Have you ever pulled on a thread in a much-loved piece of clothing, focusing on the single strand of fabric growing in your hand, but only to recoil in horror when you later realise you destroyed that favourite sweater or T-shirt?
Even when new there were a few shortcomings with the steering and braking systems of American cars back in the ’60s. Pontiac marketed their cars as “Wide Track” machines full of stability and poise, but it was all a marketing smokescreen and they didn’t really steer or stop better than anything else from Motor City (which is to say, terribly).
Compounding my feelings over such poor performance was the fact my car had the worst brakes of all – iron drum assemblies with no vacuum booster assistance. This meant the pedal was dead-heavy, and the brakes prone to either locking up or fading badly. They had to change, but how that happened wasn’t planned.
Initially, I’d considered piecing together my own disc brake conversion using caliper adaptors (also called “dog bones”) from an Australian company, with discs and calipers sourced from a 1970s-era Aussie Holden Kingswood (the large, locally-designed and engineered family car sold by General Motors down here).
This was quickly abandoned when I saw American company Master Power Brakes had a “bolt-on” complete kit to convert unassisted drums to power disc brakes. I purchased the full kit and had it shipped post-haste (see below), and isn’t it pretty!
The great thing about the Master Power parts was that everything came in a few big boxes, and I wasn’t going to have to reinvent the wheel by making complex calculations about pedal ratios, booster and master cylinder sizes, working out run-out of bearings and the like.
I went straight up to United Speed Shop (the workshop the car was living at) to fit the stoppers and rid myself of the terrible front brakes forever. You can see below the stock drum brakes.
Pulling the housing and wheel bearing assembly allowed me to get to the backing plates and shoes. Drum brakes work by using shoes lined with special heat-resistant material to press outward onto a cast iron housing with a machined inner surface. As they’re fully contained within a heavy cast iron drum it is next to impossible for heat to escape, leading to issues with the brakes feeling increasingly spongy or soft.
Here is where a story about brakes becomes a story about steering, front-ends and financial pain.
On the right, below, is the first part in the front suspension which I noticed needed replacing. The first of about 40 parts, none of which are less than $40 each (and often require two of the same part, one for each side). This is called the “rag joint” and is the coupler joining the steering box to the column. It is pretty much the same for all General Motors cars using a steering box, from the 1950s through to the mid 1980s, and cost $8. This led me to replace the entire front-end.
So, the brakes mount to a spindle that also has the steering arm attached to it. Fully torn down I started cleaning the grime off only to find much of the front suspension actually required replacement. There were loose and worn-out parts all through the front-end, including blown-out ball joints, worn tie-rods, a leaking power steering box, and more.
If I was going to have to replace some of it, I may as well replace all of it, and so I went back to Original Parts Group in Seal Beach, California, and pieced together an order for all-new tie rods (left and right), new control arm top bushes, new drag link, new steering box, new Pittman arm, new idler arm, new ball joints, and new steering adjusters.
While I’d have preferred to convert my car to a more modern electric power-assisted rack and pinion set-up with lighter weight tube control arms, I simply couldn’t afford it at this time. I plan to do this down the track when I remove the chassis from the body and redo it, including independent rear suspension.
Here is the complete stock steering assembly from the Pontiac (top), versus the all-new linkages and parts on the bottom (the new steering box was already installed).
The upper control arms came off, as did the spindles, and the worn-out bushings (including those shafts) were replaced.
That snowball sure is rolling pretty hard down hill at this point…
Control arms painted in KBS Coating’s awesome Rust Seal black, with brand new ball joints and all-new steering gear. Ryan from United Speed Shop also remounted my front shock absorbers as the old ones were completely beat-out.
Ryan also powder-coated the new Master Power disc brake brackets black for me, along with the spindles. I cleaned them up and started installing the modern stoppers to drag my car into the (mid) 20th Century.
I have to say the Master Power kit is one of the easiest I’ve ever fitted to a car.
The kit included all-new wheel bearings and seals. Packing them was great fun.
After 3 months waiting for all the parts to come from America it felt great to be able to slide the new disc brakes onto my rebuilt spindles. This has possibly been the easiest part of the whole project, although it did require me to upgrade from the 15-inch wheels I’d been using to 17-inch wheels and tyres.
The Master Power B-Body Pontiac kit comes with these large Chevy S10 single-piston sliding calipers. They don’t look like much chop for performance cars but my Bonneville is a cruiser and so they should do fine. There is a Wilwood two-piston caliper upgrade (D52) possible, so if these calipers don’t work well I’ll simply upgrade to the Wilwoods.
Much better, though it was now time to try and fit the booster and master cylinder…
The Master Power kit came with a new booster and master cylinder combo, which was meant to bolt straight up to my stock non-assisted pedal. Unfortunately, it didn’t and we had to customise plenty of parts, starting with the supplied hard lines that ran from the master cylinder to the distribution block.
The bolts had obviously been fitted to the lines the wrong way around, so this required cutting the flare off the end of the pipe, switching the nuts around, and re-flaring the pipe. A small job, but annoying given the kit was sold as “bolt-in”.
Below you can see how the hard lines attach between the master cylinder and the distribution block.
This was the second distribution block and mounting plate I’d been sent for the kit as the one originally supplied by Master Power was 100% the wrong one. It would not attach to either the distribution block or the master cylinder.
Finally bolted in place it was at this point I discovered the clevis and rod which attach my vacuum booster to my brake pedal were also completely wrong, and so long that I’d have to get a whole new piece custom made.
Below is the stock pedal clevis, threaded onto the rod supplied with the kit, next to the bright gold clevis that had also been supplied with the Master Power kit. Unfortunately I have lost the pics from under the dash showing how it sat, and the pics of the new, custom-made pedal actuator rod.
In the end we got it working fine and whipped up some new custom brake lines to run from the distribution block to each of the front calipers via fresh hard line, and also down to the original rear brake line.
The brakes bled up nicely using a pressure bleeder, but I haven’t had a chance to take them for a road test yet as the car is still off the road.