Looking to tighten up the torsion bars to get AHC pressures down, would much rather put an impact on that big old rusted bolt than fight it with a wrench. Is this OK or will it damage something? I would turn the air pressure way down so the bolt wouldn't spin too quickly.
Impact Wrench to Adjust Torsion Bar?
- Thread starter Landseer
- Start date
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Soak them with penetrating oil.
No issue with mine with a open end wrench and front lifted off ground. Texas truck though so no rust.
FWIW the FSM says to do this adjustment with the vehicle on the ground, but if your TB bolts are rusted badly I guess you should hit them up with penetrating oil and do what you have to do.
The last time I did this I lifted the front, broke them loose with a breaker bar (probably unnecessary), then used my impact to adjust. Was SO MUCH FASTER this way than by hand.
You'll drop your pressure about 0.2MPa per turn on each side, how much are you looking to lower your pressures? You should be able to hit your target pressure in two iterations based on 0.2MPa per turn both sides, drive, retest with techstream then fine tune based on your post TB turn pressure readings.
- Thread starter
- #10
Did the adjustment about 2 months ago, figured I'd report back:
I used Techstream to measure pressure, it was 8 point something MPa (front). I had just replaced all 4 globes so definitely wanted to get the pressure down. I had sprayed the whole torsion bar adjustment mechanism with PB Blaster a few times over several days, the cruiser lives in Pittsburgh so there was a good bit of rust
. I used a half inch Aircat impact wrench on is lowest setting and turned the air pressure down (I think to roughly 70psi)
The impact took about 3-4 seconds to turn the adjustment bolt one revolution, definitely slow enough to stop at the right place. I started with one full revolution on each then checked the pressure and measured the height of each side. Measuring the height turned out to be kinda tricky: you measure from the top of the front tire to the bottom of the wheel well, this seems like it should be easy but both the wheel and wheel well edge are 3 dimensional curves with no nice right angles. Ended up putting a small flat piece of wood on the tire and measured up from that. The actual distance doesn't matter (for AHC trucks), just that the measurement technique is consistent between sides. This worked reasonably well but was only accurate to probably half a centimeter.
I repeated the adjust torsion bolts measure hight and pressure procedure probably 4 times until the pressure was in spec and heights were as close to identical as I could measure. Overall this took a little less than 2 hours. The truck sits level as far as I can tell and the lower AHC pressure should help prolong the life of the globes (expensive little buggers). The impact wrench is probably unnecessary for rust free trucks but I tried using a ratchet even after I'd broken the bolts loose and I couldn't budge it. The impact made this job much much easier and I will definitely be using it again if i need to readjust in the future.
I used Techstream to measure pressure, it was 8 point something MPa (front). I had just replaced all 4 globes so definitely wanted to get the pressure down. I had sprayed the whole torsion bar adjustment mechanism with PB Blaster a few times over several days, the cruiser lives in Pittsburgh so there was a good bit of rust
. I used a half inch Aircat impact wrench on is lowest setting and turned the air pressure down (I think to roughly 70psi)The impact took about 3-4 seconds to turn the adjustment bolt one revolution, definitely slow enough to stop at the right place. I started with one full revolution on each then checked the pressure and measured the height of each side. Measuring the height turned out to be kinda tricky: you measure from the top of the front tire to the bottom of the wheel well, this seems like it should be easy but both the wheel and wheel well edge are 3 dimensional curves with no nice right angles. Ended up putting a small flat piece of wood on the tire and measured up from that. The actual distance doesn't matter (for AHC trucks), just that the measurement technique is consistent between sides. This worked reasonably well but was only accurate to probably half a centimeter.
I repeated the adjust torsion bolts measure hight and pressure procedure probably 4 times until the pressure was in spec and heights were as close to identical as I could measure. Overall this took a little less than 2 hours. The truck sits level as far as I can tell and the lower AHC pressure should help prolong the life of the globes (expensive little buggers). The impact wrench is probably unnecessary for rust free trucks but I tried using a ratchet even after I'd broken the bolts loose and I couldn't budge it. The impact made this job much much easier and I will definitely be using it again if i need to readjust in the future.