• Hello there guest and Welcome to The #1 Classic Mustang forum!
    To gain full access you must Register. Registration is free and it takes only a few moments to complete.
    Already a member? Login here then!

Torque converter. Which one?

Kooter

Member
So I think I have discovered the answer to my long ago question.

http://www.stangfix.com/testforum2/index.php/topic,8346.msg103794.html#msg103794

I have not been able to drive my car much since then until last week when I took the car for a spin around the block. While driving the tranny would barely engage and I barely got it home. I am pretty sure the tranny needs rebuilt. ( I am going to try this myself) Since I am taking out the tranny I figured I would buy a new torque converter. I am not sure what kind of stall (if any) do I need. Suggestions?
 
Higher stall speeds should be matched to you cam specs, rear gear and intended use. Ideally you would launch the car with a stall speed at or near your max torque. You need to keep in mind that even at highway speeds (unless it's a lock-up converter) it will be slipping if rpm is below stall speed. This creates heat which is bad for a trans and is bad for fuel mileage. If you have a low rear gear (numerically high number) like 3.70's or 4.11's then your rpm's will be higher at cruising speed anyway. Higher stall speed is primarily a drag racing thing. If you plan to make a street/strip car out of it you need to find the best compromise. If you go full on Drag racing you can get pretty crazy with it. If it's just a weekend cruiser to the DQ and car shows with a mild cam and stock rear gears I probably wouldn't go with a higher stall speed.
I am building a 67 just for drag racing and I plan to go with a ~5,000 rpm stall speed and I currently have 4.11 gears but may go as low as 6's. It's going to be primarily an 1/8th mile car so I need to launch hard and I'm not worried about over revving since at the 1/8 mile I'll probably be going around ~80 mph. On the other hand I have a 67 that I drive 6,000+ miles a year and take on the Hot Rod Power Tour. It has a 429 with a mild cam and stock torque converter. Even with the big block it would benefit from a higher stall speed but with my rear gears it would be slipping at most cruising speeds so I opted to leave the stall speed alone. It's obviously not going to be the best for drag racing but that was not it's intended use
 
Well Craig pretty much covered it all but I would add that getting a stall speed slightly over stock will not hurt the trans and would give you a bit more of a "set of the pants" feel launching at the occasional stop light. You can add a trans cooler if you are worried about the possible extra heat being generated.
 
I told the guy that rebuilt my converter that I wanted a stall speed targeted at 1800 rpm. My goal was to reduce the pull against the brakes that is typical sitting at a stop light. Worked out well.
 
With 3.00's and modern low profile tires an 11" converter will be fine. Be sure to have a shift kit installed in the trans when it's rebuilt and I always used the solid intermediate band and added one clutch plate to the reverse/high clutch, along with blueprinting tolerances. Those old trans were good for 450-500hp in the race car with an 8" converter, slicks and 5.43's. C4's are a good transmission if built right.
 
Back
Top