repairing hole in transmission case

randy1 · Feb 4, 2012

1991 ford f250 dropped rear drive shaft going down road and somehow bounced up hit tranny put hole in case looks like cast anyone ever patched a hole in 1? it is auto

Stephen Newell · Feb 4, 2012

I have a Jeep that the drive shaft came off and the pinion gear tried to go through the cast of the differential. It had a loose piece about 1 1/2 in diameter that somehow didn't come all the way out and get lost. I removed the axle and hammered the piece and the diformed case back into place and welded it with a nickel welding rod inside and out. I then ground the repair smooth with a angle grinder and filled with bondo and repainted the axle. Without looking inside you can't tell it was ever damaged. In my case I had all the pieces. Had I lost some of it I would have cut the hole out square and found a piece of cast iron to fill the hole and weld it in. Had it been broken somewhere mechanical I probably would have to replace the axle. It was just the case where all that was necessary is keeping the oil in.

bob15 · Feb 4, 2012

How about going to a junk yard and getting a new transmission? A new case will eliminate any chance of leaks or failures due to a poor patch job which could and usually fails at the most inopportune time.

JDseller · Feb 4, 2012

I would bet that the case is not cast iron but cast steel. Touch it with a grinder. If the sparks are yellow then it is steel. If they are orange it is cast iron. If it is steel I have had good luck just making a steel patch out of 1/4-3/8 plate. Then just weld it over the hole with 7018 rods.

I would be more worried about where the broken pieces went. If some of them are inside then they may get picked up by the transmission and break things in there.

It being a 1991 you should be able to find a good used transmission to replace yours with. I guess it would depend on how good the truck is. IF you plan on running/keeping it for a long time then I would replace it.

rocko · Feb 4, 2012

Had an 85 Ford do the same thing exepting front axle and transfer case. I took it off vechicle completely, removed the guts (paying carefull attention to where every thing belonged and setting out in same order as would need to go back in, very important, lota pieces in there) and then took the aluminum case to some one with better welding ability than myself. 12 years later it was still working fine when I sold it. May be easier to just get used trany at wreckers depending on cost. Rocko.

rrlund · Feb 4, 2012

My nephew patched one with a beer can and JB Weld.

Josh Cronk · Feb 4, 2012

Pretty much all the auto trannies that would have been in that truck are cast aluminum case.
Very difficult to weld. Would either have to be dis assembled and welded by a pro , or put a junk yard tranny in it.
How big is the hole? If its real small, may be ably to patch with JB Weld. Once cast aluminum is broken, the cracks tend to spread over time, so the JB weld is probably a temporary repair.

Anonymous-0 · Feb 4, 2012

If it's aluminum, they are TIG welded all the time, the same as oil pans from semi's and motorcycle cases etc.. You have to use the right technique so it doesn't create cracks but not a big deal for an experienced TIG welder. Depending on how well it can be cleaned and the proximity of bearings and seals, it might not have to be fully dismantled to repair. I know a guy that's done hundreds of them successfully. He even builds up the cooling fins on motorcycle engines that have been in involved in collisions. When he's done, you'd never know they were ever damaged.

locojim · Feb 4, 2012

Had a half dollar size hole in my zf trans...Took PTO off and held cardboard on the inside-filled hole with jb weld...Five years later can barely tell it was patched...........

repairing hole in transmission case

randy1

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Stephen Newell

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bob15

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JDseller

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rocko

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rrlund

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Josh Cronk

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Anonymous-0

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locojim

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