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4-Speed Shifter Tech TipsAny car character can get shifty
The name Hurst will forever be linked to the 4-speed transmission. Though in production prior to the 1964 introduction of the GTO, the coupling of the two validated the performance of one another. Today, the 4-speed transmission and Hurst shifter continue to dominate the drivetrains of musclecars.
Talk to any number of musclecar enthusiasts and most will recite moments of frustration with their 4-speed transmissions. At that all-important moment, running hard, side-by-side, a shift was missed and the other guy won. After being run hard for many years, it is not necessarily the transmission's fault-it is likely just an out-of-adjustment shifter, the mechanical one, not the one behind the wheel. We recently spent some time with fellow racer and "shifty character" Bill Baker to gain some insights into methods of keeping your 4-speed shifter on the mend. Baker has been rebuilding transmissions for decades.
Anyone with average mechanical skills utilizing normal hand tools can perform the checks, repairs and updates that we will demonstrate here. Welding may be required for some repair. The work is more easily performed with the transmission out of the car, but you can perform this Hurst 4-speed shifter tune-up with the transmission in your car. You may, however, need to remove the shifter and linkage as you make the necessary repairs.
Before any disassembly, take a good look at your shifter linkage as installed on the transmission. Give each of the shifter rods a jiggle and note the looseness of the rods. When reassembled, this rod shake will be nearly eliminated.
One of the main wear items and one most overlooked are the shift levers that attach to the transmission. On hard 1-2 power shifts, wear occurs that diminishes the ability of the shift detent in the transmission to return to Neutral. To troubleshoot this problem, first place your shifter in Neutral then insert an alignment tool (1/4-inch rod or drill bit) at the base of the shifter, aligning the three shifter levers. With your transmission now in Neutral, remove the alignment tool. Shift your transmission up into 1st gear, down into 2nd gear then return to Neutral. Place your alignment tool back in place at the bottom of the shifter. If this does not go in without interference, the likely culprit is worn shift levers at the transmission.
The lever nearest the front of the transmission receives the most wear (that hard 1-2 power shift) and is usually the culprit. Its rectangular hole becomes widened top and bottom giving the appearance of a bow tie. This slop prohibits the internals from returning to the correct Neutral position resulting in missed shifts or hard engagement. The quick and easy fix is to just swap the two levers, as the rear lever receives the least amount of wear. But this quick fix is only a short-term fix. You'll be back to complete the repair later.
Both of the levers on Bill's transmission required fixing. Depending on the amount of wear, there are two fixes easily performed. In the worst case, you will need to braze or weld the worn areas then file fit each hole to fit back onto the transmission. If the lever is not worn too bad you can reshape the hole by using a hammer and center punch. Lay the lever on an anvil (the back of your vise) and make punches around the perimeter of the hole. This will swell the metal back into place. With these levers fixed, you can be assured of positive engagement and disengagement of the gears.
Well, how do you inhibit this wear from reoccurring? Make certain that your shifter is adjusted properly. Unfortunately most of the Competition Plus shifters installed in our Pontiac did not come with this capability: shifter stop bolts. Hurst gave the "shade tree" mechanic a head start that makes the addition of shift stops easily achieved. The shifter body has holes stamped front and rear in the proper place to be used as pilot holes. Just drill, tap and install a 3/8-inch bolt and jam nut and you have added the shift stops.
With the shift stops installed it is time to reassemble the shifter linkage and adjust the shifter. This includes the tightening up of the earlier identified shift rod rattle. When making your trip to the hardware store for the 3/8-inch bolts and jam nuts for the shifter stops, you will also need to pick up a few new lock nuts and hardened washers, both flat and spring wave. You should have noted in your disassembly of the shift rods from the transmission levers that a spring wave washer was used to take up some slack. Over the years the spring gives way and the "some slack" turns into a lot of slack. We found these new heavier spring wave washers in the metric section at our neighborhood Ace Hardware.
Install the levers back onto the transmission with the new lock nuts and hardened washers being careful to not over-tighten the nuts. With a standard length wrench, you can easily put 15-20 lb.-ft. of torque on these. Next install the shift rods to the levers using the new spring wave washers. Do not tighten these up just yet. That is done during the final adjustment process.
Now affix the other end of each shift rod to the shifter levers. Before you install the spring clips, add a hardened washer to take up the slop. After you install the spring clips, take needle-nose pliers and bend up the ends of the spring clips. This will ensure the spring clip stays in place. Put the shifter into Neutral and slide in your alignment tool.
With the shifter in Neutral and the transmission in Neutral, tighten the nuts where the shift rods attach to the transmission levers. Remove the alignment tool and firmly shift through the gears. Return to the Neutral position and you will see that your alignment tool falls right into place.
Ready, Set, Go
The final operation is to set the shift stops. This is easily done, but one would be surprised at the number of shifters (with adjustable stops) that are improperly adjusted. First, make certain the stops (bolts) are backed out. Place the transmission in 1st gear then firmly shift down into 2nd gear. Tighten the stop bolt until it touches. Then back the bolt out one complete turn and tighten the jam nut. Repeat the procedure for the other stop by placing the transmission into 3rd gear. You'll now have firm positive shifts.
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