driver side rear wheel IRS alignment

[toadster]

my passenger rear IRS setup looks good, seems to be tracking well

I played with the driver side as it's got positive camber and trying to determine what's the best method to get things 'aligned' again

I see there are 2 main adjustments:

1. the upper control arm, pushes/pulls the wheel/tire inward/outward
2. the lower toe arm, pushes/pulls the bottom of the wheel/tire

both of these together I believe can affect caster and thrust angles (correct me if wrong here)

I believe the length of the upper arm can also affect how much the tire camber is affected, but length is only adjustable if you remove from the rod end

in the manual it shows these distances

upper control arm


toe-arm


how close did you guys find that these lengths were? I need to re-measure to be honest, it's been a while since I assembled the rear...

here's my current pics, car is on jacks so i will skew the angles

rear wheel angled inward (not straight)


rear wheel with positive camber

[JohnK]

Hey Todd. I don't think you can really get any meaningful measurements with the car up on jack stands. It needs to be sitting on level ground to get usable alignment measurements.

[toadster]

yeah, also playing with ride height as well - really wishing I had a lift right about now

[JohnK]

in my haste to reply I forgot to mention that, but you are correct that you do need to have ride height set as well before working on a alignment.

[edwardb]

Measurements are useful (maybe...) to get you in the ballpark. But you need actual alignment gauges to get the rear camber angle and toe. And yes they interact. And as already stated, at ride height and sitting on the ground. Roll it back and forth each time you make any adjustments. The IRS is not easy to align mainly because it's hard to reach the adjusters. A bit easier with the body off. But you'll need to check the ride height again when it's all together. If you get it back to the same spot, the alignment should be OK. If you don't have the right tools, you're better off taking it to a shop. They do put it on a lift and can reach the adjusters from underneath. Good luck.

[toadster]

as expected the toe arm was about 1/2" short - looks much better now!!!

Thanks guys!

[CraigS]

FYI rear camber can be adjusted w/o taking anything apart.
FFR UCA adjusters.jpg
The red arrow is the adjuster. The 2 green arrows are jam nuts. The adjuster has left hand threads inside and right hand threads outside. (or vice versa) If you loosen both jam nuts, you can turn the adjuster which will change the overall length of the UCA.