I want to install a 200-4R trans and a new converter in my 71 Chevelle. Do I really need a lockup converter or will simply having 4th gear do the job when upgrading from the 3-speed TH350? The car will see mostly local street duty with occasional highway trips.
There's nothing wrong with using non-lockup.
With modern converter technology, NLU works fine and is what I prefer in a retrofit application.
I've done dozens of retrofits, some on my own cars. I've been building these transmissions for years and my thoughts on this have changed over time.
I typically believe in keeping the modern technology. If the trans has the capability of locking up the converter, why give that up?
I'll tell you why...
Because the lockup is a PITA to ever make work reasonably close to how the OEM's intended it to.
Pretty much since their inception, lockup transmissions had an ECM controlling them.
Some very early units did not and the OEMs used a Rube Goldberg control scheme that you will have to try to copy if you want a reasonably well working lockup.
You can just wire in a toggle switch.
You can wire it up for 4th gear only lockup.
You can do a latching relay switch.
You can wire in a vacuum switch, which will then need a delay valve.
You can use a somewhat expensive speed control sytem.
Or you can use a combination of some or all of the above sytems.
I've played with all of them.
I've spent countless hours trying to make them work better.
Then we did a few non-lockup cars and I decided it was way better.
A toggle switch is just that. Not the safest method.
4th gear only causes chugging problems, so the first thing you do is add a vacuum switch, you then get a scenario where it will go into lockup and immediately lose vacuum, and unlock. As soon as it unlocks, it lessens the load on the engine, builds vacuum, and locks back up again, which causes the engine to load, dropping vacuum.... See where that's going?
So you add a delay valve to the circuit. That helps and usually that makes a decently working system assuming you have either an adjustable vacuum switch or a near stock engine.
Latching relay that kills lockup based on bake pedal application is a step up from the toggle switch.
The speed control system like B&M sells works OK, add in a vacuum switch aand delay valve and you have near factory control. But you also have $250 in the whole mess.
Non-lockup with a good converter is way less hassle, less expensive and works well.
I've always done them with 4th gear lockup and lived with the lugging, or manually chosen 3rd gear if speed warranted it to keep it from hunting. Houston has a lot of highways, so most of the time, it goes 3-4 and you continue to accel and there is no lugging. I'd be interested as well, I have a 2004R on deck for my '68 Caprice and would consider a non lockup based on Jake's recommendations.
A kit has to be installed in the pump that replaces the tcc valve and allows proper lube feed when in OD.
It's mandatory unless you like replacing transmissions.
you also remove the capsuled checkball in the end of the input shaft (pita).
Hi all.
We're dealing with an 88 Monte Carlo SS (30000 mile car which is also for sale at the moment) that shifts up or locks up early. Will reset the TV cable then determine next steps. Will we ever get this trans to act the way it should and not lock up so early? Apparently this has been going on for a long time but the car is being taken out of storage and been in storage for a "few" years.
I know this is an older post but any help would be appreciated.
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