Technical Turbo 400 question

Brought a new project 1966 c10 home. Has 350/turbo 400 in it. Needed brakework so I salvaged a booster out of 84 k10 and put together to drive. During the drive it would shift from 1st to second fine but wants to down shift back to first . I checked vacuum to the modulator and its good, the modulator appears to have been changed at some point so I pulled the governor. I noticed the valve would move up but sometimes would stick up and not fall down. So I pulled it apart to clean it and noticed the weights and springs are different on either side. Looks like someone used what they had left in a kit. I weighed the wings with weights/springs and they are only a gram different. My question is with different style weights and different springs will this cause shift problems even though they weigh similar?


thank you

 

probably was built that way originally. if you post close up pics of the crimp on the pins, we can probably tell whether or not it's been worked on.

I expect your problem is somewhere else. Usually the only thing wrong with a governor on a GM trans is that the plastic gear will break, and it won't upshift at all.

 

The pins are not crimped at all. They have indents with clips, which leads me to believe the governor was worked on. I thought all pins were crimped from the factory, I could be wrong though.

thanks

 

Try disconnecting the down shift solenoid and see if it shifts ok. If it does, the solenoid needs replaced or cleaned.

Pull the vacuum modulator out and see if it holds vacuum.

 

What speed does it shift into second?
If it is at what you would call normal road speed than the governor is not the problem.

 

Like Squirrel said, the different springs are probably stock. The light spring gives you some pressure at lower speed and the heavier spring controls the pressure at higher vehicle speed.

Does it ever shift to high gear? Does the engine have low vacuum? Does reverse work okay? Answer those questions and I can give you direction to explore.

 

I’m getting almost 20 of vacuum at the engine, reverse works fine no issues with that at all, it did not seem to want to shift to third just back to first I didn’t drive it long not wanting to burn anything up

 

Also the downshift solenoid was already disconnected

 

Was the solenoid or switch disconnected? Switch is on the gas pedal, solenoid is in the trans. Either way, the solenoid or valve could be stuck in the downshift position. since you have reverse the direct clutch is working.... that points to the kickdown valve.

 

I checked and No switch was installed by previous owner, no wire leading back to the solenoid

 

Thanks you guys are a major help!!! I will start to install switch and checking the solenoid function, much appreciated

 

you don't need to wire the solenoid. But you do need the solenoid to be in place, as it blocks a hydraulic port (except when it's engaged, and you are kicking down)

 

If reverse works that means the high/reverse clutch is good. However, this clutch piston has 3 seals on it giving two apply areas. In reverse fluid is sent to the whole of the piston for good holding power. In high gear a smaller area is used. If the center seal is bad or installed backwards you will have a good reverse and no high gear or a severely slipping high gear.

Good vacuum to the modulator should give you normal upshifts. You should be able to get in high gear at light throttle before 30 mph.

The fact that it wants to go back to first makes me think something like the kickdown solenoid is delaying the shift (as others have mentioned), or governor pressure is very low. If you drop the pan and find the kickdown solenoif to be okay, take a good look at the governor bore in the case. Sometimes these get scored and leak off governor pressure.

 

Peelout, I see the weights from the Superior or Coan governor kit in it. It will shift higher at WOT than it would with stock weights. The springs, like others said, will affect the low speed, light throttle shifts.

 

Ok, here is what I found. Aftermarket solenoid with pinched wire, also when I removed it the shim fell out. I watched a guy on YouTube (YouTube.... I know, I know) say not to use the shim with aftermarket. When I got the solenoid on the bench the shim does not line up correctly with the top of solenoid, will this cause problems? I also attached a pic of the pan had sludge in the bottom and filter not sure what amount of sludge is ok. Thanks again

 

that is the later style solenoid, with a rubber seal built in, it should not have the metal gasket. Make sure there's no dirt in the orifice in the solenoid, keeping the needle from closing all the way.

If the sludge is fine powdery stuff, it's probably normal wear. If there are strange chunks of metal or fiber, then things are coming apart.

 

Want to thank everyone again for their help. Not sure exactly what did it, but I dropped the pan replaced the kick down solenoid, vacuum modulator , filter and had a good drive.