The Unijig Pro from DCS Peformance Engineering accepts frames from GM,Ford, Off-Road, Wins
Wrecks and bent chassis are part of racing here's how to use a jig toget it all straightened out.
Consistency in racing is what brings a driver and his team achampionship. However, if you think about it, this consistency does notjust relate to a driver's performance on a given Saturday night orSunday afternoon. Not only does the driver have to drive a consis-tentlygood race lap after lap, weekend after weekend; the car itself has to beconsistent as well. Of course, engine performance is a major factor inthis equation, but another major factor is the chassis, and how good ofshape it is in.
We have all seen, or even been through, this scenario--you have builtthe best car you have ever driven, and you already won three out of thefirst five races of the season with it. Minor adjustments need to bemade here or there with each race driven, but that is a given. Then thatfateful sixth race comes along. After leading the majority of the race,you and the rear end of your prized race car meet the wall of Turn3--hard. What are you going to do now? The damage to the rear end is sobad that you have to work on the car just to get it in the trailer totake home. Why not just junk the whole thing?
Luckily, you don't need to take this drastic and ultimately expensivestep. The good thing to come out of this scenario is that the rest ofthe car is in fairly good shape. Those rubber donuts can always berubbed out, your front end is still straight, and the motor seems to berunning OK. So what do you do about your race car that now looks like ahatchback?
This is where the chassis jig comes into play. "A chassis jig is what isused to manufacture a frame in a manner where every frame is exactly thesame from one to the next," says Wayne Lensing of Lefthander Chassis inRoscoe, Illinois. "The jig keeps the chassis square and consistent."
Lensing and Lefthander Chassis build frames for short-track oval racers.According to Lensing, there are a few key measurements when building orrepairing a frame. "When you build a chassis, you want all yourframerails to be parallel," he says. "One key point to measure is yourlower control arms. You always want them to be in the same spot so yourtrailing arms are consistent. Every Lefthander Chassis comes with thesepoints of measurement."
Fixtures (the white square tubing) for specific chassis may be madeavailable through chass
Wes Van Winkle of Maxx Racing Chassis in Enid, Oklahoma, measuresseveral different points on the chassis to make sure it is consistentall around. "I measure the overall X on the frame, from one end to theother," Van Winkle says. It is wise to note that the overall X on aframe can be determined differently with each chassis builder but isbasically a set of crossmembers to make sure the frame is square. "ThenI go back and measure from the center of the front spring pad to thecenter of the rear spring pad. And of course, I always measure thewheelbase."
A good tip to remember is to ask your chassis manufacturer what theyconsider to be the overall X of the frame. In some cases, it could befrom the right front to the left rear and the left front to the rightrear. Others might measure just the rear in an X fashion. Van Winklealso suggests that you measure the steering linkage to make sure theyare at the right angles.
When you have damaged either the front or rear clip of your car, thereare a couple of options you can take. The first, and maybe easiest one,is to send your car back to the chassis builder. They will already havethe jig and measurements of your car in its original condition. Thisoption might take longer than you had hoped, especially if the buildertakes care of many of the racers at your track and it was a particularlymessy night. Many times you only have a span of a week, two at the most,to get your car repaired and ready to go back on the track.
There is always the option of getting your own jig. You can buy one, oryour other option is to build one.
Maxx Racing Chassis specializes in building frames for I.M.C.A. as wellas Limited Sportsman, Pro Stock, Street Stock, Factory Stock, and MiniStock classes. Because of the variety of chassis that Maxx RacingChassis puts out, Van Winkle built his own jig.
"I just used four-inch I-beam. You want to use something pretty rigid,"he says. "Though, a lot of guys will build their jigs out of 2x4 squaretubing. With my own jig, I can set it so we can just bolt a frame towhere everything will be level and square. I have built so many frameson it that I can now just lay a pattern on the jig and know where to cutthe hole in the frame to weld a piece of pipe, or I can drill holes torelocate all the front steering linkage in order to get the steeringgeometry correct. If you are going to work on a variety of cars, youmight be better off to design your own jig. With the jig I built, I canput a metric frame on it or I can put a full size GM frame. I can evenuse that same jig with a Ford frame."