DefSport

Does anyone make an offset front lower spherical bearing to get more camber with a stock type lower balljoint? Seems an easy thing to do for people that make existing sphericals.

Some local track guys have cracked their front knuckles with offset ball joints. The failure mode makes sense given it puts a bending moment into the lower casting area that's not really designed for it, and while the offset is small, the full vertical load of the tire as it's transmitted to the spring and damper are going through that lower balljoint. It doesn't need a huge offset to build some pretty high stresses in the thin lower casting of the knuckle.

B serious

You don't want to just use an adjustable upper?

Maybe $omeone make$ tubular adju$table arms$$$$$$$.

DefSport

Adjustable upper arm, or ball joint? The arm is too much $$$ for what I want to do with the car. The upper adjustable ball joint has some negatives on how it loads the ball joint bore when it's offset. Some people have cracked the upper arm ball joint bore as a result - which is not a fun time.

The front lower bushing seems like the best one to replace with a bearing from a camber retention in loading scenario. It's a relatively large bushing, and any compression means a loss of camber on the outer wheel. The compliance bushing is probably fine to keep as hardened rubber since it won't deflect much under typical cornering loads to cause a loss of camber or caster.

I'm at about -2.4 deg as measured in my garage (using a straight edge and distance measurements to wheel, should be fairly accurate +/- a couple tenths of a degree), and I think the car would do better with about -2.8 to -3.0 up front, as it does punish the outside of the fronts a tad on track. This is with stock adjusters maxed out for max caster (compliance bushing all the way OUT, pushing wheel forward) and max neg camber (front inner adjuster all the way out). I guess if I backed off caster the static camber might pick up, but in my experience, the more caster the better for keeping front tire wear at bay by buildilng up more negative camber on that outside front. Plus it just tends to make things handle better up front and give more steering feedback.

I figure I only need roughly half a degree of static offset, which should be possible on a slightly offset bearing shell, and slightly offset misalignment bushing that adapts to the stock bolt.

If I got a 4 jaw chuck for my mini-lathe, I suppose I could make a set myself, but it seems odd to me that no one makes them given it'd be an easy camber gain AND a spherical bearing in the most useful pivot.

B serious

Eh. Like...2 people had some issues with their RUCA's cracking.

I can see how bolting the ball joint in (using 135LB-FT), and creating a larger bending moment from having the longer ball joint length are definitely stressing the arm further.

But...is it being stressed enough to create a failure if the installation is properly done without ham fisting everything and making notches and nicks/scars in the bore? Idk.

I know of people...and I AM someone, who has run them for years sans issue. As much as I hate to be part of the ZERO problems club...I really haven't seen problems even after smashing track curbing and bending my spindle. UCA was fine.

Also, the ball joint is not loose in the bore. The sandwich plates are "pressed" in. The ball joint travels along those plates.

Or...maybe offset delrin/poly UCA bushings? Buy them or make them. If you have a lathe, making them to your own custom offset would take a few minutes.

B serious

A good solution may be to lathe a steel rod to match the UCA bore (press fit). Then make a slotted hole in the rod large enough to fit the SPC ball joint's threaded (upper) stud. Make a groove for a C-Clip for safety also.

That way, the steel rod emulates the stock ball joint's housing.

The adjustable joint clamps to, and slides along that steel "bushing" you made.

No clamping load on the UCA.

B serious

Or....for massive ease, you could weld the adjustable ball joint plate to the UCA (360 deg around). The pulling stresses will distribute back to the UCA body...and the bore won't crack. Even if it does, the plate will hold to the UCA body.

I'm giving all these MASSIVELY brilliant ideas for free. This should be a tax writeoff or some sort of genius grant at least.

DanielB

Why not this?

B serious

...the first post


Though, I'm not sure that enough a bending moment exists to damage the knuckle. OP is worried about this. So he is looking for alternatives.

DefSport

The offset is small, but the forces are very large, since you're getting all sway bar and spring/damper forces translating through the LBJ. The lower knuckle is very thin, because it's only designed to deal the moment created by cornering forces pulling through the ball joint. When you then add to that the moment created from offset spring/damper and swaybar forces, you're probably doubling the bending stress (give or take).

gptoyz

not a spherical but origin and a few other places have made offset UCA bushings to artificially shorten the upper arm. You don't get the benefit of a wider track but its another option to skin the proverbial cat.

I think I'm ok with cracking the knuckle as a failure point, it's relatively inexpensive piece to purchase and easy to access and repair. If we shift the failure point else where, I would guess it's only going to get more expensive (control arms, subframe, frame) and more technically challenging to fix.