D99: Scuttel & Upper A-Arm

I've been dying to get an idea of what this car will eventually look like, so I threw some spare wood together to build a scuttle mock up. I'm still deciding what I'm going to build the scuttle out of in the end, but for now, at least I can picture it.

I also rebuilt the upper a-arms. I had to do this to mount them to the new geometry created by rebuilding the front end. Below is the new design built out. It's not as easy to adjust, but it gives more space for the shock and of course, works with the frame redesign.

Oh, and I built some shock mounts. I'm not finalized on the placement of the upper mount yet, but it'll do for now.

D96-97: Front End Rebuild + Radiator Mounts

I've never been happy with the front uprights I had, so I decided to rebuild these. Below is the new set. Now, both uprights are 1 1/2" square 1/8" tube instead of the normal 1" 16awg. This should provide plenty of strength to the upper a-arm mounts. If (big if) I keep the upper mounts in single shear, these will provide a much stronger mounting point and should hold up better to the torsional load created.

I haven't added the 3/4" DOM tube yet, but the front and back will now be in-line. I haven't figured out how to modify the upper a-arm yet. With the two mounts being in-line, I need to figure out the best way of using the heim joints without maxing out their travel. With the old design they were already close to being maxed out. I might just have to settle for less points of adjustment.

I've also got the radiator mounted to the new uprights. I'm still using the factory BMW radiator and mount points. However, I'm mounting from the rear instead of the front of the radiator.

The last piece of progress was finally adding some supports to top level of the frame in the engine bay. This is also a better view of the radiator upper mounts.

D83-84: Upper A-Arm Mounts

I got a little time tonight and a last weekend in the garage working on the upper a-arm mounts and here is (hopefully) the final product.

I replaced the rear vertical tube with 1 1/2" square tube. This should allow for a stronger support of the upper mount. I'm mounting the upper a-arm to a piece of 3/4" DOM (.120 wall) tubing. This mount allows me to use a 1/2" bolt.

The front mount is 3/4" DOM through a piece of 1"x2" tubing. I tried to align the mount so that the tubing was horizontal, but more importantly that the mount is 9" above the lower control arm. I'm still trying to figure out how to add sufficient support to this mount.

Here is the finished product with the upper a-arm "installed". One thing I like about this design is there is plenty of space to fit a coilover shock and spring.

The last part of the front suspension is modifying the driver side steering rod end. Then it is on to final welding the frame and building the cage.

D82: Front Suspension Rebuild #4 D2

I built new mounts for the upper a-arms. I've got the mounting bolts vertical now instead of horizontal. I wanted to try this out and see if it would work better than the old design.

With the new suspension design, I needed to move the steering arm from mounting on the bottom of the spindle to the top of the mount. This required a new steering arm. I've used 1/2" rod ends on the spindle side. On the steering rack side, I cut the threaded portion of the factory arm off and used it as an "M14x1.5" weld bung. Saved me having to buy a random metric tap.

A picture of the completed lower control arm and the upper a-arm along with the new steering arm all assembled with the tire.

D79-80: Suspension Redesign and Rebuild #4

I've spent the past week redesigning the front suspension yet again. After getting the last design tacked together I realized that bump steer might be an issue. I did a little research and modeled my design in CAD to realize that, YES, I did have a bump steer issue.

The design below is what I've come up with for the (hopefully) last build. I've raised the steering rack and plan on mounting the tie rods to the top of the spindle instead of the bottom. This allows for adjustments to control bump steer. I need to modify the spindle and build custom tie rods to complete this conversion.

The new design brought the mounts for the lower control arms in about 1.5" on each side. Below is the design for the new control arms. I've gone back to the style of the second design maximizing the steering range. This won't cause the same issue I ran into with the second control arm because the tie rod is on top of the spindle mount and won't hit the rim.

I built the new arm on the frame. It was easier to tack the mounts and build the control arm on the frame than trying to build a jig for the arm. I did the same on both sides and I'm much happier with the latest build than with the previous one. There is much less slop. I also plan on adding some additional plates to strengthen the mounts.

D76-77: Radiator Mounting + Driver Side Front Suspension

Yesterday I was able to get the driver side lower and upper a-arm finished and assembled. I'm excited to have both sides done and the freedom to move onto something else.

Today I worked on fitting the radiator. I haven't finalized the mount design in my head yet, but figured I'd get started on what I've got figured out. Below is what I've got so far. I had to make some frame mods to get the radiator to fit where I wanted, but with the appropriate additional bracing, I thin it'll be fine.

My favorite part of this design is I can build a "short" nose cone shrinking the overall length, which was stretched by some of the drivetrain decisions I made early on.

Finished front suspension with mocked up radiator.

Close-up of radiator mount frame cut-out.

D75: Lower A-Arm #4 D2

I got the passenger side lower arm tacked together. I reassembled the spindle, steering rack, and upper a-arm and threw a tire on to check out if the new design works. The tire hits AT both ends of the rack travel... a couple of shims will solve that.

The finished a-arm.

Assembled passenger side arms and steering rack.

Steering arm and lower arm.

D74: Lower A-Arms #4

I got a chance this evening to get a little work on the new a-arms. Here's my progress so far. Next step will be tacking in the steering rack mount, moving the rear a-arm mounts, and then adding in the rear bar to these a-arms.

D73: Lower A-Arm Redesign #4 + Steering Rack Mount Rebuild

Yesterday I had another realization... the new a-arm design allows the wheels to turn fully outward, but now the wheel hits the steering arm when turned in. After for most of the evening I sat down and redesigned the lower a-arms for a 4th time.

Below is the latest and hopefully greatest design for the lower a-arm. I've done a few things with the design this time.

• I went back to the right triangle shape. This more closely emulates the donor setup.
• I've also kept the width the same as the last set to keep the full range of wheel motion when the wheel is pointed out.
• I've measured the distance that the ball joint is moving forward to plan for enough clearance for the steering rod when the wheel is pointed in.

With these changes and the change to the steering rack mount, I've moved the steering rack 4 1/2 inches closer to the ball joint. This should give me full range of steering motion in both directions.

Lower A-Arm Design #4.

As I just mentioned, I also made a change to the steering rack mount. I cut out a section so that the steering rack could slide back closer to the mount. This moved the rack 1 inch closer to the mount helping achieve the 4 1/2 inch difference mentioned above.

Recessed notch for steering rack.

Steering rack installed in mount.

I plan on installing the modified mount about 3 1/2 inches further back to keep the wheelbase the same as it was with the previous a-arms. This also means no rework on the upper a-arms. It'll move the rear lower a-arm mount behind the upright similar to the first (or second) design.

Steering rack mount in the frame.

D72: Upper A-Arm Mounts

If you noticed, I missed day 71. I finished the second lower a-arm a couple of days ago and didn't blog about it since it looks almost identical to the first one in D70.

With one upper a-arm finished, I was ready to get the mounts in to make sure everything would come together. I also needed to figure out how long each tube + weld bungs is going to be.

Last night I spent a little time with CAD figuring out the layout of the mounts. I went in knowing the following:

• The mounts would attach to the two uprights
• The mounts would be made out of 1/8" thick 1 1/2" square tubing
• The angles of each of these mounts is 17 deg and 30 deg

I didn't want the rod ends to operate at an extreme angle, so I figured out a rough estimate for the angle of the front and rear.

CAD design of mount layouts. (They are wider than 9in.)

Next up was some CAD to figure out how far apart the lower and upper mount should be. I can't remember where I read this, but I remember 1" of travel should change the camber by 1 degree. The design has the distance between the lower ball joint pivot point and the ground along with the intended ride height of 6" (close to the donor) and then measurements from the frame.

CAD design of front suspension.

Upper a-arm mounts.

This design creates an optical illusion. Every time I look at it, I can't believe that the mounts are parallel. I keep seeing funky angles or thinking one mount is crooked.

[Top] Finished mounts + upper a-arm installed.

[Side] Finished upper/lower arms + mounts.

Note: The new location of the rear lower a-arm mount required a small addition to the frame. The mount only covered about a 1/4" in of the frame tube. It needed a little more reinforcement. I'm planning on more support later.

D70: Lower A-Arm D3

After a little thought and some quick design work. I decided on the design below as my third and (hopefully) final attempt.

I've narrowed the distance between the two bushings and centered the ball joint between them. The other change I made in this iteration is tilting the ball joint sleeve in two directions, both toward the frame and toward the rear. This should help minimize the ball joint angle with the stock spindle design.

The finished driver side arm.

Lower A-Arm: The Realization

While pulling everything apart, I put the front end back together to take a moment and appreciate all the work I'd accomplished the days before. I even attached the steering linkage and turned the wheel around a couple of... oh crap! I only get one full turn out of the wheel before the rim makes contact with the lower a-arm.

Since I'm not a huge fan of 17 point turns to flip a U, it looks like it's back to the drawing board for round three of lower a-arm design and rebuild.

D69: Upper A-Arm D1 + Engine Removal

With the lower arms together, it was time to get the upper arms built. These are much easier to assemble as they are adjustable and don't require everything to be precisely positioned.

The concept here is very similar to that of Jim McSorely over at sevenesque.com except a little more homemade. I got the weld bungs for a great discount making it cheaper to make my own tubes instead of getting real swaged tubes.

Front tube with fixed end.

Rear tube with clevis end.

Upper assembly attached to the spindle.
The tabs on the ball joint sleeve are cut from 3/8" plate.

My wife and I were having people over for New Years Eve and the garage was needed for some of the festivities... so I began pulling everything apart. Learning from my last experience of installing the motor, I decided to remove the tube that goes across the top of the transmission right behind the engine block. This allowed me to lift the engine straight up and out. Much easier. I plan on making that tube removable to make this process easier in the future without having to cut that tube out every time.

D68: Lower A-Arm D2

The second day working on the lower a-arm started out with a new design. Attach the tubes directly to the ball joint sleeve. This required some grinding to get all the necessary notches into the tubes. I needed something to easily hold a tube while I could grind it down.

The tube holder device thingy.

The front tube and ball joint sleeve mocked up.

The finished product installed.

Both sides finished. One with a ball joint installed.

Lower a-arm with spindle installed.

I am much happier with the second iteration of the a-arm design.

A quick note here. Use a threaded rode when mocking up the bushing sleeves before tacking them in place. This will ensure they are straight and won't bind with travel. I thought I had a decent jig setup until I installed the arm on the frame with the rear mount loose and realized the mount moved when rotating the arm. Turns out the bushing sleeves weren't in line.

D67: Lower A-Arm D1

Here is my first attempt at the lower a-arms. The plan was to make a right triangle shape to simulate the factory control arms. A single plate welded to the ball join sleeve would link the sleeve to the tubes running back to the frame.

3/8" plate with a template outline.

The finished plate next to the sleeve.

The bushing sleeves, front tube, plate and sleeve mocked up.

When I finally got all the pieces mocked up I decided I didn't like the idea of cutting a notch in the tube to attach it to the plate. I feel like this is asking for failure at the end of the notch. Final result of day 1: mulligan.