'79 K20 vs. an '84 K20, which would you choose?

[handloader90]

and there is no gasket between the pinion housing and diff housing .

RTV?

Thought I saw a little metal gasket, kinda like a shim in the last one I took apart.

Kinda like the metal gaskets that are used between the axle shaft flange and hub?

 

[handloader90]

This seal?

 

[handloader90]

He's a little video of the truck. Starting it up with a good battery and such.

 

[diesel4me]

I think the starter needs a shim--its too close to the flywheel,when it makes that "zip-zing" noise right after it fires up...when the starter is too far away you get a grinding noise while cranking it over,not so much after it starts..

 

[handloader90]

I think the starter needs a shim--its too close to the flywheel,when it makes that "zip-zing" noise right after it fires up...when the starter is too far away you get a grinding noise while cranking it over,not so much after it starts..

I was gonna do the starter today but it was extremely windy out.

Gonna take a look at the flywheel while I'm down there and make sure the bendix didn't eat into it.

 

[handloader90]

Craigslist scores from yesterday and today.

 

[sweetk30]

@handloader90 that metal shim thingy is just that the shim that sets the pinion depth on the ring gear . . there is different thickness ones for setting it up .

 

[diesel4me]

The best method I've used came with the instructions on a rebuilt starter I got years ago--they said to measure the clearance by shoving a 1/8" allen wrench or drill bit between the armature shaft the starter drive rides on ,and the outer edge of the flywheel gear teeth,it should fit snugly--if not,add or remove shims until it is at the proper clearance..

This beats other methods that required manually forcing the starter drive "out" to mesh with the flywheel somehow,and try to measure the backlash with a wire feeler gauge,you need 4 hands to do that!..

 

[handloader90]

@handloader90 that metal shim thingy is just that the shim that sets the pinion depth on the ring gear . . there is different thickness ones for setting it up .

Gotcha! I always thought it was some kind of gasket.

 

[diesel4me]

They look like this--or you can get "offset" ones if you wish if you have the starter that has the bolts "diagonal" instead of straight across--the ones pictured here work on both types..

I also found a picture explaining the method of measuring the drive gear clearance..

 

[handloader90]

They look like this--or you can get "offset" ones if you wish if you have the starter that has the bolts "diagonal" instead of straight across--the ones pictured here work on both types..View attachment 258921

I also found a picture explaining the method of measuring the drive gear clearance..View attachment 258922

Thanks!

 

[handloader90]

Got a question.

Does a TH400 use a TV/ Detent cable like a 700r4 or Th350? I didn't see anything running parallel under the throttle cable...

Never had a truck with a 400 either.

 

[imiceman44]

Got a question.

Does a TH400 use a TV/ Detent cable like a 700r4 or Th350? I didn't see anything running parallel under the throttle cable...

Never had a truck with a 400 either.

It uses vacuum and an electric kick down on the pedal, no cable

 

[handloader90]

It uses vacuum and an electric kick down on the pedal, no cable

Interesting.

I'll keep an eye out for a vac line that runs down there.

 

[sweetk30]

single orange wire from gas pedal switch under dash to trans plug on left side of case just above trans pan rail lip .

 

[diesel4me]

The vacuum modulator on a TH400 downshifts it under part throttle conditions,the detent switch on the gas pedal kicks it down when you floor it...the modulator on a TH400 is located on the front passenger side near the bell housing...

I'd make sure its good,if the diaphram in it ruptures it'll suck ATF into the intake manifold and burn it off,and eventually lower the fluid level enough to harm the transmission..it also controls the shift firmness and speed that it'll upshift at also,by regulating line pressure..driving with a defective modulator can harm the transmission in a short time..

 

[imiceman44]

The vacuum modulator on a TH400 downshifts it under part throttle conditions,the detent switch on the gas pedal kicks it down when you floor it...the modulator on a TH400 is located on the front passenger side near the bell housing...

I'd make sure its good,if the diaphram in it ruptures it'll suck ATF into the intake manifold and burn it off,and eventually lower the fluid level enough to harm the transmission..it also controls the shift firmness and speed that it'll upshift at also,by regulating line pressure..driving with a defective modulator can harm the transmission in a short time..

Yeah I had a bad one and I had to manually downshift so I didn't burn the transmission

 

[handloader90]

The vacuum modulator on a TH400 downshifts it under part throttle conditions,the detent switch on the gas pedal kicks it down when you floor it...the modulator on a TH400 is located on the front passenger side near the bell housing...

I'd make sure its good,if the diaphram in it ruptures it'll suck ATF into the intake manifold and burn it off,and eventually lower the fluid level enough to harm the transmission..it also controls the shift firmness and speed that it'll upshift at also,by regulating line pressure..driving with a defective modulator can harm the transmission in a short time..

I'll give it a look! Thanksfor that info.

 

[handloader90]

Got my other starter swapped into the truck and man does it fired up beautifully! Fires up nice and smooth!

 

[handloader90]

Put my plates on today, saw this stuff and thought I'd share.