Hey Guys,
I took the engine/transmission out of a donor '92 Dodge Cummins and put it in my '74 Grumman Kurbmaster Stepvan/RV Conversion. As far as I know, the engine and converter is stock. The transmission has been rebuilt.
I have a question about torque converter slip in this transmission. It's a non-locking A518 4spd with the electronic overdrive in 3rd.
I wired the OD to a switch. It functions.
This truck has 4.88 rear end gears and 32" tall tires.
Flat out in 3rd gear on the governor it does 45mph. I did the math, and assuming a 2600RPM governor limit, that works out correctly for this gearing and shows me that I'm getting 250RPM converter slip under those conditions.
Flat out in 4th gear on the governor it does 58mph. Assuming the same 2600RPM governor limit, that works out to 600RPM converter slip to achieve that speed.
Does that sound right? For this to be correct, that means I have more than 2X the amount of converter slip between 45mph/3rd and 58mph/4th in a vehicle with probably 3x the frontal area of a dodge pickup. I find that surprising, but maybe that is normal with this much load. Are these converters that slushy?
I do not have a tach on this engine. The RPM is a guess based on where I think the governor is supposed to do its thing. I do think I'm riding the governor in both gears, especially since the math works out pretty close in 3rd gear and the engine feels like it noses over.
I do not have a pyrometer, or boost gauge or fuel pressure gauge. They are coming. The speedometer is correct and has been verified with my GPS.
Does this converter slip sound normal? If so, I need to change my rear end gears sooner than later. I have a dana 70 that can be put in this truck, I just didn't plan on doing that right now. I need to be able to cruise down the freeway, and if the converter slips this much...gearing it is the only solution.
Thanks for any input!
Byron