Help with drive shaft problem cause by lowering

[JGross]

I’m putting my 65 short fleet back together and I think I may have caused a problem with the drive shaft. The PO had installed a 350 small block and a TH400 trans but had never driving the truck. When I got the truck I pulled body off the frame and started my rebuild. The PO had already put 2.5 inch drop spindles on the front so I put stock springs on the front and 3 inch drop springs on the back. I looked at the frame crossmember that has the hole In it for the drive shaft and noticed that the drive shaft was closer to the passenger side of the hole. There was only about a half inch between the drive shaft and the crossmember.

Well I now have the body back on the frame and last night while I was under the truck bolting down the bed wood I noticed that the drive shaft has moved further toward the passengers side, now there is only a 1/16 inch between the drive shaft and the crossmember. I think the panhard bar is pushing the diff over because I lowered the frame. Do I need to shorten the panhard bar?

Thanks

[PGSigns]

You need to put an adjustable panhard bar in it to get the rear back in the middle of the truck at ride height. With it at ride height check the spacing of the tires to the frame rail and see what it is going to take to get them back to equal.
Jimmy

[JGross]

Thanks,

Is there any reason I can't just cut and reweld the stock bar?

[turbostar]

J,something does not sound right here.I also have a 65 swb with the same setup-2 1/2 drop spindles in the front and 3 in lowering springs in the rear and I have no problem. I will crawl under mine later and see if I can visualize your problem.

[61_FL_Apache]

Originally Posted by JGross

Thanks,

Is there any reason I can't just cut and reweld the stock bar?

This can be done. Thats the way my 65 was, but installed an adjustable one on my 61.

[PGSigns]

The adjustable ones are not that expensive and it makes the job much easier. You can cut the bar and put a sleeve around it and weld it up but if it is a little off then it is hard to change. And if you decide to drop it again it is just a simple adjustment and you are done.
Jimmy

[turbostar]

J,I just crawled under my truck without jacking it up and took some rough dimensions which will show that there is probably another problem with your truck. From the front u-joint to where the drive shaft passes thru the crossmember is roughly 15 in and from that point to the center of the rear axle is roughly 53 in. My driveshaft is pretty close to centered in the crossmember and for the rear end to be offset enough to move the driveshaft 1 in at the crossmember would mean the rear end would be offset by around 4 1/2 inches. Surely that would be noticeable. I think you have another issue and changing track bar length would only mask another problem. I would start by checking to see if the transmission tailshaft is centered in the chassis.

[JGross]

Originally Posted by turbostar

J,I just crawled under my truck without jacking it up and took some rough dimensions which will show that there is probably another problem with your truck. From the front u-joint to where the drive shaft passes thru the crossmember is roughly 15 in and from that point to the center of the rear axle is roughly 53 in. My driveshaft is pretty close to centered in the crossmember and for the rear end to be offset enough to move the driveshaft 1 in at the crossmember would mean the rear end would be offset by around 4 1/2 inches. Surely that would be noticeable. I think you have another issue and changing track bar length would only mask another problem. I would start by checking to see if the transmission tailshaft is centered in the chassis.

Thanks for the info I'll check the trans tailshaft before I do anything to the panhard bar.

[JGross]

Originally Posted by turbostar

J,I just crawled under my truck without jacking it up and took some rough dimensions which will show that there is probably another problem with your truck. From the front u-joint to where the drive shaft passes thru the crossmember is roughly 15 in and from that point to the center of the rear axle is roughly 53 in. My driveshaft is pretty close to centered in the crossmember and for the rear end to be offset enough to move the driveshaft 1 in at the crossmember would mean the rear end would be offset by around 4 1/2 inches. Surely that would be noticeable. I think you have another issue and changing track bar length would only mask another problem. I would start by checking to see if the transmission tailshaft is centered in the chassis.

Thanks for the info I'll check the trans tailshaft before I do anything to the panhard bar.

[turbostar]

J,here's some more info that tells me your problem is not with the track bar. That bar is about 24 in long and I just measured distance from the ground to the pivot points. The axle pivot is 17 inches high and the current frame pivot is 16 inches high. This would mean with a 3 in drop spring,that it was probably 19 in at the frame before(went from 19 to 16). Since the transition went thru horozontal,the effective foreshortening was the same as with a 1 in drop. I calculate that to be less than a tenth of an inch that the axle would have shifted side to side with the drop. That will not cause the problem you are describing,obviously. Hope this is clear enough to help.

[Str8axle]

There's further discussion on this topic here......

http://67-72chevytrucks.com/vboard/s...d.php?t=430738

[JGross]

I checked last night and the trans tailshaft is pushed 1 inch to the passangers side. I'll relocate it and that should take care of the drive shaft problem. Thanks for all the help.