Revalving And Repairing QA1 Shocks - Shock Therapy

Since we are using QA1 shocks on our Fastruck, we thought we had better learn how to revalve and repair them. These are the QA1 Twin Tube Series 50 bearing end shocks. They are steel-bodied, as called for in the Fastruck rules.

All race cars need shock absorbers, and they need the right ones in order to perform properly at the racetrack. Ordinarily, you select the valving you want whenever you buy shocks. The valving you think you want may be incorrect, so you have to go to the store and buy some more shocks. Then the track changes and you need more shocks, but the store is closed at this point. This is why you want shocks that you can revalve, even at the track.

We put four of the QA1 Series 50 shocks in our pocket and visited Dave Pletcher Racing. Pletcher's is a full racing shop that builds cars and engines and has two dynos. One of those is a Roehrig shock dyno. It so happens that Pletcher's is a QA1 dealer and authorized repair/revalve facility. With Dave's experience and equipment, he can revalve a shock in only a few minutes. It will take you a bit longer the first few tries, but this is not a difficult job. Having built the chassis for our Fastruck and knowing the tracks where we will race, he suggested the initial valving for us to run.

First, Dave put a new QA1 9-inch Stroke Series 50 on his Roehrig shock dyno. This was a 7/8 shock: a 7-valve in compression and an 8-valve in rebound. After letting the shock warm up till the Roehrig's temperature sensor said OK, Dave pointed out that shocks need to warm up, as the oil will change in viscosity. He said it may be one cause for a car's handling to change sometime during the race. Removing the shock from the dyno, Dave waited for the computer to print the results. The valve ratings from QA1 were very close to the ratings on his Roehrig.

Satisfied that everything checked out correctly and that we had a proper baseline, we watched as Dave disassembled a new QA1. It was easy enough, just like it says on the QA1 Web site where I downloaded the instructions. He laid out the discs, pistons, and base valves. All of the pieces should be placed so they can either be changed or replaced in the same order. With some parts it is necessary to not only replace them in the same order, but to also replace them with the same side up. Therefore, it would be a good practice to always keep the parts facing the same way.

Dave changed the valving to 7/5 to go on the left rear. The QA1 revalving kit had all the necessary parts labeled and in their own compartment. QA1 lists some tools to go with the kit. There is a spanner wrench to fit the top nut on the tube. A 31/44 wrench as well as a 17mm or 111/416 wrench takes it all apart. A dial caliper will be necessary to help in selecting the correct discs. QA1 provides a sheet that specifies what parts to use for a given valving. Dave told us that the spec sheet for selecting valving was usually close to what the Roehrig dyno indicated. However, due to wear and oil contamination, among other factors, the shocks should be run on a dyno when it is available. We discussed the process of revalving when at the track. He felt this was not a problem. All that's needed would be the revalve kit, the tools, a clean place to work, and a fixture to hold the shock.

Since we were there, we asked Dave to revalve all our shocks for the Fastruck. It took him about an hour and a half to answer our questions, show us what he was doing, and revalve all four of our QA1s and run them on the dyno before and after.

Easy enough! The problem is that Dave Pletcher and the Roehrig dyno won't be with us at all times. So we decided to revalve an additional shock we happened to have in the shop. The first time took a little while since we didn't have hands-on experience. I fabricated a few tools to make the job easier. Joe's Racing Products makes a nice shock workstation. It holds the shock body and the shaft for changing the valving. I fabricated the fixture in the photos from a few scraps around the shop. It is not as sophisticated nor as quick, but it works.