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.

D81: Steering Rack and Column Updates

With the newly redesigned front suspension I needed new mounts for the steering rack. Below is the design for the new mounts. From the previous post, I knew how high above the lower control arm pivot I wanted the center of the rack to be and from the original design I knew how far in front of the front cross bar I wanted the rack to be. Thus, the design below.

Below is one of the two mounts for the steering rack that will attach to the front cross member.

Both mounts tacked onto the front cross member and the steering rack in place.

The new design I have for the steering column required a few mods to the firewall. The first was installing a firewall mount for the steering column. I replaced part of the firewall with this 1"x2" piece of tubing.

With the firewall mount in place, I wanted to make sure the the column cleared the brake booster. From the pick below, there is plenty of space.

The new steering column connected to the steering rack. Getting rid of the extra piece of linkage makes for a clean install. I also think it'll be a safer/stronger design.

The last pic is the steering column next to the pedal assembly. The new column will come almost directly out at the driver instead of the previous design where the column was at an angle. Again, a cleaner design.

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.

Junkyard Finds

Made it to the junkyard today and found a few parts that I've needed. A new clutch slave cylinder since I broke the bleeding valve off the original one, a transmission mount to replace the one glued together, and a rubber plug for the lower radiator mounts. Glad to get these things so I can continue with the progress I've been making.

D78: Steering Column + Radiator Mounts D2

Today I worked first on finishing up the steering column extension, and then the radiator mounts. I welded a 3" extension between the two pieces of the steering column I had a few weeks back. The hardest part of this was getting all three pieces aligned so that the steering shaft inside wouldn't bind. The extension is fully welded around both ends along with a couple of plug welds.

Column outer sleeve to add 3" to column.

The next step here is going to be finalizing the placement of the steering column and wheel and getting the last bit of mounting in place to hold it all together. Also, since I moved the steering rack back while getting the front suspension figured out, I also need to modify the linkage between the rack and the column. I'm going to wait to finish this until I have the engine back in, just to make sure there is plenty of clearance.

Steering column mocked up.

Next up today was the radiator mounts which I started yesterday. The BMW radiator has two rubber plugs along the sides which sit in cups in the frame. The top is held in via removable arms that fit into a couple of slots. Below are a couple of pictures of the radiator in place. I love that the radiator doesn't hang out in front of the frame allowing me to build a nose that is "shorter". Also, I can install it upright meaning I get the best performance out of the radiator over installing it at an angle.

Radiator front.

Radiator side.

Below is one of the "cups" that I've added which the bottom rubber plugs will sit in. Obviously there is a lot of finishing work to be done here before I can consider these done. But functionally, they work, which I'm pretty pleased about.

Radiator mount close-up.

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.