What is the best way to get an overdrive auto in a 67 Barracuda?
I wanted to take my car for a spin to refresh my memory on excact numbers that were in question IE rpm vs mph an so forth but the county decided to dump salt on the frosty roads this morning, lets just say driving between 55 and 65 my engine turns at an rpm which makes me very uncomfortable without getting too technical with exact numbers. I don't want to sound obtuse here but your converter is a 3600, when you are cruisin trying to keep the rpms down say under 2600 does your converter heat up or stall or does the "lockup" part of the converter prevent that? I'm not sure exactly how that works, I would like a 2800 stall but I don't want it slipping or causing excess heat at cruising speed. Does your lockup work on a switch or does it kick in automatically?
Good questions. I had always been a manual trans guy until this car. I realized that with the traffic around my house and with decades of rowing gears, I had tired of always having to push in the clutch and shift. I still have and enjoy my other hotrod with a five speed, but driving an automatic car is a pleasure too.
The torque converter I bought is a very high quality unit from Precision of New Hampton. It uses the same 3 carbon fiber clutch set-up that they put in 3/4 and 1 ton diesel trucks. It does allow the engine to spin up to 3600 rpm when I press the gas pedal more than say 1/4 of the way to the floor, but when I am cruising along below 1/4 travel, it feels like a regular stall converter with very little slippage. Another benefit to having a looser converter is that with the larger cam I am running, I can drop the car into gear and I don't really effect the idle, which I have set at 800 rpm. If I take my foot off the brake, the car will creep forward like a normal converter.
I had a buddy who bought a cheap converter and his experiences matched all the horror stories from the 80's of excessive slippage, heating up of the transmission and his car would not creep forward idling in gear. I heard all those stories before, but learned on these forums and Moparts that converter technology has come a long way. I also am glad I listened to experienced members and bought the best converter I could find. There are a lot of great coustom converter shops, but most off the shelf converters don't fall into that category.
I have to use more than 1/4 throttle to put enough power into the torque converter to "break loose" from its seemingly tight "normal" stall it exhibits in normal driving, and free spin up to the higher stall of 3600 rpm where it solidly engages the power to the driveline and puts my motor right into its power band. It's frigin' awesome! If that makes sense.
Cruising on the freeway at 70 mph and 2600 rpm it feels like any other automatic transmission. However, with the flip of a 12v toggle switch, the lock-up feature engages and it solidly connects the engine to the transmission, just like a manual trans does and drops my rpm down to 2300. It cruises at 2500 rpm at 80mph locked up.
I have mine set-up so that it will only lock up in 4th gear when I flip the toggle switch. Its a simple 12v circuit with a normally open pressure switch connected to the 4th gear apply circuit in the transmission. There are several other ways to hook it up too, but I prefer this way.
If I mash the throttle to the floor, the lock-up automatically cuts out and it down shifts like a normal trans. I cruise around town in third "D". When I get on a freeway, I pop it into 4th "OD". I leave the switch engaged at all times unless I'm racing.