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Drive Shafts

By Jeff Zurschmeide

Many restorers spend thousands of dollars to refresh their engines and transmissions, but neglect the driveshaft by giving it just a simple cleaning and a coat of spray paint. This is an error, and the consequences can be catastrophic if a universal joint or flex disc fails while youíre driving your car!

The most surprising thing about driveshafts is their low cost of restoration. Even if your car requires doughnut-shaped rubber flex discs (also known as a ďGiuboĒ [joo-bo]) or several universal joints, a complete inspection and restoration generally runs less than $200.

At that price, it makes sense to take your driveshaft to a professional shop for the whole treatment. A professional driveshaft shop will begin by cleaning and inspecting the whole assembly, making repairs if necessary. Most driveshafts are hollow to save weight, and they are often dented or bent by rocks, speed bumps, or other hazards.

Then the shop will perform the first of several critical jobs that are difficult for the amateur -theyíll replace the universal joints. These are the cross-shaped bearings that allow the shaft to spin at varying angles as your carís moveable rear axle rises and falls in relation to the fixed-mount transmission. Some U-joints (as they are commonly called) are held in place with removable mounts and are easily replaced, but some must be pressed in and out of their fittings. More than one amateur restorer has damaged or ruined a U-joint, or wasted hours trying to get the old one out and the new one installed!

After the U-joints and flex discs have been replaced, a driveshaft shop will perform the other service you canít do at home. They will spin the shaft and dynamically balance the entire assembly. This eliminates unpleasant vibration and excess bearing wear on your transmission, differential, and drive axles.

Before they return your parts, the driveshaft shop will also inspect any splined fittings and replace any needed carrier bearings. Longer two-piece shafts often have a rugged center support with a carrier bearing that holds the middle of the shaft in place beneath the car. Finally, they will paint your driveshaft and return it to you ready to install.

If your driveshaft is missing, consult your local driveshaft shop before you start searching for a new one. Often times, a new shaft can be made for not much more money than buying a used one and restoring it. Many shafts use standard ends, and the shop can cut and mount a new main tube easily.

Whatever your needs, getting your driveshaft restored at a reputable shop is a bargain, and you should make this step part of your restoration plan.

Dos and Don'ts
Thumb up  DO
  • Take your driveshaft to a reputable shop for restoration
  • Be observant of dents, bends, and U-joint noises in all driveshafts
  • Lubricate all U-joints at every oil change

Thumb down  DON’T
  • Assume that the driveshaft will be OK with a coat of paint
  • Re-use worn or scratchy U-joints
  • Neglect rubber flex discs or carrier bearings
The Popular Restorations Project Car
Author photo

1946 Packard: Rebuilding the split driveshaft

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The Popular Restorations project car has a split driveshaft. That is, there is a short driveshaft that goes from the transmission to a carrier bearing supported by a cross member a couple of feet back. The front driveshaft is coupled to the longer rear driveshaft and the rear connects to the differential. There are three U-joints in all.


1946 Packard Split Driveshaft

The U-joints cost around $100 each from Packard parts suppliers. DriveLine Service of Portland was able to look at the U-joints and determine that only two of the three needed replacing. Furthermore, they were able to replace them with generic U-joints for less than what the specialty Packard parts suppliers charge. All told, the price to clean and paint the drive shafts, replace two U-joints, lubricate the spline and replace its seal, and balance the driveshafts was $300.

If I had have done it myself I would have replaced all three U-joints. That would have cost just as much money plus several hours labor. And the driveshafts would not have gotten balanced.

One note is that many services will clean and paint your parts but unless itís agreed on in advance, donít expect show quality.

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Comments
Interview
 

Driveline Service of Portland

By Jeff Zurschmeide


Jim Wahl
9041 NE Vancouver Way
Portland, OR 97211
503-289-2264
www.driveshafts.com

PR: What steps do you go through when you restore a driveshaft?

DS: The first thing we do is talk to the individual to see what their needs are. We need to know if they want to keep the shaft original or if they just want to get it back in functional shape. Then we completely disassemble the shaft, hot tank it, and inspected. Then we reassemble it to meet the customerís requirements. We dynamically balance the shaft and paint it. We have quite a supply of new and used components, probably the largest supply of old pieces that canít be purchased new any more.

PR: How can someone tell if their driveshaft needs restoration?

DS: If the shaft has dents, dings, balance weights missing, obvious spline wear, or the yoke bores are worn out, itís fairly obvious. In most cases, the factory made shafts to looser tolerances than we do. We use much tighter tolerances and can almost always make the shafts better than the factory.

PR: Iíve had trouble pressing U-joints out of a driveshaft yoke. Should someone be able to replace a U-joint in their garage, or do they need to bring the shaft to you?

DS: Itís so much easier if we do it. The guys here have been in this business for 15 to 30 years changed tens of thousands of U-joints over the years. And we have the right tooling and fixtures and techniques to do the job. The proper way to change a U-joint bearing requires an arbor press. Most people donít know what theyíre looking for, and can miss potential problems. I would certainly suggest that they take it to the experts.

PR: If I bring you a driveshaft thatís basically OK, but with dents and dings, how much should I expect to spend to have it completely restored?

DS: On average, to disassemble and inspect a one piece shaft, replace two U-joints, restraighten, dynamically balance, and paint it would be between $110 and $125.

Recommendations
Click on any item below for more details at Amazon.com

Tom Birch
Manual Drive Trains and Axles (3rd Edition)
Prentice Hall, Paperback, 2001-05-22

Manual Drive Trains and Axles covers the traditional rear wheel drive, the modern front wheel drive, and four-wheel and all-wheel drive systems. This book is arranged so the major areas of the drive systems are described completely--the theory of basic operation as well as the methods used to diagnose, adjust, and repair them.


Matt Joseph
Collector Car Restoration Bible: Practical Techniques for Professional Results
Krause Publications, Paperback, 2005-10-14

This book covers it all, from buying a restorable car to the finishing touches. And in between, it touches on every part of the car, from sheet metal repair to engine internals. If you were to have just one book as a guide, this would be that book. The book is photo-rich and provides both procedural details and collected wisdom from experienced restorers.


Jim Richardson
Classic Car Restorer's Handbook: Restoration Tips and Techniques for Owners and Restorers of Classic and Collectible Automobiles
HP Trade, Paperback, 1994-11-01

This book covers a lot of ground in comparatively few pages, and while it has step-by-step procedures, the steps are often large. This book is a good choice if you want to understand the restoration process and all the pieces youíll touch. However, itís not sufficient to be your main guide to the restoration process.

External Links
PopularMechanics.com has a very good three-page illustrated article on replacing U-joints.
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