I am just about ready to do an overdrive transmission swap in my 1973 Plymouth Satellite. I've seen some debates about going with or without lock up. What do you guys recommend? My car currently has a 360 but I plan on putting an aggressive engine in it. I'm running 3.73 gears but may step up to 4.10s. I want a powerful street machine but I also use it as a daily driver. I also plan to do some highway trips.

Definitely get the lock up, it's like having a 4 1/2 speed, TC slippage can be 7-8%.
I have 340/3.73

If you are only going to do occassional freeway jaunts with limited distance, skip the lock-up as the converters are significantly heavier and will cost you ET time. If you plan on somewhat regular freeway trips and some longer road trips, go for the lock-up. The nice thing about a high quality lock-up converter with the correct stall speed for your application, is that it is like having a 5th gear.

I have a 3200 stall converter in my 200R4 with a triple carbon fiber disc lock-up clutch. It was not an inexpensive converter, but I believe it was worth every penny. The performance with the correct stall combined with the ability to lock it up is awesome. The car would be a bit quicker without the added weight though.

If you are considering a 518, then the choices on lock-up converters is very limited. Call PTC and talk to them about it BEFORE you pull the trigger.

I can think of no disadvantages to a lock-up convertor, if is there any what are they???

Stu

If I had the choice Id go non lock-up. One less part to fail. It used to also be easier to control OD only when you were setting up controls for a 500/518. I don't know how people are doing it lately tho.

I have 3200 rpm lock up in my 68 512 charger a 518, I use switches for the OD & lock up, so far its good.

The main disadvantage is that lock-up converters are significantly heavier due to the plates, frictions and springs, which means it takes more power to spin them. More power to spin means less power to launch, and less usable power to launch means slower ET. That is a disadvantage to many folks.

I built a control module for the OD and LU, works great.
The 518 & TC adds 60lbs to the car over a 727.

Check out pages 8 & 9 for details

http://www.cuda-challenger.com/cc/index.php?topic=84774.120

So if i understand it just in racing applications there a disadvantage then but with normal driving it aids in helping keep the heat down in the convertor. Correct??

"So if i understand it just in racing applications there a disadvantage then but with normal driving it aids in helping keep the heat down in the convertor."

and rpms down at cruising speed. = Better mileage.

Correct. Modern non-lock-up converters, although very efficient, will generate more heat than the solid connection of a lock-up converter.

Heat is always the enemy of an automatic transmission, so be sure you have an adequate transmission cooler and use the highest quality transmission fluid available. In a serious performance car, change the fluid and filter regularly/annually too.

If you are willing to spend the money for a good a/m converter with a better clutch pack in it then the lock up will bring rpms down and you will have a cooler running trans.

Another thing to consider on a high hp/tq motor is the input shaft on a lock up trans is hollow while a non lock up input shaft is solid. Stronger a/m hollow input shafts are available for the lock up trans.

my torque converter rebuilding shop friend sent me out looking for a non lockup 518 out of a dakota as he was building a 6.4 hemi into a 27 chrysler sedan--he said lockup clutch failure is becoming a common rebuild causation---and it saves only 300 rpm.....and modern cars computer turns the lockup off in the tranny temp gets too cool...

@jbc426, Your trans set up is exactly what I'm looking into.

@mgoblue9798, a/m converter?

Yes, I recommend talking to Lonnie at Extreme Automatics. I went with Precision of New Hampton for the TC, ask for Milt. It's one of their top-shelf units with a 3200 rpm stall, anti-ballooning plates and a triple carbon fiber disc lock-up clutch. The were originally designed to handle the big supercharged diesels.

A lot of people avoid computer controlled transmissions due to the lack of adequate aftermarket programing for the Chrysler units.

I went with a 200R4 for many reasons including that it can be wired with a single switch to lock-up only in 4th gear. It drops out when it downshifts or if you flip the switch. Simple, light, takes less power to spin, its very strong and heavy duty when properly built.

Yeah, I've been eyeballing Extreme Automatics for awhile, the stage 2 model. Who did you go through for the bell housing adapter?

I used a Reid bellhousing. It's SFI rated, but I did have to trim off a small section to fit my headers.

I also went with the Stage 2 and adapter. If you plan on running lower gears than 3.91's with a lot of power, make sure you calculate your driveshaft's critical speed.

Thanks for all the great advice. Any recommendations if I upgrade the drive shaft?

For others doing similar projects, here are two drive shaft critical rpm calculators:

http://www2.dana.com/expert/wc.dll?hvtss~decrits~warn1

http://www.wallaceracing.com/driveshaftspeed.htm