Just got done cutting these for an FC subframe installed in an FB (hence the offset). Replaceable uni-ball ball-joints with high-misalignment spacers fitted into 1/2" cold-rolled steel plate. Designed them in CAD and cut them using a MACH3 3-axis plasma table. Pretty happy with the results so far. Just a little TIG'ing and drilling left and I'm done. What do you guys think?

 

those are "smart lookin"!

 

I think - you should make me a pair.... you know, for practice!

 

Here's a couple more pics. TIG work isn't the prettiest in the world, but it's strong. Should be 100% assembled tomorrow.

Thinking about making a few more sets to sell, or maybe just the pre-cut blanks. This uni-ball hardware is expensive!

 

Would you ever make these for the FC and extend them 10mm or 15mm from stock? If you do, I would be very interested in a couple pairs. Also how long did you take you to make it?

 

Done with all the shop work. Probably going to have to clearance the edge for fitment, then drill the mounting holes. The stock balljoints have about a 10 degree bend in them, but I'm getting so much angle with the high-misalignment spacers it's not a problem.

 

So,If they work out for you,are you going to sell them?..I'd be up for a set!

 

i love how he comes here telling people about the cool **** he made, and never replies to them.

 

At least he doesn't come on here with a cool idea, saying he's going to sell them, then never follows through. That happens at least 95% of the time

 

Very true, props to anyone who actually makes cool pieces fit the RX, whether or not they chose to share with the rest of us (unless they are piston swap related, them no props)

 

ducktape has responded to my answer via private message. I'm sure he will come back on here after everything is installed on the car. I am very interested to see how these come out. Looks great can't wait to see the final part.

 

Ditto. Would be good to know if these can be made taller than stock to improve the FC suspension geometry. 'Did you design these to stock vertical offset?

 

I am liking this roll center correction idea!

 

Sorry for not replying in a while. I'm in Nevada trying to finish up some work so I'm 1900 miles away from my car.

I used a suspension analysis program to model the TII suspension. My main focus was identifying the change in caster incurred by moving the ball-joint back an inch, so I didn't pay much attention to anything else. I should probably model the 10-to-15mm added length to check for issues, but my gut tells me it shouldn't be a problem. I'll check when I get back to my terminal.

The vertical offset is the same. I had to correct for the lack of the 10 degree angle bend that exists in the stock ball-joint. I doubt I could add more vertical height without trying to reproduce the bend, but I can take some vertical height out (up to 3/4").

Suggestions always welcome. Will update when I have more data.

 

the bolt holes that connect them to the hub look pretty small... they would worry me.

I'm running one of the first sets of AWR roll center correcting ball joints. They're really nice and have more or less the same design, but with no misalignment spacers and a bend.

they're also using a pretty large dowel and a spacer instead of the smallish bolt you're using.

 

Just got home yesterday night, and couldn't wait for the test fit. I went ahead and clamped the joints into position, installed the bolts and spacers, and ran through the travel. I'm pretty happy with the results; The joints are not maxed-out in any position, including full-droop. As expected, the misalignment spacers made the 10 degree bend in the stock joint completely superfluous. Clearance on the brake rotor is good, but may require notching or removal of stock backing plates. Most importantly (for me), the wheelbase has been restored to original length. I am a happy camper.

 

First, I didn't want to put the 10-15 degree bend in as heating and bending introduces it's own set of problems. As you can see from the pictures I posted above, the misalignment spacers allow the joint enough angle without the bend. Why complicate it?

Second, Those are 1/2" Grade-8 bolts, the same bolts used on the A-arms of long-travel off-road cars (including mine). I checked the book on all the hardware from the cups, spacers, uni-ball, sleeves and bolts (Minimum Yield and Tensile strength, Static Axial, Radial, and Dynamic Oscillating Radial Load). Everything on this joint is so overbuilt it's almost comical. Have some faith in the math, my friend.

That said, I probably won't be able to compete with AWR on price so this may end up just being another one-off part. What did they cost, if you don't mind me asking?

 

yeah, but the bolt is also in single shear... quite a bit of it when turning or braking. the shear strength of a 1/2" grade 8 bolt is 17870 lbs... is that enough? I don't know. but I'd be a little worried if I was on a track in a high speed corner with race tires and hit a bump...

AWR's kit is $400 for both ball joints + you'll need spaced out tie rods because your bump steer will go to crap when you space out the arm.

 

the stock ball joint has a groove machined into the shaft that gets inserted into the bottom of the steering knuckle and has a bolt that will go thru the knuckle and keep the ball joint in. Is that bolt on the knuckle not needed anymore?

 

It looks to be there on the installed pics on both of them.

 

On mine there is a threaded collar with the machined groove. I didn't install the clamp bolt during my test fit simply because it wasn't necessary to test the up-travel.

 

AWRs:
https://www.rx7club.com/attachments/...7-img_1340-jpg

 

^^^ Link is whack?

 

sure is... I have no idea what the new adds did to it.

Here it is:

 

Thanks. Did they use a Metric bearing, or SAE?

Also taking notice of your tie-rods. Did you cut them shorter and thread them with SAE thread to make that work?