TH2004R torque converter question

[malicad]

Ok, Here goes: Over this winter, I am planning on putting in my new drivetrain combo in my 79 Bu. Cadillac 472 (478 after rebuild)...TH400 trans, Currie 9" rearend with Detroit locker, 3.25:1 gears with disc brakes. Tubular suspension (front and rear) QA1 coil overs up front with Aluminum SSBC twin piston calipers, etc...my question is, I was going to use the TH400, but now want the benefits of overdrive. After much reading/contemplation, I have decided on a non-lockup TH2004R. Well, my cam's out of steam at 5000 RPM, and I will be using a non-lockup converter. All the non-lockup converters I see have a high stall-around 2500-2800 RPM...way past my torque peak of 1800-2200 RPM. I want a LOWER stall speed, but I don't want constant slipping at highway speeds. Anybody out there have any ideas? My motor's got around 375 HP, but near 550 lb/ft torque. What type of converter should I get/what is available? Thanks in advance!

 

[t5montecarlo]

Why not use a lock-up? The stall you want sounds like what my MCSS had stock.

 

[malicad]

I don't want a lock up converter because I believe they are larger in diameter, and therefore heavier than a non-lock up. Art Carr, owner of California Performance Transmissions really steers people away from using the lock up style converter in most TH2004R trans he builds. I called and talked to someone in their tech line, and they told me the same. They however, wanted to build me a custom converter for around 800 dollars. :shock: I'm just wondering if anyone has a low-stall converter that will hold up to my motor's torque without slipping at highway speeds. It's a very low RPM engine that I didn't build for horsepower, but becaause of the mild gearing, I think the car will still haul a$$. I had a ride in a 70 Cadillac Deville with a mild build 500 cid engine that ran mid 13's. I figure if my Malibu weighs a good 1500-2000 pounds less with a similar build and a more efficient drivetrain, it should be good for high 12's at least.

 

[t5montecarlo]

I am not understanding why you are concerned with diameter. A smaller diameter torque converter will have a higher stall rating; you want a low stall rating.

 

[malicad]

I know that generally, a larger diameter converter will have a higher stall, but I thought that a lock up converter was even larger, and has more internal components, allowing it to lock up. The tech from Art Carr said those were heavier, and would decrease performance because of more inertia. Because of my motor's torque, he said an average stock converter would probably not last long. I guess I'll do more reading on the subject....I should have in the first place, as I wouldn't have looked like such a knucklehead not knowing what I'm talking about #-o ...I'm still learning, though :-k

 

[prairiehotrodder]

If you want a cheap convertor use the stocker. The lockup feature is OK and with the torque you will be making and the low RPM peak, convertor weight and inertia don't matter. If you are running highway gearing I'd just stay with the turbo 400. I did the whole caddy swap and I used the turbo 350 with 3.42 gears and it wasn't bad to drive because i was using 28" tall tires. Your combo would work real good with either 3 speed and a 3.08 gear.
Brian

 

[transbuilder1]

I have built a couple of 2004r for some Tri 5 guys and they love having the lock-up feature for cruising on the highway,The TCI kit has a manual override on top of their regular wiring.We have been using the stock converters from a Grand National and they hold up very well and give you some real nice low end grunt.

 

[malicad]

Well, problem solved! I talked to Art Carr himself, from CPT, and we worked out what I need. Looks like my rear gear of 3.25:1 is too mild for my engine/trans setup. I will need a 3.50 or deeper gear to keep the trans working more efficiently. Really sucks, cause I just got my 3rd member all set up with new Motive gears, and sold my Richmond 4.11's I already had. ](*,)