The Hacky Throttle Repair That Got Me On The Road Again

Old cars are great. For the nostalgia-obsessed like myself, getting into an old car is like sitting in a living, breathing representation of another time. They also happen to come with their fair share of problems. As the owner of two cars which are nearing their 30th birthdays, you start to face issues that you’d never encounter on a younger automobile. The worst offender of all is plastics. Whether in the interior or in the engine bay, after many years of exposure to the elements, parts become brittle and will crack, snap and shatter at the slightest provocation.

You also get stuck bolts. This was the initial cause of frustration with my Volvo 740 Turbo on a cold Sunday afternoon in May. As I tried in vain to free the fuel rail from its fittings, I tossed a spanner in frustration and I gave up any hope of completing, or indeed, starting the job that day. As I went to move the car back into the driveway, I quickly noticed a new problem. The accelerator was doing approximately nothing. Popping the hood, found the problem and shook my head in resignation. A Volvo 740 Turbo is fitted with a ball-jointed linkage which connects the accelerator cable to the throttle body itself. In my angst, the flying spanner had hit the throttle body and snapped the linkage’s plastic clips. It was at this point that I stormed off, cursing the car that has given me so much trouble over the past year.

Getting Back on the (Broken) Horse

Of course, I didn’t give up that easily. A few hours later, my enmity for the insolent Volvo had cooled down to a low simmer. I inspected the broken linkage and decided it would be an easy fix after all. I lathered the broken pieces in epoxy, wrapped them in paper to add strength and topped it all off with a small ziptie for good measure. I left it to set over night, and popped it on first thing in the morning.

Success! I started the car, and got a full 200 meters down the road before the accelerator once again became limp and useless. After pulling over, I found that the other half of the linkage had now broken off, and having fallen out on the road somewhere, I wasn’t going to find the pieces anytime soon. I left the car at the side of the road, got myself off to work, and began the search for replacement parts.

New linkage on the left, old linkage on the right. Note the extended length of the new linkage, and the paper-and-epoxy repair on the old one.

Alas, owning a European classic in Australia was hurting me. I could source the plastic ball-joint clips I had broken, sure – but for the princely sum of $50 by the time shipping was over with. This wouldn’t do. Instead, I decided to head to the wrecking yard, which appeared to have a car matching mine.

Upon arriving, I was dismayed to find that there was no car akin to mine at all! A day driving my race car to work had been irritating enough, so I wasn’t ready to give up yet. I scoured the yard for similar cars, and found a couple with similar linkages, and in the end, a Volvo 850 bore fruit. Pleased with what I’d found, I headed home, with the wrecking yard giving me the part for free. Kind chaps!

Getting home, I found that while the ball joint clips were the same size, the new linkage was far too long. The linkage uses an interesting method of adjustment. One plastic clip is permanently attached to the shaft, and doesn’t move. The other clip has a screw-on cap, underneath which there are several washers. When the cap is tightened onto the clip, a special washer inside is deformed and expands outward, gripping the shaft tightly and stopping the linkage from changing length.

Customizing Salvaged Parts

The new linkage, disassembled prior to cutting it to size. Note the circlip, which holds a spring and several washers on the shaft which make up the adjustment mechanism.

At the maximum extent of adjustment, it still wouldn’t fit, so I got creative. Undoing the adjustable clip, I found a circlip fitted to the shaft which acted as a stop for an internal spring. However, this only seemed to serve the purpose of stopping the washers from falling off the shaft. I removed this with pliers, and then all the internal washers. I then simply took out the angle grinder and cut the shaft down to the necessary size.

After some fiddling, I determined that the washers had to be assembled in a particular order to make them work properly. I then laid the new linkage next to the old one to set the length the same as the original part. This was important, as I had no interest in spending hours tinkering with the full adjustment process for the throttle body. I gingerly approached the car, and to my great relief, the new linkage clicked into place without a problem. Happily, the car has since completed many miles and has been free of further breakdowns.

There is Power in Greasy Hands

Be not afraid

In this day and age, it can be very tempting to just throw one’s hands up and replace something broken, or in the case of cars, just give up and trust the dealership to fix it. Granted, when the chips are down and your only ride is out of commission, sometimes the choice is out of our hands. But something to remember in this replacement culture is that repair can be possible, and can even be remarkably easy.

The real bonus is that you can learn something along the way, and if you’ve got the love for the project, putting your own labour in doesn’t sting so bad.  The lesson I learned was that while you can’t always source the correct parts, that doesn’t mean it’s over. With a little ingenuity and a willingness to do the work to make things fit, it’s often possible to get yourself out of a bind, and usually pretty cheaply, too.

Now, there’s every chance that my “new” part will only last a few years, given that it came from a car that itself was only a handful of years younger. But for now, I am once again enjoying my classic vehicle on a daily basis, and it cost me practically nothing! I’m calling that a win.

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