Do all 1981s with 350 trans have locking converters? I disconnected the computer control and went with a HEI dizzy and carb. If it has a locking converter, I'm sure I did something to stop the switching on and off when I did this. Is there a way to put a jumper wire somewhere to get the converter to work properly again?

I know it still has the original converter, I'm just not sure if they were locking.

 

The '81 transmission had the lockup feature. The ECM made the decisions on when lockup activated/deactivated. You could have left the ECM intact and connected to the transmission. As long as it was getting speed/throttle/braking signals, the lockup feature should have worked fine, even though the dizzy and carb were no longer connected to it.

 

I can plug it back in. The only reason I unpluged it was to keep the check engine light off. I can plug it back and remove the light bulb. How does it check throttle if the original carb is removed?

 

Hmmmm.... good question...

It shouldn't hurt anything to plug it in and try it. Make sure the brake pedal switch connection is still intact. That way, no matter how it is operating, you can cut power to it by touching the brakes.

If it engages on its own [like it is supposed to do], and disengages with brake apply or significant increase in throttle, you should be fine.

 

Thanks 7T1vette I will let you know how it turnes out.

 

do some searching around, I'm pretty sure they sell an aftermarket switch that works off engine vacuum to tell it when to lockup and not.

 

I believe there is a pink wire, going from memory here, from under the left side of the dash.

Check your wiring diagram to be sure.

Simply wire in a toggle switch.

 

My '84 MCSS has the TH350C w/ lock-up convertor.

I tossed the computer and went HEI/Edelbrock.

No lock-up function for the convertor, either.

It won't overheat like an OD trans will.

Been like this for years now.

 

My '84 MCSS has the TH350C w/ lock-up convertor.

I tossed the computer and went HEI/Edelbrock.

No lock-up function for the convertor, either.

It won't overheat like an OD trans will.

Been like this for years now.

 

I did not like the way the CCM worked on mine so I rewired it using the wiring diagram from a 80 model. It still uses the pressure valve inside the transmission although I change it for one with a higher pressure point. That raised the speed it kicked in slightly. It also goes through the brake light switch. It works great and the CCM in not in charge anymore.

 

dburgjohn
So all you have is it wired with your brake light switch? Does it only entergize when it is in 3rd gear? I saw on line where I can buy a vaccume diaphram switch for something like a 1984 truck with overdrive and wire it in so the overdrive will know when to go in and out according to the vaccume on the motor.
Any thoughts on this?

 

The lock-up “feature” isn’t much of a feature at all. It was originally meant to improve gas mileage. That’s it, end of story. And even when it works properly, it isn’t very effective. You may realize one tenth of a mile more per gallon on the highway.

It is often thought, mistakenly, that the lock up “feature” is a performance enhancement. This is not true. It isn’t. It was another method GM employed back in the day to try and better meet the government mandated gas mileage guidelines. It was not a good idea.

You can add a pressure switch that triggers the solenoid. You will need to remove the cover if you want to do this. The switches come in sizes that are roughly equal to speed, 33 psi = 33 mph, 45 psi = 45mph, and 59 psi = 59 mph. They cost less than 20.00 and you can get one almost anywhere.

The switch needs to be wired into the ground going to the solenoid. I forget exactly which wire. You can use the 59 psi switch and wire it in, in about an hour. But do the research and find the right wire!!!!!!

OR, you can simply wire in a manual switch and trigger it yourself at 60 mph.

OR….you can do nothing.

Quite frankly, doing nothing is a good alternative. The only thing that MIGHT happen, is that if you are running 110 mph on the open highway through the heat of summer in Arizona for about 15 hours straight, you may overheat.

Overheating is very rare and probably won't happen. Toss the CCC and put in a manual switch for your own piece of mind.

 

The ONLY purpose of a lockup clutch in an automatic trans is to eliminate the inefficiency of the fluid coupling in the torque converter. The lockup clutch mechanically joins the converter pump and turbine so that the power flow is a "direct-thru" drive, instead of the fluid coupling. It should save about 10% on fuel mileage, IF it were ON all the time. But, it's only on a portion of actual driving time, so there's not much gain in city/suburban driving. For highway driving, it should allow a 10% increase in fuel mileage.

The lockup clutch CAN NOT be a performance enhancement, as it can't take the kind of torque that any C-3 engine can produce. That's why the CCM (or ECM) cause lockup to drop out when the throttle is increased significantly.

 

B&M has an easy lock up converter kit that goes for @$100 from summit racing. I think that would be the easiest way to go, unless you have a very good understanding of the ECM.

 

I saw that kit and the summit warehouse is 20 minutes from me. I will look over the wire diagrams tonight and see what I can find. I'm just thinking off the top of my head, if I jumper the throttle sencer and try to activate everything else in the ECM maybe it will work fine. If not, the B&M kit may be my next step.

 

convert it to 80 style.
the ECM is a dead end.

 

I've got to disagree with you there. In an overdrive ratio the lockup is essential to keep the heat down. The slip speed (ratio between impeller and turbine) becomes greater and that energy is converted to heat.

The 10% slip is only a couple hundred rpms and not likely a gain of 10% in fuel economy.

An yes there are racing transmission that use a lockup clutch. You can even buy a racing powerglide with a lockup converter. The big power diesel guys all use converters with double or triple lockup plates to gain in torque capacity.

 

Uhhh....the inefficiency of the fluid coupling is what causes the excess heat.....

 

I tried just plugging in the ECM over the weekend. IT didn't work sence the carb & dizzy is no longer connected. My next option will be to either look at the 80s wiring and see if I can incorporate something like that or just go to the B&M kit that measures the RPMs and locks at a set point you give it.

 

go with the kit from summit, it will save you tons of time and agrivation trying to "jury rig" something and it will work correctly, is the risk of tearing up your tranny worth the cost of the kit (Not in my book).