View Full Version : driveshaft twisted like taffy and broke

Ricky Jones
05-24-2016, 02:55 AM
Had my 62 Cadillac Eureka Hearse in the shop for brake work. Mechanic called me and said they put it in reverse and the driveshaft broke in the shop.

Mechanic said be thankful it did not happen on the freeway as the yoke would have torn up the floor.

It was twisted and broke a foot or so from the yoke. My mechanic said he thought the tube was too small and thin.

Had this rebuilt with new tubing 10 years ago.
Driveshaft shop said it should not just twist and break unless under very heavy torque like wheel stuck in a hole. They were in doubt of the mechanics story.

I look at the driveshaft and it seems small for a 7300lb Hearse. That is what it weighed in at when it was brought to Hawaii.
Can anyone tell me what diameter of front and rear tubing? And thickness.
Thank you

Paul Steinberg
05-24-2016, 08:55 AM
The tube diameter, has to match the end yokes, and there is no variables about this, because the end yoke has to have a specific cross bearing installed into it. As for the thickness of the tube itself, I have never seen a variable in that thickness, since any driveshaft shop worth its salt, wouldn't use sub quality materials. I would take it back to the driveshaft shop that did the original work, and have then repair and balance the new driveshaft. Once they see it, they will be able to tell if it was abuse or not. Only time that I have ever seen a twisted driveshaft, is when there is abuse involved.

Peter Grave
05-24-2016, 09:32 AM
I am with Paul ABUSE like dumping it in reverse either revved up or just started at very high idle. Reverse is to lowest ratio gear in the transmission and thus will put the MOST torque into the driveshaft. We towed many a dump truck with the driveshaft split from the driver getting stuck and revving in reverse to try and get out and bang there is the shaft split.

Ricky Jones
05-24-2016, 01:55 PM
Yes that is basically what the drive shaft shop guy said.
My start up cold idle is high. About 1,100RPM till it warms up.

Like you said maybe they started and just put in reverse.
Thank you Peter and Paul.

John ED Renstrom
05-24-2016, 11:43 PM
strange to say the least. 1100 doesn't sound high enough to wind one up. that got to be close to normal on high idle. the tube size is always a question they go up they go down. big dimanter ones are paper thin the small ones are thicker. mu question would be did something brake first?

Darren Bedford
05-24-2016, 11:55 PM
Kim had her drive shaft twist into a 90 degree angle and fly out at highway speed going to the PCS meet in Rochester MN when the differential locked up.

Wasn't figured out until she had a new drive shaft made and installed before finding out the differential was the issue. They originally thought it was a u-joint that let go.

There are photos and a story here... http://www.professionalcarsociety.org/forums/showthread.php?t=16098&highlight=drive+shaft


Darren Bedford
05-25-2016, 12:01 AM
Yours help up for 10 years so it must have been fairly decent when rebuilt.

Hopefully you find the real reason it twisted. You just need to get it done again. Just make sure it is done properly if it wasn't done very well the last time.

At least get them to inspect it and find out more before doing it this time.

Hope you driving down the road again real soon,