66 Transmission

[Ed K.]

Help!! My 66 427 with a 4 spd tranny has the numbers 3885010. Although I have several books with Corvette data I cannot find any info on whether this is the correct tranny for my car.

[Joe L.]

Re: 66 Transmission

Help!! My 66 427 with a 4 spd tranny has the numbers 3885010. Although I have several books with Corvette data I cannot find any info on whether this is the correct tranny for my car.

Ed------


GM #3885010 is the correct casting number for the main case of 1966 and 1967 Muncie 4 speeds.

[Ed K.]

Re: 66 Transmission

Thank you. Perhaps you have an answer to my second issue. I cannot remove the tranny fill plug. The tranny had been leaking and during the 1-1/2 years it took to rebuild the rear the leak stopped. Whoops - must be out of fluid. Now the bolt is rounded off somewhat from trying. I've been told heating it may crack the aluminum housing. I don't have a lift. Doing this on jack stands so removing the tranny is a problem. I'm told I can add fluid through the speedo cable but must not overfill because excess fluid will be forced out onto the clutch. Any experience with this situation?

[Joe L.]

Re: 66 Transmission

Thank you. Perhaps you have an answer to my second issue. I cannot remove the tranny fill plug. The tranny had been leaking and during the 1-1/2 years it took to rebuild the rear the leak stopped. Whoops - must be out of fluid. Now the bolt is rounded off somewhat from trying. I've been told heating it may crack the aluminum housing. I don't have a lift. Doing this on jack stands so removing the tranny is a problem. I'm told I can add fluid through the speedo cable but must not overfill because excess fluid will be forced out onto the clutch. Any experience with this situation?

Ed------


Yes, I have a lot of experience with it. The exact same thing happened to me once upon a time. Finally, the plug got rounded off and there was no way to remove it. As a "temporary" measure since I did not want to disassemble the transmission at that time, I ground the plug flat and very carefully drilled and tapped it for a 1/8" NPT plug. I have the transmission out of the car now and when I rebuild it, I'll drill out the plug until it's paper thin and remove what's left with an awl.

A recent thread involved a situation similar to the above. In that case, the member was able to successively apply penetrating oil to the threads over a period of days and, finally, was able to remove the plug. I did the same thing but it did not work for me.

[Ed K.]

Re: 66 Transmission

I can't imagine getting a drill in there? I've tried the penetrating oil effort for about 2 weeks, no good. How about heat?

[Joe L.]

Re: 66 Transmission

I can't imagine getting a drill in there? I've tried the penetrating oil effort for about 2 weeks, no good. How about heat?

Ed------


It might be possible to use a 90 degree drill. However, I did it with the transmission out of the car.

As I've mentioned in past threads, I think that heat might work but there would be a lot of risk involved, especially if the transmission is in the car.

[Ed K.]

Re: 66 Transmission

Hi Joe,

90 degree drill - Cannot see well enough to be sure on center. I thought about removing the carpet and drilling a hole in the side of the footwell but plug appears to be about level with the floor. Don't want to start removing floor material. Not sure what to try next???? Probably try heat. and be sure not to heat the tranny tunnel. Other than the fiberglass tunnel and carpet, don't believe there is anything else to be concerned with, but I'll check it out before heating. Thanks for jumping in.

Ed

[Edward J.]

Re: 66 Transmission

Ed, I think your correct if you don't start on center when drilling that could create a problem, not to mention all the metal pieces that may fall into the case, I would try first a heat gun and then maybe a pair of vise grips first, if this fails you may have to remove the transmisson to do the drilling process and you can use a left handed drills bit to keep the metal from falling into case.And if the fill plug is metal you can magnatize the bits to help hold the bits of metal.( they do make a tool that does this) There may be a problem using a torch if the case gets to hot when trying to remove you may crack the case.

[Ed K.]

Re: 66 Transmission

Thanks. I'll try the heat gun. I have a Wagner Power Stripper that puts out 600 and 1100 degrees, start at 600 and see what happens. As for torch heating, any idea why the aluminum may crack? I've previously discussed this with my son (hands-on car nut, Associates Degree in Automotive Engineering and now a High School Technology Teacher) my primary care physician (hands-on car nut - if he does not know how to do something regarding restoration, takes a BOCCES class for it). Neither understand why it may crack. I discussed this with two local good-rep speed shops, one cautioned about cracking the other did not see an issue????

[Edward J.]

Re: 66 Transmission

Ed. If the heat gun doesn't work, the torch can be a last opition but, theres always the element of something going wrong, I have heated aluminum before and It can be done, But would have it done by someone experienced with the use of a torch and heating aluimnum.

[Joe L.]

Re: 66 Transmission

Hi Joe,

90 degree drill - Cannot see well enough to be sure on center. I thought about removing the carpet and drilling a hole in the side of the footwell but plug appears to be about level with the floor. Don't want to start removing floor material. Not sure what to try next???? Probably try heat. and be sure not to heat the tranny tunnel. Other than the fiberglass tunnel and carpet, don't believe there is anything else to be concerned with, but I'll check it out before heating. Thanks for jumping in.

Ed

Ed-------


I wouldn't even consider drilling or cutting any holes in the floorboard. I would remove the transmission from the car before I would even consider doing that.

[Joe L.]

Re: 66 Transmission

Thanks. I'll try the heat gun. I have a Wagner Power Stripper that puts out 600 and 1100 degrees, start at 600 and see what happens. As for torch heating, any idea why the aluminum may crack? I've previously discussed this with my son (hands-on car nut, Associates Degree in Automotive Engineering and now a High School Technology Teacher) my primary care physician (hands-on car nut - if he does not know how to do something regarding restoration, takes a BOCCES class for it). Neither understand why it may crack. I discussed this with two local good-rep speed shops, one cautioned about cracking the other did not see an issue????

Ed------


Keep this in mind: aluminum melts at about 1,200 degrees F. The transmission main case is an aluminum alloy and probably has a higher melting point. Nevertheless, I wouldn't chance that.

A propane torch will develop about 3,400 degrees F so if you use a propane torch I would be very careful. I have used a propane torch to remove bellhousing ball studs by VERY CAREFULLY heating the area surrounding the ball stud and quickly turning out the ball stud before the metal cools very much.

I would not even consider using an oxy-acetylene torch as there's WAY too much risk of over-heating.

Whatever you do, there IS a risk of cracking or otherwise damaging the case with heat, especially heat from any sort of flame-type torch.

[Eric D.]

Re: 66 Transmission

Ed, If theres still some corners left on the plug, try a 9/16" eight piont socket with a long breaker bar, and slooowwwwllllyyy apply force...

This is a common problem Muncie 4-speeds, because most people don't use the right tool for the job...

First a cresent wrench, and take some corners off, then a pipe wrench and finish off the whats left...

Of the 50-75 Muncies I rebuild a year, this problem happens tooo often...

Sorry about the rant... Crash

[Domenic T.]

Re: 66 Transmission

Ed,
maybe it's time to get it on a hoist if all else fails.
The trans can also be unbolted (linkage & all) and rotated to drill the hole as Joe sugested. What you don't want to do is over fill as many are. The level is 1/2" BELOW the fill hole when cold, otherwise you will have to pull the trans when you wet the disc with oil and have to replace the clutch.
The drain plug is tapered pipe thread and very hard to remove as you already know.

DOM

[Joe L.]

Re: 66 Transmission

Ed,
maybe it's time to get it on a hoist if all else fails.
The trans can also be unbolted (linkage & all) and rotated to drill the hole as Joe sugested. What you don't want to do is over fill as many are. The level is 1/2" BELOW the fill hole when cold, otherwise you will have to pull the trans when you wet the disc with oil and have to replace the clutch.
The drain plug is tapered pipe thread and very hard to remove as you already know.

DOM

Dom, et all------


I think that the biggest reason that these plugs are hard to remove is because of galvanic corrosion between the cast iron or steel plug and the aluminum case. The exact same thing occurs with the steel clutch fork ball studs and aluminum bellhousings---they can be a bear to remove, too.

I've learned my lesson and recommend that anti-seize compound always be applied to the threads of the plug before installing it in the case.