Pinion angle has been over explained on here several times. I searched and didn't find much on this piece of the puzzle. My question is WHEN? When is the time in your build to weld the leaf spring pads on the rear axle? I know - at ride height. So, optimal time is when the car is complete, on level ground, spare in the trunk, half tank of gas, and 2 p***engers sitting in the front for as close to "normal" conditions as possible. Can I do it with a bare ch***is and be close? Do I wait until eng/trans is in and have a couple big guys sit on the rear? Or, do I need to wait until the body is back on? It would be much easier now with the bare ch***is. Not trying to kick the hornet's nest again, just want to know how the experts attack this part of the build.
^This is how I've always done it. I'm no expert, but I always wait until everything is done and locate the axle last. Never had a problem doing it this way.
I’ll get flamed…… maybe bet the last couple I did, I welded those in last. Sitting at ride height on a lift (drive on)with everything in it. But sometime during the build stage, there should be a time when most of its together. Probably minus interior. For folks that build multiple frames for a living, that’s usually figured out on the first frame build and duplicated on the rest
I want to take the easy way out and do it before the body is back on, I understand the "tighten the U bolts and wait" approach, and I'll probably do that. I'm not an engineer and don't know how much it changes, or even how far it will drop with the weight on it.
Technically, if you build it at ride height, the angle will not change if you keep it at ride height. If it drops height when you are done, and you don’t make the changes to correct the ride height then it makes no sense to build at ride height. That’s building at whatever happens Kinda hard to set pinion without an engine and trans on custom build
We dropped a 50s step van without the body on it We figured the ride height off the body mounts. We established a datum line and zero plane from the body and used those on the ch***is. So we were able to do suspension mods, engine mounts, rear end set up and drive line angles at our imaginary ride height. When we sat the body on, it all worked out.
@anthony myrick That all makes sense. I've never been able to know where the ride height ends up, without having the springs compressed. If you know the spring rate and the weight over it, should be easy to figure out. I don't know those factors, so I guess I'm stuck with waiting until I get farther along to weld those in. I might have to adjust ride height after it's all together and I can see the stance, so waiting seems correct. Thanks.
I had one instance where it didn't work out. I put a SBC in a one ton AD panel truck using a '60's truck bellhousing with modified crossmember mounts. Bolted up the trans and left the pinion angle as the factory had it. Had a vibration at speed and determined the pinion angle was too far off and had to be corrected by cutting the axle pads loose and adjusting them to get proper angle. Learned something on that one and ever since have always waited until last to set pinion angle. Never a problem after using this method on the others I've done.
I dont know spring rates either. most of my springs are from junk yard but if you build at ride height, and know the spindle and axle centerlines work, then it’s just figuring out the spring.
I always went the simple way. Build the car, put the rear end in and just tighten the U bolts. When the car is finished with all the parts put together, interior, engine, trans, gas tank etc. Then I set the pinion angle and weld the spring perches to the axle. Always comes out perfect.
I guess I knew the answer, but just wanted a shortcut. I've seen it done before the car was completed, but didn't know how it was achieved. I can understand building to ride height and adding the correct height springs after, but if you have no height adjustability, you will have to settle for whatever spring gets you the look, regardless of spring rate. It may not ride well. And I'm not going to add race car style adjustable suspension to this street car.
I’ve done it with factory springs Educated guessing that involves measuring. One just required 1/2 front coil removed and a 2 inch blockin the rear to get it how it was built once ***embled. Built with a 4 inch Z on 3 inch spindles in the front with junk yard springs and hangers on an axle flip Pinion angle was welded after the 2 inch block was installed I call that a win building from the s**** yard
Although the approach was a little different, the principle was the same with how I did it. I am using C10 truck arms on my Buicks that have rear coils. With the body and ride height weight still on, I measured with a straightedge the angle from X-member where the arms mount to the axle and subtracted the pinion angle "up" to match the driveline angle "down". Set the mounting pads on my 9" rear at that angle. I also had to account for the angle side to side the pads required for the arms. The other thing I had to account for was the 14-degree angle the arms have at the rear end of the arms.
Driver and p***enger weight really isn't something I ever considered when setting pinion angles. If it was that critical you'd always need others in your car to keep the angle right. I wouldn't even worry about driver's weight. I do make sure the whole car is together, and my tires and wheels are on it before tacking the perches to the axle. I put equal height blocks under each tire to maintain the ground height. Then once the perches are tacked I drop the axle out and weld things up permanently.
Facts. The angles change when you drive if. E****slly a loaded truck You make the best educated guesses you can. So far so good for me. one reason I like 2 piece driveshafts. Easier to set up on stupid low stuff
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