Slotting Strut Mounts for Camber

This is an option for the Fiesta ST per the rules, so I am doing some research into methods, concerns, etc.  I can see how slotting the holes in the unibody will allow more lean-in at the top of the strut mount. I am leaning this way because coil-over options for the FiST cannot be adjusted on the car without a lot of cutting to gain access.  My big concern is making sure that the shocks are secure, that they do not slip around in the slots under load.  Any tips or techniques?  

Just make sure the top bolt hole is slotted in the correct arc around the lower bolt hole, and go for it. You might be surprised how much force they stand up to without slipping.

Are you going to slot for caster at the same time?

This- you’ll get more dynamic camber improvement by running as much caster as you can.

Assuming the rules allow the shock towers to be slotted for caster...

When people were slotting Neon struts, the conventional method of keeping them in place was to squirt a little spray paint on them before installing the nuts, and tighten them down while the paint was wet.  The paint adhesion seemed to add enough grip force to keep them in place.  The added bonus was that if you used contrasting color paint, it became immediately obvious if they did slip, and how much.

I did this once (not on an ST) and the strut shafts eventually bent.  Unless you can fit a plate on plate with a spherical in the tower, the safer way is to look low--either slotting the bottom of the strut or offset the lower control are bushings to effectively lengthen the lower arms.  You get more camber working low.

We have done this on a number of endurance road race cars.  Just use big washers and tighten them down well.

I don't think the strut is under any additional load in this manner.

Side loads on the strut top mounts are surprisingly low. Any of the above techniques are OK. joeg1982's suggestions are not legal in your application, nor is the spherical, but I have never seen a strut shaft bend without crash damage in 50 years of strut servicing.

The rules for STH are a little hard to understand as they apply to modify the lower mounting points, but it is clear that the "original mounting holes may be slotted" and that "the center clearance hole may not be modified", so that is why I am looking at this option specifically.

I will be using camber bolts at the bottom and will see what that gets me, plus I will be running lowering springs which may gain a bit as well.  The slotting is to max out the neg camber and try to save my outer tire edges and get the contact as flat as possible.  I don't want to affect caster because that is another dimension and gets too complicated for my one-dimensional mind. 

Caster is like free camber, but only when you want it! (To a certain point). 

You may need to stack spacers or washers under the strut mount if You are not able to modify the middle hole.  The struts usually have a lip that fits in that hole.  No big deal.  The forces are mostly vertical.  The couple of extra degrees of angle are well within the safety factor.

Do eet.  Naow!

Shoot Alex with the grey 13 wrx a message, lprnesia on YouTube and RacePA forums. I know you know him from NHSCC.  He did the ones on his WRX and he's sorta close to you, might be a good way to check them out in person before doing it. 

In reply to wvumtnbkr :

The limitation on the center hole, for me, has more to do with coil overs or adjustable camber plates.  Without a larger center hole, you can't adjust any of them without removing the strut.  I'd like to be able to knock the camber back a few degrees between events to save wear, so slotting is the best option.  
 

In reply to RevRico :

Alex is always a good resource, but since I will be destroying him in STH this year, he may be loath to offer advice. 

(I'm kidding of course, I couldn't beat Alex with an STH GT3-RS)  

I did this on my ZX2SR but the pocket wouldn't allow much movement.

Best thing I did was install offset control arm bushings.   It nearly doubled the stock caster and allowed me to run  less negative camber.

I will have to look into the "caster" of which you speak.  Apparently, I can change the oil in the shocks through the Upper Strut Perch (U.S.P.) to gain more caster?  I am a little scared of the side effects however, only port-a-johns available. 

I heard the Kia rondo has all the caster!