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T-350 problems in 1979 c-10

8K views 34 replies 9 participants last post by  SBC-Torque 
#1 ·
I have a TH350 trans in my 79 c-10

recently its been slipping while cold (i live in canada so about -20) after it heats up it doesnt slip.

i added some lucas transmission fix, and now even after it warms up it only will work in reverse.

i noticed the tranny fix was really thick and hard to go down the dipstick tube (its thick as is and the cold doesnt help)

any ideas?
 
#4 ·
Sounds like an old trans that has given up. Hard seals are hurt more by cold temps and the tans slips.

If the trans is old , high mileage , it may be time for a peoper rebuild.

It is easy to drop the pan , change the filter , inspect the pan for debris.
 
#6 ·
i do have a heated garage but i had to put my boat in a little sideways to get it to fit and now my old ladys van is the only thing that fits.

i have a filter kit, but i dont wanna waste it on a blown tranny. i may just buy a used one to use while i rebuild mine thanks for the help guys.

ive never dropped a tranny in a chev before, what am i looking at.
 
#7 ·
If you've dropped an auto tranny from anything else, it's pretty well the same.
Drive shaft, torque converter bolt's, fluid lines, speedo cable, shift linkage, detent cable, modulator hose, starter, tranny mount and cross member, and last, bell housing bolt's. Don't forget to remove the dist. cap as it can hit the firewall and damage the cap or dist. ;)

Also, disconnect the battery first!
 
#10 ·
Throw a can of "Trans Medic" in it, or a like product. Something "thin" that permiates the seals to soften and expand them, not a stop leak product. Sounds like a space heater under the trans might help some initially. Honestly, it's never worked for me, but my sisters old 68 Camaro, and several friends, have had good results doing this. I just put a TH400 in my truck, I've had it long enough it's gone through 3 TH350 trans. Put a TH400 in your truck, and never look back. I just bought another TH400 yesterday, to use for a future project; complete and rebuilt, with very low miles; the truck it was in got totalled. $150.00 with converter, yoke and driveshaft, cooler with braided lines! Watch your local Craigs List postings.
 
#12 ·
SBC-Torque said:
pulling the truck into my garage last night, and she blew and pissed fluid everywhere,

wondering if a th350c will bolt up?
or if its even a good idea for my truck, basically stock besides headers and intake
found one in good shape for $350
thanks.
It will as long as its got the right length tail on it.
You will need a new torque converter as well.
 
#15 ·
SBC-Torque said:
The right length tail?
How can i check for this

use a tape measure device.

Look for a 6 inch or a 9 inch tail housing measurement from where the tail housing bolts to the main case of the trans... these are the two most common lengths
 
#19 ·
The tailstock doesn't matter. Its just that the output shaft inside the tailshaft has to match as well.
You would have to take apart the whole tranny to swap them.

Pics below show the same tranny with a 9" and then a guy asked me for a 6" so I swapped them out.
 

Attachments

#22 ·
Your th350 should be the 9" and the 700r4 is the same length so no need to cut the driveshaft.

You will need to move the crossmember. Just drill a few new holes.

Also:

Lockup wiring kit...you may want a new brake switch as well.
TV cable and brackets

Your shift rod will work with a minor (Bolt) adjustment.
 
#24 ·
Update

Tranny from a 78 'vette,
B&M shift Kit installed, running great!

The guy that had the truck before me sure did a sloppy job installing the previous tranny,
2 out of the 6 main bolts were nonexistent, many of the bolts could be loosened by finger. kickdown cable nonexistent.
i love working on vehicles but i sure hate having to correct other peoples mistakes

Old tranny


New tranny


the only thing thats still giving me trouble is that the dipstick tube doesnt have an o-ring, so when the tranny fluid settles it leaks out.
 
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