centering rearend?

well i back-halved my truck and never gave any though on centering the rearend. whats the best way to determine where it should be. hindsight is always 20/20.

get a wheel base deminension of your truck .. set the wheel base on it by measuring from the center of the front wheel to the center of the rear wheel on both sides.. then measure from say the notch to the lip of the wheel on both sides and equal it out..

now you're centered!

thats if your backhalf is square

Originally posted by 72bumpside



thats if your backhalf is square

Exactly! I usually measure form several different places to find placement for the rearend. You may need to run a string down each side of the cab (make sure that they are tight) and measure from those. You can align a vehicle the same way.

I would probably measure from somewhere up front if possible, something you HAVENT changed...

Measure from the front suspension?

Aligning it to the center of the truck should be easy, don't do it from each rail though, both sides should be even from the exact same location (centerline of frame).

Making sure its straight once its centered can be done with the front wheels, measure it as you would for checking wheelbase, from center of hub to center of hub.

This should keep the wheels aligned even if the backhalf isn't square. Once you get into travel, it not being square will bite you in the ass..

Measuring from the front suspension can be tricky. It's tough to get to and the front end turns.

So how do you get a good place to measure from?

Unless the cab is off an you have it on a rack, your only real bet is to find a few markers on the frame (ie. a factory hole) that you can make fairly certain is square. Most of the time (after I have leveled the truck out on jack stands, to within a 1/16") I will take a square and find a point on the frame that is mirrored on the opposite side and mark the ground, using the square as a repeatable transfer tool. After checking several points (probably about 3 if all goes smooth) to each other then I can base the rearend off of that.

This all takes a lot of time. The last truck that Steve and I did here took us one full day to lay everything out and make sure that we were comfortable with all of our geometry. But spending that time is always an advantage. The entire rear subframe and 4-link only took 5 days to finish, becasue it had all been figured out already on the ground.

Max you need to get a publishing deal to come out w/ your own chassis building book or your own magazine or whatever either way I would think every single person on this site would buy

I actually sat down to write a general rule-of-thumb type book for airbag syspension, but the time that even the first chapter took was way more than I had to spare. I still think about it though, maybe some day.