GrandPrix34 Posted July 22, 2004 Report Share Posted July 22, 2004 GM FWD Torque Converters GM uses the same type 4-digit ID method of identifying FWD torque converters as with the RWD units, however the digits have different meanings. All 125-C, 440-T4, 4T60, and 4T60-E transmissions use the same style torque converter, and they are interchangeable before 1996. 1996-up converters are built to be compatible with GM's PWM TCC apply strategy which means that you can use the newer converter on the older trans, but not the older converter on the newer trans. 1st Digit (application trans) F -- 125C, 440-T4, 4T60, 4T60-E 2nd Digit (approx stall (depends on engine) A -- 2795 rpm B -- 2560 rpm C -- 2385 rpm D -- 2095 rpm E -- 1865 rpm G -- 1630 rpm H -- 1515 rpm J -- 2060 rpm K -- 2760 rpm L -- 1895 rpm M -- 1525 rpm Y -- 1420 rpm Z -- 2375 rpm 3rd Digit (TCC clutch material) 0 -- Clutch omitted by factory 5 -- Clutch contains poppet valves All other digits (pre 1996): Red Fiber material 1996-97 C, E, H, K, P -- Carbon filled clutch 1998-up F, H, K, Q -- Woven graphite clutch 4th Digit (Clutch Type) B -- standard C -- viscous (stay away from these type) Pertaining to the TCC Clutch material: starting in 1996, GM implemented a new TCC apply strategy. The 1996-97 trannys (exc 3T40), used a soft-apply (PWM) TCC strategy which was designed to soften the TCC apply so the "customer" would not feel it come on. This means that the PCM is actually making the TCC slip during apply. Only Carbon clutch torque converters should be used in 1996-97 trannys. You can use the carbon clutch TC's in earlier trannys that did not have PWM technology, however the lockup feel will not be the same. However, I have heard that these carbon clutches rarely burn-up or go bad. I have personally used the carbon filled clutch TC's on earlier trannys and the only experience I have witnessed with them is they apply firmer. Starting in 1998, GM revised the lock-up strategy once again only this time the TCC may never completely lock up and may always slip about 20-60 rpm, depending on the vehicle. This means that even the carbon clutch units would not work well for these applications thus GM started using woven-graphite TC clutch material. I have heard that the woven graphite TC's should not be used in any earlier transmissions because the lockup will not work correctly. Quote Link to comment Share on other sites More sharing options...
GrandPrix34 Posted July 22, 2004 Author Report Share Posted July 22, 2004 so all I have to do is go to a junkyard and look for a torque converter with the "A" second digit and I have a 2795 stall TQ?? Which vehicles came with that?! Next trip is a junkyard trip to find a 3.33 carrier (i believe the 3.1L 4T60E has this right??! SOMEONE ANSWER THAT QUESTION!!) and a torque converter with the "A" second digit! Quote Link to comment Share on other sites More sharing options...
BIGBULS Posted July 22, 2004 Report Share Posted July 22, 2004 so all I have to do is go to a junkyard and look for a torque converter with the "A" second digit and I have a 2795 stall TQ?? Which vehicles came with that?! Next trip is a junkyard trip to find a 3.33 carrier (i believe the 3.1L 4T60E has this right??! SOMEONE ANSWER THAT QUESTION!!) and a torque converter with the "A" second digit! Sounds correct. I recently drove a 95 Beretta Z26 with a 3400 swap (4T60-E) and a Q4 TC from a THM-125C (~2700rpm stall). Compared to Canada's 3400 Beretta (with the stock ~2200rpm stall TC.......it WAS ~2050rpm, but the 3400 RAISED the stall speed), the high stall car definitely launched better. As for the 3.33 carrier........ You can get that from all 3.1L/3100 W-Body 4T60-E's, along with 94-95 L and N Body 4T60-E's (they have a 37/33 sproket setup though [the opposite of the 33/37 you want], so their effective FDR is 2.97). Quote Link to comment Share on other sites More sharing options...
GrandPrix34 Posted July 23, 2004 Author Report Share Posted July 23, 2004 The stock Cad 4T60E has a final drive ratio of 2.84 to 1, changing gears requires removing and disassembling the trans BUT it will give you a very noticeable performance improvement albeit at the loss of some top end speed and fuel economy but it will get you to the next stoplight a lot quicker. Simply swapping the 35/35 drive sprockets from the Cad trans for the 33/37 sprockets from a 4T60E out of a 3.4 DOHC car will change your FDR to a 3.18 to 1 without changing the ring and pinion. Use the DOHC's 3.06 R & P as well and you get a 3.43, that's a difference you will definitely feel on the old "butt dyno". Or you can swap in the 3.33's from a 3.1 powered car as is or combine them with the 33/37 sprockets for a FDR of 3.73. If your doing a trans overhaul anyway it's the perfect time. Take a look at a torque converter out of a 3.8 full size car while you're at it to bump the stall speed up a couple hundred RPM but don't go crazy, the 4.9 will make it stall a couple hundred higher than what it was rated for behind the 3.8. The stock Cad conveter is a 1500 stall, a 3.8 converter rated for 1600 will probably be enough as the higher torque of the 4.9 is probably going to make it stall closer to 1800. Don't get carried away here, too loose of a converter will make your car MISERABLE to drive and generates a ton of heat which in turn will cook your trans. Wow, when I need some info, GOOGLE rocks! Quote Link to comment Share on other sites More sharing options...
Mike J. Posted July 23, 2004 Report Share Posted July 23, 2004 I believe the 90 Lumina Euro 3.1 I owned b4 had a good TQ Conv. because it would fry tires easily even without much power and it had the bigger tires 225/60/16's. Quote Link to comment Share on other sites More sharing options...
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