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Torque Converter Gearvendor OD

Started by 7212Mopar, February 15, 2018, 01:03:38 PM

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7212Mopar

I got a 3.23 SG, 275/40/17 tires and an A904 AT non lockup with a trans cooler. The stall converter is a ATI Streetfighter that supposed to stall between 3000-3500 RPM. Engine is a stroked 340 that dyno 491 HP and 528 Ft-LB. Based on the RPM calculator, at 65 MPH, RPM is 2745. At 70 MPH, RPM is 2956, At 75 MPH, RPM is 3167.  Would you think my converter is too loose and I will be over heating the trans at legal HWY speed or I worry too much? I am thinking if a Gearvendor would be a good application, not for low RPM cruising but more like staying near the converter stall speed rating in manual mode.
1973 Challenger Rallye, 416 AT
2012 Challenger SRT8 6 speed Yellow Jacket

Marc70challenger

I've got the same RPM calculations as you.

The Gear Vendor is going to reduce the final drive ratio about 22% ... and thus the RPM about the same percentage.

Convertors can be tough to figure out without actually experimenting with them installed - how loose, how tight, the stall, lock up and flash ... these points (rpm) are very dependent on the motor, it's torque/power curve, car weight, etc.   Then you have to consider how good/effective your trans cooler is, driving habits/conditions, what you want car to do (launch hard, medium, be quick, be fast)

Best thing I would suggest is too see what you get with the set up.  If you don't have trans temp gauge put one in.

On face value you're probably fine. As long as your not thrashing it constantly I would think your temps be fine but ....

Convertors with advertised "stalls" can behave considerably different in varying cars.  Once you see what you have now, how it drives, how hot it gets, etc.  you can go from there before Investing in ODs and especially different convertors.  IMHO


Chryco Psycho

I am on the other side of this , seems the converter is too loose already + you have a lot of tq so the stall may be higher than spec already
dropping the the ratio by 22% gives you a 2.52 rear gear ratio so now the rpm is very far below the stall .


Brads70

Sounds like you need more gear with your OD. I have a automatic od  4 speed ( 4L60) and started out with a Dana 3:54 then switched to 4:10 as it just was not " happy" on the hwy at 65mph , sort of lugged? I suspect you will have the same issue.   I have the ability to electronically chose when to ,lock up the converter, but also added this for a cooler. ( I got a used NASCAR take off) They work extremely well, I replaced my new temp gauge as I thought it was faulty on  another project when using it for an engine oil cooler. I had to block airflow to get the temps up enough to even read on the gauge. I have another on the Challenger for my tranny cooler.
https://www.fluidyne.com/product-page/db-30816-26-oil-trans-cooler
Hope that helps?

Marc70challenger

Quote from: Brads70 on February 15, 2018, 04:05:13 PM
Sounds like you need more gear with your OD. I have a automatic od  4 speed ( 4L60) and started out with a Dana 3:54 then switched to 4:10 as it just was not " happy" on the hwy at 65mph , sort of lugged? I suspect you will have the same issue.   I have the ability to electronically chose when to ,lock up the converter, but also added this for a cooler. ( I got a used NASCAR take off) They work extremely well, I replaced my new temp gauge as I thought it was faulty on  another project when using it for an engine oil cooler. I had to block airflow to get the temps up enough to even read on the gauge. I have another on the Challenger for my tranny cooler.
https://www.fluidyne.com/product-page/db-30816-26-oil-trans-cooler
Hope that helps?

@Chryco Psycho summed up what I was trying to say in a paragraph ... just wonder how loose it actually is ... I had a "loose" one that wasn't anywhere near what we thought. . lol.

@Brads70  - that's awesome fluid cooler.  We were thinking of going to this one. https://www.summitracing.com/parts/bmm-70297

You're able to control on/off (or use it's internal 170 deg thermo switch) it's small and in slow/stop-n-go you've got a fan.  It's what a lot of guys use with high stall convertors and they say it works well. 

@7212Mopar have you gotten this out on the street yet.

RUNCHARGER

I have to agree with CP as well. Honestly this just doesn't seem like the optimal setup. It sounds like lower gears, Gearvendors unit and less stall would be a better choice if the engine has enough lowend torque to support it.
Sheldon

7212Mopar

Got to tune and setup engine first and then front end alignment before test drive. I just have a tranny cooler in front of the radiator, not the fancy one Brad has. I suppose best to drive it and see how it feel first. Not sure how far is too much from stall. With OD aside, I am almost at 3000 at 70 mph. That is not fast on the freeway around here. Should the temp gauge be at the cooler line between the front pump and cooler?
1973 Challenger Rallye, 416 AT
2012 Challenger SRT8 6 speed Yellow Jacket


Marc70challenger

I'd put the temp sending unit in the trans pan. 

Unless it's a race or off-road application then that's a decent location

screamindriver

#8
I've run the GV unit in a vehicle that is very close to the specs you posted minus the 3;23...If there's no issues with the vehicle as is then the GV unit isn't going to change it much...Just use it as an overdrive for highway use...You couldn't possibly split every gear faster than just letting the trans run it's normal operation 1 through 3...Then just hit the manual GV for od....Occasionally I drop the GV out for a "passing gear" on the highway without pushing the pedal hard enough to drop it into the actual trans throttle pressure kickdown..Yes, you're overthinking it...But that's not a bad thing....Remember how the "stall speed" is calculated...In this instance it doesn't  necessarily mean you'll be generating a ton of heat under a light load for highway cruising.....But I'd probably opt for a steeper ratio gear if using the GV unit for your vehicle remember the GV unit will turn a 4:10 into a final 3:21...Anything from there and you'll have a fun ride out of the hole with the OD as the icing on the cake...