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I just purchased this 71 F-250. Great truck and the body is straight and all and very little rust. It drives great, but on the highway, it seems to run higher RPM's. Seems like it should go one more gear into an overdrive mode or something. I think it is a C6. What is a possible solution or check to see. I haven't driven an older truck like this in a while and I hate to think of a new or rebuilt tranny at this point. How can I tell? If it is not hitting that last gear, how hard is it to go into and fix?
you should feel two shifts. if not then it could be linkage or tranny itself. if it does shift to third then its probably the gearing. the solution for gearing is to swap the gears for a set better suited for highway driving.
If you post up the trans and axle codes from the door plate, perhaps we can pinpoint where you need to go next. Also, I'm guessing it is running a 360?
a taller tire will help some also but the speedo will be off then but that is a cheaper way to get a lower rpm on the road than a gear swap. just an idea.
Based on your tag info, I think you probably have a C6 auto and an open Dana 60 with 3.73 gears. With this setup, you're going to rev pretty high at 70.
Sorry Rich but I'm not too keen on the codes for the "newer" trucks. I would have to agree that if you have a set of 3.73's out back, your highway rpm range is right on the money. A FE engine, be it 360 or 390 will not have a C4 bolted up out back but a C6, and with it appearing to have 170 HP at 4100 rpm, my vote is a 360. If you want less rpm's on the highway, you can always go to a lower numerical gear set, like a 3.07 or so.
i know what you mean russ when i get out of my 92 and in to my 72 i swear its about to blow 3000rpms @ 65mph. but when i get in to the edelbrock carb it still sets me back in the seat. think i need taller gears to but 1/4 mile speed is super been smoking mustang gts everytime they try me
Mike G, he has a 250 Dana 60, 3.54 is the highest ratio available. Your speaking 100 with 9" rear for 3.07's. Taller tires like 9.50 x 16.5" will help. How loose is your convertor, not stall speed? Tire diameter? I have 12.00 16.5 rear, 3.54 with C-6, 410ci with a custom tight convertor, 2,460 rpm's at 60 mph. Only time it needs higher gear is on a "mission run" at 90-100 mph.
Carl...=o&o>....
Mike G, he has a 250 Dana 60, 3.54 is the highest ratio available. Your speaking 100 with 9" rear for 3.07's. Taller tires like 9.50 x 16.5" will help. How loose is your convertor, not stall speed? Tire diameter? I have 12.00 16.5 rear, 3.54 with C-6, 410ci with a custom tight convertor, 2,460 rpm's at 60 mph. Only time it needs higher gear is on a "mission run" at 90-100 mph.
Carl...=o&o>....