F-Body 4L60E + Truck Driveshaft Input = Leaks?

[LS1GMCTruck]

Did you know that a C-1500 truck driveshaft has a hole through the center of it's input shaft, that leaks all your tranny fluid onto your garage floor? Yup!, this will happen when you are using a late model F-Body Camaro 4L60E, together with the truck driveshaft input. I guess the suspension travel is greater on a truck, so they needed a relief hole down the center, so it did'nt act like a piston & blow out the internal tranny seals? Anyways, what's the answer to this problem? I don't go off-roading or anything...it's a street truck...should I simply weld up this breather hole, or is there another seal or bushing that should be added to the inside of the tailstock?, or...? Help! Thanks in advance, Gar

[RedHeartbeat]

I welded mine shut. No problems. One thing you can do is remove the tailshaft housing from the transmission and then grind one of the splines off of the output shaft so that the area can be used as a vent. Some output shafts have that done to them already.

[LS1Nica]

I didnt know that, I never even noticed but maybe is because I have a T56. Ill look into it though, thanks for the info.

[88leadsled]

That hole is originally filled with some sort of plastic from the factory, its just the way its cast and its cheaper for them to fill it with plastic. You can weld it up and you won't have any problems anymore.

[RedHeartbeat]

Yeah, when they manufacture the yoke, they drill and broach the splines and then press a cap in the end. It makes no sense that they have a hole in the center of the cap unless its to bleed off air pressure created as the yoke slides in and out. I guess that is their way to guarantee trans fluid will stay on the output splines.

[LS1GMCTruck]

Discovered an interesting cure to the vented driveshaft slip-yoke problem... I called a couple transmission shops, one a performance tranny shop...and they both offered a simular cure for the problem. Remove the driveshaft, use some brake-clean to degrease the inside of the slip-yoke splines all the way to the bottom. Then simply push down, all the way to the bottom, a steel beer bottle cap, bedded in silicone sealant. The cap fit snug all the way down, like it was made for it! I let the silicone cure over night, just to be safer, and re-installed it the next day. Done. Over. Finito! Thanks for everyones input. It helped. Gar