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Since GM uses some different terminology, just to be safe I'd appreciate any confirmation someone could give that I'm reading the manual correctly for u-joint strap torques.
specs from 1980 GM shop manual
What most of us call a drive shaft, I take it GM calls a propeller shaft. And they spec 30 ft-lb for the u-joint strap, which they call a retainer. Is that correct - it seems high for a 1310 Spicer u-joint.
Then for what we call half shafts GM calls a drive shaft. Since my cars an automatic the recommendation would be 15 ft-lb. Again seems a little high for Spicer 1330's. Spicer spec's 12 or 13 ft lb I believe.
GM manual is correct. been using those torque values for 20 years on drivelines
Actually, I just noticed something. Clearly there is an error in the table. Note that on one line it lists 28 N-m as 22 ft-lb and then on the next line it lists the lower metric value of 22 N-m as as a higher 30 ft-lb value. The correct conversions should be:
17 N-m to 13 ft-lb
28 N-m to 21 ft-lb
22 N-m to 16 ft-lb
The question then is which conversion is messed up, N-m to ft-lb or the reverse. My guess at this point is it's the N-m to ft-lb. I can believe the manual value should be the highest since on a 1980 the half shaft would have been a Spicer 1350 U-joint with a 5/16 bolt while the half shaft on an automatic used a 1330 and thus a 1/4" bolt, the same bolt as the drive shaft which used 1310's for both transmissions.
I guess since the bolt dominates the torque requirement and since the the 1310's and 30's use the same bolt I will stick with the lower torques. Of course, then the question becomes which is right, the 17 N-m or 15 ft-lb since they are not equivalent. Splitting the diffeence would be 14 ft-lb which happens to me an engineering recommendation for a 1/4-28 bolt, unplated and unlubed. As good a guess as an any. Chalk up one more error in the shop manual.
Actually, I just noticed something. Clearly there is an error in the table. Note that on one line it lists 28 N-m as 22 ft-lb and then on the next line it lists the lower metric value of 22 N-m as as a higher 30 ft-lb value. The correct conversions should be:
17 N-m to 13 ft-lb
28 N-m to 21 ft-lb
22 N-m to 16 ft-lb
The question then is which conversion is messed up, N-m to ft-lb or the reverse. My guess at this point is it's the N-m to ft-lb. I can believe the manual value should be the highest since on a 1980 the half shaft would have been a Spicer 1350 U-joint with a 5/16 bolt while the half shaft on an automatic used a 1330 and thus a 1/4" bolt, the same bolt as the drive shaft which used 1310's for both transmissions.
I guess since the bolt dominates the torque requirement and since the the 1310's and 30's use the same bolt I will stick with the lower torques. Of course, then the question becomes which is right, the 17 N-m or 15 ft-lb since they are not equivalent. Splitting the diffeence would be 14 ft-lb which happens to me an engineering recommendation for a 1/4-28 bolt, unplated and unlubed. As good a guess as an any. Chalk up one more error in the shop manual.
I think the important part is to not put so much torque on the strap that it deforms the u-joint bearing. The strap does the work and the bolt just needs to be tight enough to hold it there.
I use blue locktite to insure the bolt stays in place and an inch-pound torque wrench to tighten them since 15 ft-lbs would be hard to achieve on a ft-lb wrench since it is such a low value. French locks would also keep the bolts in place, if you got them.
I think the important part is to not put so much torque on the strap that it deforms the u-joint bearing. The strap does the work and the bolt just needs to be tight enough to hold it there.
I use blue locktite to insure the bolt stays in place and an inch-pound torque wrench to tighten them since 15 ft-lbs would be hard to achieve on a ft-lb wrench since it is such a low value. French locks would also keep the bolts in place, if you got them.
Thanks for the reply. I am using a an in-lb wrench for these as I agree that these levels are down in the mud for most ft-lb level graduated tools.
I guess this confusion is due to trying to do things right. About 20 years ago I pulled the half shafts off the spindle yokes and pulled the spindle yokes off to grease the spindle bearings (let's avoid the debate on that). I had no torque wrenches so for the spindle nuts I just counted the turns taking them off and then put back on the same number of turns. And for the u-joint strap bolts I just tightened as best I could with whatever little box wrench fit. Nothing ever fell off in the 5 or 6 years of driving I did after that.
Fast forward to today and I bought the wrenches for this rebuild project figuring that I can't wing torques on everything I do. Interestingly, when I put the strap bolts in this time I used a small box wrench as before just to tighten them up before going to the torque wrench which I had set initially to 140 in-lb. On the first bolt it clicked almost as soon as it started to turn. So I guess I wasn't too far off 20 years ago.
Thanks for the reply. I am using a an in-lb wrench for these as I agree that these levels are down in the mud for most ft-lb level graduated tools.
I guess this confusion is due to trying to do things right. About 20 years ago I pulled the half shafts off the spindle yokes and pulled the spindle yokes off to grease the spindle bearings (let's avoid the debate on that). I had no torque wrenches so for the spindle nuts I just counted the turns taking them off and then put back on the same number of turns. And for the u-joint strap bolts I just tightened as best I could with whatever little box wrench fit. Nothing ever fell off in the 5 or 6 years of driving I did after that.
Fast forward to today and I bought the wrenches for this rebuild project figuring that I can't wing torques on everything I do. Interestingly, when I put the strap bolts in this time I used a small box wrench as before just to tighten them up before going to the torque wrench which I had set initially to 140 in-lb. On the first bolt it clicked almost as soon as it started to turn. So I guess I wasn't too far off 20 years ago.
Been there. I probably wrenched on my cars for 15 years before I ever owned a torque wrench either. Never used locktite and never had anything fall off. Even changed heads without a torque wrench, lol.
But I figure now I'm of the mind better safe than sorry now, and I can afford these things so why not have them and use them.
Been there. I probably wrenched on my cars for 15 years before I ever owned a torque wrench either. Never used locktite and never had anything fall off. Even changed heads without a torque wrench, lol.
But I figure now I'm of the mind better safe than sorry now, and I can afford these things so why not have them and use them.
Last edited by vince vette 2; Jun 15, 2018 at 06:39 PM.
u-joint strap torque confirmation
