The tools needed when revalving a shock are laid out here. The dial caliper is necessary t
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.
Dave has clamped the shock in a Joe's Racing Products shock vise for disassembly.
The shock tuning kit from QA1 holds all the discs and parts to revalve a shock. The spanne
This is the Joe's Racing Products vise. It holds both the shock body and the removed rod.
Dave Pletcher runs our QA1 shock on his Roehrig shock dyno. The dyno is coupled to a compu
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.
Study the disc selection chart. This will tell you what parts are necessary to achieve the
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.
The story of two base valves. One has two discs while the other has only one. There are no
Changing ValvesBegin by cleaning the outside of the shock. If it is clean on the outside, there will be less dirt to fall inside when you take it apart. With the shock body held in the vertical position, remove the bearing end.
QA1 says these tools will be needed for teardown and reassembly:
*A shock holding fixture
*QA1's spanner wrench
*Torque wrench with 17mm or 111/416-inch socket
*Fine-pointed pick (scribing tool) for O-ring removal
*A 91/416 and a 31/44 end wrench
*A dial caliper, while not required, should be used to verify the measurements of the valve discs.
*Also required: the QA1 rebuild/revalve kit and QA1 shock oil.
I made two more simple tools to streamline the process. One is a 15-inch length of 131/44x0.095-inch rollcage tubing. Instead of using the mallet to remove the gland, the whole inside assembly can be dropped into the tube to remove the top gland. The 131/44-inch tube catches the gland and pops it out, althought it might take several strokes.
The other tube is a piece of 1-inch pipe about 15 inches long. Once the gland is removed, the base valve will need to be removed from the other end. The 1-inch pipe will drop inside and remove the base valve.
The ends must be square on both of these tubing tools. If you use a chop saw, once the cut is made, the tube can be rotated against the side of the cut-off wheel to make it true.
My homemade fixture to hold shock bodies. I picked up some scraps around the shop to make
I won't go into all the revalve procedures here. QA1's tech manual covers all the revalving and rebuilding procedures. QA1's redesigned Web site should be up and running by the time you read this. The tech manual will cover all the details. Otherwise, call the tech line (see source box).
My natural tendency is to read the instructions when all else fails. However, being a little awed with taking a shock apart intentionally, I read the instructions first. I followed them as closely as possible. My only problem came when I finished the assembly. After a hard pull to extend the shock, I discovered that it would suddenly become an easy pull. It was readily apparent there was still air inside. After opening the shock again, I made sure the air was eliminated by holding the inner tube in the manner indicated by the instructions. More oil was added as needed, and the shock buttoned up. I would suggest you have a clean drip pan under the shock so the oil can be filtered and reused.
With a bit of practice and all the tools at hand, I think you could reasonably expect to revalve a shock in about 15 minutes. Having these revalvable QA1 shocks will reduce our inventory.
After watching Dave revalve shocks, I wanted to do it myself in the SCR shop. Here, I'm ho
By dropping the inside tube into a piece of 131/44x0.095-inch rollcage tubing, the top gla
Be sure to cycle the shock several times after reassembly. It must be full of oil with no
Dave Pletcher Racing
Joe's Racing Products
QA1 Precision Products
Tech line 952-985-5675
Order line 800-721-7761