[Hans Buijnink (72challeng]

When balancing the driveshaft (or propshaft Dave) are there any special things to keep in mind? With/without joints/jokes? I just got it back for the second time from the balancer but the vibration it gives me is very bad. Even worser then after the first time. From 3000rpm you get the idea the car is coming apart. So after installing I drove 500meters and got it off again. And yes I'm sure it's caused by the driveshaft. Hope somebody can shed his/her light about this!

[Dave-R (Roppa440)]

Yes it is usual to have it set up and balanced with the universal joint and the front slip yoke included although I don't know how they actually do it and if those other bits may be just to set the driveshaft up in the machine.

Are you 100% sure the engine/trans centerline and the pinion in the diff are completely parallel? Also the driveshaft needs to be at exactly the same angle at each end to the part it is connected to. That angle should be between one and three degrees as shown in the diagrams here http://www.challenger440.pwp.blueyonder. co.uk/cgi-bin/disc/show.cgi?tpc=6&post=1 0062#POST10062

I had my diff set at an angle as recommended by drag racers, mopar performance etc and it caused a vibration exactly as you describe above over 3000rpm.

[Hans Buijnink (72challeng]

Nop, not sure... I never checked it and changed it either. As there wasn't that vibration in the past I assumed it should still be ok.

How did you check the angles Dave? I mean the driveshaft is a staight part to put measuring tools along but what with the transoutput and pinion... I guess I'm missing something here...

[Hans Buijnink (72challeng]

OK, I just studied the service manual a bit.

- Centerline of the engine/trans is the oil pan rail = underside of the engine block.
- Centerline of the diff is the mounting pads of the pinion snubber = the same as housing gasket minus 90degree. Using this is more calculating but there's more 'room' to measure.
- Centerline of the shaft is duhh...

The angle between the engine and driveshaft have to be between 177&180 or 0&3 degree depending how you look at it. (in fact it's same) and the same thing for the angle between the driveshaft and diff. Then both angles have to be as close to eachother as possible. Just like the fig. in the link. From your earlier message (see link) I understand if it's possible go for 2degree for the smoothest ride.

I'll take an anglefinder from work this week and check the whole thing. I will then measure all the different angles in contraction with, please help me out here, the "waterline??". Them with some calculating I hope to be able to set it all as it should by shimming the trans as I don't want to go the "shim the rear axle" route. I'll keep it all posted.

[Dave-R (Roppa440)]

I believe the starter motor case is level with the crank too Hans if that is easier. I removed the pinion snubber and placed the angle finder on the machined flats. I hope your angle finder works better than mine. The cheap one I bought measures different depending which way around you hold it!

The only other thing it could be is the tailshaft bush that the slip yoke fits into. If that bush is worn, or if the driveshaft does not slide into it far enough, you can get a bad vibration from that.

One more thing. If the engine has been allowed to drop at the back at some point (removal of the trans for example) it can result it the crank pulley at the front hitting the k-frame and the pulley bending slightly. This happened on my friends small block Barracuda and he had a vibration above certain speeds.

[Hans Buijnink (72challeng]

It has to do with the shaftspeed as:
- with changing gears in the rear it kept coming in on the same rpm while the mph differs.
- it's not engine rpm dependable as it's only when running 3000rpm in 3th gear, or very high rpm in 2nd gear (the mph is that time the same as 3000rpm in 3th)

So what's left is the driveshaft.

It's not the bushing on the end of the tailshaft as it's replaced last winter. My quess is or bad balancing company or what you said about the angles as the whole thing (engine & trans etc.) has been out last winter.

[Dave-R (Roppa440)]

I agree with your last statement.