probably don't belong here but here gos!

[rjewkes]

Ok better milage IYHO
Is acheived with 3.10
or 3.54?
or3.55?

[FORDification]

Generally speaking, the best mileage is going to be with the tallest (lower numerically) set of gears you can find, since at highway speeds the engine will be turning fewer RPMs, and thus using less gas. You'll increase mileage but your take-off will suffer.

However, if you go TOO far, the engine will have to work harder to GET to highway speeds, causing your mileage to take a serious downward spiral. The best gear ratio is the one that will keep the engine in the optimium RPM range, which varies depending on what engine and transmission you have, the weight of the vehicle and your driving style.

[rjewkes]

reason i was wondering is ai picked up a 72 camper specail 250 bed with frame turned into trailer with 6 spring plus helper spring in new condition the springs that is and the axle seems to roll fine. But My engine seems to lug loaded and empty with 3.10 it has now when i try to get up to highway speeds.

and i believe that 3.54 is the lowest on the f250 CS and i was wanting to transfer the 6 spring plus helper spring plus rearend as a set(no miss alignement problems that way) it rolls realy good but if this is a bad idea then how easy(hard) is it to realign the rear?

and if so what about the axle shaft mine is damaged on passenger side (swelled it then ground it to get it of and may have warped that drum)will they swap no matter what gear ratio? As long as they are both same lenght(designed for 9"?

also keep in mind that there is slip in my rear end and i'm wondering about my trany if i have rear in air in nuetral my tranny still moves (realy slowly rear tires). Is this somethoing that needs to be adjusted and can be adjusted? Seems like it is too easy for my truck to turn my tires but no peel outs (just loud lugging)!

[FORDification]

If your bed trailer is from an F250 it should have a Dana 60 rearend, and that is the rearend style with the tallest gear available being a 3.54. The 9" was never installed by the factory in an F250, AFAIK. However, it's possible that a previous owner pulled the Dana 60 out and swapped in a 9-inch so that they could use the 5-lug bolt pattern wheels instead of the F250's 8-lug setup.

You'll have to refresh my memory....is your truck an F100 or F250? And what kind of transmission? An automatic transmission's torque converter will still be flinging fluid at idle speeds, enough to slowly spin the tires if there's nothing holding them....but not enough to actually move the truck on the ground. If you've got a manual trans and it's doing this, then you've got some seriously heavy-weight oil in there.

A 9" third member will bolt into any 9" housing, but you have to also have the axle to mate up to it. Different vehicles have different width housings, and thus different-length axles...you'll also have to make sure that the axle spline count is the same on both the third member and the axles.

[rjewkes]

F100, 360 c6 ok that tranny thing sounds like atleast my tranny is as strong as i thought. And it is a 9"! Maybe only the bed and springs came from a 250 CS? But they are extremely strong compared to my week ones.

[FORDification]

...and the rearend in the bed trailer does have a 5-lug setup, right? If so, then someone definitely swapped in the F100 rearend into the F250 trailer. Are you sure the trailer was made from an F250? The '68 F100 parts truck that's sitting in front of my shop right now also has a 6-leaf spring pack with the factory overload spring on top.

http://www.fordification.com/board/68pa ... ngpack.jpg

It should bolt up as a unit or just using the third member and axles should work too, unless the 9" that got swapped into that trailer was from a different vehicle, with the owner relocating the spring perches to make it fit.

[rjewkes]

HMM, OK thats what the trailer looks like underneath but i thought 250-350^ was the only ones with 6 pack springs, with overload on top.

and defineitley a 5lug i'll check out how many times the third member rotates compared to the drive tire and see what rear gear actualy is.

what was that turns of third memb vers tire rotatoin again?

1 full turn tire =? = ?.?:1?

plus was certain thaty 250-600 were only ones with bedside storage compartment especialy camp Special? actual never saw a 600 with bed on it unless dump or flat.

also i measured her and both sides perches in same spot just flexomatic.

[Hawkrod]

not that it is relevant here but it was noted that 3.54 was the tallest gear for teh Dana 60 and that is not quite correct. The 60 was available with a 3.31, 3.54, 3.73, 4.10 and 4.56 that I know of. I had the 3.31 in my 67 and loved it. I know its a rare ratio but makes for a great highway truck. Hawkrod

[rjewkes]

Hawkrod, More relevant than you think Thanks.

went to show last night with trailer attached all were interested.

Told them plans cuase the bed and bedside storeage box are both in excellent condition so are the springs. And the springs barely get wieghed down with three 250 pounders(me and my buds standing or sitting in back)
but previous owner rigged up some 1" blocks that we had a fourth person look at and shure enough it never moved like it needed the blocks they never touched the axle at all. Extra precuation? also has rubber roller things just above where the block is bolted to the frame? In case of blowout? to keep tire from destroying the wheel well?

[FORDification]

hawkrod: I'd be curious to find out anything more you know about that Dana 60 3.31 ratio. None of my reference books even mention it as being available, including the factory shop manuals. This is the first time I've ever heard of such a ratio....in a Dana 60, that is. The 3:31 WAS available in the rear Dana 44.... are you sure that yours wasn't actually a Dana 44?

[Hawkrod]

No, it was a 60, unless they are disguising 44's with 8 lugs and using them in F250's! LOL There is actually a lower one in the 70's that is like a 3.07 but it is really rare, I actually bought one before I found out about the wider spring perches and housings of the 73-79 2 wheel drive. I still have the gears and limited slip out of that one sitting in the garage for someday. The 3.31 was not out of a 67, I put it in but it was a 67-72 I pulled it out of. Hawkrod

[greenbank]

This is kinda funny, in a way. Another car I'm into, a British machine, uses a Dana rear end inside it's pumpkin. 2.88, 3.07, 3.31, and 3.54 were the available ratios. Most came with a 3.54 for acceleration but a lot of guys swap in a 3.07 just to make freeway driving affordable. I did the same, my machinist found the gearset new pretty easily.

[rjewkes]

Cool. I still have yet to check it ratio but a 3.25:1 would be good accelaration and decent mileage at same time.

[flyboy2610]

Way back (longer than I care to remember ) when i was in high school I took a 2 year auto mechanics class. I recall the teacher telling us that it would be wise to avoid a gear ratio such as 3.00:1. The reason being was that such a ratio would wear the ring gear faster. If the pinion had any type of imperfection on a tooth, every 3 revolutions it would hit the same tooth on the ring gear and cause faster wear on it.
I don't know if the wear would be a whole lot faster than on, say a 3.25:1, which is what I plan to go with in my '68 when the time comes.
But I do remember him saying that.

[willowbilly3]

No, it was a 60, unless they are disguising 44's with 8 lugs and using them in F250's! LOL There is actually a lower one in the 70's that is like a 3.07 but it is really rare, I actually bought one before I found out about the wider spring perches and housings of the 73-79 2 wheel drive. I still have the gears and limited slip out of that one sitting in the garage for someday. The 3.31 was not out of a 67, I put it in but it was a 67-72 I pulled it out of. Hawkrod

There was a dana 61 that is very similiar to a 60 and it came with 3.31 or maybe taller. I have heard it said the 61 gears can work in a 60. Also I think aftermarket has a 3.31 for the 60. Ford never sold one stock taller than 3.54.