Swapping limited slip between axles

[superj]

Dang, that sucks they did that.

 

[don4331]

I'll leave the controversy to a 2nd post.

Back in the 80's/90's, Ford (Sterling) was building 100s of 1ks of 7.5 & 8.8 rear axles (Rangers, Mustangs, F-150s, etc, etc). While they had multiple lines, they needed to assemble them efficiently.

As the "pumpkins" and gears are machined, the tooling slowly wears; so, there are tolerances. Ford didn't have time to assemble, check pattern, disassemble, add correct shims, reassemble, recheck pattern and send down the line. What they could do is measure the components to a high degree of accuracy. As result, after measuring, the gears and "pumpkin" are stamped with their deviation from ideal. That way, the assembler, reads the deviation, grabbed the appropriate shims, assembled the axle and sent it on down the line. A statistically appropriate number were pulled off the line and measured. If it was in tolerance, the line continued running, if not the line shutdown while more were checked...

As a result, we get away with swapping ring & pinion from one axle to another, just transferring the original shims. And 99% of the time, its good to go.

So, swapping 3.27 gears from an Explorer axle to a Ranger one, is easier than it originally sounds. You do want to check to see, if you are the 1%, but many on the forum have just swapped and went!

Next, Ford was all about commonality. In the differential, there are 2 carriers (LS, and Open) and 4 sets of spider gears (LS 28, LS 31, 28 Open & 31 Open).

So, when you pick up the Explorer LS Carrier with 31 spline spider gears, you toss the spider gears, walk over to a Ranger with LS rear axle and grab the 28 spline LS spider gears and drop them on your cart.​

And with that you have all the right pieces to build a 3.27 Ranger LS 28 spline rear axle.​

[Normally, people go the other way - steal 31 spline LS gears from Explorer and buy 31 spline Ranger axles* (from Moser or Dutchman), so I know it works],​

​

*Explorer axles have 1.620" bearing surface, so don't fit in Ranger housing; Ranger axles being 1.400" bearing surface. But aftermarket made 31 spline/1.400 bearing surface axles.​

 

[scotts90ranger]

Scott,
As far as rear discs not taking a different master "the ranger master works fine" that one has been beat to death in the '48-56 crowd... some real smart fellas there explained it pretty clear... disc take more pressure as well as holding a residual pressure in the line. If you don't, what happens is the discs are there but they never ever wear out, seem to last forever (cause they aren't doing anything useful). I'd ask how much your rear discs are wearing, I bet they are just riding around doing nothing and since 80% of the brake happens in the front wheels anyhow you just don't realize that on your truck 99.5% of the brake force is happening up front.

I'm pretty sure the T56/6060 is out, it requires enlargening the tunnel or a body lift to fit (big tranny). More work and money than I want to do... and I ran the calculator with it's final gear #6.... 0.5 ratio drops way too low, you would want 3.55 or 3.73 with that kinda final drive, which is a really nice combo (probably the best) but that is replacing 4 parts to fix the problem instead of 2 (trans, axle, tires and a new driveshaft). For you guys wanting a stronger tranny, no weak slave cylinder, and a real wide trans that means you can still drive your lifted crawler on the highway that is probably the way to go.

Cost of the custom driveshaft alone probably kills both T56 and brownie box - not gonna come up with anything out the yard that is "just right".

I think I have kinda decided a short term path that will help me decide long term better.
Gonna grab the radiator out of an Explorer 4.0 w/ AC that is on my todo list (improve cooling system for the 2.9L), and while I am there scout everything out. Probably get the 3.45 LS 7.5" and do that swap... then drive it for a good while and figure out what my fuel mileage really is. I'm figuring a trip to Austin (901 mi one way) will show me what highway mpg is pretty definitely. The front tires are a little dry rotted, so I might not be waiting as long as I hope for tires, might get pushed into that sooner than later. I won't be putting anything so low profile that it is impossible for a guy to dismount em at home with a handyman jack and a bumper... I've figured out that is like 60 series or 65 - no rubber band 40 series tires for me.

I'll also be adding running boards/nerf bars and just tell my sweet thing to climb on the step to get in.

Further down the road if the MPG is still bad enough that I can justify the cost, go to the yard and get just the ring and pinion of a 3.27 or 3.08 and learn how to do a rear end rebuild.

On my '48, I have a 9" axle with 3.00 gears and a non world class (common) T5 trans. It turned it into a grocery getter... and at 68mph you hit an aerodynamic wall and can't go any faster, the rpms are there, the engine is happy - plenty of space before redline, just not enough ponies to push all the air out of the way. I'd say it took the fun out of it, but the original axle was a 4.86 or 4.27 which coupled with the original trans was slow marching speed for infantry (ford was still using up surplus trannys well into 1949 from the war) so I didn't really have a lot of fun with it to begin with. I know I went too far with that one (it was the only 9" older than 1972 in the yard), and it is on my list to find another set of gears for it 3.50 or 3.75.

I'm a little gun shy of going all the way to 3.08 because of my experience with my '48. The tires on the "full size pickup" 48 are bigger than the ranger but not much. F-1 is basically a small truck, they use S-10 and Ranger parts on em a bunch (like the bench seat is typically from a Ranger anything "full size" is way too wide).

Either way, I probably will end up with 6 different speedo gears when this is all done , thankfully the 'yard looks at that as "junk plastic" they would have to pay to recycle and they let it out $1 / ft - so I bet those are $1 each for me.

Before all this started I read every thread with the 2.9L and "mpg" or "fuel economy" in em - nobody really said what kinda mileage they get bone stock doing 20mph faster than Ford designed for. And those threads that collected fuel mileage had highly modded crawlers and dropped minitrucks, but the details were filtered out to just raw mpg numbers... not really useful.

On 35" tires I WOULD know if the rear brakes weren't working, as for how fast they wear I don't know, that rig doesn't get driven as much as I would like, need to rebuild the turbo... I'm pretty sure an oil cloud is frowned upon driving on the road

 

[19Walt93]

Keep your overdrive ration in mind when deciding on gear ratio. Not sure what Rangers had but T5's ran a .67 overdrive. A Mustang with 4.10's in overdrive had an effective ratio of 2.75. As a guess your Ranger has at least a .80 overdrive ratio, making 3.45's act like 2.76 gears when in 5th. In 1972 I had a 70 Cuda 340 with 4.10's and a 4 speed that would scream at even 60 mph. My 2004 Ranger had 4.10's and a 5 speed, it cruised at 75-80 effortlessly.