Unable to get enough Caster & Camber

[skidd]

I have an unexpected issue with my front suspension. I got an alignment done a couple weeks back. took it to a pretty good shop I've used many times.. full of fellow AutoX races and gear heads. :)
Anyway... We were unable to get more than 3deg of caster, and less than 1deg of negative camber. I was hoping to get as much as 8-9deg of caster, and at least 1-2deg of camber.
it seems the upper control arms could not be adjusted in any more. The rearward upper adjustment swedge tube was pulled in all the way. The forward tubes had more room, but they were nearly maxed pulled in also.
it seems like I need to either shorten the rearward swedge sleeve, or buy shorter ones. Seems like cutting off 1/4" at each end might be enough.
Does that sound right to everybody else? Is this a surprise?... or should my suspension have been trivial to dial in the alignment specs I wanted.


https://www.ludicrous-speed.com/zp/cache/Shanes%20Cobra/TheBuild/IMG_20161106_180157521_595.jpg (https://www.ludicrous-speed.com/zp/albums/Shanes%20Cobra/TheBuild/IMG_20161106_180157521.jpg)


Specs:
- 2016 MK4 base.
- FFR Upgraded lower front control arms, and fully adjustable FFR upper control arms.
- SN95 (1995) front spindles.
- Fox Power Rack with rack extenders.
- 17" x 9" FR500 front wheels with 275 Nitto tires.

Cheers

[Joee]

I maybe wrong but I have not heard about this with Mk4. On the Mk3 we have used longer sleeves instead of cutting one. I think something might be wrong in your build I know -1 1/2 camber and 5 deg caster is possible with FFR parts. We added the extra sleeve to be able to run 7+ deg caster ans still have plenty of thread engagement.

[boat737]

I cut the Upper Rear Arm about 3/16 on each end and each threaded rod. Used a band saw on all except the welded stud on the ball joint mount, and on that used a cut-off saw. All worked out fine.

Check the upper control arm pivot mount on your build. It looks like you have it mounted on TOP (ie a horizontal surface). I believe that UCA pivot should be mounted on the outside of the vertical surface just below where you have it. Hard to tell from your picture. Others with more knowledge than me can give chime in and see if that is correct or not.

[Jeff Kleiner]

No, not a surprise at all when using the latest upper arms with the angled ball joint plate. Cut 3/16"-1/4" from the end of the rear sleeves and a similar amount from the male threaded stubs otherwise they'll probably bottom out in the threads before you reach your desired settings.

As Joe mentioned early Mk4s and Mk3s with the zero degree ball joint plate UCAs pose a different and opposite situation and require a longer front sleve to achieve proper/safe thread engagement when going to the higher positive caster ranges.

Jeff

[skidd]

Thanks guys... I was planning to cut those sleeves... and now I'm feelin' pretty good about it knowing others have seen the same thing.
@boat.. I'm pretty sure I have mine mounted correctly. though I'm happy to admit I don't know what the front/face holes are for on the frame. FFR Custom Spindles perhaps? If I was to move the control arms to that location, I'd end up with a crazy amount of positive camber. The FFR build manual indicates to install the uppers where I have them. That said.. thanks for the pics of your cuts... that's what I'magonna do. I'm hoping some more caster can help reduce the "twitchy" steering feel. .. which might also be caused somewhat by my installing a 2.5 lock-to-lock steering rack. I'm starting to regret that choice. I might do that cut mod, and swap out racks all in one go.

[JoeAIII]

Looks like your UCAs are in the wrong holes, it I my understanding they should be in the vertical holes if you use the f5 lower arms

It may be with their spindles though. The base manual doesn't discuss it, so if you have a base kit those instructions will be missing

[rich grsc]

You have your control arms in the correct location when using SN 95 spindles. The side mount location is for FFR's custom spindles, as you said.

[boat737]

Looks like your UCAs are in the wrong holes, it I my understanding they should be in the vertical holes if you use the f5 lower arms

It may be with their spindles though. The base manual doesn't discuss it, so if you have a base kit those instructions will be missing


You have your control arms in the correct location when using SN 95 spindles. The side mount location is for FFR's custom spindles, as you said.

I always forget that there seems to be 100 different iterations and configurations on these builds. Sorry for the confusion on the UCA pivot mount, but good to know info.

[Jeff Kleiner]

...I'm hoping some more caster can help reduce the "twitchy" steering feel...

Don't necessarily blame "twitchy" on the quick rack. Be absolutely certain that you are set for toe IN. Toe out or even too little toe in will cause twitchy; I like around 3/32" on a street car. Properly set up a car with 2.5 turn rack will respond quickly but be rock steady.

Jeff

[skidd]

My total toe is at 0.15deg. I think that puts it pretty close to 3/32 with my 26" tires. My main issue with the 2.5 is it just seems too quick at highway speeds. Like the weight of my hands alone when I hit a bump in the road pulls the wheel just a bit, yet has a big impact on steering. I already did the cut spring power steering mod. Its an explorer pump. I was planning to take a bit more off the spring to firm it up a bit more. Then again, perhaps I just need to give it more seat time too.

[CraigS]

W/ PS and only 3 deg of caster it ill be twitchy. I would get the caster fixed first, the pressure spring would be 2nd, and a 3.0 rack third. BTW, your UCAs are mounted correctly for an Sn95 spindle UNLESS you also have the SAI mod. If you have, or later get, an SAI mod, then you would move them to the vertical surface.

[rich grsc]

I have a 2.5 rack, 7* caster and it's not twitch at all, It's fast but very easy to drive on the highway, I like being able to think about a lane change and it just happens. :rolleyes:

[skidd]

Good call.. thanks guys. One step at a time then. Cut back the swedge tubes and get me the caster and camber I want first. I'm on it!!

[Joee]

I have a 2.5 rack, 7* caster and it's not twitch at all, It's fast but very easy to drive on the highway, I like being able to think about a lane change and it just happens. :rolleyes:

Yup the whole point of driving a race car is it is supposed to be responsive. They aren't your Daddy's pickup trucks......

[CraigS]

One other thought. What is your front tire pressure. Should be about 22 but I have run as low as 18 to experiment.

[skidd]

Fronts are indeed at 22. Rears are at about 24.

[skidd]

Just wanted to add.. ok.. the 2.5 rack is totally staying in!!
Got a little generous on the go-fast-pedal today around a quick corner... no surprise the back end came out. ok.. so it was intentional. This time it came out bit faster than I expected though.. Took only a quick jerk of the wheel to bring it back under control. Way way way easier to recover than other RWD cars I've played around with. I'm convinced.