Wondering if anyone has tried putting a 1986 Ford rear axle assembly into a 1949 Ford F3 pickup.
I just completed a rebuild of my drivetrain and ran the old beast down the highway. With the super low rear gear currently on board my max MPH was around 55. I don't plan on trailering this thing around, so I would like to lower the RPMs. I have a complete rear assembly with code V131A from a 1986 F250 with a .411 locker.
Anyone with any experience with this install?

 

Have you measured the width of the later rear? Guessing it will be much wider.....

 

I'm told F250 up to 1972 is correct width. I put a 1972 Dana 60 in my F3.

 

Oh, It is wider, by about 7" total. But this is an offset rear. The left side is exactly the correct width, with the right side being longer. My local mechanic suggested cutting the right side down to fit and getting another left side (Short) axle for the right.

 

Scotty, I have the 86 axle on hand. That's why I want to use it.

 

Sounds like a plan. 411's and a locker would be nice.

I don't have a tach but my tired flathead and T98 trans will push my truck to a max of 65-67 MPH according to my GPS. That's with 3.73's and 235/85R16 tires which are just shy of 32" tall.

Let us know how it works out.

 

Scotty,
I am also considering going with the highest tire that will fit. But according to your results it won't gain me that much. I was looking at 265 75R16s which are also a tad under 32".
If my plan is too outrageous I'll look for another rear.
Thanks guys,
Dave

 

While 4.11's will be an improvement over the stock 4.86's, it still might not get you where you want to be. Depends on your goals and how you plan to use the truck.

My 79 F250 has 3.54 gears and 32" tires. 2300 rpm at 65 mph. Still pulls a load pretty well too...

 

I had considered the T5 trans swap. It would be great to have more usable gears to get through traffic AND have overdrive for the top end speed for the freeway.

I think the 4.11's would be perfect for that.

 

Is the F3 still a flathead? If so I wouldn't gear it down too much. F3's are heavier than the typical F1's, PA has plenty of hills, and the flathead needs some RPM to make power. I think the 4.11's with those tires would be OK, 2400 RPM at 55, 2800 at 65 mph. A flathead will run just fine at those speeds. Gear down too much and you'll just be into the power valve on the carb all the time. What trans do you have, I'm guessing the 4-sp crashbox?

 

OK Guys,
It is still an 8BA engine just recently overhauled about 80 miles ago. It is the 4 on the floor with a granny first gear. I too believe the T5 swap would be great but I am trying to stay close to original.
Tinman, My goal is simple. I want to use it mostly around home for local shows and stuff. BUT I also want to be able to take it on trips averaging 500 miles. What I don't want to do is redline that 239 for hours on a trip. AND I don't want to spend any more money on my truck than my divorce will cost me if I do.
Guess I will look for a different rear?

 

The only thing about narrowing your '86 axle is that it is likely to cost as much to do that as to get a "drop-in" axle.

But 4.11 is not a bad ratio in my opinion. If you drop down to 3.50 or so, cruising will be great as long as you're on flat ground, but pretty darn doggy the rest of the time. If you want to go faster than 60 -65, better start thinking about better brakes, too.

PS I assume you are aware of "widowmakers"?

 

Yes ALBUQ I don't have the widow makers. The rims were changed to 16" standard rims by the previous owner. They interfered with the rear drums so I had a machine shop make me a pair of 3/8" thick spacer plates cut for the 8 lug pattern. This made the wheel studs too short so I found 2" studs with the proper diameter serrated collar and replaced all the rear studs.
Dave

 

Dave welcome to FTE, the best Ford Truck Forum on the world wide Web! Glad to have another PA guy here! It looks like you are practically in NY state! I'm in Lock Haven.

 

Hi Dave, welcome to FTE!

Another option to consider is keep the timken rear end and swap the gear set. Chuck from chucks trucks makes a 4.10 (or 4.11 depending how you round) conversion for the timken 51524 which I have in my F3. Stock look with drive ability

I only have about 5 miles on mine so far and haven't gotten it over 35 yet as I'm not quite finished on the restoration but have no complaints so far.

Here's a write up from another user: https://www.ford-trucks.com/forums/1...l#post13945034

There's also a stock 4.11 gear set for your timken but I've only seen one, they are very rare!