and rear disc brake mods (complete with ABS).
Finally getting somewhere....
Could be a daily driver soon....