Driveshafts

aluminum-drive-shaft

Rocky Mountain Drive Line specializes in providing high quality Driveshafts at an affordable price. Our products are American Made in Denver, CO, and we have been providing superior parts and service for over 35 years.

At Rocky Mountain Drivelines’ state-of-the-art facility, our experienced staff can re-manufacture or custom build high quality Driveshafts. The driveshaft service is done in one day from the time we get the shaft. We offer free estimates for all our services. We have a 90-day warranty on all Driveshafts.

Driveshafts Always In Stock

View a list of the driveshafts we always have in stock.

How Driveshafts Work

A driveshaft provides power between the transmission and the differential. The driveshaft consists of many different lengths made up of a hollow tube. The best type of driveshaft is made out of steel but they can also be made of composite material, or aluminum shafting with weld yokes welded on either end. A driveshaft can consist of a variety of u-joints (universal joints) depending on the weld yoke and the transfer case yoke and differential yoke. Most universal joints are equipped with rotating caps, placed on each end of the weld yoke. The u-joints enclose small needle-shaped bearings…a grease zerk on the u-joint to allow grease to enter the u-joint cap. The grease allows low friction between the cap and u-joint body. The driveshaft is connected to the transmission or transfer case by a slip yoke.

The slip yoke and the u-joints allow movement between the suspension as it reacts to the road surface. When the rear suspension moves to compensate for the road, the driveshaft must become longer or shorter. The slip yoke is designed to slide back and forth on the transmission output shaft to change distance between the differential and the transmission. In addition…as the rear suspension moves, the angle of the rear differential and the transmission output shaft also changes. The u-joint compensates for the angle changes between the differential and the transmission. When the suspension height of a vehicle is lifted or modified, the driveshaft length will be either too short or too long due to the distance between the rear differential and the transmission. The driveshaft could easily fall out if the driveshaft is not lengthened to make up the distance between the differential and the transmission.

Some vehicles use a double cardan u-joint assembly at the rear of the driveshaft. Sometimes this is called a CV (constant velocity.) By using a double u-joint, the driveshaft operates at a greater angle. A CV kit holds the double u-joint in place. This CV kit rides on a stud so the CV kit can swivel to give this type of shaft a better angle.

A two-piece driveshaft uses a center support bearing mounted on a frame crosspiece to hold up the front half of the driveshaft. On this type of driveshaft, a slip yoke going to the transmission is not needed. The slip joint works the same as transmission slip yoke. On this shaft, the slip yoke on the driveshaft compensates for the suspension changes.

 

How we Replace Parts

Most Driveshafts have u-joints (universal joints.) This is what connects to the transfer case yoke and the differential yoke. On a driveshaft, the first thing that always goes bad are the u-joints. The u-joints go bad because of the needles becoming dry and warn down, which in turn eats through the u-joint cap and eats through the weld yoke (the part that the u-joint rides in.) Once the u-joints eats through the weld yoke, this is when the price gets higher because we have to cut and weld the new yoke in the tube. It is very important to grease the u-joints during every oil change to make the u-joints last longer.

At Rocky Mountain Driveline, we replace the u-joints by pressing the u-joints in and out. If your driveshaft did have grease able u-joints, we will press grease-able u-joints in to make sure you have a long lasting u-joint as long as the u-joint is always greased.

A slip and stub (slip joint and stub shaft) on a driveshaft is designed used for suspension travel. When the truck or car suspension moves…the slip and stub move with it. If the slip and stub did not move, the driveshaft would pull itself off the yokes.

The slip and stub will go bad if it doesn’t get liberated. When this happens, the friction between both metals will cause the slip and stub to lock up. At Rocky Mountain Driveline, we will cut out the old slip and stub and replace it with a new one. We will press in the new slip and stub weld to the shaft then straighten the shaft and balance the shaft.

A CV kit (constant velocity kit) is the part between the double u-joint or double cardan u-joint. This part of the shaft bolts up to the transfer case and gives the shaft a better angle. This style of shaft is meant for lifted vehicles, trucks, and SUV’s, giving the shaft a greater angle. If there were a single u-joint, it wouldn’t give it an angle.

If the CV kit is not greased, the CV kit will melt the stud that the CV kit rides on. If the stud is undersized, we will cut out the weld yoke that the stud is welded to and replace it with a new one. When we do this, we recommend that all three u-joints and the CV kit be replaced.

When a driveshaft is made new from a factory, the driveshaft is out of round. A factory driveshaft is only balanced and not straightened. This is why there is so much weight on the shaft, and it could make the driveshaft vibrate. At Rocky Mountain Driveline, we straighten our shafts first then balance them. This will keep the driveshaft within 10 one-thousandths tolerance to insure the driveshaft will not vibrate. Straightening the driveshaft first is important because when the driveshaft is running at 3500 rpm (highway speed) and it is not straightened, the driveshaft will have a jump rope effect. Once the straightening process is done, then we start the balancing process. Balancing a driveshaft is a must because not all the parts are machined perfectly. The weight on a driveshaft is to compensate for the uneven metal. The weight on the driveshaft will make the driveshaft equal all the way down the shaft.