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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Trail_Boss110103 on October 18, 2015, 01:39:17 pm

Title: Big 10 Transmission Fluid Change Problem
Post by: Trail_Boss110103 on October 18, 2015, 01:39:17 pm

I have a '78 Big 10, (350 cubic in, auto transmission, Cheyenne) and last week decided to change the transmission fluid and filter.  I don't have much in the way of a shop so slid under the truck and began the process of removing the pan etc.  There were two bolts in the rear of the pan that were difficult to remove due to the proximity of a cross member but I finally got a socket that was narrow enough to get them out.  It was then I realized that the pan was not going to come off!  I read the Haynes manual for changing the fluid and it mentioned in some trucks you must support the engine and take off the cross member (there is another name for this piece but I don't recall).  Before I proceed any further I would like to know if others have run into this issue and what they did to finally get the pan off.  Without being able to take the pan off I'll not be able to replace the gasket since the clearance between the edge of the pan and the back of the transmission/front of the cross member will not allow me to set the gasket.  Any help in this matter would be much appreciated.

Title: Re: Big 10 Transmission Fluid Change Problem
Post by: Irish_Alley on October 18, 2015, 02:53:44 pm

what ive done is undo the transmission mount bolt on the cross member then jack the trans up. this might give you enough room for the pan to clear the cross member or you might have to unbolt the cross member and slide it back

Title: Re: Big 10 Transmission Fluid Change Problem
Post by: Trail_Boss110103 on October 18, 2015, 03:32:24 pm

This may work as I only need about an 1/8th inch clearance or so.  Thanks.

Title: Re: Big 10 Transmission Fluid Change Problem
Post by: Irish_Alley on October 18, 2015, 04:54:49 pm

i want to say ive also slid the trans over a inch and the trans bolt will just sit on the cross member. this is also a good time to replace the mount if its oil soaked or broken

Title: Re: Big 10 Transmission Fluid Change Problem
Post by: Trail_Boss110103 on October 18, 2015, 07:56:22 pm

I'm not a mechanic so which of the two options is easier?  Can you give me a little detail on moving the trans.  I assume all the bolts connecting the trans to the engine will need to be removed and will need to be supported with a jack or something similar.  Then on the other end you have the knuckle joint connecting the trans to the drive shaft.  Does that have enough play to allow me to move the trans?  This seems to be a lot of work for someone without a lot of equipment (really none).  I don't want to get in over my head and damage something.

Title: Re: Big 10 Transmission Fluid Change Problem
Post by: Irish_Alley on October 18, 2015, 08:41:55 pm

yeah there should be plenty of play just to slide it over a little