Re: Threads and torque Twin Ultramatic

Posted by BH On 2011/3/21 9:08:52

Rocky46 -

I had to check one of your other threads to find out that you are working on a 55 Twin Ultra. The reason this is important is because the 1955 version of the Twin Ultra. had a cast iron case, but the 1956 version used an aluminum case.

The torque specs in the shop manual are correct for the 1955 cast iron case, but they were not updated for 1956. Though there are some good notes about valve body torque, I've never seen any reference on bell housing screw torque for 56th Series in any service newsletter or bulletin, either. However, I've found more than one car where one of those screws pulled through the aluminum case. Anyone working on a Twin Ultra. with aluminum case might want to take a look at this thread:packardinfo.com/xoops/html/modules/newbb ... orum=3&post_id=53801#forumpost53801

Now, if you have a cast-iron Twin Ultra, then the 55-60 ft. lbs. specs is correct and should be followed. I can't imagine that as a problem for most torque wrenches rated in foot-pounds - a tool that is needed for all sorts of work on these cars. Yet, when working on any U.S.-built automatic transmission, you will also need a torque wrench rated inch-pounds.