73 Cheyenne Help!

[4x4man09]

I just got a 73 Cheyenne 3/4 ton. Has the 350 engine in it. The truck runs fine but wont shift into second. It will drive just fine in first. But once you get going fast enough and she tries to shift into second it doesn't happen. Mind you it's an auto. We are going to drop the tranny this weekend. Is their anything we should check out before doing so?

[60ratrod]

is the vacuum modulator valve connected to a vacuum port on the engine?? i had my modulator valve line blow off during a back fire and wouldn't do any gear above 1st until i managed to hook the line back up. typically it'll be connected to a port behind the carb, in front of the dizzy

[4x4man09]

Originally Posted by 60ratrod

is the vacuum modulator valve connected to a vacuum port on the engine?? i had my modulator valve line blow off during a back fire and wouldn't do any gear above 1st until i managed to hook the line back up. typically it'll be connected to a port behind the carb, in front of the dizzy

My dad will have to check today as I can't do much with a broken arm lol. The guy we got it from said he was driving down the street and it just locked it's back wheels and then wouldn't shift into first. Like I said, it tries to shift but it can't. If that isn't the problem what could be?

[enaberif]

What transmission are you running? That will make all the difference in the world.

[4x4man09]

Originally Posted by enaberif

What transmission are you running? That will make all the difference in the world.

I'm not sure. I think it's the 350? I don't know much about it, my dad does. It came with another tranny, the guy said it works fine. It's a 400? tranny ( like I said, I don't know much about any of it lol.) He said the tranny in it was working fine then one day while driving it, it just locked up the rear tires and wouldn't shift into second.

[Chlsnk]

I know its a simple thing but have you checked the tranny fluid? Is it burnt smelling or black insted of cherry? Does it need fluid added?

[enaberif]

Originally Posted by 4x4man09

I'm not sure. I think it's the 350? I don't know much about it, my dad does. It came with another tranny, the guy said it works fine. It's a 400? tranny ( like I said, I don't know much about any of it lol.) He said the tranny in it was working fine then one day while driving it, it just locked up the rear tires and wouldn't shift into second.

http://www.maliburacing.com/auto_tranny_id.htm

This will allow you to look at the pan and figure it out easier

[4x4man09]

Originally Posted by enaberif

http://www.maliburacing.com/auto_tranny_id.htm

This will allow you to look at the pan and figure it out easier

Ok the spare one we have is the TH400 and the one thats in it is the TH350. If we can fix the 350, what one would be better? For things like driving through a lot of snow/of roading and haulings quads around?

[enaberif]

Originally Posted by 4x4man09

Ok the spare one we have is the TH400 and the one thats in it is the TH350. If we can fix the 350, what one would be better? For things like driving through a lot of snow/of roading and haulings quads around?

General consensus is the TH350 is a reliable and bulletproof transmission if built properly.

If it locked up the rear tires and won't go into 2nd anymore I'd say as someone suggested make sure you check the fluid levels.

Then I'd say put the rear wheels up in the air (truck blocked well) and see if it would go into 2nd again.

If fluid is good and truck still don't go into 2nd then you definitely have a transmission problem and problem something with the gears inside.

Either way looks like a possible rebuild of that TH350