Louisiana Classic Truck Club

I have some questions about overdrive transmissions. I will be running an overdrive and started looking for the one I will need but I dont remember what the difference is between a lockup and non-lockup converter and which is best for gas mileage.

I appreciate any help so I can get the right one. Also, anyone have a 2004R trans?

Keith,

The lockup converter is better for gas mileage. All the overdrives come with a lock up converter so you are good there. The trick is getting them to work right in an older application. I have heard the 200R4 can be built to be very good behind a small block but the 700R4 is probably more common. There are people who swear by both although I'm not a big fan of either. They are hard to set up right but once you get it right they are real good. You may know all this but I'll throw my take on them out there for you.

The TV cable controls everything in them. There is no modulator or external device or cable to control the detent (or downshift such as passing gear) this cable which is connected to the throttle linkage on the carb controls the shift point and firmness. This is what determines if it lives or dies, get this wrong and you'll be replacing the tranny. Lokar makes a nice setup but the best I've found which we put on the hoopti is made by bowtie overdrives. They have a great website. They have a setup that bolts on your carb linkage . They sell it for many carb models. It not only sets the length of the cable it also enables you to change the ratio, or rate of opening. The more you pull the cable the more pump pressure it allows and firms the shift and scoots the shift point up higher. You have to balance this opening rate with the throttle opening. They also sell a gauge and hose set up where you connect it to the trans and temporaily run the hose up inside the cab and drive it. You can then adjust the cable to get the pressures in the right range so the trans will live. It's a great setup. You can easily change the firmness and shift point while maintaining the proper pressure. Once you get it set you are done, check out the website it explains the whole procedure. We used a wiring harness on Kevin's truck, I think made by flaming river. It contained all the wiring, solenoids and switch's, vacuum switch, double pole brake light switch etc. to connect up the converter wiring to make it operate just like it came from the factory. A lot of guys simply hook a toggle switch up but you have to remember to keep flipping the stupid switch when you want the converter to lockup. Get it wired wrong and you could lock the converter up in any gear and burn up the converter. Anyway this kit will engage the converter in over drive only, unlock when you accelerate or down shift(vacuum switch and pressure switch inside trans) and unlock when you tap the brake(brake light switch). It's a good set up too. You can home build this setup by scavenging all the parts from the junkyard a lot cheaper. I think I have a diagram somewhere with a parts list at home. You can find this info on the web though with a google search. A better choice is a later model 4L60E but it requires a stand alone computer to make it work. Way better though.

I an going to keep my 400 turbo and probably go with a gear vendors overdrive later on.

One last thing. We fried one 700R4 in the hoopti before we got it right.


Mike

Thanks Mike, thats exactly what I was looking for. I was confused because I thought all overdrives used the lockup converter but when I was looking on Summits site they show a 200-4R with a non lockup and one some with a lockup.

I will be using the 200-4R because I am buying the 455 from Wynne and that trans is the only overdrive that bolts up without an adapter plate. Just have to get a VERY well built one to handle the torque that motor puts out.

That answered every question I had or could have had. I believe I will take it to a freinds shop and let him set it up!

Thanks a million Mike.

No problem Keith, I hope it helps.

I think you can buy a non lockup converter for both trannies aftermarker but as long as you use the factory converter it will be a lockup.