Ford F834 Posted January 24, 2020 Share Posted January 24, 2020 Bob - The three manuals I've owned and driven in these trucks, the NP435, T-19, & ZF5, have all driven pretty much the same - like truck transmissions.... "Like truck transmissions" doesn't scare me. But when a friend (who drove a Dodge with the HEAVY NV5600) drove my '08 and had to crawl off a higher speed section road in 1st gear because he couldn't get it to upshift, that makes me leary of a manufacturer! (That friend had wanted to drive my truck because he couldn't believe it was as bad as I said. After driving it he said I was being to kind to it, it was way worse than I was saying.) I have not driven a ZF6, but this is not the first negative comment I’ve heard regarding how it shifts. The ZF-5 that Jan and I put in his ‘86 F250 shifted very well. It has a long throw and does not change gears quickly, but was a pleasure. In the desert with the ambient temperature at 110*F it had that gear rollover clatter that most diesel owners report, but Jan says that isn’t as bad since he changed fluid. My particular T19 is probably the nicest shifting truck transmission I’ve ever used. It is almost car-like, and very smooth. I would prefer this over the ZF except for the lack of overdrive and the smaller input shaft is not strong enough for the engine I am building. I have not owned or driven a NV series transmission, but what I have heard is that they are inferior to the ZF5. To the original poster of this thread, I would second the suggestion for a stouter transmission before going lower on the axle gears. Then if you really need it, reduce the axle ratio. I have the close ratio T19 with 3.00 axles gears and I love mine. I pull approximately 5,000 lb trailer with it. Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 24, 2020 Share Posted January 24, 2020 I have not driven a ZF6, but this is not the first negative comment I’ve heard regarding how it shifts. The ZF-5 that Jan and I put in his ‘86 F250 shifted very well. It has a long throw and does not change gears quickly, but was a pleasure. In the desert with the ambient temperature at 110*F it had that gear rollover clatter that most diesel owners report, but Jan says that isn’t as bad since he changed fluid. My particular T19 is probably the nicest shifting truck transmission I’ve ever used. It is almost car-like, and very smooth. I would prefer this over the ZF except for the lack of overdrive and the smaller input shaft is not strong enough for the engine I am building. I have not owned or driven a NV series transmission, but what I have heard is that they are inferior to the ZF5. To the original poster of this thread, I would second the suggestion for a stouter transmission before going lower on the axle gears. Then if you really need it, reduce the axle ratio. I have the close ratio T19 with 3.00 axles gears and I love mine. I pull approximately 5,000 lb trailer with it. I think you two have suggested a good approach - a stouter tranny with the existing rear gears. You should easily be able to do such a tranny for the price of new gears, and to tow very much the tranny will need to be changed anyway. Then, if the rear gears don't cut after trying the combo out, it change them as well. But if it was me, I think I'd look for a ZF5. I say that because, using the calculator and assuming 235/75-15 tires, the engine will be turning ~1800 RPM at 65 in 5th with the 3.08's. That's just about right to get good MPG when not towing. And when towing it would be turning ~2300 RPM in 4th, which is also about right. Link to comment Share on other sites More sharing options...
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