36 Ford truck on Ranger

[Old Iron]

Do you have the vibration when you're running at speed, put the tranny in neutral and coast?
When does it vibrate?

[jfg455]

I know yow have been checking the up/down angles of the shaft but don't forget to check the side to side angles. If the rear is square and the motor and trans are cockeyed it can make the same vibration as the up/down relationship.

[MercuryMac]

OI, the little vibration is from 60 km to 80 km [35 mph to 50 mph], more so on acceleration but still there, slightly, coasting or holding back. It's the same as coasting with the clutch disengaged or the gearshift in neutral and the clutch engaged. The motor can be revved up or at an idle.
The vibration seems to get a little better from 50 mph to 70mph, but doesn't go away.
Jfg, the horizontal driveshaft to rear-end angle looks perpendicular but I haven't built a square to measure it exactly. My motor/trans to driveshaft angle is unmeasured, as I went to find my plumb line to line up the motor front to back and transmission, but couldn't find my transit, plumb line kit box. I think I lent it to a neighbour and forgot which one. I never got back to finding an ordinary piece of string. So it's one of my many neighbours fault.
How many degrees can I be off square and still be O.K.?
Oh ya, I measured the level of the frame in the only straight flat area and it is level. My frame can sleep comfortably in a grain auger, as can some of my acquaintances.

[jfg455]

Originally Posted by MercuryMac

How many degrees can I be off square and still be O.K.?

It is kind of like the up / down area. It the rear is zero and you start having 1.5-2+ degrees off on the front it will start to have weird harmonics. This is made worse when you start having lower rear gears (3:73, 4:10 etc) because the drive shaft speed is getting faster. If it is getting worse on acceleration but is still noticeable on coast speeds I would look for something moving like a bad mount, center bearing etc. Or in the pinion angle area.

[Skip]

http://ratrodsrule.com/forum/showthread.php?t=32943

A few good drive shaft setup tips here.

[MercuryMac]

Thank you guys.
Jfg, I used to think pretty good was good enough, now I'm thinking pretty dang good would be better. I had better get my angles closer to equal.
Skip, I looked at that U-tube before, and think it is the best thing since sliced bread.

[Skip]

Have you had the balance on the driveshaft checked yet?

Another thing that is suggested in the Freightliner troubleshooting is to disconnect the drive shaft, flip it over (180 degrees) and reinstall it. This can make it better or worse if there is a slight variation in the components. This can go for the yoke also.

[MercuryMac]

This is the second driveshaft Skip. Last year when I took the first new one back to town to a different machine shop, they threw it away, saying it was neither balanced nor really straight. This second one is all new and has a balancing weight on it so I assume it's balanced.
I'm going to try a few more things before I unbolt the driveshaft and clock it around, but thank you for suggesting another trick.

[MercuryMac]

So this spring I took the driveshaft off and measured the angle of the pinion flange. Whooa, not one of the flatish surfaces on the rear-end that I've been using to get my pinion angle, are actually the same as the pinion angle. Except where the back tin plate bolts on. If all of the bolts have the same height of heads, you could use that, I guess. While I had the driveshaft off I clocked it 180*, and then used four different holes in the pinion flange to bolt the back U-joint to. Oh yes, I also filed down the hatchet wounds on the pinion flange, so the U-joint will have a flatter surface to sit on. I then put 4* wedges under the springs and roared out on the maiden voyage for this year. Here's pictures of the truck this evening when we got back from the successful trip. We didn't feel any vibration through our seats. There was a little time, at 35 mph, that if you held your finger on the gearshift you could still feel the stick dance. I'm good with that.

[DozerII]

Congrats on getting the vibration worked out, now it's driving time.