Driveshaft Measure Guide
In this section you will find the proper ways to Measure for Driveshaft Fitment on all vehicles as well as Universal Joints, Pinion Yokes and Flange Yokes.Driveshaft Measure Diagrams
In this section you will find the proper ways to Measure for Driveshaft Fitment on all vehicles as well as Universal Joints, Pinion Yokes and Flange Yokes.Expert Driveshaft Solutions
The following information will help identifying all| the basic U-Joint Series which are easy once you have the proper information. There are many more U-Joint Series than listed, we stock over 150 part numbers.
Outside Lock U-Joints by Series
| Series | Width | Cap |
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| Handy Measurement Conversion |
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Inside Lock U-Joints by Series
Inside Lock U-Joints are measured from the grooves in the caps where the C-clips fit not the overall width of the U-Joint like the outside lock type.| Series | Width | Cap |
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| Handy Measurement Conversion |
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One note on Inside lock U-Joints. The GM 3RL and 7290 are fairly close, but will NOT interchange. Always check the dimensions if not sure. Note: There are other inside lock U-Joints not listed. We have them all. Just call. GM 3RL is 2.556 Inside Lock Up and 1.125 cap
The GM 3RL U-Joint (also called S44)is used mainly on GM vehicles. It has been used since the early 1960’s and is still in current production.
Interestingly it was also used on a very few Ford LTDII and T-Bird in 1979. It was also used on some Dodge 4×4 Truck Front Driveshaft Double Cardan CV (constant velocity) Joint. CV-3 in the Driveshaft Types
7260 is 2.125 Inside Lock and 1.078 cap.
7260 is referred to as the “small Dodge” joint. It is similar in size to the 1310 but the locks are on the inside. This U-Joint series was used extensively up to 1980’s in cars and trucks. The 7260 was even used in Dodge Dually trucks.
7290 is 2.622 Inside Lock and 1.126 cap.
The 7290 U-Joint is known as the “Big Dodge” U-Joint. This was used in early passenger cars typically with big block power and manual transmissions. For trucks it varies dramatically and both are usually listed. The only sure way to tell is with dimensions.
Ford Big Cap U-Joints
Inside Lock U-Joints are measured from the grooves in the caps where the C-clips fit not the overall width of the U-Joint like the outside lock type.
In the early 1960s, Ford introduced a pinion yoke slightly larger by 1/16 inch, meaning only the two caps in the pinion yoke are .062 larger. Most 8″ Ford and many 9″ Ford Differentials have 1 1/8 caps, using 1310 and 1330 U-Joints, with 1350 available for high horsepower.
The photo shows the difference: the left yoke has a standard 1 1/16 cap, while the right BC (Big Cap) yoke needs a 1.125 cap. A loose fit indicates play, which is too much. This could mean a worn yoke or the wrong UJ cap, causing high-speed vibrations and shiny rub marks inside the yoke.
Ford’s Big Cap might have been used to prevent U-Bolt distortion of the U-Joint cap, which can ruin a U-Joint quickly. Torque should be 15-18 lb.ft. Use Blue Lock-Tite for security, and avoid over-tightening.