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Car Forum / Antique and Collectibles / Studebaker / April 2005drivetrain vibration revisited
don't know if I posted this... don't think I did actually, I've been real busy this week... anyway just following up on my vibration issue... history: '55 Stude coupe, total mutt mechanically, has '63 motor and late Flightomatic, original 3.31:1 rear end, driveshaft of unknown history and too short. I replaced the driveshaft myself with one that I believe to be correct for a Hawk with a single-piece driveshaft, replacing the U-joints at that time. Upon (finally!) driving the car I discovered a vibration starting at an indicated 30 MPH or so. Felt like a U-joint. what I found this weekend: put the car up on jackstands and crawled under it. For some reason when I replaced the driveshaft I had the car supported by the frame; this time I had the jackstands under the rear axle so the rear springs were loaded. I rolled under the car and immediately said "A-HA!" The tailshaft of the tranny is pointing down toward the ground, but the pinion of the rear axle is not pointing up AT ALL. So the driveshaft is making a sharp angle up at the slip yoke and going almost straight into the rear end. I pulled the driveshaft and the front U-joints were nicely worn in but the rear was still tight. I actually R&R'd the U-joint just to make sure the needles all were where they were supposed to be and they are; it just hasn't worn in because it apparently is running with zero angle on it. I've already got some springs on order... hope that cures it... darn thing runs so nice otherwise it's driving me nuts not to be able to cruise around in it... I guess if the springs don't bring the angles into a reasonable range I will have to look into some angle shims... does anyone know if the pinion angle WRT the ground changed when they went to the single piece driveshaft? nate  Signaturereplace "fly" with "com" to reply. http://home.comcast.net/~njnagel You want them both pointing in the same direction and about the same angle. I don't think the springs will change much. Use the shims. Alex M > don't know if I posted this... don't think I did actually, I've been > real busy this week... anyway just following up on my vibration [quoted text clipped - 29 lines] > > nate FWIW, on my current GT Hawk, and on a couple of hawks I parted out, the two U-joints on the one-piece driveshaft are deliberately mis-phased by about 2-5° I think this is an effort to prevent the rollers from brinelling the journals in the trunnions. Gord Richmond From '58, the nose of the rear axle points down slightly. At the same time, they went to a one piece drive shaft, rear springs that were shorter from the axle to the front mount, a flatter floor in the rear, and a one piece rear seat cushion - no center arm rest. Mike M. > From '58, the nose of the rear axle points down slightly. At the same time, > they went to a one piece drive shaft, rear springs that were shorter from > the axle to the front mount, a flatter floor in the rear, and a one piece > rear seat cushion - no center arm rest. > Mike M. really? I was assuming that I was shooting for something like this... _________________/ / <- axle tranny-> but it sounds like you are saying the driveshaft is actually arranged like this... \_________________/ (angles exaggerated of course) wish I had a later Hawk sitting around to look at... nate Signaturereplace "fly" with "com" to reply. http://home.comcast.net/~njnagel I put a '61 engine and 4 speed in a '57 Hawk, doing the same conversion to a one piece drive shaft; first with the '57 rear, then with the '61. Late '50's Oldsmobile's used small diameter drive shafts, that helped with clearance problems. You would probably have to steal one at a car show, these days. It was easy to find one the right length at a junk yard, in the '60's. The 4 speed yoke was very long and gave a lot of range; so close was good enough. Hurst sold what they called a cross member stiffener for Stude coupes. If you were converting to a one piece shaft, you cut the bottom center out of the crossmember that mounted the middle U-joint, and replaced it with their dropped piece. It really only amounted to a safety hoop. If the cross member was stiffened, it wasn't fastened to the frame well enough to help much! It's simpler just to remove that cross member. Looking from the side, I remember little or no angle at the rear, with the '57 axle. There was some, as you show, with the '61 axle. It would straightened out under power, as the springs twisted. From the side I think it was pretty straight at the front. Looking down, I think the engine and trans were offset, and maybe angled in the chassis. It's a 3D car! This would have kept the U-joints busy, and prevented brindeling. Mike M. When I first got my '63 Lark, it had a similar vibration. The previous owner had tied off cables under the dash with string and placed tape and cardboard all over to keep all of the rattles quiet. What it finally wound up being, was a distorted front yoke, which slides into the transmission. Upon inspection it apparently resulted from a failed u-joint driven to destruction. I replaced that and the problem was gone. N8, you might want to try the drive shaft that was in the car when I sold it to you, the shaft under the porch could be bent or out of balance. > When I first got my '63 Lark, it had a similar vibration. The previous > owner had tied off cables under the dash with string and placed tape [quoted text clipped - 3 lines] > u-joint driven to destruction. I replaced that and the problem was > gone. SignatureJP/Maryland Studebaker On the Net http://stude.com My Ebay items:http://www.stude.com/EBAY/ 64 Challenger (Green Wrapper) 63 R2 4 speed GT Hawk 55 Speedster 50 2R 10 truck That would only be a stopgap; I think I'd be right back where I started with the e-brake cable interference! n (if it ain't one thing...) > N8, you might want to try the drive shaft that was in the car when I > sold it to you, the shaft under the porch could be bent or out of balance. [quoted text clipped - 15 lines] > 55 Speedster > 50 2R 10 truck |
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