Dinged drive shaft

[47heaven]

A few weeks ago I had taken my P15 out to show Bob Amos at his shop. While it was up in the air, he noticed that there was a dent in the drive shaft and said that it would cause it to spin off balance a bit, which is true because I notice a viberation as I reach higher speeds. Can the dent be taken out and fixed or do I have to buy a new/used one, and if so, where? I was told a driveline place could fix it, but where do you find one of those?

[PatS....]

I don't think you really have to remove the dent as much as have the driveshaft balanced to negate the effects of the dent.

[p15estep]

i believe that have a decent used drive shaft. but i live on the east coast and shipping would be alot probably. if you would post in the wanted section you may find someone near that has one.

[greg g]

Depending on where the dent is, you may be able to do a couple of things to mitigate the vibration. (which may or may not be caused by the dent) First thing to do is mark the shaft at both ends in reference to the flanges. Then swap the shaft end for end. If you have a ball and trunion u joint on both ends some of the vibration may be coming from either or both of them. Flipping the shaft forces them to work in a different spot in the trunion. Sometimes the trunion will get worn in the areas where the balls rest most consistantly, and glipping it will alter that relationship. You put the reference marks on so the shaft will go back on is the same rotational position fromwhichit was removed. If this doesn't work, try then rotating one end 180 degrees in relation to its flange. Probably most effective at the tranny end. Just drop the retaining bolts, turn the shaft 1/2 turn and reconnect. This should put the reference mark 180 degress off on that end. If that doesn't work, then do the same to the differential end. Of course this will require a road test between ieach step, but it may lead to a solution to your at speed vibration. Some one also suggested you can use a strobe light, like a timing light, flash it on the drive shaft with the car runing and the rear wheels off the ground probablyin second gear. The strobe will showuo if it is spinning truely or wobbling from the dent. You can also use hose clamps around the shaft to attempt to balance the shaft. The mass of the tightening screw works like a tire weight to damp rotational imbalance. try all these before looking for a driveshaft shop. The drive shaft shop wopuld most likely be foundin your Yellowpages under drive shafts or U joints. And is probably located in that seedy industrial side of town where they fix commercial equipment and trucks.

[De Soto Frank]

A little ding, not too deep probably isn't too bad; if it's a deeper ding that has also "sprung" the driveshaft out of "true", then it would be best to replace it...

A driveline shop should be able to put a new tube between your stock ends, or even give you a complete new driveshaft with modern u-joints and adapter flanges to bolt-up in place of your old Ball & trunnions...

If you're running the car at highway speeds ( faster than 40 MPH), having a sprung driveshaft "whipping" around at 2,000+ RPM will take its toll on the entire car: tranny and pinion bearings, motor mounts, will begin to shake chassis stuff loose...

I'm probably going to have a new driveshaft made-up for my '41 De Soto when I swap in the Overdrive tranny... ( if I live that long... new tranny's been sitting on the garage floor going on 4 years now...)...

Good luck !

[47heaven]

Depending on where the dent is, you may be able to do a couple of things to mitigate the vibration. (which may or may not be caused by the dent) First thing to do is mark the shaft at both ends in reference to the flanges. Then swap the shaft end for end. If you have a ball and trunion u joint on both ends some of the vibration may be coming from either or both of them. Flipping the shaft forces them to work in a different spot in the trunion. Sometimes the trunion will get worn in the areas where the balls rest most consistantly, and glipping it will alter that relationship. You put the reference marks on so the shaft will go back on is the same rotational position fromwhichit was removed. If this doesn't work, try then rotating one end 180 degrees in relation to its flange. Probably most effective at the tranny end. Just drop the retaining bolts, turn the shaft 1/2 turn and reconnect. This should put the reference mark 180 degress off on that end. If that doesn't work, then do the same to the differential end. Of course this will require a road test between ieach step, but it may lead to a solution to your at speed vibration. Some one also suggested you can use a strobe light, like a timing light, flash it on the drive shaft with the car runing and the rear wheels off the ground probablyin second gear. The strobe will showuo if it is spinning truely or wobbling from the dent. You can also use hose clamps around the shaft to attempt to balance the shaft. The mass of the tightening screw works like a tire weight to damp rotational imbalance. try all these before looking for a driveshaft shop. The drive shaft shop wopuld most likely be foundin your Yellowpages under drive shafts or U joints. And is probably located in that seedy industrial side of town where they fix commercial equipment and trucks.

Greg...thanks for the detailed troubleshooting information. Unfortunately, I don't have the means to be able to work on the car like that nor do I have a hydralic lift to lift it into the air, but I will keep the info in my notes.

Most likely I will end up taking it to a driveline place and either have it balanced or replaced. Bob A. said that the dent was big enough that it could cause vibration. Not sure how well off the u-joints are either. I certainly don't want to cause any damage to the rest of the car with the vibration, as Frank had mentioned.

[Normspeed]

Darin, you might check with Robert Smith on this forum. I believe he recently had modern driveshaft and u joints made up for his P15. He's local. I have an old shaft but it's a mess and wouldn't do you any good. Look in the yellow pages for driveshaft shops.

[47heaven]

Darin, you might check with Robert Smith on this forum. I believe he recently had modern driveshaft and u joints made up for his P15. He's local. I have an old shaft but it's a mess and wouldn't do you any good. Look in the yellow pages for driveshaft shops.

Norm....is this stuff pretty pricey?

[Normspeed]

I would imagine a new shaft with modern u joints might run between $100-$400 but that's just a guess. Robert could fill you in on that.

Some day I'd like to do that to my car, but it's not in the budget as long as I'm still muddling along with the old stuff. When it comes time to buy and replace stock u joints or shaft, that's a good time to look into switching over. New shaft, nicely balanced, with new technology joints would be a money saver down the road.

Here's a recent article with the name of a shop in Azusa:

http://www.hotrod.com/techarticles/driveshaft_custom_reworked/

[Normspeed]

Here's a shop right in Banning. Makes me wanna go get one made up right now!

http://www.banningdriveline.com/

[bob_amos]

Darin, Try this guy for the modern replacement drive line. Ed Moore Drivelines. (800) 200-9895. He's in San Bernardino, Ca. A customer of mine used him and his driveline is perfect. An easy install too. Price was in the $350 range for the entire set up. His car is a 53 Chrysler. Tony C. also had the same thing done to his car. Not sure who did it for him. He gave me the name and number but things being as they are, some one here at the shop lost it.. (Read that, I misplaced it.) Tony might still have the number. His price was about the same if I remember correctly.