ECU converter 200r4 lock up control

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corkatoa

Burger Flipper
Jul 6, 2013
111
93
28
Creston, BC, Canada
That's another point, I'm not sure how well the 200R4 does if the TCC isn't used but it may overheat?
I think that logically, any time you can take the load off the clutches, it is a good idea. Now if
Yeah, I'm not aware of any factory 200r4's that weren't equipped with TCC converter. I'd like to try one if I had a 3.21 rear but my 2.73 is too tall.

Lots of threads at many chevy sites debating whether to have a lockup or non lockup converter. Endless debate.

But, again, logically if you are driving at a high speed in overdrive and your speed varies, the factory lockup is never going to be on, or if it is then it will be constantly switching on/off. plenty of roads in the mountains where this would happen.
Essentially, o/d without lockup is like every other transmission before that had no lockup and the top gear clutches were being utilized at all times.
As well, I think I read that when not under lockup at cruising speed, there is less flow through cooler, therefore higher temp in the transmission. but again, if you are flogging the car when it is in overdrive, lockup is not necessary, and if you have too much hp, it is not going to help you anyways as it cannot handle it while in lockup mode. I would assume that is when the vacuum control comes into play, as more vacuum would take it out of lockup? But if there is an issue with it coming out of lockup under power increase in a timely manner (has to have a slight delay in releasing), then breakage is a lot more likely.

My cheap relay solution will work for me because I will be aware of why I did it. If I am going to accelerate at highway speeds with the 450hp 400 that I am putting in, I will turn lockup off or I will break the transmission I suppose. probably break it anyways, but that is just how it goes.

As well, I read that lockup contributes to premature failure due to breakage( I assume for my earlier reasoning of faulty control), but non-lockup causes higher temps, and therefore faster wearing out of the clutches but not breakage. Hook up the TCC, then keep it in third around town or towing, save o/d for the highway. This advice is the same for any o/d transmission no matter what it is in.

I am just trying to reason this all out myself, as I am putting a 200-4r from my GN into my cutlass along with a lot more engine. So if I am wrong, I need to find out and this is definitely the place for the right answers.
 

hoffa65

Master Mechanic
Mar 11, 2019
319
416
63
Atlanta GA
the 4th gear clutches do not unlock when the TC locks up, trans stays in 4th just the stator and turbine in the TC become 1 and no longer has a fluid coupler that slips it is mechanically locked together. if you have sufficient HP and decent RPM at cruse you should have no problem mildly accelerating with a locked TC . The TC can lock and unlock tens of thousands of time without issues of failing. Accelerating with the TC locked is similar to accelerating with a manual trans in 4th gear, if you got HP and TQ its not an issue. Just do not let the trans shift with TC locked its a very hard bang, don't ask me how I know lol
 

corkatoa

Burger Flipper
Jul 6, 2013
111
93
28
Creston, BC, Canada
the 4th gear clutches do not unlock when the TC locks up, trans stays in 4th just the stator and turbine in the TC become 1 and no longer has a fluid coupler that slips it is mechanically locked together. if you have sufficient HP and decent RPM at cruse you should have no problem mildly accelerating with a locked TC . The TC can lock and unlock tens of thousands of time without issues of failing. Accelerating with the TC locked is similar to accelerating with a manual trans in 4th gear, if you got HP and TQ its not an issue. Just do not let the trans shift with TC locked its a very hard bang, don't ask me how I know lol

So what you are saying is that if you are locked with a circuit like i am going to build, that if it is locked and the transmission tries to kick down it will break? or just have a manual uncoupling? How harmful is that? I thought that if it was locked, only the control circuit can uncouple it in a stock setup, but if it is on via a switch then can the transmission actually even kick down? Or does it just try to and cannot and stays coupled?
 

hoffa65

Master Mechanic
Mar 11, 2019
319
416
63
Atlanta GA
Without going in the pan you can easily mount an external 4th pressure switch so it will unlock when down shifting to 3rd dropping out the maintained relay then you relock it again after shift to 4th manually
 
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pagrunt

Geezer
Sep 14, 2014
9,127
15,257
113
Elderton, Pa
Square bodys with lock up trans use a vacuum switch on the engine tired into a stand alone harness that could work.
Here something I found in my one advance info shop manual for '81. It has the diagrams for the C10/20/30 with lock up TH350C (w/ vacuum & w/ EGR bleed) w/o computer. I edited down just to the 2wd diagrams. I even cropped a portion diagram for the B bodies with the TH200-4R w/o computer (gas engines, diesel simular). You can grab up the truck set up & replace the 2 prong with a 4 prong plug. Canadian cars can be a good source for the standalone harness.
 

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