In building a 924S for the track, I didn’t want to take the time setup the rear ride height with the torsion tube assembly out of the car. I instead swagged it and hoped to get a ride height that was usable until I could get around to messing with it later down the road.
In order to do this, I had to first setup the car to support rear ride height adjustments with the torsion tube assembly installed.
The first step in accomplishing this comes when you have the torsion tube assembly out of the car and completely disassembled. The outside end of the spring plate carrier has a pressed in cap that "seals" off the outer end of the torsion bar which splines into the spring plate. This must be removed to expose the end of the bar to the outside world. I have found the easiest method is to just take the spring plate with bar inserted and while holding onto the spring plate, pound the other end of the torsion bar on a hard surface. The cap should pop off after one or two good pounds as the torsion bar starts to exit that end of the spring plate. When building a new car, I usually use the old torsion bar so I don’t damage the new one.
***WARNING: Don’t look down directly over the spring plate as you pound away since the cap will go flying***
The next step is to fabricate a way to grab the outer end of the torsion bar after it’s installed. There are really two main options: weld a nut or drill and tap. Since the torsion bars are spring steel and require a lathe with special tools to drill and tap, I chose to weld a nut. Simple and straightforward, just pick a nut large enough to do the job and in a known thread size so you can find threaded rod to engage it. I went with a ½”-13 nut since Lowe’s has an ample supply of both hardware and threaded rod. It is also a common size for the large eyelet’s that come in handy later. I researched if welding would be a problem on the end of the torsion bar and concluded that with the minimal amount, it’s not going to hurt anything. My Miller MIG running off 110V had no problem attaching a nut to the end of the torsion bar.
***NOTE: Be sure to weld a nut to the spring plate end of the torsion bar, as the inner and outer end of the torsion bar are a different spline count! You want the OUTER end!***
The last step allows access to the torsion bar with the assembly installed. The rules allow a hole drilled in the side of the car outside of the torsion tube. This allows you to pull the torsion bar out with the assembly still installed, then move the rear suspension and re-insert the bar allowing for rear ride height changes. I have seen templates for this on a 944, but none for a 924S so I just assembled and installed the torsion tube assembly so I could estimate where to drill the hole after installation. If you were spot on with a hole saw, you can get away with about a 2.25” hole, but since I never end up being spot on, I ended up going with a 3” hole saw and called it good enough.
Now that you have everything installed and ready to go, you need a tool to pull the torsion bar out for re-indexing. I know of one racer who can just pull his bars out with little to no effort once the suspension is unloaded. He took a lot of time to clean up the splines to work them in which is extra work I didn’t want to do. Instead, I came up with a puller tool that uses the nut on the end of the bar and presses against the end of the spring plate as you tighten the nut.
Always wanting to repurpose old parts, I figured I could use an old rusted spring plate from a junkyard car I scrapped a year ago. Using a chop saw, I cut the end of the spring plate off at the weld on the outside of the plate. This ensures the diameter of the pipe on the puller is the same size needed to both press on the installed spring plate and allow the installed bar to exit the end of the installed spring plate.
Next I repurposed the slotted hole on the old spring plate as well using a chop saw to cut it down to size, then a bench grinder to clean it up for welding. The slotted hole allows you to account for differences in hole cut in the body and angles between the tool and installed spring plate.
I ground down the end cap oblong so I had a ridge to weld to.
***NOTE: Be sure to weld the end cap onto the splined end! If you close off the other end, it will be extremely difficult to use the tool since you would have to match up the splines between the installed spring plate and the tool.***
Clamp it down and weld it up. Extra credit if you weld all the way around.
All cleaned up.
Final tool set. I use the eyelet after pulling the bar out so I have something better to grab onto and an end that you can feel better about hammering on a little for re-assembly. I use the two nuts on the end of the threaded rod to release the rod from the end of the torsion bar if during tool use the threaded rod get tightened beyond hand tight in the end of the bar. I thought about welding a nut on the end of the threaded rod, but I like to use a ratcheting wrench on the tool so need it to fit.
***CAUTION: When making ride height adjustments using this tool, upon re-inserting the bar, only light force with a hammer is needed to seat the bar inside the inner splines. If you find you start to hammer harder, apply pressure down on the eyelet to rotate the inner bar end up as the bar may not be centered in the torsion tube carrier. Heavy hammering may damage the inner bar end or torsion tube carrier preventing later removal.***
I'll be adjusting rear ride height shortly and I was going to go with the slide hammer approach. This looks like an easier way, just have to make the tool.
