700R4 in a 73 K5

[misweetrevenge]

So I searched around and couldn't find anything that could confidently answer what I was looking for.

I bought my 73 K5 about a month ago with a 700R4 mounted to a NP203.

I brought it by Aamco to have them look and give me a quote on all new seals.
Their in house rebuilder said something about it not shifting right because of wiring issues. Now he didn't look at it but he's an old timer who has been building transmissions for 35 years. He seemed like he really knew what he was talking about.

Is he right about it not working correctly? What should I look at or make sure is done for it to work properly. I really like the OD.

[bd]

From memory, the only electrical control over the 4L60 (700R4) is for engagement of the TCC (torque converter clutch).  If TCC doesn't function, a 700R transmission will overheat and fail. 

As delivered from the factory, TCC is generally controlled by an ECM with brake override (later models) - or by mechanical switches that monitor engine load (a vacuum switch) and brake application.  The method of control depends on the year and original use.  There could be hydraulic switches in the valve body of the trans, as well, to allow TCC engagement only in higher gears (2nd/3rd/4th); otherwise, most internal switches are for output to an engine ECM that a '73 doesn't have.  Regardless, valve body switches have no control over trans shifting between gears. 

When adapted to a vehicle that didn't originally come with a 700R4, TCC can be hydraulically controlled by valve body switches that eliminate the need for an external engine vacuum switch.  Or, TCC can be manually operated by a dash mounted toggle.  In all cases, TCC should disengage when the brake pedal is depressed or when the transmission is not in a forward gear.

Regardless, if the AAMCO tech didn't look at the vehicle, he wouldn't have known whether or not the TCC was wired to function.  You should question him about his comments.   

[misweetrevenge]

Thanks for the info. Good to know. thats what I was looking for. Is there a way to tell if it has any of those things without pulling it?
If not I gotta have it pulled when I can afford it because it needs new seals (front seal, pan and rear output are leaking). they want $800 for remove and install alone. Plus about 100 for the seals (might as well do all the seals while its out), though the Customer Service Manager told me if I get the rear brakes and the seals done at the same time they can give me a package deal and the brakes become pretty cheap.

If I install a toggle switch for the TCC Lockup, how often would I need to lock it up? Or does it only need to be locked when I'm cruising in 3rd or 4th gear for a longer than a few miles? I drive around town a lot and feel it would get really annoying having to flip the switch off and on every quarter mile or so in between lights.

[bake74]

      This thread by Mike Ervin Mike Erwin might shed some light on your conversation.

[bd]

Is there a way to tell if it has any of those things without pulling it?

...If I install a toggle switch for the TCC Lockup, how often would I need to lock it up? Or does it only need to be locked when I'm cruising in 3rd or 4th gear for a longer than a few miles?...

If engine RPM jumps up 100 - 200 RPM while driving down the highway at 50+ MPH as you ever so slightly step on the brake pedal - not enough to engage the brakes, but just enough to illuminate the brake lights, then TCC is alive and well and you probably have no worries.  Otherwise, look at the driver side of the transmission, just above the oil pan flange and rearward of the shift lever for a wiring harness (1 to 4 wires) that plugs into the transmission.  If there isn't any wiring connected to the trans, you may have a problem and will have to dig deeper.  If a harness is connected, then look for an engine vacuum switch.  Early 700R and MV4 (350C) trannys used a vacuum switch mounted to the firewall just right of the power brake booster.  Begin looking there. 

There are aftermarket kits for adding automatic TCC control to retrofit 4L60s (TCI 376600 and Painless 60109, for examples).  The Painless kit closely resembles OE factory wiring and function.

[misweetrevenge]

Is there a way to tell if it has any of those things without pulling it?

...If I install a toggle switch for the TCC Lockup, how often would I need to lock it up? Or does it only need to be locked when I'm cruising in 3rd or 4th gear for a longer than a few miles?...

If engine RPM jumps up 100 - 200 RPM while driving down the highway at 50+ MPH as you ever so slightly step on the brake pedal - not enough to engage the brakes, but just enough to illuminate the brake lights, then TCC is alive and well and you probably have no worries.  Otherwise, look at the driver side of the transmission, just above the oil pan flange and rearward of the shift lever for a wiring harness (1 to 4 wires) that plugs into the transmission.  If there isn't any wiring connected to the trans, you may have a problem and will have to dig deeper.  If a harness is connected, then look for an engine vacuum switch.  Early 700R and MV4 (350C) trannys used a vacuum switch mounted to the firewall just right of the power brake booster.  Begin looking there. 

There are aftermarket kits for adding automatic TCC control to retrofit 4L60s (TCI 376600 and Painless 60109, for examples).  The Painless kit closely resembles OE factory wiring and function.

perfect. thank you. I will dig into it tomorrow while im doing my pan gasket. how hard is the rear output shaft seal of the TC to do on the side of the street with no special tools?

[misweetrevenge]

      This thread by Mike Ervin Mike Erwin might shed some light on your conversation.

that is excellent. I will for sure be reading more into that tomorrow. I like the sounds of that set up.