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Tranny questions and more...

Clod_King

Clod_King

1/2 ton status
Joined
Jun 7, 2005
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Location
Grimsby Ontario
I have an 85 Chevy pick up, and it has a 700R4 in it. There is a vacuum line coming off of it. I'm geussing it's a torque converter lock up line.

I don't know where to hook it up...

I swapped in TBI 350 motor, and I don't know where to feed that vacuum line into...

I also need the torque specs for U-bolts...

My truck is gonna get towed away if I don't finish it soon. The town by-law enforcers are breathing down my neck.
 
140 ft lbs on the u-bolts

And 700r4s do not have vacuume lines, Are you sure its not a th-400 or a th350? Is it a diesel/1ton/3/4ton? If it is only a 3 speed tranny then the vacuum line goes to constant vacuum off of the manifold
 
It's a 3/4 ton 2WD.

The guy said it was a TH350, but the column has an OD selecion, and the tranny will go through every notch on the column...

Maybe I should check out the pan. I had it off already, but I never compared it to that identification chart that is on here.

Thanks for the torque specs!
 
transpan.gif
 
Are you talking about the vent line on top of the trans? 700s have those, but don't connect them to vacuum. :D
 
Are you talking about the vent line on top of the trans? 700s have those, but don't connect them to vacuum. :D
Click to expand...

I'll double check that too! hahaha.

I think it is a TH400... This is a 2WD tranny if that makes any difference.

I included a picture of where the rubber hose feeds into the side of the tranny. I don't know where to hook the other end up too. And two of the tranny pan. Tell me if I'm correct or not.

Article numberH41388061
part number 4RD 960 388-06
Old part number 87408
Contact Form SPDT (1 Form C) change over
Nominal Voltage (V) 12-36 Heavy Duty
Amperage (A) 20 40
Supression Resistor
oil Resistance +/- 10% (Ohms) 75
Contact Material AgNi
Must Operate Voltage (V) 8.5
Must Release Voltage (V) 1
Package Quantity 1
Feature Skirted relays are suitable for Ohmic loads, lamp loads.
Are waterproof in the area of the plug.
Come in a compact design.
Have standardized dimensions.
Package - Height (in) 1.7999964
Package - Length (in) 2.8999942
Package - Weight (lbs) 0.100000656
Package - Width (in) 1.8999962
Product Description (long) Mini 20/40 Amp SPDT Skirted
Country Of Origin United States
UPC Code 760687874089
Click to expand...

I found these Hella relays nestled in behind the glove box in an early 90's TBI pickup, right next to the computer. There were three of them, and I want to use one for my windstar fan setup. I don't know if these are good enough, but those are the stats that Hella has on them... What do you guys think??

101_0254.JPG

101_0258.JPG

101_0252.JPG
 
Thats a T400, hook the vacuum line (from the vac. modulator) to full manifold vacuum
 
What does that vacuum line do anyways??

I mean I know the what the line does, but why does it need to be hooked up? Curiosity really...
 
well i had a similar problem my 81 k5, if that hose isn't connected to the modulator, then the tranny won't shift gears. leaving it in first gear the whole time.
 
I have another question for you guys.

I am having trouble finding the correct Kick down cable for the TH400. Is that also called the TV cable??

I went to the local Chevy dealer, and they checked my VIN#. The truck is supposed to have a 700R4 in it... So he couldn't check for the cable that way. And he couldn't find a cable for the TH400 by searching. He found a couple for the TH350, and 700R4, but nothing for my tranny.

NAPA only has them for the 700R4 aswell.

And the Canadian Tire doesn't sell them at all.

Where do you guys get your kick down cables from??
 
T400's didn't have a TV cable...it was attached to the throttle linkage.
Let me look some more.

looks like some models had a switch on the acc. linkage that activated a solenoid in the trans. It is supposed to make contact at about 3/4 throttle.
 
look up a cable for a previous year truck that came factory with a th400, like my dually, even though mine came with a BB454, it now has a 350 and still using the same cable.
 
400's used a switch for kickdown. Switch mounted to the drivers pedal, solenoid/connector is on the opposite side of the transmission as the modulator. Not necessary, but you'll need to manually downshift without it, if you need to pass, pull a hill, etc.

Vacuum line was to control shift firmness by modulating line pressure based on engine vacuum. SHOULD shift without being hooked up, but it should be more firm than normal. IME difference in shift RPM or MPH was negligible. Hose in my car always fell off, I never noticed the difference.
 
I took two pictures for you guys. They are of the side oppsite the Vacuum Line side.

Which of these are for the switch?? I don't have one near my gas pedal at all... So I have to set something up I geuss. Is the extended part of the pedal bracket with the hole in it the mounting part for the solenoid/switch??

101_0260.JPG

101_0261.JPG

101_0262.JPG

101_0263.JPG
 
It will still shift it will just think your at WOT (except for the kickdown solenoid) and shift at higher RPMs and very harsh all the time. (so if you don't reach the shift RPM it will seem like it isn't going to shift) The vacuum modulator senses engine load and adjusts trans shift pressure accordingly. There is also a kickdown switch (should be above the gas pedal) that connects to the other side of the trans with this applied it shifts around 5K and much firmer. It will also kick it down a gear for passing and acceleration.
 
Can anyone with a truck that came with a TH400 from the factory hook me up with the last 7 digits from their VIN# ???

It would really help me out trying to source the parts...
 
Maybe your spec is different on the 1/2 ton, but my 91 v2500 burb ubolt specs were 135 or 125 lb/ft rear axle, 155 front axle.
 
Sorry I didn't see the follow on posts. :(

Never had a truck with TH400, but I pulled parts from one once. As I recall, the switch mounted to the gas pedal in the bracket you show in pic 1, with all the holes in it.

I believe thats the kickdown solenoid shown in the last pic, if it's the only plug on that side, that must be it. But on my TH400 (in a previous car) I swear it was up near the bellhousing. That picture makes it look like it's further back.

ANY C/K/R/V truck 1973-1990 with the TH400, AFAIK, will have the right pieces.

Cars used TH400's, at least some, if not all, used a carb mounted switch.
 
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