Trans Bolts after 39 years
Thread Starter
Racer
Joined: Nov 2014
Posts: 269
Likes: 1
From: Flemington New Jersey
Trans Bolts after 39 years
Quick question for the group. I have a 76 automatic l48 with 26K miles on it. I had I very minor trans leak from the trans gasket. Happened randomly. When I checked the bolts on the trans pan they were torqued are less than 8 ft lbs. I guess this is from the years of compression.
Should I go back and tighten to 11 / 12 ft lbs or just leave leaking dogs lie? Seems if I can turn them by hand they should be tighter.
Thoughts?
Should I go back and tighten to 11 / 12 ft lbs or just leave leaking dogs lie? Seems if I can turn them by hand they should be tighter.
Thoughts?
Thread Starter
Racer
Joined: Nov 2014
Posts: 269
Likes: 1
From: Flemington New Jersey
I am just fiddling until the spring comes. I will go to 8 then 10 then 12. I really feel that leak is from the pan being so loose. But I have a new gasket and filter anyway...
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Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Cork or cork/rubber gaskets will continue to compress with time & heat cycles. Usually, when that pan gets resealed, you want to go back and re-torque those bolts after a few days use.
Try to re-torque them (for now). If you find that one or more don't want to snug up, you'd better leave them be. When you do change the fluid/filter, you'll also need a Heli-coil kit to repair the holes with 'loose' threads.
Try to re-torque them (for now). If you find that one or more don't want to snug up, you'd better leave them be. When you do change the fluid/filter, you'll also need a Heli-coil kit to repair the holes with 'loose' threads.
Thread Starter
Racer
Joined: Nov 2014
Posts: 269
Likes: 1
From: Flemington New Jersey
Went and tightened all back to 12 ft/lbs but did so in 2 lb increments. They were all around 6lbs to start with and they all took the final 12 nice and evenly so no heli-coils.
If it drip now its replacement time but have to believe that the pan bolts being torqed to half their spec had something to do with a drip. Actually is shows just how little force is needed to hold a gasket and pan in place.
If it drip now its replacement time but have to believe that the pan bolts being torqed to half their spec had something to do with a drip. Actually is shows just how little force is needed to hold a gasket and pan in place.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Actually, at 6 ft-lbs torque, a 5/16-18 bolt will have around 1000 pounds of clamping force. With 15 (or so) bolts on a tranny pan, that's a lot of clamping load. 12 ft-lbs torque would have about 1 ton of clamping load per bolt.
Most likely, the pan gasket is compressed, oil soaked, and basically used up. If it stays dry for a while, great. If it doesn't...no big surprise.
Re-do it when you get the chance. You probably should consider re-sealing all of the external seals and O-rings when you have the opportunity. That's not a big challenge, mechanically; but it takes a bit of research and ordering to get all the needed items to do that job. I never understood why some of the rebuild kit outfits didn't make up an "automatic trans reseal kit" with all the needed stuff for various trans models.
Most likely, the pan gasket is compressed, oil soaked, and basically used up. If it stays dry for a while, great. If it doesn't...no big surprise.
Re-do it when you get the chance. You probably should consider re-sealing all of the external seals and O-rings when you have the opportunity. That's not a big challenge, mechanically; but it takes a bit of research and ordering to get all the needed items to do that job. I never understood why some of the rebuild kit outfits didn't make up an "automatic trans reseal kit" with all the needed stuff for various trans models.
Thread Starter
Racer
Joined: Nov 2014
Posts: 269
Likes: 1
From: Flemington New Jersey
7T1
Thanks, great info on Torque. I figured on replacing the pan gasket, dip stick tube and speedo seals.. also do the filter while I am at it.
Just wanted to see what getting it torqued to spec would do if anything out of curiosity.
Thanks, great info on Torque. I figured on replacing the pan gasket, dip stick tube and speedo seals.. also do the filter while I am at it.
Just wanted to see what getting it torqued to spec would do if anything out of curiosity.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
You may also want to redo the shift shaft seal. If so, just remove the arm from the shaft, clean everything really well on the outside, then drive the existing seal down to the bottom of its bore and install the new seal on top of it (to proper depth). There is room to do that, if it hasn't already got 2 seals in there; and you actually end up with redundant seals! (Plus you don't have to screw around trying to remove that 1st seal.)
If you don't have a 'driver' for that seal, select a properly sized deep-well socket that has an O.D. just smaller than the seal's O.D., and an inner diameter that will clear the shaft. Be careful not to scratch/damage the journal on the shaft and the bore the seal fits in. Also, take care not to cut the seal lip on the sharp edges of the flats machined on the shaft.
If you don't have a 'driver' for that seal, select a properly sized deep-well socket that has an O.D. just smaller than the seal's O.D., and an inner diameter that will clear the shaft. Be careful not to scratch/damage the journal on the shaft and the bore the seal fits in. Also, take care not to cut the seal lip on the sharp edges of the flats machined on the shaft.