I am ready to install my rearend in my 69. I have multi leaf springs and multi leaf mounting brackets on the rear end. my question is, are the factory T bolts strong enough or should I use U bolts. Sorry ,I could not find a straight answer.
I ripped my spring perch of an axle tube, 327, 2bl, pg, and the 1/4 panelEveryone always advises to go from t-bolts to U-bolts (which I just did two weeks ago), its obvious U-bolts are stronger, but I got to thinking, and if the T-bolts have worked for 41 years and haven't let you down yet (assuming your not drag racing it), then maybe.... just maybe... they are OK.
But like I said, I switched mine out too.
I don't understand why y'all are saying the u-bolts are "obviously" stronger. The T bolts are twice as thick in diameter as the u-bolts. I had my spring perches rewelded and "gusseted". I figured I'd go with both U and T like was stock. Why are the u bolts obviously stronger?
Huh? Last I checked they were both 7/16-20. (as originally built by GM))I don't understand why y'all are saying the u-bolts are "obviously" stronger. The T bolts are twice as thick in diameter as the u-bolts.
Seems pretty simple to me. The T-bolt itself will likely never fail, but they place all of the stress on the welds that hold the spring perch to the axle tube. The U-bolt seems like it would share that stress with the welds. Since GM decided the "performance" models needed one u-bolt per side, it only seems logical that all four u-bolts would be even stronger.I suppose that (as an engineer) I could technically figure out the difference.
But I'll take the simple approach, if the T-bolts and U-bolts are the same diameter, and the same hardness, then the shear strength of them will both be the same.
It would however, seem that the U-bolts would have an advantage for more tensional strength since the U-bolt would have more contact area across the top of the axle, along with the forces of both ends being pulled from under the perch.
With that being the case, that extra tension could keep the axle from sliding sideways on the shock plates which would then bring the shear strength of either bolt into question.
For the small amount of $$ difference, I went with new U-bolts.