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Posted By Discussion Topic: Vibration in new drive shaft, maybe -- page: 1 2 3     35gal 04-16-2011 @ 5:53 PM reply profile send p.m. Member Posts: 66 Joined: Jan 2010 I had my 1936 driveshaft modified by cutting off the existing 10 spline female coupling and welding a new 6 spline coupling. I put in new 3:54 gears. Now, with the new modification, when I drive the car, it drives smoothly till I get around 45 mph and then there is a slight vibration and a little faster and it goes away. Am I correct in thinking that if the coupling was not welded in round with the shaft centerline, that there would be a vibration regardless of the speed I go. It has been so long since I drove the car before the modification that I do not remember if the vibration was there or not prior to installing the new 6 spline coupling. ford38v8 04-16-2011 @ 6:05 PM reply profile send p.m. Senior Posts: 2736 Joined: Oct 2009 35gal, Never having had an unbalanced driveshaft, I can only guess at the cause, but you can certainly inquire of the shop that did the work whether your crank had been balanced or not. If your crank is solid, you may have damaged the center bearing in the removal/replacement. No such worry if it is hollow. Another possible cause of your vibration is the condition of the tires. Since your car is a '36, you may not have had the wheels properly balanced due to the wide 5 bolt pattern. And even if they had been balanced, the long term storage may have had an effect on them. Alan supereal 04-16-2011 @ 6:07 PM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 It it likely you have a "periodic" vibration caused by an out of line driveshaft. Any will cause a vibration to come and go as the shaft resonates. Anytime a driveshaft is altered or welded, it must be checked with a dial indicator to be sure it is true. We did one last year for a customer with the same problem. The place that had worked on the shaft had done two for him, and neither was correct. We do them in a long bed lathe and both check for straightness and balance. Just sticking an adaptor on a shaft and welding it usually doesn't work. I suspect you are right in your suspicion. kubes40 04-16-2011 @ 6:30 PM reply profile send p.m. Senior Posts: 3370 Joined: Oct 2009 Super is right on with this (as usual). I might ad that driveshaft issues (poor universal joints, out of balance shafts, bent / out of 'true' shafts) have a tendency to show their worst at approximately 35 to 45 MPH. 35gal 04-16-2011 @ 8:11 PM reply profile send p.m. Member Posts: 66 Joined: Jan 2010 I don't think anyone could of done a better job then this guy. I took it to a drive shaft shop and stay with the guy that worked on it. It took him about 4 hours. He had a long bed lathe. He center the shaft up in the lathe with a mick on the front and rear. Bored out the old 10 spline and press in the new 10 spline. Mick it and then made 4 spot welds equally spaced on the diameter of the spline and then finished off by welding all around. supereal 04-17-2011 @ 10:17 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 From your description, it sounds as if the process was right. It may be that the rear spline adapter was not aligned with the rest of the shaft. We use a piece of an old pinion spline to chuck the adapter, and a steady rest for the shaft, and check the finished results with a dial indicator. It only takes a few thousanths misalignment to cause vibration. We spin the modified shafts up in the lathe to be sure they don't whip. This message was edited by supereal on 4-17-11 @ 10:18 AM 37RAGTOPMAN 04-19-2011 @ 9:31 AM reply profile send p.m. Senior Posts: 1941 Joined: Oct 2009 try balancing the wheels before you remove the driveshaft,or have them balanced. you could also remove the rear wheels, start the car up, make sure is stable on jack stands,or blocks so it will not come off,,,, go though the gears, get it up to where the vibration should be, and if the vibration is still there without the wheels. if it is still there,, I would locate a solid drive shaft and tube, and replace the whole assembley. being it would be hard to repair what has been done, there should be some driveshafts and tubes available, this is what I did on my 37, when I installed the 354-1 ratio. I also had the hollow driveshaft, and saw the adapter, and said no way,welding,,, will I go though this, hope this helps. hope you have good luck, 37RAGTOPMAN MOXIE 04-21-2011 @ 7:23 PM reply profile send p.m. New Member Posts: 102 Joined: Oct 2009 I plan on modifying my 35 hollow driveshaft and was wondering about the solid drive shaft. I did not know they had solid driveshafts for 35/36. Could you give more detail about what type of shaft you use and what was modified about it 37RAGTOPMAN. supereal 04-21-2011 @ 7:38 PM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 The solid shaft requires a torque tube with a center bearing. Most problems with a shaft adapted for a six spline pinion are caused by the adapter, which has the splines out of line with the outer part. Even though the adapter is welded carefully to the shaft, it wobbles. That is why we mount the adapter on a spine in the lathe and machine it to be true before welding. Driveshaft work is exacting, and requires special attention to avoid vibration. 37RAGTOPMAN 04-22-2011 @ 6:00 AM reply profile send p.m. Senior Posts: 1941 Joined: Oct 2009 Moxie you will have to find a driveshaft tube with the grease fitting on it , close to the center, this should have the solid shaft, it might be from a 37 or 38 you have to measure the length, I have some solid axles that came out a 39-40 MERCURY, these have the longer 6 spline adapter,[ these made up the difference from FORD to MERCURY ] but do not have the correct shorter size tubes to go with them, it is a whole lot easier,to go this way, I was not too impressed with the idea, of a weak link in my drive system, you will have to check out a few flea markets, hope this helps 37 RAGTOPMAN,,,, hope this helps.

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