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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: CameronTaylor on April 19, 2012, 04:58:07 pm

Title: Transmission troubles
Post by: CameronTaylor on April 19, 2012, 04:58:07 pm
So I thought I just had a small leak of transmission fluid. That was, until it had a hard time going into gear. I took it to a small shop as they said it is leaking bad around the yoke. I don't really understand this stuff, so I'm calling on some help. The shop said it will most likely need to be rebuilt. So here is where I have questions.

What's an approximate cost to rebuild?
That better than just pulling one from a salvage yard?
And for a 78 with a 350, what transmission is that? And would it be a good time to upgrade to 700R4 that everyone raves about if it's not the one it has?

Thanks a million.
Title: Re: Transmission troubles
Post by: thirsty on April 19, 2012, 05:14:53 pm
It should be either a th350 or a th400 in your 78.

I may be wrong about this but you should be able to replace that seal without doing anything but removing the driveshaft. If it where mine I would add some fluid and test drive it before I committed to a replacement or a rebuild. If it works out that the transmission did not get hurt and the seals go in from outside the transmission you can fix it with a $10.00 seal in your driveway.

We have many members here that know a lot about automatic transmissions. If I am wrong somebody will correct me and give you the info you need.
Title: Re: Transmission troubles
Post by: bd on April 19, 2012, 05:41:06 pm
x2

You should also check the loosness of the yoke in the tailshaft of the trans, before you drop the driveline.  Just wiggle the yoke side to side/up and down to see how much it moves.  The greater it moves, the greater the tailshaft bushing wear.
Title: Re: Transmission troubles
Post by: CameronTaylor on April 19, 2012, 10:56:43 pm
Thats what I was originally thinking, but unfortunately, it's not the seal. The guys told me that it is actually leaking from inside. And of course, after filling it full of fluid, it still slips driving down the road. It kind of feels like it doesn't want to shift up when taking off, and once you are driving, it tends to try to get out of drive into neutral.
Title: Re: Transmission troubles
Post by: Donut on April 20, 2012, 07:17:17 am
Sounds to me like your transmission has more issues than leaking around the yoke.  Do you trust the shop you took it to?
If not, find another one.  Also start weighing your options for a replacement.  Enlighten yourself, figure out what you have and make an educated decision.

I'm not nor claim to be a trans expert.  However you did take it to someone that has physically seen it and knows what it's doing.

As far as upgrading,  would depend on your usage and goals.  May be something else to discuss with the trans shop.
Title: Re: Transmission troubles
Post by: Fairlane514 on April 20, 2012, 07:33:42 am
There are rebuild kits and instructional DVD's out there so you can do it yourself and save money. I have done it to several transmissions (several Muncies, T5's, C4) with success. 
Title: Re: Transmission troubles
Post by: bake74 on April 21, 2012, 06:03:00 pm
And for a 78 with a 350, what transmission is that? And would it be a good time to upgrade to 700R4 that everyone raves about if it's not the one it has?

     I am assuming that it is a 2wd 78 that we are talking about ?  If you have mechanical skills you should be able to rebuild this with the advice fairlane514 gave.  With as much support and help there is out there today, almost anybody can rebuild these trans and it can give you some great experience.
Title: Re: Transmission troubles
Post by: CameronTaylor on April 30, 2012, 09:19:43 pm
Well ended up taking it to a trans shop that rebuilt it, including a new torque converter for $700. And it was done in two days. Pretty good I thought. So now I used a lot of that extra time to work on the interior. Today I pulled out the carpet and replaced all the padding/sound deadener and installed the vinyl liner. Gotta work in stages.
Title: Re: Transmission troubles
Post by: bake74 on May 01, 2012, 06:56:10 pm
     Rebuilt and new torque converter for $700.00, that is a good deal.