9 Inch Issues

[cldonley]

Yesterday, for the first time in a long time, the Bronco moved under his own power. Celebrations were occurring. But then...
My rig is a 69, with 96 351W from a van converted to carb, original 3 speed, D20, hydraulic clutch using 1980 something F250 bell housing, master cylinder and slave cylinder, original 9 inch with original limited slip that I upgrade to 4.11 with parts from WH. Explorer rear disc setup.

Cranked the beast, put it in gear and started backing out of the shop. At the end of the drive way, engine was revving up, speedo was indicating 10 mph (when in a forward gear), driveshaft spinning like a wild thing, but no movement was happening at all. Placed T shift in all the positions, tried all the gears. When letting out the clutch you could hear a "thunk" from the rear end. Clutch, transmission and transfer case seem to be doing what they're supposed to do.

Fast forward to this morning, it's on jack stands, axles out. The yoke on the diff spins freely and you can see the gears moving when looking down the axle tubes with a light.

I put the diff together using the Ford Differentials "How to rebuild the 8.8 and 9 inch" book. It passed all the tests.
Since I reinstalled the old limited slip, I didn't use any additive in the gear oil.

Before I pull the 3rd member, I was hoping to get some input from y'all. It seems to me that if the clutch pack in the limited slip failed, it would just turn into an open diff, is that true? So it should still move under it's own power.

Lil help?

Thanks y'all!

 

[JB Fab]

Sounds like one of your axle shafts is too short to engage the side gear.....

 

[cldonley]

Sounds like one of your axle shafts is too short to engage the side gear.....

Makes sense.

 

[DirtDonk]

Or maybe both!
Super easy to turn and spinning freely, does not sound like a normal function of a limited slip. If one of the axle shafts is too short, you’d still feel resistance through the clutches. At least I would think. But not being a differential expert, I don’t know if that has an error or not.

 

[cldonley]

Or maybe both!
Super easy to turn and spinning freely, does not sound like a normal function of a limited slip. If one of the axle shafts is too short, you’d still feel resistance through the clutches. At least I would think. But not being a differential expert, I don’t know if that has an error or not.

I think you're right, and that makes sense. Way back when I rebuilt this thing, I put it together and the axle flanges rubbed the parking brake components, so I added spacers. Since both you and JB mentioned this, I'm thinking those extra spacers have to be the issue. Getting all the pressed on components off to remove the extra spacing is going to be fun, but I think that's what is needed.

 

[jamesroney]

I think you're right, and that makes sense. Way back when I rebuilt this thing, I put it together and the axle flanges rubbed the parking brake components, so I added spacers. Since both you and JB mentioned this, I'm thinking those extra spacers have to be the issue. Getting all the pressed on components off to remove the extra spacing is going to be fun, but I think that's what is needed.

and yes...if you installed the clutches wrong, or even left them out, it just reverts to an open diff.

 

[nvrstuk]

Sounds like one of your axle shafts is too short to engage the side gear

Good call... I think you called it! OP stated shims...

Wonder if he has the wrong axle years installed for the housing/brg. Wasn't there a funky change with a '74 due to the larger brg size or offset? Pass side?? I just know Ford couldn't leave well enough alone and changed something again so parts wouldn't interchange again...

All I know is I gave up on 9" axles a long time ago but I remember this funky "non-fit" issue.

 

[cldonley]

Good call... I think you called it! OP stated shims...

Wonder if he has the wrong axle years installed for the housing/brg. Wasn't there a funky change with a '74 due to the larger brg size or offset? Pass side?? I just know Ford couldn't leave well enough alone and changed something again so parts wouldn't interchange again...

All I know is I gave up on 9" axles a long time ago but I remember this funky "non-fit" issue.

These are all good questions for which I have no answers...they are the same length as the ones I replaced, so that should be good. I shimmed them because the flanges were rubbing on the park brake components from the explorer rear disk swap. At the time I posted questions about it here on the forum, and I think it was DirtDonk that said he'd never run into that particular issue before. Long and short of it is I've pulled the axles, removed bearings and shims, installing bearings and we'll see what happens. Hopefully it heals itself

 

[DirtDonk]

Gotta love it when things heal themselves and pesky gremlins chase themselves away!
We’ll see soon I guess…

 

[jamesroney]

These are all good questions for which I have no answers...they are the same length as the ones I replaced, so that should be good. I shimmed them because the flanges were rubbing on the park brake components from the explorer rear disk swap. At the time I posted questions about it here on the forum, and I think it was DirtDonk that said he'd never run into that particular issue before. Long and short of it is I've pulled the axles, removed bearings and shims, installing bearings and we'll see what happens. Hopefully it heals itself

It won’t. Your strategy needs improvement. While you have them out, REMOVE the explorer backplates and get them out of the way. Slather the splines with gobs of sticky grease. Insert the shafts, and seat them in the splines. No need to install retainers. Pull the shaft back out…and look at how much engagement you actually have. Do both sides. It’s not going to fix itself.

 

[cldonley]

It won’t. Your strategy needs improvement. While you have them out, REMOVE the explorer backplates and get them out of the way. Slather the splines with gobs of sticky grease. Insert the shafts, and seat them in the splines. No need to install retainers. Pull the shaft back out…and look at how much engagement you actually have. Do both sides. It’s not going to fix itself.

That was the plan. A was being facetious. At least a little.

 

[Broncobowsher]

Do check the spline engagment. Many years ago someone at work did an axle build, air locker, custom axles, lot of money. Pulled out of the garage, blipped the throttle. Axles were too short. Blew off the end of the splines and destroyed the axle and locker. Only engaged a fraction of an inch spline engagement.

 

[nvrstuk]

Do check the spline engagment. Many years ago someone at work did an axle build, air locker, custom axles, lot of money. Pulled out of the garage, blipped the throttle. Axles were too short. Blew off the end of the splines and destroyed the axle and locker. Only engaged a fraction of an inch spline engagement.

If he destroyed the locker by twisting splines off my hard earned money was he grenaded a DETROIT!!


I have seen so many Detroits grenade because a ujoint or axle or whatever grenades & the Detroit explodes.

 

[cldonley]

If he destroyed the locker by twisting splines off my hard earned money was he grenaded a DETROIT!!


I have seen so many Detroits grenade because a ujoint or axle or whatever grenades & the Detroit explodes.

Still running the almost 60 year old limited slip that came with the rig, to the best of my knowledge. Still had the tag on the pumpkin and 3:50 gears when I pulled it apart. My intent is certainly not to grenade it! My intent is to spend the money on a locker for the D44 I've got waiting to be narrowed and rebuilt.

 

[Broncobowsher]

If he destroyed the locker by twisting splines off my hard earned money was he grenaded a DETROIT!!


I have seen so many Detroits grenade because a ujoint or axle or whatever grenades & the Detroit explodes.

Not Detroit, I think ARB?. There wasn't enough spline engagement. It would have happened to any differential when there was probably less than a ¼" spline engagment.

 

[nvrstuk]

Could be, just never heard of an ARB grenading when anything "out"side of the carrier/diff blew. The way ARB's work when engaged I don't know how that could happen... not talking issues with them not locking completely due to load on them when engaging and then internally stripping the (can't remember the name) locking mechanism up- totally different scenario. Also not talking about twisting the case in half, which I have done on their 35 spline 9". I just have never heard of it with an ARB. Detroit? Yes, it's as common as the sun rising in the Sahara... they way Detroits engage and disengage (internal design) grenades them when one side is unloaded under extreme load. It's supposed to be due to a back spring or load reaction ( Eaton used to address it as a failure point for Detroits) from when the one side of the carrier doesn't have load anymore and therefore literally causes the internals to fail.

 

[nvrstuk]

Still running the almost 60 year old limited slip that came with the rig, to the best of my knowledge. Still had the tag on the pumpkin and 3:50 gears when I pulled it apart. My intent is certainly not to grenade it! My intent is to spend the money on a locker for the D44 I've got waiting to be narrowed and rebuilt.

Yeah, LS's usually don't "grenade" per se... they just lose their ability to transfer torque to either side of the diff. Linings wear...

 

[BigB]

Looking at the thread title I figured this would be a talk about your girlfriend/wife complaining....I was going to commiserate....

 

[cldonley]

Remember back in the day when NAPA had the good parts? I bought rear axle bearings from them because they had them in stock. Made in China. Tried pressing both bearing and seal race on at once with a 30 ton press. Nothing doing (first pic). Tried the second set on the other axle one at a time. Bearing went on fine, race cracked. Got my money back and ordered a set from WH. Turns out the set from WH was cheaper even with shipping. Guess we’ll finish this job next week.

 

[cldonley]

Got the new bearings from WH. They pressed right on. They are National brand, but still made in China. Installed the axles and have plenty of engagement. Note to all you beginners like me-since the axles weren't fully engaged in the limited slip, the splines on the driver side got misaligned and the axle wouldn't go all the way in. My buddy held the driver side side and applied pressure while I turned the passenger side until everything lined up and went together. Working on the parking brake assembly on the driver side now because the wheel stud heads are catching on the pins that retain the shoes and the top outer spring. Once that's corrected, it'll be time for a test drive.