The Huntress - AWD '69 Vert Ghia Project

[56SemaRag]

Cut down and had a friend mill the knuckles. All the suspension hardware came in this week, so I'll be building the a-arms this weekend and get started on the upper del-sphere bracket.

20171009_184242.jpg

20171021_183114.jpg

[GS guy]

Nice machining '56. That definitely shortened up the spindle height!
I'm sure you have good reasons, but can't "see" why you'd not fit a standard BJ onto the top of the spindle? Something like the SPC screw-in "Chrysler" joint shown on the previous page which is readily available? The FFR upper BJ adapter basically uses 2 steel plates attached to either side of the spindle (I think similar to what you're planning), with a simple steel block welded in between. The block has a tapered hole to accept the BJ stud. Only tricky part is getting the $$ tapered reamer for the BJ stud. I presume you're limited by overall resulting spindle/BJ/A-arm height. Looking forward to your design and how it interfaces with the other components!
Jeff

[56SemaRag]

I presume you're limited by overall resulting spindle/BJ/A-arm height.
Jeff

You nailed it...that is what forced me to mod the knuckles. I could put something together, but either scrub, SAI, camber rate would end up with a poor handling car or I would have to modify the vehicle structure or sub frame to make it work.

The biggest issue was spacing. I couldn't just mount the BJ to the top of the spindle because it would make the overall height too tall an would interfere with the inner portion of the rim if I stayed with a reasonably sized rim. Raising the UBJ higher would also increase my upper control arm angle because the frame side mount for the arm is limited due to the body. I didn't want to design complex double curved arms to reach the UBJ around the fender openings. I would have loved to get an old Suby strut, cut off what I don't need and put a receptacle for the ball joint on the modded strut piece, but it wouldn't work well. I couldn't mount the ball joint further inward either due to excessive SAI with a massive negative scrub. It also caused the upper control arm to be so much shorter than the lower, the byproduct being camber rate increases beyond acceptable. The ball joint should be mounted close to original SAI determined by the lower BJ and the upper strut mount on the vehicle, this meant the the new upper ball joint had to be located within the rim or right on its inner lip. The upper BJ location is pretty much figured out once you determine where your lower BJ mount is going to be (me using the OEM location for ease) and what SAI and scrub you want with a given rim size & width, rim offset (ET) combination. As I experimented with different mount positions and physical limitations due to the other variables, it became clear the upper ball joint pivot needed to sit on top of the knuckle.The difference between 8 degree and 14 degrees SAI is only about an inch, but there was a bigger change on the scrub as I approached 14. This is the basic design. The upper bracket will be slotted so I can alter the SAI a few degrees if needed.

Note: The UBJ bolt shaft will pass through one plate, the bolt head will be welded to the pass thorough plate. A backer plate (thickness of the bolt head) will secure it all by being welded to the bolt head, pass through plate and side plates. It's not depicted on the drawing

Knuckle.JPG

The weldable Del-Sphere will end up with a tab and threaded attachment like the one pictured below. The stud welded to the mutli-plate bracket sitting on top of the knuckle will pass through the ball of the Del-Sphere. Tapered spacers provide clearance up to several inches of travel. Out of all the designs I was considering, this one seems to be the most adjustable for caster, camber, SAI and track width. All of the inner arm mounts will be threaded Del-Sphere ends so i will be able to dial in track width and fender clearance. I will post up as I go through the build. Figure I will make a project plate to ensure the control arms are symmetrical.

Delshpere.jpg

UBJ.jpg

[GS guy]

Makes sense. For that del-sphere bolt I'd avoid using bolts that have threads except for where the nut has to go - for such a critical load area (similar to an aircraft fastener).

I hear you on trying to make everything fit within the constraints of the car and wheels. I had to get creative too when I was trying to adapt the MII spindles and related A-arms to the constraints of the front end of my buggy. Lots of complicated measurements, diagrams, modeling and mock-ups to pull it together!

[56SemaRag]

I'd avoid using bolts that have threads except for where the nut has to go - for such a critical load area (similar to an aircraft fastener).

Agreed, my background is aerospace so the stress risers of the threads was a concern initially. Only the nut and a half of the upper spacer will be exposed to threads. The majority of the stress will be at the base of the bracket but due to it's diameter it shouldn't be a problem. The bore of the Del-Sphere is 3/4", so a grade 8+ will easily handle the shear forces felt by the upper control arm. The threaded lowers will see the most stress and they have run them on heavier cars with no cracks or breakage. They are very sturdy units. Appreciate the feedback!

[56SemaRag]

Started building the lower control arms. Since the lower ball joint resides in the knuckle I had to come up with a way to accept the tapered 10 degree stud. I couldn't find any receptacles only in 7 degree. Luckily the STi has aluminum control arms and have a tapered steel insert. I used 2" Chromoly and enclosed it.

20171102_223738.jpg

20171102_214840.jpg

20171102_220044.jpg

20171104_113035.jpg

20171105_171020.jpg

20171105_181937.jpg

Shifted the bracket to the exact opposite side of the project plate and started the RH side tonight.

20171107_213050.jpg

[panel]

Great looking work and nice jig. More time in the prep and engineering than the actual end result eh.

[56SemaRag]

Thanks Panel. You are correct. The time spent putting theorizing, crunching numbers, checking dimensions and finding parts that work together is indeed the hardest part.

[GS guy]

Interesting the lower arm design you wound up with (given all the fitment and parts selection criteria) is very similar to the lower A arm I wound up using, which was sourced from a MII based drag-race car design from Chris Alston Chassisworks. This despite two completely different chassis and final product designs.

ChassisWorks A-Arms.jpg

Of note too is the slight shift forward of the lower outer pivot vs. inner rear pivot on your design. I "may" need to do something similar if my as-built doesn't provide enough caster, although it should have ~4.5*, give or take (on paper). I made provisions to do this adjustment with the upper arm and mount, but found when I put it together with the bodywork I didn't want to "move" the general tire position any further rearward, which shifting the upper pivot rear-ward would do. If I need to go that route I'd likely build in some kind of adjustment in the lower A-arm. Best laid plans...

Those spherical joints are nice, but seem rather large? What's the approximate diameter of the joint housing (for future reference)? do they incorporate any type of seal to keep the grease in/dirt out? I made provisions to use spherical joint lip seals in most of my pivots, not sure if they'll do that much good or not? Sure was a pain to design them into the mounts!

Nice work!
Jeff

[56SemaRag]

Interesting the lower arm design you wound up with (given all the fitment and parts selection criteria) is very similar to the lower A arm I wound up with.

I figure this has to do with where the arms need to mount on the frame to fit through the inner wheel arches and where the axle centerline (fore/aft) is. As you know there isn't a ton of room in there.

Of note too is the slight shift forward of the lower outer pivot vs. inner rear pivot on your design. I "may" need to do something similar if my as-built doesn't provide enough caster, although it should have ~4.5*, give or take (on paper). I made provisions to do this adjustment with the upper arm and mount, but found when I put it together with the bodywork I didn't want to "move" the general tire position any further rearward, which shifting the upper pivot rear-ward would do. If I need to go that route I'd likely build in some kind of adjustment in the lower A-arm. Best laid plans...

I went with the widest arm I could for the lowers with the rear absolute limit being defined by the compact master cylinders coming off the firewall with ½” clearance. The front limit is the edge of the lower frame where i still have to make provisions for the steering rack and radiator. It’s why I recessed the firewall and gained about an inch. The bend gives me about 3/4” fwd offset.

I like how you use the term (on paper) Jeff because it’s exactly what I am continually thinking. I “should” have a minimum of 3* caster based in the inner pivot points being mounted directly over one another. I will probably utilize the threaded bar and temp brackets to dial in both control arms fore/aft position and wheel placement in the fender arch. I figure with 3* caster and -.5* to -.8* camber set for ride height, and the upper adjusters set to increase 70% and decrease 30% value I will optimize the adjustability. Since I am running 235’s all the way around I want caster at tolerable minimum and tire scrub near zero, especially since I am running a manual quick ratio rack.

Those spherical joints are nice, but seem rather large? What's the approximate diameter of the joint housing (for future reference)? do they incorporate any type of seal to keep the grease in/dirt out? I made provisions to use spherical joint lip seals in most of my pivots, not sure if they'll do that much good or not? Sure was a pain to design them into the mounts!

They are large without a doubt. I wanted to run the Del-Spheres for several reasons. Unfortunately they only have ¾” bore sizes which makes the housing around 2”. The nice thing is that they are adjustable for ball tension, they can be rebuilt and have a large bearing surface area to dissipate force. With this being AWD, I wanted the front suspension to be beefy and ride smooth. There should be around 200HP pulling the front of this car. I wanted to eliminate some of the issues folks have had with heim joints with respect them gaining slop over time, being a sealed unit (once dirt gets in, you can get it out) and transference of road vibration. Those who run Del-Spheres or Johnny Joints say they are a good improvement over heim joints. Would be nice if they offered a “lighter” application. I know at his point the front suspension won’t be the weak link in the build, I would have liked to use 1/2" or 5/8" Del Spheres if they made them.

I do like the idea of a seal. I could see a small notch grooved in the edges of the circumference then use something that looks like a ball join seal. That would be a great, simple idea while keeping it clean.

After bouncing prices of steering racks that meet my center to center pivot requirements...I will be shortening my own. Shortened racks that have <20.5" CtoC were around $600. A new regular length rack was less than $100 and I'll get to make it the exact size I need. Going to finish the rest of the A arms, mount them then do the rack.

[56SemaRag]

So i finished the upper ball joint brackets. I used a Grade 8 3/4" bolt and turned the head down to 7/8". It was welded to 1/4" thick base plate with an additional 3/16" top plate. I didn't slot the holes yet and I don't know if I will. The steering angle is right at 9.0 degrees.

20171125_194215.jpg

20171124_220511.jpg

20171125_214708.jpg

They fit within the 17" WRX/STI wheels....figured if i kept close to the original knuckle height It'd be in there.

20171126_162838.jpg

20171126_162921.jpg

Since i really want everything adjustable and the fact that I am using a Mustang II rack, I'd go with steering adapters and heim joints. Unfortunately the Ford / Chevy pins weren't long enough on the shaft portion. I matched the taper of the Suby knuckle and lengthened the shaft portion. Fits great for a $10 experiment.

20171122_190454.jpg

20171125_122458.jpg

20171122_190522.jpg

Knew it was going to happen sometime during the build....but it looks like I will redesign a portion of my lower arms. The wheel makes contact with the forward part of the lower arm too soon during turning movements. Not that big of a deal but a small setback non the less.

[56SemaRag]

This is the redesigned lower arm. Fabricated a wheel profile tool for the wheel assembly (235/45/17 x 8 ). Since all the tires are identical I can use it for the rear clearance as wheel. Had to widen the track a couple of inches. Since I had to redo the arms the frame geometry changed a little, but the roll center now only moves 3mm up to 7 degrees roll. Managed to save the threaded ends and retain the adjustment capability.

20171217_230950.jpg

20171217_230734.jpg

[GS guy]

Nice - ready for some Drifting???
Don't forget the sway bar brackets!
Jeff

[petew]

That's fantastic. Love your work on this.

[56SemaRag]

Nice - ready for some Drifting???
Don't forget the sway bar brackets!
Jeff

Probably will do that last since it will be the easiest to locate. Getting busy on the left side with the steering shaft, shock, drive axle and sway bar keeping them from touching each other through their range of motion. Still hoping to avoid a pushrod shock system.

That's fantastic. Love your work on this.

Thanks Pete,appreciate it.