Packard Forum Index » V-8 (1955-56)

Randy wrote: "After talking it over with Ron, I am going to leave the internal bolts (55-60) alone and torque the..."

You got 55-60 out of them.???

Yes, I guess I didn't make that plain enough. The manual states 55-60 and that's what we torqued to. When I went to bolt the trans to the engine and saw the 25-30 spec I knew something had to be wrong.

G'day all, especially Randy, I have been pulling a reasonable number of 55-56 trans apart lately and encountering a lot of stripped threads in the housing to casing area. It is not usually a problem unless it is the bolt (56) or two bolts (55) which are pressurised. I helicoil the failed threads and have no problem attaining the 55-60 lbs, although I opt for the 55 lbs setting on my recently re-calibrated Warren & Brown torque wrench. On the housing bolts I have no problem with the lower Packard factory torque setting as once you install the vertical lower housing attachment bolts, they almost negate any torsional stress on the periphal housing bolts. I appreciate that the factory specs appear to be inconsistent but I have run into trouble before trying to second-guess Packard engineering. I suppose it depends on your faith in Packard engineering. Best regards, Peter Toet

Peter, I know what the manual says and I believe it is correct for 1955. I also think Packard didn't update the specs for 1956 when they went to the aluminum case. I'm not second-guessing Packard, just looking at it logically.
35 ft-lb should be plenty on bolting the converter housing to the case. Your own experience with stripped threads apparently bears this out.

I'm suprised Packard didn't go to fine thread fasteners when they went over to the aluminum case in '56.
Owen Dyneto hit it right on the head (as is his habit)--re:clamping pressure, that it is the ultimate goal in any bolted joint. Some folks get very focused on a given torque value, and in a perfect world the specified torque value is published to insure even, adequate clamping force between parts and to insure that the fasteners stay in place and don't loosen themselves under load and vibration.
Sometimes you have to test and determine what the best torque is for a given situation.
Clamping force is the goal, torque is how you measure it in simple, everyday terms.

I spent 14 years in the torque testing field (manufacturing/testing strain gage sensors) with a heavy emphasis on bolted joint anaylsis--this thread is sort of deja vu all over again for me!

With the exception of some very modern applications nearly all castings Al or Iron that i have seen have COARSE threads, not fine threads wheather studs OR bolts are used. ONE EXCEPTION: my 48 Chief has 7/16-20 threads for head bolts into cast iron cylinders. If i remeber rite, the Packard V8 has COARSE thread 7/16 for head bolts.

Randy, i'm suprised u got away with 55 pounds of torque in the Al case without stripping. That's probably the limit.

In Al and with out specs, i would have pulled up the bolts with a 3/8 ratchet until they 'just stop' and then check it with a torque wrench and add 5 pounds over the highest reading. A good ball park guess is usually just fine when specs are not available. THE MAIN ISSUE is to have all of the bolts torqued to the SAME reading.

Good advice Packard V8, One other method widely used in automated assembly and lab/racing assembly is to torque fasteners to an angle (like 360 degrees of angle in a complete rotation) while monitoring torque. With this method you start counting angle of rotation after crossing a torque threshold, about 3-5 ft. lbs. and torque the final value based on angle while monitoring torque. The final torque is never that far off of each other, but this system yeilds the most uniform tension between parts, which is what torque alone used to be used exclusively to monitor.
Sears, Snap-On (for the rich fellers), Lisle and others make an inexpensive angle gauge the clicks on to your torque wrench drive like an extension. I wrote about this over on the AACA site and the backyard boys kept coming back saying "it's not as accurate as torquing to the same value so it's not a s good" and I gave up after trying to explain surface tension, fastener elasticity, thread variation, etc.