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How to Install Chris' Hotrodz Straight Axle Kit - Going Gasser!

We install a Chris' Hotrodz gasser straight axle kit for some retro fun and style.

Patrick Hill Feb 3, 2014
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Back in the '60s, straight-axle cars started popping up at dragstrips all over the country, as racers found using this trick helped get weight on the poor gripping rear tires of the time so they'd hook up, helping them go faster. As tire technology improved, the need for this radical suspension setup faded away, and the straight-axle gassers they were bolted to with them.

Flash forward about 50 years, and the nostalgia craze for the golden age of muscle cars and drag racing started bringing vintage styles and methods back to life. And one of those resurrected was the straight-axle gasser clip. The front end sitting a mile high, skinny front tires, and fenderwell headers sticking out the side is one way to get a nostalgia junkie giddy like a schoolgirl.


To meet this demand, Chris' Hotrodz (CHR), in partnership with Dave Kiff and Pacific Tool & Gauge, came up with a weld-on gasser clip for Tri-Five Chevys, but it has the flexibility to fit other models as well. Even though it requires a little more fabrication than others on the market, that extra fabrication gives the CHR kit enormous advantages over its competitors, with enough installation flexibility to make sure everything will fit even if the original frame has been previously modified.

To get a feel for how good the CHR stuff really is, we contacted CHR's Chris Darland and arranged to check out an actual installation. There were actually two installs going at the same time, so we went back and forth between two different cars to get our photos. So, don't be alarmed if it looks like the Tri-Five we're working on changes during the story.

To get started, and before removing anything, set your car up on jack stands at the ride height and angle you want it at AFTER the gasser front clip is installed. Once that's accomplished, the real work begins.

And if you're a big fan of gassers and love seeing them in action, check out www.atrmovie.com. Every car in the movie features a Chris' Hotrodz gasser front clip.


1. Here's the kit from Chris' Hotrodz. You get everything you need except a steering column to convert your stock Tri-Five front end to a straight axle gasser style. It can be purchased from Pacific Tool & Gauge through www.tri5gasser.biz.


2. First you have to measure from the center of the front wheel to the front of the door. Mark this measurement down, as it will help make things easier later on. After that, measure your wheelbase. All '55-'57 Chevys have a wheelbase of 115-inches, no matter what model they are. After that, go ahead and remove the front clip.


3. Measure the top of the core support to the floor. Make sure to write this one down, as you'll need it to set your front end height when installing the clip.


4. After verifying the frame is level (side-to-side), the factory steering system is removed. Then a measurement taken from underneath the A-arm (on the frame) 7.5-inches back, or about three inches back from the split in the frame. Mark this, then draw a line from this measurement all the way around the frame.


5. Next, tack weld in a temporary frame support, behind where you'll be cutting, made from either tubing or angle iron. This will keep the frame rails stable when the original front clip is cut loose. After the support is welded in, support the front frame section with a pair of jack stands. Then, using the line you marked around the frame rail, cut the front section of the frame off. It makes the job a lot easier to start first with the bottom and sides of the frame, leaving the top portion for last. A sawzall or plasma cutter can be used for this.


6. Once the front frame is out of the way, remove the gussets from inside the frame rail. Then clean the frame stubs of rough edges and any funk that could affect welding later.


7. Time to test fit the subframe. First, set a jack stand to the height you measured earlier from the old core support to the floor. Once the stand is in position, verify your height by measuring from the floor to the TOP of your crossbar.


8. Measure from the center of the leaf spring mounting bolt hole back 15 5/8-inches on both sides, and mark the frame. Then clamp a straight piece of metal (box tubing works best) based on the marks you just made. Then (using your previous measurement from the door to the front wheel) measure again from the door to the marks you just made on the frame. This will tell you how much needs to be trimmed off the gasser clip frame rails.


9. The Chris' Hotrodz frame features rails that are longer than typically necessary. CHR does this in case you accidentally cut too much off your stock frame, have a damaged frame, or plan to install this clip on something else besides a Tri-Five Chevy. We measured and saw 2.5-inches needed to be trimmed off the new rails.


10. Measure twice, cut once. Using a sawzall we cut our new gasser clip to the length we needed.


11. At this point, the clip is cut to proper length and clamped in place, ready for us to start the next phase.


12. First we assembled our leaf springs, attached them to the new front straight axle, and bolted them to the frame. The axle is set back at an angle of seven degrees.


13. Next, a measurement is taken from the bottom of the frame to the leaf spring, on both sides. We also measured from the frame to the axle using a square, to verify the axle was centered on the frame. Then it was clamped in place so it wouldn't move. From there, we measured our wheelbase, verifying we had 115-inches on both sides. Since our rear was still in the stock location, we measured from the center of the rear axle to the front axle.


14. Verifying we had 115-inches axle to axle on each side, the next measurement was cross measuring from left rear to right front axle, and right rear to left front axle. Both measurements should be the same. If they're not, then something has moved, and you'll need to back up a few steps and start over. With all our measurements verified, we could tack weld the frame rails in place, along with our straight axle. Then we checked all the measurements again, making sure nothing had moved while welding.


15. After tacking everything in place, the front clip is set in place. The core support will sit on top of the cross member, and with no shims in place, the front nose should have a downward tilt, with a bigger gap at the top between the door and fender, than on the bottom. Next, we placed a pair of wheels on the approximate center of the axle. Once we saw everything was lined up properly, we pulled the front clip back off, along with the axle assembly.


16. Now we can start finish welding the new frame clip to the factory frame. You start by welding the inside of the inner rail to the factory rail, and along the bottom. Do not start on the top or outside. You'll see why in the next steps.


17. For proper fit, the top and outside of the original frame must be pie cut, then clamped down on the new frame and welded in place. First, make cuts like these so the factory frame can be "squeezed" to fully mate and support the gasser frame.


18. Next, the new "tab" is hammered down to the gasser frame rail, clamped, then welded.


19. Before moving on, we went back and cleaned away any welding splatter and high spots from what we just did.


20. Now you can remove the temporary crossmembers tack welded in place at the beginning.


21. To strengthen everything, the side gusseting/boxing plates are welded on. The plate with the notch goes on the outside, to clear the firewall body mount. The outer and inner plates are clamped in place, then skip welded to the frame. The plates won't sit equal with each other when in position, but don't be alarmed, that's how they should be.


22. Once the side gusset plates are in position, the top and bottom boxing plates are set down, marked for grinding/trimming, trimmed, then welded in place. On a Tri Five frame there's a nub on the bottom the lower boxing plate will butt up against. With all of the gusseting/boxing plates staggered, this spreads the load out, creating three areas of strength, one on each end of the boxing plate, plus the center welded part from your original frame to the new gasser frame.


23. Time for the leaf springs. First, the rear shackles need to be mounted to the original frame. These pieces come anodized. Any area that has to be welded on the shackle must have its anodizing ground off.


24. Measure from the center bolt of your front spring mount to the shackle center 31 and 5/8 inches. Once the rear shackle lines up at that measurement, tack it in place on the frame. One more time, use a square to verify your axle is centered on the subframe, and the axle is set back at an angle of seven degrees.


24. Measure from the center bolt of your front spring mount to the shackle center 31 and 5/8 inches. Once the rear shackle lines up at that measurement, tack it in place on the frame. One more time, use a square to verify your axle is centered on the subframe, and the axle is set back at an angle of seven degrees.


25. The tips of the spring perches are tack welded onto the axle. This is followed by tack welding the steering stops onto the axle ends.


26. Grease the inside of the loops on your spindle mount. On the kingpin, make a mark on the top of the pin that lines up with the notch in the middle of the pin's shaft. Then check the fitment of the kingpin in the axle. The big end of the spindle goes on TOP of the axle. Set the spindle in place, then slide the kingpin in halfway. Then slip the bearing in the bottom gap of the spindle mount. Then tap the kingpin all the way in place, and tighten your set screw.


27. Now the brake caliper brackets and lower steering arm can be installed. Once the caliper bracket is in place, the lower steering arm is bolted on, with the lower steering link facing towards the REAR of the car. Then the upper steering arm is installed, with the steering link facing towards the FRONT of the car.


28. The draglink goes on after that, connecting to the lower steering arm. Be sure to install one Heim spacer between the Heim joint and the steering arm.


29. After packing the bearings and installing them, we bolted the rotors onto the spindles, followed by the calipers.


30. The shock brackets are installed at this point, and checked for clearance, to make sure the lower shock bolt clears the spring perch. With the shock fully extended, measure from your boxing plate inward (towards the firewall). This will be the upper mounting bolt for the shock absorber. One the bolt is in place, tack weld it in. Then make sure the brakes don't hit the shock when the wheels are turned to full lock. The steering stops welded on earlier should keep that from happening. If they don't, move the stops to a different location till they do.


31. Pretty simple here, install the steering box and drag link.


32. The motor mount crossmember comes next. The included crossmember will need to be cut down to fit and center your engine in the frame. You'll need a block to mock this up, and with the distributor installed to make sure you don't set the engine too far back and create clearance problems with the firewall. The engine should be set back 2-3 degrees. Keep in mind when you set the engine location what you'll be using for headers, and a steering shaft/link.


33. With all that work complete, you can finished weld everything, tear it all apart, and get it ready for finishing painting/powdercoating/whatever. Then it can be reinstalled, and move onto the next step in your car's build. When it's all done, you'll end up with something as sexy looking as this!


Chris' Hotrodz
White City, OR 97503



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