'89 B2 rear end

[19turner73]

Hey guys! I have a few questions concerning a 2.9l to 4.0l swap. The motor swap is complete and running smooth, but I am having vibration issues from the rear. Obviously we're looking at bearings and raceways....but.....I am still using the original pumpkin. Should I check out the bearings and replace them all, or swap the rear end. Has anyone done the rear end swap? What would be a good donor? Replacing the bearings is fine, but I don't want to replace them if the rear end can't take the torque of the 4.0l.

[Shran]

You sure it is the axle and not a u-joint or the carrier bearing?

The 7.5 axle is decently strong, I'd not focus on replacing it if you don't have to. Otherwise a Ranger 8.8 with drum breaks is the next best option to swap in.

[adsm08]

What he said. The 7.5 is not the preferred axle behind a 4.0, but in reality is not any weaker than the 8.8 that came in the Ranger for years and years. I think the preference for the 28-spline 8.8 by Ford was mostly for the larger brakes.

[country0001]

I'd definitely check the driveshaft, especially if its a CV style shaft. I've been running a 7.5 behind my 4.0 for 2 years. I haven't had any problems out of it.

More info will probably be needed

[Shran]

My bad, I was thinking Ranger driveshaft, thus the carrier bearing reference. Ignore that.

There is a good chance you have the CV style driveshaft, and there is an even better chance that if you do, it's worn out.

[19turner73]

First of all...thank for all the speedy replies to everyone.
yesterday I put the rear end up on jack stands and the pass. side axle slides in and out about 3/16". secondly...when I turn the driver tire. It turns about 10° before the pass. side tire starts to move. So...there is a good bit of slack between the differential. As, for the drive shaft....I ripped the CV joint style out months ago. replaced it with one with u joints.

[Shran]

You know that there is naturally some play with those shafts, right? They MUST have some play so that you can get the c-clips in and out.

Also, both tires should not turn at the same time unless you have a locking differential.

Sounds pretty normal to me. Vibration is usually not a symptom of worn differential bearings anyway.

[adsm08]

Originally Posted by Shran

Also, both tires should not turn at the same time unless you have a locking differential.

If he left it in gear and the trans is holding the drive shaft still the other wheel will spin in the opposite direction as which point 10* is still not bad.

If you had a trac-lok rear they should both spin together in the same direction. If you have an open rear it will need to take up a little slack (gotta have some space for oil to get between the gears) and then the other tire will spin in the oppostie direction.

Keep in mind that what amounts to thousandths of an inch of play at the gears themselves will multiply out and become inches by the time you get to the wheel because the wheel is much bigger around than the ring gear (see "radial vs linear distance"). The only true way to measure the slack in the rear end and see if it is out of spec is to set up a dial indicator on a tooth of the rigng gear and then rock the ring back and forth, see how far it moves before making contact with the pinion.

[509lifted]

first off check ur driveshaft and see if its true and straight cause i didnt know what the vibration was in the back of my b2 and then my driveshaft broke after two months of that happening and now the vibration is gone found out my driveshaft was .09 off as it was tweeked a bit.

[19turner73]

Hey Guys,
Man you guys are awesome!!! At my mistake. My problem turned out to be a U-Joint. lol
I guess the reason I was looking at the rear end is because, the axle slides out of the rear end about .25" on the pass. side. I have owed and worked on Fords for the better half of my life. Knowing that there is some slack in this application, but normally not as much as I am experiencing. Normally about an eighth of an inch. Thus causing me to think that this was the vibration. Stupid U-Joints.
My B2 is 2WD and yes it did come with the CV style drive shaft. Yeah...Well that shaft lasted about a week w/ my heavy foot and a freshly rebuilt 4.0l out of an '92 Explorer. I heard the ball bearings hitting the undercarriage of my truck lol. I replaced it w/ one from a 4WD B2. All is good now.....Thank you very much for your insight! I Love this site!!!!!
I have some other concerns with my trans. It's the FM145. I prob. should make a different thread....

[Shran]

Glad to hear that you got it fixed