Putting a 12 Bolt Chevy rear end in my 1970 Skylark. What U-Joint do i need to use? Looking for something strong without grease fittings. Thanks.
They come in three sizes, 1310, 1330, and 1350. If it's a stock setup, you'll have one of the first two. It goes by the cap size. U-joint series Joint width (W) (inches) Cap diameter (D) (inches) Maximum Angle Continuous rating (lb-ft) Short Duration rating (lb-ft) 1310 3.219 1.062 30 130 800 1330 3.625 1.062 20 150 890 1350 3.625 1.188 20 210 1240 1410 4.188 1.188 37 250 1500
If it is the smaller 1310 yoke most popular chevy yoke size then the 372 percision u-joint or a cross reference of that will work. 20229 TRW - 3022x spicer all different numbers same out come. Ok? Jim If you have the 1330 you should NOT have a difference should be square and 1 1/8 cups square...I think. Will have to double check the chevy 1330 yoke cup size again though. Jim
Most OEM 12 bolts used the 1310 series u-joint. On your rear end yoke the measurement between the inside of tabs that hold the u-joint caps will be 3 1/4. The cap diameter is 1 1/16. The 1330 series is rarely found on the 12 bolts but there are some out there. The 1330 has the same cap diameter but is wider across (3 1/2) the u-joint. Last but not least is the OEM 3RL (saginaw) series which is what your cars driveshaft has. It uses an inside lock-up in which the caps have grooves which retain the snap rings on them. The cap diameter is also larger at 1 1/8. In most Buick driveshafts to Chevy 12 or some 8.2 10 bolts the u-joint number will be a 5-3022X or something similar from a part store. I recommend calling a drive ;ine repair shop as they usually carry the best (non offshore) u-joints. Precision NAPA u-joints are crap IMHO. Since you are near Cleveland i'd recommend Custom Clutch or my old digs, Henderson Driveline in Westlake. The majority of the 8.5 ten bolts on the other hand use the 3RL series so you don't need a combination u-joint. The 1350 series is an optional aftermarket differential yoke available for 8.5 and 12 bolt rears but the u-joint is much larger and uses 1 3/16 caps. So you won't be looking for the 1350 to 3RL although they do make that combo joint. Hope this helps straighten out the info you've received.
Geez i did not see you were just south of me. Just call me I will help you out like Ai said i do that swap all the time 372 percision u-joint and have them cross reference the joint in a super joint and your done. 372 is the same joint i use for that and also the modified monza rears i do with the small drive shaft and large yoke. Works on both just use in the oppisite way big /small, small/ big... pm me i will get you a number. Jim
OR what would make things even easier is swap yokes to the correct BOP 12 bolt chevy yoke which I also have. Jim
Also before you get your combo u-joint to install make sure of a few things otherwise you're putting the cart before the horse so to speak: The driveshaft in your Skylark should be of the one piece design with the rear most of the shaft having a rubber isolator (looks like one smaller shaft was pushed into the larger part) which tends to twist with age as the rubber dries out (38 yrs) and causes an out-of-phase condition. Take a good look at the yokes and make sure the shaft yokes still are lined up exactly. If it is then thats good but you still may have to have the shaft altered to fit with the 12 bolt installed. Always check the length. Good rule of thumb is 3/4 to 1 in. of transmission slip yoke showing past the seal and generally no more. If the shaft is going out of phase and you are going to be putting some decent power / tire to it you may want to think about a new driveshaft with the correct yokes and at least a 3"X.083 tube for RPM/power purposes but 3 1/2"X.065 or .083 is better. Also this way you won't have a combo joint at either end. Just Buick (3RL) at the trans and Chevy (1310) at the rear.
