Quote:
Originally Posted by aggie91
Why are you using 88-98 lower ball joints?
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Good question. It's kind of a hodge-podge snowball of staying under budget and working with what I have and what I want.
1. I will be running a turbocharged LS, planning on 600-650hp to the wheels.
2. I'm not happy with the durability of the 12-bolt in my '77.
3. An 8.8 is narrower than I want, and I want to run the same size wheels front and back.
4. I've seen people on here using Jeep wheels in 18" and 20", but they need to use spacers. I like the look and the idea of those wheels, but I do not want to run spacers. I got a sweet deal on some 18" steelies.
5. I got a sweet deal on a 9" axle which I
could narrow, but with the fwd-offset of the Jeep wheels, I don't need to - the wheels would be placed in approximately the same location as stock, which provides good clearance for turning while riding low (I have not decided if I want to air bag it or not).
6. The width of the 9" requires widening the front track quite a bit, which means relocating the ball joint location, or fabricating new upper and lower arms.
7. I got a sweet deal on a set of 2" 88-98 spindles, and since I need to relocate the ball joints anyway, I might as well make them work with the spindles. They are a bigger ball joint as well, and the 73-87 ball joints are not awesome. Plus, the 88-98 spindle seems to have more Steering Axis Inclination (SAI), which means I don't need to alter the upper control arm at all (saves work), and my calculations indicate I only needed to move the lower ball joint 1/2", which is (theoretically) a lot less than if I used 73-87 spindles.
NOTE: a larger SAI might have been employed by GM to reduce the scrub radius (the distance from the steering axis to the wheel centerline, at ground level). Ideally you want to be within 10% of the wheel width for scrub (in my case, 0.75" would be ideal). The 73-87 spindles have a fairly LARGE scrub radius, and my guess is GM tried to reduce it by increasing the SAI. A smarter way is to run more backspacing (FWD-style offset). The downside to a high SAI is you lose significant camber on turns (watch any MacStrut car). You then need a fairly high amount of caster to counteract that dynamic camber loss on turns. Lots of caster is almost always good, but can un-weight the inside rear wheel on a corner, resulting in wheelspin.
8. (I didn't plan this one) The 88-98 spindles mount the tierod below the steering arm (73-87 is above), which improves steering rack placement. Many kits that use the 73-87 spindles run a heim joint for a tie rod, mounted
under the steering arm (easier to reduce/remove bumpsteer for sure). I don't want to run a heim joint, I want a proper tierod.
I think that's most of my train of thought.
Make sense?
And honestly, I like "the build" and "creative solutions using OEM parts" and my labour is free.