Hi folks, I am looking for some advice on rear end gears, I want to put in a gear set that is more highway friendly, I do not pull or carry anything with my truck, it is my daily driver, when I am on the highway my truck revs high at 60 miles an hour. What do you folks suggest that I put in and what has worked well for you guys?

thanks for your help.

BigRed

 

What is your current ratio? What rpm are you at now, and how big is the tire in the rear?

 

I can only guess what I have for gears right now 4:11, I am running LT265/75R/16 tires, as far as revs go, I rev high at 60 mph and at 70 mph the truck shakes, I do not have a tach.

 

LT265/75R/16's are roughly a 32" tire, w/4.11's @70mph that's 3,000rpm's.

Same tire w/3.25's @70mph would drop you your rpm's to 2,400.
Same tire w/3.00's @70mph would drop you your rpm's to 2,200.
Same tire w/2.75's @70mph would drop you your rpm's to 2,000.

(rpm's are rounded off but in the ballpark)

 

The highest gear [Dana 60] available from factory on those trucks is the 3.54 ratio.

If yours is a 2WD, you may swap in a Dana 61 which would have either 3.31 or 3.07 ratio. As using a Dana 61 on a 4WD, dunno.

2.75/3.00/3.25 is only available on the 9" axle, F100/F150.

 

It would help if i read the OP's title first lol.

 

Hey guys don't mean to jump into your thread but i have a similar question. I have a 1977 f250 4x4. I like where my gears are at, 4.09 in the front(dana 44-9f) and 4.10 in the rear(dana 60) but when i get up around 60-65 she shakes pretty good. I have a 4 inch suspension lift with 35" Mickey Thompson Baja claw radials. At 55 mph im at 2500 rpm at 60 im up around 2800-3000 rpm. Any ideas on how to cut the shaking down? The major concentration is in the gas pedal and the steering column. I dont want to change anything so if its something i have to live with thats fine with me.

 

Are your tires balanced? loose tie-rod end? go over the front-end and check for any worn or loose components.

 

The AXLE code is listed on the Warranty Plate, which is located on the left door face below the latch. Post what it is.

If the AXLE code begins with a letter: Limited Slip / If with a number, no Limited Slip.

1980/85 Dana 60's were available (for the first time) with rear axle ratios of 3.07-1 & 3.23-1, but these two are very hard to find.

The 3.54-1 ratio is another toughy to find. Everyone is looking for one, few find it. Most Dana 60's rear axle ratios were 3.73-1 / 4.10-1 / 4.56-1.

 

Would old u-joints also contribute to this?

 

I just put into a tranny shop yesturday to see what they say. I know these trucks were not designed to go very fast, they were made to work. I have a 390 cu motor and at 60MPH (Need a tach) way too loud and burns too much gas. Seems like I really need another gear all together.

 

You folks are all used to modern vehicles with overdrive trannys. My highboy does 3000 rpm at 70-75 mph all day long. Does it sound like it's screaming? That depends on what you compare it too. They don't have overdrive guys. They are going to rev a bit higher than a newer vehicle.

-Jared

 

My '73 F250 has 38J as the axle code, any ideas on the ratio? TIA

 

38J = Dana 60 rear end, open differential, 3.73 ratio. J = with power steering.

 

My 76 has the 4:10 rear-end and at 60MPH it's running 2500RPM and at 70MPH it's just under 3,000RPM. I'm running a 235/75/15 tire on it. It's the trailer special model with the stock rear-end ratio. It doesn't pull anything, but it can sure wind up fast.

OJ