Help- Solid axles for dummies

[Chapap]

Ok so I know basically how axles and diffs work, but I don’t know what’s serviceable or how they’re put together. My goal is to raise my current ratio.

Differential: pop off the diff cover and what can I do? Are there bearings in there that should be inspected? Change ratio by changing a couple gears? Change the diff?

Wheel bearings: changed from the end? Pull out one side’s shaft and one bearing is on the end (near the differential when reinstalled) and one is is out by the brake? Are they packed or lubed by diff oil?

Just looking at the rear axle under the truck: there is the big diff ball in the middle, one shaft going to the wheels on either end, and drum brake stuff on the end. Are the shafty things bolted to the diffy thing or is it all one piece? Drum brake mounting plate thing replaceable?

 

[fastpakr]

The shafty things go into the diffy thing (but they're all separate pieces).

 

[cbxer55]

They're complicated. There is the ring and pinion gear, which determine final drive ratio. There are spider gears. The ring is the largest gear in there, it's vertical. The pinion turns the ring. The Spider gears are what make it work like a differential. They wear out. I recently had the final ration on mine changed to a 4.10. I just took it to a friend's shop and let him and his son do it. I had them put new spider gears in there while it was apart. My old ones had some wear on the corners. They were rounded off a bit. Not terribly, but my friend told me not to sell them to anyone. LOL!!!

Depending on the year, you can change the final drive without speedometer worries. The 98 - 00 use a "tone" ring that bolts to the back of the ring gear. The speedo sensor is on top of the pumpkin and counts how many times the sensors on the ring go past it. So the only thing that messes up the speedo reading is different size tires.

 

[RustyShackleford94]

Thats how the innards work ☝

Big ball in the middle = center section
Shafty thing = Axle tubes
Axle tubes are removable from the center section but its not easy. Usually they’re pressed and welded in. Drum brake backing plates are removable with 4 bolts.

 

[dvdswan]

This is an exploded view of a Ford 8.8 rear axle...

 

[Curious Hound]

Big ball in the middle = center section
Shafty thing = Axle tubes
Axle tubes are removable from the center section but its not easy. Usually they’re pressed and welded in. Drum brake backing plates are removable with 4 bolts.

The video was a good idea. But, for clarity, let's clean this up a bit.

The axle housing consists of the round part in the middle and the tubes on either side with flanges on the end. In the center, is the differential, as shown in the video. The differential has a carrier. That is a frame that carries the ring gear, side gears and spider gears. The carrier rides in bearings on either side. The pinion shaft comes in from the front and has its own bearings. The pinion meshes with the ring gear and turns the carrier. The axle shafts go from the differential. Out to the wheels. They engage the side gears via splines and are held in place with a c-shaped clip. At the outer ends, the axle shafts ride on bearings in the end of the axle tubes. The brake backing plates mount to the flange on the end of the axle tubes and provide mounting for the stationary components of the brakes. The brake drum or rotor mounts to the flange on the end of the axle shaft and then the wheel is bolted on.

You can change the ratio of the differential by replacing the ring and pinion gears as a set. This is a job best left for experts with the proper tools and experience. It is a precision assembly. If the truck is 4x4, both front and rear gear ratios must match. Otherwise expensive stuff breaks fast.

 

[Chapap]

It looks like there’s a lot of bearings that would want to be repacked after a while. From everything I read about wheel bearings, and I’d assume the rest of the bearings, they’re meant to be packed even though they have plenty of oil flowing to them. Some assemblies even have seals keeping the axle tube dry. The only thing I don’t see in that diagram is an inner bearing for the axle shaft.

looks like there’s really no reason to crack any portion of this thing open… unless there’s a reason to give any bearings some love. It’ll be cheaper to source an axle with my desired ratio than to throw parts into this one, but I’ll ask the local shop if they have a price to change ratio just to see.

 

[Curious Hound]

All these bearings ride in an oil bath. No grease packing. The differential oil flows all the way to the wheel bearings at the ends of the axle tubes. One reason why it's important to make sure that oil level doesn't get low.

 

[Chapap]

All these bearings ride in an oil bath. No grease packing. The differential oil flows all the way to the wheel bearings at the ends of the axle tubes. One reason why it's important to make sure that oil level doesn't get low.

Thats what I figured. It seems that’s the prevailing thought, but all the manufacturer instructions people post say to pack them.

and what is axle compatibility? I have a 1994 ranger single cab with a 7.5

 

[RustyShackleford94]

For the rear any ranger axle will bolt in plus first and second gen explorer axle. If you swap for one with disc brakes you have to also swap brake master cylinders.

 

[Curious Hound]

I believe most Explorer axles are "spring under" which means additional fabrication work to move or add spring perches on top for use in a Ranger.

 

[Chapap]

For the rear any ranger axle will bolt in plus first and second gen explorer axle. If you swap for one with disc brakes you have to also swap brake master cylinders.

Why swap the master cyl? Discs take more fluid to actuate? I think I’d prefer drums anyway. The back is so light, the rears lock up under heavy braking as it is. Don’t think I’d want more brake power back there.

 

[fastpakr]

I believe most Explorer axles are "spring under" which means additional fabrication work to move or add spring perches on top for use in a Ranger.

This. No Explorer axle is a bolt in.

 

[Dirt Squirt]

Thats what I figured. It seems that’s the prevailing thought, but all the manufacturer instructions people post say to pack them.

and what is axle compatibility? I have a 1994 ranger single cab with a 7.5

Axle spline count (28 or 31) = compatibility

 

[RustyShackleford94]

I believe most Explorer axles are "spring under" which means additional fabrication work to move or add spring perches on top for use in a Ranger.

Ahh yes. Forgot about that. Its been a minute.

Why swap the master cyl? Discs take more fluid to actuate? I think I’d prefer drums anyway. The back is so light, the rears lock up under heavy braking as it is. Don’t think I’d want more brake power back there.

People swap to disc for the ease of maintinance. The master swap is the keep the fluid properly proportioned from front to back. If you swapped for a disc rear without the MC they would lock up far quicker than the original drum brakes.