Trans fluid change

[BGPick]

Auto Trans is shifting a bit hard only into and out of first gear. Is there a write up for changing the fluid on these? I assume I might as well drop the pan and change the gasket too, should I use only RTV or the actual gasket?

 

[Goldie Driver]

Auto Trans is shifting a bit hard only into and out of first gear. Is there a write up for changing the fluid on these? I assume I might as well drop the pan and change the gasket too, should I use only RTV or the actual gasket?

I used an AC Delco tranny kit that had a rubberized cork gasket.
It held the bolts in while you hand tightened them.
Nothing to it, really - just have a big pan and cardboard as more than likely your gonna spill.
Loosen all the pan bolts and then remove them on one end until fluid starts draining.
13 half inch bolts, IIRC.
(No drain plug ...)
Keep going backwards on the pan removing bolts until most of the fluid is out, then remove the pan.

Clean the residue out of the pan.

Remove 2 screws that hold the filter, and reinstall the new one with the new little gasket.

Reinstall the pan, and add about 3.5 quarts of tranny fluid.

After that you can start it, run it through the gears, and add fluid as required.

A few pics for you.

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[BGPick]

Thanks brother! Hopefully it cleans up the shifts a bit. I imagine the fluid is pretty old.

I need to replace the seal at the rear of the trans also I’m pretty sure.

Any idea how to find what “trans code” I have? There’s tons of options on rock auto.

 

[1987 GMC Jimmy]

How hard are we talking? Mine was totally slamming into second, and it was a governor gear problem. That’s not always the cause of rough shifts, but it’s something to keep in mind.

 

[BGPick]

I mean, it’s not SLAMMING. Not really audible even. Just a bit of a jolt when you feel it shift. The rest of the gears seem fine It’s only the first shift.

 

[Goldie Driver]

Thanks brother! Hopefully it cleans up the shifts a bit. I imagine the fluid is pretty old.

I need to replace the seal at the rear of the trans also I’m pretty sure.

Any idea how to find what “trans code” I have? There’s tons of options on rock auto.

The shape of the pan - mine is a TH350C.
The service parts sticker may have that info - not sure.

Here is something I found - the title is misleading. About halfway down:

https://www.700r4transmissionhq.com/identifying-a-700r4/

 

[1987 GMC Jimmy]

I gotcha. I’ve noticed marginal shift feel improvements after doing a transmission service so that very well maybe all you need.

 

[BGPick]

Awesome! Thanks fellas. I’ll check it out tomorrow and then order a gasket. Is it worth switching to a synthetic trans fluid like the Valvoline max life?

 

[1987 GMC Jimmy]

The filter should come with a gasket in there so you should only plan to get the filter and fluid. My Jimmy’s got 183K miles on it, and I just put the cheapest Dexron III equivalent I can find at Walmart, Dollar General, or wherever has it. I’ve been told you can also run Type F for firmer shifts, but for me the Transgo kit and Dexron make for a pretty nice, moderate shift feel - not too mushy and not too firm.

 

[CorvairGeek]

The OP will have a Turbo 400 if a 3 speed (probably not), and a 700R4 with 4 speed automatic.
Just watch the o-ring or seal on the filter pipe in either of these transmissions.
I'm a big fan over changing over the Dexron VI as GM says is fully reverse compatible.

 

[1987 GMC Jimmy]

The OP will have a Turbo 400 if a 3 speed (probably not), and a 700R4 with 4 speed automatic.
Just watch the o-ring or seal on the filter pipe in either of these transmissions.
I'm a big fan over changing over the Dexron VI as GM says is fully reverse compatible.

Are you talking about having to pick the old seal out of the valve body? I had to do that for the Jimmy the first time I serviced it because the new style filter had the seal made onto the neck.

 

[Rusty Nail]

*use the gasket

 

[CorvairGeek]

Are you talking about having to pick the old seal out of the valve body? I had to do that for the Jimmy the first time I serviced it because the new style filter had the seal made onto the neck.

Absolutely! Seems like some are already on the filter pipe, as you have seen, and others will be in the package, ready to install.
Some people can do a lot of damage to the bore trying to get the old seal out. Forgetting an o-ring (T400) or the seal (700R4) on the filter can be a memorable experience too.
To the OP, stay away from RTV on the pan gasket.

 

[bedwards]

While I am a big fan of regularly changing the tranny fluid, with the 700r4 I think the properly adjusted cable gives a firm first second shift. Someone might correct me. I would rather have a firm shift than a sloppy slippy soft one.

 

[Billy]

While I am a big fan of regularly changing the tranny fluid, with the 700r4 I think the properly adjusted cable gives a firm first second shift. Someone might correct me. I would rather have a firm shift than a sloppy slippy soft one.

I feel the same way. I interpret firm shifting as a firm transmission. It's worked so far! Lol