Machined Front Suspension - 1954 Pontiac
I figured that I can build new 1" tube control arms and use balljoints instead of kingpins. I've started modeling the suspension in 3D using Autocad. Originally the upper balljoints were 76 Camaro and the lower are 67 Chev Nova. The 67 Chev Nova is one of the few lower balljoints that are bolt-in as opposed to pressed in. I need the bolt-in ones for camber and caster adjustment. I changed and went to 73 Nova parts for the reasons listed down below...
Why not place caster and camber adjustment on the control arm mounting points on the front crossmember like modern cars? Well, the 54 line had a choice of a straight 8 or 6 cylinder engine. For engine clearance, they moved the front crossmember far forward and then arced it so that the control arms face backwards at a 63 degree angle. The control arm's mounting points are not adjustable, easily reached and would adjust in the wrong 3 dimensional plane.
Original crossmember and kingpin suspension showing 63 degree angle
I originally planned on using the upper balljoint to adjust camber and the lower to adjust caster. This will allow perfect adjustment in the correct 3 dimensional plane. Toe-in will be adjusted using adjustable tie-rods. In order to see how this goes together, I've drawn the driver's side front suspension in 3 dimensions in Autocad. I found out that this was just too hard to do and talking to a frontend mechanic, it would be almost impossible to align. Wouldn't be able to get the tools in to adjust it.
Been playing with changing the kingpin to balljoint conversion for 8 weeks now. Been modeling everything in 3D in Autocad. Decided that I can't use the original 54 spindles - just too difficult to manufacture proper mounting. Spent 3 hours at the wreckers one Sat. until I found 68-74 Nova and 67-69 Camaro rear steer spindles that had the correct balljoint spacing (roughly 10"). The nice part is that the steering arm is bolt-on, so it can be changed easily for my application. Unfortunately, the disc brake spindles are highly valued for conversions and are tough to find.
Picked up a set of 73 Nova spindles and hubs for drum brakes - now the clincher was that I also picked up a complete 4 wheel disk brake set (from the brake pedal to rotors) off of a 85 Toronado, that the rotors will mount to the 73 Nova drum brake hub and 76 Camaro rear-end (std 10 bolt) with minor mods. The calipers will require a mounting plate to be made. So it looks like I'll get balljoint front suspension and 4 wheel disk brakes.
73 Nova hubs and spindles from drum equiped vehicle
Spindles machined out of uprights and turned on a lathe
Finished machining the new uprights for the spindles. We made it an interference fit. The spindle is 0.004" larger than the hole in the upright. We heated the upright until it expanded enough to slide the spindle in. To be on the safe side, we welded the spindle in and then let the weld cool slowly for 6 hours in a special cooling oven.
I was only able to drop the spindle about 1.25" due to clearance problems with the steering arm, its mounting bolts, disk brake mount and lower balljoint.
Spindle/upright back view
Side view
Front view
I looked at aftermarket 2" drop spindles for 73 Nova (Fatman, NNNova, Classic Performance, ~US$360 pair) and all have the steering arm cast in place. They also use Malibu disk brakes. The disk brakes would work with the Camaro rear-end but the steering arm angle and position is all wrong.
Another interesting site called Pole Position Racing Products that I came across makes fully adjustable crossmembers using turnbuckles for Camaros and Mustangs. With a little modifications, they may be made to work. My upper control arm is machined similar to theirs.
I came across my Dad's 1988 Buick's rear suspension and it has turnbuckles that could be adapted rather than start from scratch. They may be metric thread though but that shouldn't be a problem.
1988 Buick rear suspension uses turnbuckles
The control arms will be made out of 1" steel tubing with 3/16" wall mounted to the original 54's crossmember. I've spent a lot of time consulting with steering experts, machine shops, fabrication shops and safety inspectors. I had a scare when an "expert" hotrodder told me that the car will never pass inspection. It's supposed to be a daily driver so everything better pass. Talked to a guy who certifies vehicles and builds rods for a living and he says it's not a problem. So to the inspector's I go with my plans for their input. Better to be safe than sorry.
I finished the upper control arm. It is similar in design to the Pole Position one. In hindsight, I would build a new crossmember that fits 68-74 Nova control arms rather than machining all these parts - it would be simpler, faster and easier to replace parts if something breaks.
Upper control arm - top view
On the frame the control arm mounting stud is about 1 1/2" long. I've machined a long 2" threaded sleeve that threads on to it (I've outlined the sleeve part in dark blue). At the end of the sleeve is the nut. The nut is actually part of the sleeve. You turn the nut, you turn the sleeve.
A 1" wide "donut" of SBR-80 rubber slides over the sleeve. The control arm end bushing slides over it and two large washers hold the rubber and control arm bushing from moving. I initially used SBR-80 rubber washers between the metal washers and the control arm but SBR-80 is too pliant and squeezed out when compressed. I switched over to a cloth/rubber style isolation material and it holds its shape quite well.
A large bolt locks the sleeve into place kind of like a reverse locking nut. Instead of a nut locking a stud, I have a stud locking a nut. The control arm end cannot slide off of the stud because of the retaining washers. I have thought of replacing the rubber with polyurathane but will wait and see. It takes about 30-45 minutes to assemble one side of the control arm cause the rubber expands inside the control arm end and I've run grooves on the inside of it to further stop sideways movement. The rubber expands into the grooves which help stop the rubber donuts from slipping out. Which just make it more tougher to try and slip on. We'll see how well everything works when its on the street.
There are 2 turnbuckles for adjusting the caster and camber. I have about 0.5" of adjustment in each for a total of about 4 degrees. This way if I screw up on the lower crossmember, I can still align the front end. In the above picture, you can see the top of the upper balljoint located at the bottom of the pix - it is black.
Front disk brake mount
73 Nova hub installed
Rotor installed
Caliper on and surprisingly everything fits!
You can see the 73 Nova steering arm peeking out of the lower right corner of the pictures. I had to modify the 85 Toronado's rear disk brake mount to fit the front calipers. 2 knotches were made in the circle portion - you can see the small knotches in the first pix.
I'm using the original spring basket from the Pontiac rather than make my own for the lower control arm. I'm building up an alignment jig to hold the control arm pieces in proper position while welding and bending. I was hoping to get it finished before July 1, 2001 but my Honda's timing belt fiasco put a damper on that.
Pontiac's lower control arm's spring basket and brace
Lower control arm ready to be installed (no brace)
Lower control arm in place
I decided not to use the original brace. It is not needed structurally and would be very difficult to weld. The bending and welding of the control arms was performed by Allan Automotive in Calgary and they did a superb job for a reasonable price. Great guys!
There is still some minor welding required on the lower control arm. A sway bar mount has to be added to the front and a bracket to hold the rubber bumper to stop the control arm from bottoming out on the crossmember. I'm not looking forward to taking off the control arms as it took me 2 hours to install them in their rubber bushings. Oh well...
The coil springs are not installed yet as I have to be able to easily move the front suspension up and down to in order to find the correct position for the rack n pinion unit. I will be measuring the movement of toe-in as the front suspension goes through its travel, this will let me eliminate any bumpsteer.
Swaybar, springs, bumpstop and steering arm installed
The swaybar mount has been TIG welded to the lower control arm and the swaybar link attached. I'm pretty proud of the bumpstop mount and the bumpstop. It looks like a 50s dagmar (bullet). I truly lucked out with the original coil springs. I expected them to be too tall. I planned for a ride height of 11" for the steering geometry and was pretty sure I would have to cut some coils off. The springs gave exactly 11" ride height! I think I'll go and buy some lottery tickets..
If you go to install springs, coat the upper coils with a lubricant so that they slide into the ring at the top of the crossmember. I had to reinstall the first coil cause it didn't slide on to the upper ring. I found an interesting spring calculator on the web which will calculate the spring rate from unloaded spring dimensions. The stock unloaded spring measured:
- Height: 14 1/2 inches
- Outer Diameter: 4 1/2 inches
- Coil diameter: 1/2 inches
- Number of coils: 11 (including 1 nonactive coil)
The spring rate calculates out to about 137 lb/inch - for what its worth..
You can see the 73 Ford Courier's steering arms attached to the upright with 1 7/8" spacers to clear the lower balljoint and to give proper steering geometry. It's bolted together with 1/2" grade 8 nuts, lockwashers and bolts. I found that lower grade lockwashers would actually split when used with grade 8 nuts and bolts.
3D drawings of balljoint suspension
Here's early 3d drawings of the control arms, spindle and disk brake caliber, shown from the frame rail looking out (front of car to the right): leftside. This image is a top view showing the upper control arm. The wheel rim is shown and is pointing directly forward, the front of the car is to the left. The 63 degree angle of the control arm to the frame is quite evident. The lower control arm uses the original spring mount basket and bumper mount plate, the location of the upper arm crossmember mounts is shown just above the spring basket. The relationship between the unequal length control arm length is quite clear from this view.
This image shows both the upper and lower control arms, spindle and rim. I'm still playing around with the scrub distance, which is the lowest part of the rim. Basic design theory says that no suspension part should be lower than the rim in case your tire goes flat. You don't want to have suspension parts rubbing on the ground. This is currently set up for a 2" drop but I probably will go to 1 1/2".
