What This Mod Does:
When half-shafting your throttle body, what your doing is removing the front half of the throttle blade shaft. This mod allegedly increases airflow, but there is no evidence that it increases horsepower.
Should You Do It:
Probably not. The info is here because some people have an interest in doing it. I wouldn’t recommend this on any forced induction engine with a supercharger or turbo. The risk to this mod would be that you would weaken the shaft and cause it to break or bend. While some people recommend grinding the butterfly and making it thinner, this could cause it to bend and stick.
Activities and vehicle modifications appearing or described at The Ranger Station and it’s pages may be potentially dangerous. We do not endorse any such activity for others or recommend it to any particular person – we simply describe the experiences and opinions of other Ranger/Bronco II owners. If you choose to engage in these activities it is by your own free will and at your own risk. Any and all modifications will likely cause a vehicle to behave differently than stock. Some modifications may significantly increase your risk when driving the vehicle or be dangerous in some driving situations. Use good judgment when engaging in any activity or making any modifications. Do not take unwise risks. Consult a certified professional if you are not sure of something. The Ranger Station and the authors of these articles assume no liability for how any particular individual chooses to use the information presented here. Some of these modifications may void your vehicles warranty. Please also read our Legal notice HERE.
With the throttle wide open, carefully grind the threaded ends off the throttle plate screws (since they are “staked” to keep them in place), and remove the butterfly plate. Look CAREFULLY at the throttleshaft, as you are going to cut the drilled side off, leaving just the threaded half of the shaft (know as “half-shafting”).
Once you are absolutely positive which side is to be removed, use a coping saw or cutoff wheel to remove that half of the throttle shaft. Carefully grind the remaining nubs flush. This simple mod will increase the air through your stock TB at least 5%.
To reassemble, center the shaft and tighten ONE screw. Treat the other screw with 3m Loctite 271 “Red” for a permanent mount. After it has set (5 minutes or more), remove the remaining screw and Loctite it as well. After they have completely cured (24 hours), grind any exposed threads flush with the throttleshaft. Cheap and easy!
When comparing the photo above and the photo below, you can see where the throttle body will get a smoother flow after the mod has been performed.
Make sure you clean everything up and polish when you have it all apart!
I’ve also seen this mod done where the shaft was ground down, but not completely cut off from one side.