I just finished sorting out the camber on the front end of the M3W. I got them both to about 1.3 degrees negative. I then checked the caster and found that the passenger side was 2 degrees negative and the driver's side is 5 degrees negative. Empire calls for 6 to 8 negative. The only possible way I see to adjust the caster is to move the two small washers both to one side allowing the heim joint to move backward. Is this the accepted adjustment?
Based on what I've seen of the upper Empire A-arm, this is where I would start to add caster.
You may be tight on available adjustment on the heim joints. It will also require a recheck of the camber. As you move the front heim joint out (lengthen the heim joint out of the A-arm) it will move the upper ball joint rearward, but it will also tweak your camber.
So it will end up being a combination of constant checking both caster and camber, but there "should" be enough adjustment to get what they recommend. There is always the possibility that each frame is a bit different and you may have to settle for just 5 degrees of caster.
I did the adjustment for caster angle as shown in Dans picture. You can only do it in half turns of the rod end bearings, so it ends up being a compromise but close. The chassis brackets for the wishbones are not very symmetrical from side to side and needed shimming. The car had a chassis change in 2015 and that chassis was better in this respect than the original 2013 one. With the latter chassis I had to cut a couple of mm off ends of the wishbones to get enough adjustment on the rod end bearings as they bottomed out against the lock nuts. There is plenty of material to allow this. This wasn't needed to get the adjustment right for the 2013 chassis, maybe some slight changes or different manufacture tolerances?
Thanks Dan. That is indeed how it works. I had forgotten basic high school geometry and was hung up on adjusting caster by physically moving both pivots to the rear. There just wasn't enough movement to get it adjusted. Once I realized how it worked, I pulled the rear in to about 7 degrees caster, I had to readjust camber about half a turn in and then go back and re adjust toe. They all affect each other. Now for a new set of tires...
Great job... I'm sure it handles better now that you're even on both sides.
I would think for caster 5 to 6 would be good, but at 8 and how light this car is, it may be okay. On a "regular" car, 8 would be very hard to maneuver at slower speeds, parking lots etc.
I should add that initially, I was only able get about 5.6 degrees of caster. I was about to go through the hassle of removing the a-arms and removing material from the caster end of the wish bone when it occurred to me that by taking 125 thou off the lock nut, I could probably achieve the desired result and put off disassembly for a rainy day. The thinner lock nut still does its job and I wound up with the needed adjustment room. YMMV
I should add that initially, I was only able get about 5.6 degrees of caster. I was about to go through the hassle of removing the a-arms and removing material from the caster end of the wish bone when it occurred to me that by taking 125 thou off the lock nut, I could probably achieve the desired result and put off disassembly for a rainy day. The thinner lock nut still does its job and I wound up with the needed adjustment room. YMMV
A great bit of lateral thinking - well done Roland.
