1/8 mile gearing for a 71 f250???
 

whats the best gearing for a ford f250 with a 557 doing the 1/8th? nuthin saucy bout the tranny. just need the rear axle ratio. thanks guys!

How would anyone be able to answer that without more info?

What tire? What suspension? What trans? Weight? Engine redline?
Any info from 1/8th mile runs with the current set up? What is the current set up? What axle? You going to drive it too, or is it a trailer job?

Shorter answer: Whatever gear ratio that results in you hitting the engine redline in top gear at the finish line.

2x and 10-4. Concur with your assessment of the question.

But this is the Google age where supposedly typing on the keyboard spits up the answer every time. And that's why the future of this country is in trouble.

Oh this is so simple to answer. You have a mule. Designed for pulling not for running fast. You can't make a race horse out of a mule just like you can't make a mule out of a race horse.

4.56 would be my guess.

Ill go to summit.

Blah blah blah. Your opinion is worthless boomer.

Thank you for the real reply. C6 stock 1:1 final gear, dana 60 stock, stock weight, about 6000the rpm redline, 10.5 slicks 29" dia. Not sure on the mph at the trap. I was hoping to get some input on that too. Haven't seen many "pulling/mules" racing lately at my track in cali. Maybe I should consult that google age and have it spit out an answer about racing a mule.

Go to banks performance with that reply. See what their reply to that would be.

The heart of Banks is in diesel. That is a different animal. A diesel has monster torque numbers. They are also selling turbos. Not anywhere close to what you asked about. I guess maybe we differ on definition of going fast. When you realize weight is your enemy when trying to go fast you will realize that the tried & proven Ford 9" is a much better selection for a rear axle. Not only is it much lighter but it is also far less expensive to buy parts for & locate parts for. We are only talking about the rear end. Your chassis is heavier than a F100 chassis. Your entire suspension is far heavier. Can weight be overcome? Certainly but it is gonna cost you & everything you do can be done in a much lighter vehicle to start with that will win.

You never stated what you wanted to see on a time slip. There are plenty of gear calculators out there. Plug in what you have & they will let you try different gear options. Make your choice from there. Just remember you also have to make it bite. When it does you will break parts. Something has to be the weak point. If you haven't swapped to a performance single piece driveshaft you may find it in your best interest before you get too serious about this. This swap will also lighten the truck some which will help with E.T.s. Aluminum wheels. Again all about weight. How much less expensive are wheels for a 9" when balanced against your rear end? Once again cost.

Ditch the rear springs. Go with a 3 or 4 link rear suspension with coil overs. Same story, weight plus you can dial the suspension to control wheel spin. Do this with a 9" & I would bet you easily drop a couple hundred pounds, probably more.

"Speed costs money son. How fast do you want to go?" Sorry don't remember who said that.

Have you run it through the 1/8th "as-is"? That would give you some benchmark info on which to make changes.

I would look for you to run close to 9 seconds. You've got enough power to run a little quicker, but your traction situation needs to be assessed, along with suspension issues. Axle wrap and wheel hop will break you drive shaft and the axle. Lower gearing will make this worse, so best see what's going on now before you change gears.

You probably do not need gears low enough to hit redline in 3rd. You will probably only be using 1st and 2nd.

With a 29 inch tire, you would be going 86 MPH at 6000 rpm in 2nd gear with 4.10 gears. For running the 1/8th, I think that would be a good starting point.

And yes, gear changes in the Dana are a real PITA compared to a 9, so you don't want to do this more than once.

This is where I would like to be for a 1/4 time. Actually I would be very happy if I can get my truck into the 10s. I am not giving up my IRS to do it though. I would be 1 happy camper to see a 10.2 at the end with a wheel stand at the start. Now for the best part. No broken parts! :-hair Yeah like that will really happen with an IRS.

_________________:-huh______________

Your lesson is over.... No need to thank me for the reality check.

I would love to see a 9 sec time for 1/4 mile run.