When building a custom street rod or muscle car with driveline components from multiple sources, it is not uncommon to encounter u-joints of different sizes. Because your vehicle is now a custom application, going to the local auto parts store and looking up a u-joint by year-make-model won't work. But don't despair; with some simple measurements, it's possible to determine the required u-joints.
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Most common driveshaft u-joints applications will use outside locks, where lugs (image 1) or snap rings (image 2) are used to secure and align the u-joint caps in the yoke.
Determining the u-joint series for external lock applications is a simple matter of measuring a few critical dimensions.
Measuring for Driveshaft U-joint Fitment
If you don't have the u-joint
1) Measure the distance between the lugs of the transmission and pinion yokes and the distance between the snap rings of the driveshaft yoke to attain the overall widths
2) Measure the yoke gap and the diameter at the cap location to get the cap diameters.
Make sure to check all of the width and diameter dimensions, as they may be different. If the dimensions do not match, you may require a conversion u-joint.
If you have the u-joint
1) Measure the outside distance across the u-joint (with caps installed)
2) Measure the diameter of the caps
Make sure to check all of the width and diameter dimensions, as they may be different.
Standard u-joints sizes are classified by series, with each series having specific cap diameter and overall joint width. Typically speaking, a higher series number translates to a stronger joint.
Standard U-joint Series, Dimensions and Part Numbers
Series
Cross Width
Cap Diameter
Spicer P/N
3.219 (3 7/32&#;)
1.062 (1 1/16&#;)
5-X
BC*
3.219 (3 7/32&#;)
2 @1.062 (1 1/16&#;)
2 @ 1.125 (1 1/8&#;)
5-X
3.625 (3 5/8&#;)
1.062 (1 1/16&#;)
5-X
BC*
3.625 (3 5/8&#;)
2 @ 1.062 (1 1/16&#;)
2 @ 1.125 (1 1/8&#;)
5-X
3.625 (3 5/8&#;)
1.188 (1 3/16&#;)
5-X
*BC denotes Big Cap, a Ford creation with two thicker caps to resist the deformation caused by over-torquing of the u-bolt straps.
Conversion or combination u-joints include a mix of two different series specifications in the same joint so that that mismatched yokes and driveshafts can be connected. The caveat is that the joint is only as strong as the smaller series.
Conversion U-Joint Series, Dimensions and Part Numbers
Series
Cross Widths
Cap Diameter
P/N
/
3.22 (3 7/32&#;)
3.625 (3 5/8&#;)
1.062 (1 1/16&#;)
Spicer
5-134X
/BC*
3.22 (3 7/32&#;)
3.625 (3 5/8&#;)
2 @ 1.062 (1 1/16&#;)
2 @ 1.125 (1 1/8&#;)
Neapco
1-
/
3.22 (3 7/32&#;)
3.625 (3 5/8&#;)
2 @ 1.062 (1 1/16&#;)
2 @ 1.188 (1 3/16&#;)
Spicer
5-460X
Moog
348
/BC*
3.625 (3 5/8&#;)
2 @ 1.062 (1 1/16&#;)
2 @ 1.125 (1 1/8&#;)
Spicer
5-X
/
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3.625 (3 5/8&#;)
2 @ 1.062 (1 1/16&#;)
2 @ 1.188 (1 3/16&#;)
Spicer
5-648X
BC*/
3.625 (3 5/8&#;)
2 @ 1.125 (1 1/8&#;)
2 @ 1.188 (1 3/16&#;)
Neapco
2-
Moog
459
*BC denotes Big Cap, a Ford creation with two thicker caps to resist the deformation caused by over-torquing of the u-bolt straps.
Strength Ratings
U-joint strength depends on many factors, including material type, body design, the presence of a zerk fitting, cap size, etc. The chart below summarizes the continuous lifetime operating torque and yield torque values (the point at which the u-joint begins to deform)
U-Joint Series Torque Ratings
U-Joint
Series
Continuous Lifetime
Operating Torque
Yield
Torque
130 lb-ft
1,600 lb-ft
150 lb-ft
1,850 lb-ft
210 lb-ft
2,260 lb-ft
U-Joint Strap Kits
U-JointCE-
BC* 1.590 in. 14-17 Ft-LbsCE-
/ 1.666 in. 20-24 Ft-LbsCE-P
*BC denotes Big Cap, a Ford creation with two thicker caps to resist the deformation caused by over-torquing of the u-bolt straps.
Classics and Antiques Carrier bearings for the older Buicks and Cadillac's as well as can rebuild most of the CV driveshafts. Dodge and Chrysler Ball and Trunion driveshaft conversions.
How to measure (if needed) Info on measuring vehicles for a custom driveshaft. U-Joint Flange- Pinion Yoke measurements. ID of different Driveshaft Types.
This outside lock pinion yoke is used with outside lock U-Joints. The 2 extra snap rings are not used.
The driveshaft tube weld yoke has grooves machined in the edge where the snap rings clip in. Measure from groove to groove.
U-Joint Series is a small U-Joint not used on any current production vehicles. 1.062 cap and 2.438 width. (1 1/16 x 2 7/16)
U-Joint Series is the most common U-Joint ever used. It is still used on OE applications. 1.062 cap and 3.219 width. (1 1/16 x 3 1/4 close)
U-Joint Series is very common and used on OE production. 1. cap and 3.622 width. (1 1/16 x 3 5/8)
U-Joint Series is used on trucks mostly for OE. It is also a Hi-Performance upgrade on cars. 1.188 cap and 3.622 width. (1 3/16 x 3 5/8)
U-Joint Series is on 3/4 and 1 Ton or larger trucks. 1.188 cap and 4.187 width. (1 3/16 x 4 3/8)
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On the left is a Pinion Yoke and UJ for inside lock. The C-clips are facing up to photograph. The clips should be turned down, so they fully insert in the back of the yoke. This locks U-Joint for side to side play and centers it perfectly. Never rely on the bolt and straps to hold it in place and it will not be centered.
On the right is a Inside Lock Weld in type yoke. The C-clips fit on the inner edge.
One note on Inside lock U-Joints. The GM 3RL and 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 's and is still in current production.
Interestingly it was also used on a very few Ford LTDII and T-Bird in . It was also used on some Dodge 4x4 Truck Front Driveshaft Double Cardan CV (constant velocity) Joint. CV-3 in the Driveshaft Types
is 2.125 Inside Lock and 1.078 cap
is referred to as the "small Dodge" joint. It is similar in size to the but the locks are on the inside. This U-Joint series was used extensively up to 's in cars and trucks. The was even used in Dodge Dually trucks.
is 2.622 Inside Lock and 1.126 cap
The 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.
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I hate to pick on Ford but here is another "Better Idea". Starting in the early 's Ford started using a pinion yoke that was just 1/16 bigger. This means only the 2 caps that go in the pinion yoke are .062 larger than all the others. Only those 2 caps.
All 8" Ford to our knowledge have 1 1/8 caps and a high percentage of 9" Ford Differentials have 1 1/8 caps. Both differentials were only produced with and U-Joints. was never an OE yoke. We do have Pinion yokes available for High Horse Power applications.
This photo (click it) illustrates the difference in Ford Pinion yokes (both are quite similar). The pinion yoke on the left is a standard cap at 1 1/16 and has the correct U-Joint cap. The yoke on the right is a BC (Big Cap) and requires a 1.125 cap. A standard 1 1/16 cap is in it and it fits loose. A paper clip is inserted in one edge to illustrate the amount of play. Check this carefully. We have other ways to check. Please call.
If you see any play in the UJ cap and the pinion yoke. IT IS TO MUCH! If there is play there are 2 possibilities. One is the pinion yoke is worn or 2. (more likely) is the wrong UJ cap is on the driveshaft. If you have the wrong U-Joint in the pinion yoke it will typically have a hi-speed vibration, this would be speeds from 50 on up. In addition you will see shiny rub marks inside the pinion yoke. There should never be any shiny rub marks.
In defense of Ford I can see a (possible) reason the Big Cap was used. All of these yokes use a U-Bolt to hold the U-Joint in place. With a U-Bolt you can apply enough force to distort the U-Joint cap slightly. Then the needle bearings do not rotate and you will ruin a U-Joint in less than a miles. Torque load is 15-18 lb.ft. With the thicker cap it was harder to distort the cap. You can not get a torque wrench to the nuts. So pull it snug and a bit more. STOP. Do not tighten as tight as tight as possible. For security use a little Blue Lock-Tite on the threads.
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