The Stovebolt Site Forums The Shop Area Engine Shop Pinion nagle and driveline length

I'm setting up a 12 bolt rear end in my 53 AD 1/2 ton and have 3 maybe obvious questions. How do you get the pinion angle from a tork tube with the driveline attached? Take the measurement at the front of the driveline ,I'm thinking. Also, do I set the angle on the new rear end with the leaf springs fully relaxed? I mean with the truck jacked up and the springs hanging fully extended? I guess thats the only way. And finally, when measuring for my driveline length, should the yolk on the tranny, {saginaw 4 speed] be about in the middle of it's travel on the output shaft? My driveline has no slip joint, 1 piece fom a 70 1/2 ton chevy. Thanks, any help appreciated.
joethehuman
53 3100

Maybe I'm not explaining myself correctly. In order to set the new reaend at the proper angle, I think you measure the old reaend by placing it on jack stands and rotating it until the spring perches are level, the measure the angle at the yolk bolted to the pinion. But in a torque tube the pinion is inside the tube. So how is it done? And a drive line measurement, to get it accurate,should it be taken with the springs at the position they would be in with the tires sitting on the ground? In other words with the driveline a little more level than it wouldbe with the truckjacked up. Hope this makes sense.
joethehuman

Try this post, https://www.stovebolt.com/ubbthreads/ubbthreads.php?ubb=showflat&Board=1&Number=340366&Searchpage=1&Main=47196&Words=dana+%2Bspicer+%2Bdriveshaft&topic=0&Search=true#Post340366
and download/print the Dana/Spicer manuals I linked to. They will answer all your questions and then some.

Some quick answers:
Don't worry about pinion angle with a torque tube, that's a whole different ball game, and nothing you can do to change it.

Set pinion angle with the truck on a reasonably flat surface, and loaded how it will be most of the time when driving, full tank of fuel, driver, and all wheels on the ground, spare tire installed too if you carry one.

Pinion angle is not so much a number, but a measurement that must be the same angle as the angle of the front u-joint, simplified it means you need the pinion centerline to be parallel to engine/transmission centerline (one piece open driveshaft) read the manuals for more details.

Yes, driveshaft length is measured with truck loaded as it will be most of the time, and with the slip portion of the shaft in the approximate center of it's travel. Also good to test that there are no problems with the frame bottomed out on the axle, and the axle at full droop, wheels off the ground.

If you don't have a slip section in the driveshaft its self, Then you have to have the slip yoke in the back of the transmission, many automatics are this way, many manuals are not.

Grigg

keep angle as close as you can around 2 or 3 deg on each end with tk sitting as it would be driving,,,you can do it on stands doesnot have to be level just figure angles as it sets...doc

Griggs and Doc 41's advice is right on the money. Just a suggestion....I use a cheap plastic angle gauge with magnet(from most hardware stores) and get my initial angle reading off the flat surface where the starter mounts to the engine block. On the diff, I work off one of the flats on the pinion yoke.

Dave

Thanks a lot guys. I think I've got a handle now. This project has been a little more difficult than anticipated, but what project isn't. If it goes too easy, I never remember how to do it the next time.Of course if it goes too hard, I may never want to do it again. But I'm sure looking foward to driving my new improved 53. I'm off to the hardware store for cheap plastic angle gauge. thanks again~~~~~~~joethehuman