Took the 66 out for the first time since buying it. It ran pretty good, rides like a tank and it seems like the top speed is around 50-60. I still need to go over the front end and brakes to feel safe. I thought everyone would be waving at me and liking the truck but they were flipping me the bird because its so slow.
Is that the top speed of all f-250 4x4s? Has anybody on here done a trans swap to get an extra gear? Are there any fairly easy swaps I could do to make it more of a daily driver? I have been wondering how hard a axle swap from a later model F-250 would be? I can weld and know that would be involved. It would be nice to have power disc brakes and a truck that could do 70-75 on the highway easily. Any write ups on here from someone who has done something similar?

I had a bang 2 times right under the drivers floor when I hit a bump. I'm going to check that out more tomorrow but is there something that is known for loosening up in that area. Looks like the transfer case is about where it came from. Hopefully it's something stupid like when I thought the transmission was shot and I adjusted the clutch in 15 minutes and now its great. lol

 

Unless you're installing an overdrive transmission, changing to a 4-speed non-overdriven transmission isn't going to change the condition of your top speed. A (non-overdriven) 4-spd. will have one more gear but, the top gear (4th) will still be 1:1 just like a non-overdriven 3-spd manual or a non-overdriven automatic.

 

To me an axle swap with different gearing seems like it would be the better move. Until I start thinking about steering and the steering column. And that's where I want to talk to someone that's done it. I know the frame rails are different and the spring perches would have to be moved. I would have to find/ make brackets for power steering pump and steering box. That all seems like it would be easy to me. I'm sure it probably isn't. It all seems easy when you are typing on the computer. lol

I need to do a lot more research first. I need to figure out what my axle gears are. By looking at the manual it says I should have a Spicer 44 6-F. But when I look for brake pads I see 2 sizes. A 2-1/2" pad and a 3" pad. it says one is for an axle rated 3000# and the other 3500#. Not sure which one I have.

Are the front and back brake pads the same? I can't find front ones at a lot of stores in my area. But I look at rock auto and it says for front and back.

 

Unlike a Ford 9-inch rear end, the Dana rear end doesn't have a removable 3rd member. Gear swaps with a Dana are more complex. Going to a higher (lower numerically) ratio will reduce engine RPMs at highway speed. The trade-off is you'll be giving up take off and low end grunt that lower (higher numerically) gear ratios have to offer. An overdrive gives you the best of both worlds. You keep your rear end gearing for pulling/hauling but, you can cruise the highway at greatly reduced engine RPMs.

If you had 4.10 rear end gears and an overdrive ratio of .68:1 (for example), your final drive equivalent would be 2.79:1 (in overdrive, with 4.10 gears, the engine would 'perceive' the rear end ratio as being 2.79:1).

If your truck has drums all the way around, it would have brake shoes. Disc brakes have pads.

Starting in 1976 ('76-'79), the 4x4 trucks got Dana disc brake front ends. You could swap the Dana disc brake front axle from a '76-'79 F250 4x4 in place of your current axle.

 

I believe that would place the drag link behind the axle instead of in front which would require different linkage. That will likely require a different steering gear which will likely require a different steering column. Unfortunately it's not a simply bolt hole swap.

Chad

.

 

The steering arm hole will end up in the same place. The hole in the steering arm is bigger though so you would need a drag link and pitman arm off of an F350 (or F250 4X4 with a D44 6CF-HD).

Should be a pretty much bolt in swap (I currently have a '75 Dana 44 6CF-HD in my '66 and it was a simple swap).

 

Where are you looking for brake pads at? You have the 3000# axle for sure, but AFAIK, both the 3000# and 3500# axle use 12 1/8" x 2" shoes IIRC.

 

As for you're original question:

Chances are, you have 4.56's (could be 4.88's or any other gear ratio under the sun). If this is the case, 70 MPH with 31" tires is about 3500 RPM. Your truck will run great at this speed, it will just recycle a few extra dinosaurs in the process.

My personal best with the same setup was a shade over 90 MPH.

If you were to swap to 3.54's, you'd be turning 2700 RPM at 70 and 3100 at 80.

4.56's with a rough .75:1 overdrive (think NV4500 @ .73 or GearVendor @ .78) would give you an overall ratio of 3.42 which would knock about a 100 rpm off the 3.54 figures.

If you want to really cruise, 3.07 gears in your axles would let you turn 2400 RPM at 70 and 2700 RPM at 80.

Either a gear swap to 3.54 or an overdrive tranny would get you what you want. The gear swap will compromise your low gears, but may be the easiest option (I despise that word).

Overdrive is the best of both worlds, but more work may be involved.

Personally, I am running a direct drive Clark 5 speed and will be swapping to 3.31:1 gears. The 7.29:1 first gear ratio coupled with my NP205 T-case will preserve my slow speeds while the 3.31's in direct drive will push me down the road at 140ish MPH at 5000 RPM.

As for your clunk, a proverbial $10 says your t-case isolators are shot.

 

My bad, I thought it was a bit more involved. That's great!

Chad

.

 

I put a gear vendors in mine but had to swap in a 205 case. Unless you find a used one it's probably cheaper to swap gear sets or complete used axles from a 70s era F250 which were usually either 3.54 or 4.09 ratios. Check your battery under the passenger floor board to ensure it's strapped down tight. I find the firm suspension can cause the battery to bounce and make a clunk when you hit a pothole.

 

Its definitely the t-case isolators. They look pretty bad. Shouldnt be too hard to fix. Only problem is im gonna have to cut the bolts off. They are rusted so bad they would probably snap anyway. I see the rubber isolator for sale but not the bolt. Do you know where i can get the bolts?

 

So it is a bolt in swap! I figured if it would be on any vehicle this should be it. It actually seems like it might be easier than trying to rebuild the axle that is in there now. I would say theres a possibility the axle i have hasnt been serviced since 1966. Everything works but it needs to be gone over to be safe. The thought of messing with all those seals and gears scares me more than welding up a few brackets.

1972redneck, did you get driveshafts made or use the original? Did you use the whole 70s steering column? If so how does it look in the truck?No interference with the stock clutch linkage?
It seems like an axle swap would be the one thing that could give me everything i want. Power disc brakes, power steering and different gearing. And i could possibly get it all from a $500 parts truck.