diff straightening

[blacksheep-1]

OK, so back from the races, as you will recall, I had an 8.8 diff with a little "wang " in it. There are several issues here, one is how to measure the wang, and 2 which side is the wang on.. so here we go.
So to determine the amount of wang, we need to create a jig whereby the angle of wang can be measured.
Looking around the shop, I scrounged up some plates used to support a roll cage, I cut a 31/4 inch hole in them


I then halve them


hold them up to the axle flange and mark the holes, I do this front to back as well as up and down because the holes are different lengths. Also, it's not so important to get the holes perfect since the whole idea is to get the plate to index on the axle flange, and miss the axle tube, so.. the holes are marked, then drilled out with a 3/8 drill, leaving plenty of wobble room for the 5/16 bolts and nuts. There is a reason the flange is cut in half, so I can use them with the axle in the car.




I then locate some 1/2 inch square tube, cut to length, I clamp the square tubing to the flange in a vice so they won't move and weld them together




I can now measure the angle of wang


But.. WHICH side is the wang on, and how do we know what is center?
and how do we determine the DBO point of reference?
Well, for the back of the unit, we measure the width of the upper TRAILING arm bracket and divide by half, I then drill an index point in the housing.
(DBO= dead balls on)


I then run a string down that reference point to the ground, checking to make sure it's 90 degrees, and mark the diff housing, you can also reference the bolt holes for the cover, they should be the same distance to center, the ring gear offset is plainly visible.


I then run the string through the pinion hole, out the bottom and mark that point, from my cover DBO center reference.


I reference that point and mark the housing, then I cross reference the string mark with a measurement from the "pig" or center section, flanges where they meet the axle tubes. This will establish the DBO for the pinion side of the unit.


I clamp this with a furniture clamp and now I have a Golden DBO referenced center of the diff
(GDBO= really , really DBO)


I can now measure from my GDBO reference to the flange jigs and tell which side has the wang in it, in this case it was the right.


Barring being able to cram this into some kind of press, or someone you know actually owning a diff press
how do we adjust this? you say..
I thought you'd never ask
Enter the maximum force adjustment tool.


I place the unit on jack stands, off set so that the bent side (the side I wanted narrower) would face up, and that side was supported at the end of the tube, and on the other, the opposite side of the pig, so according to the Geneva convention, when you strike the pig on it's flange, the unsupported (right in this case) side must bend straighter.. after awhile, and honestly after a few misses as well, it did move, was able to get within our spec of 1/8 inch and then that sucker refused to move again.. but I had one more card to play.
I cranked the welder up to nuclear, welded the section that I wanted narrower and quenched it with a rag dipped in water, and it took another 1/16 inch out of it.
So the unit was within 1/16th of straight, totally in "close enough" range. (We started with a 1/4 plus toe out)
I then welded the tubes in (not quenching them), and I'll tell you right here and now, I apologize for the welds, apparently I forgot how to weld after a few months, ground off the crudeness (or most of it anyway) and primed it with metal etching primer.
I then rechecked for camber and toe, and camber was 1/8 toe (out) was 1/16th.
Done, my back is screaming at me...
I don't think I left anything out.

 

[blacksheep-1]

now that I've had time to recuperate...

Picked up a rebuild kit, from the local parts store, remarkably all the bearings were marked "made in USA"

After a thorough cleaning and delousing, I decided that I wanted to replace all the bearings, the 3.55 gear is the correct one for the T4 class, and it was in decent shape.

I used my press to disassemble all the bearings, then pressed on a new pinion bearing, using the old shim. this is why I keep misc lengths of exhaust tubing lying around




used the exhaust tubing/ bearing installer for the axle bearings


I had to go old school on the pinion bearing races, I started off with a block of wood, to start the race square to the bore


then tapped it in with a brass drift, I like brass because if a shard gets away from you and makes a lap someplace, it probably won't destroy anything too badly. It also won't damage the race.


I then flip the old bearing race over to seat the new race, since it is recessed in the pumpkin


I pressed the bearings off the carrier, along with the ring gear, after marking it's location on the carrier (just because, it prolly shouldn't matter)
I noticed that there were several "steels" back to back in the limited slip unit.. hmm I think maybe someone has been here before me and decided to add some preload to the shim pack. I need to check this out further, as I'm not sure.


and that's it for now

 

[blacksheep-1]

Ok.. so time to install the pinion, since I'm using the same gear set, it should be pretty easy because I can simply reuse the old shim. . At this point I have to install the new crush sleeve.

Now I've oiled up my trusty 70s vintage Chicago Pneumatic, 'Merican made impact, jacked the pressure in the compressor and after 15 minutes, the PITA still would no collapse. So what to do?
I placed the crush sleeve in my press and gave it a little help to get started.
Once it realizes that you are serious, you can place it back on the pinion and finish collapsing it with the impact.
So.. you only need to collapse it a bit, (i used the gap from tightening the pinion nut down, and there was still some slop because it had just contacted the crush sleeve as the barometer).




FWIW, if I was just changing the pinion seal, or had to remove the companion flange, I would just remove the part, and rattle the new piece on, using the old shim. I've never had a problem doing that, your results may vary.
In this case I'm using new bearings, so that means a new crush sleeve, here's the old vs new .

It would be better to use a couple of wrenches to tighten the pinion nut, but I'm not Tarzan, and my back is trashed, I've known guys that use impacts on these all the time so that's what i used. If you hold the bearings tight against their race, you shouldn't beat them up
. Again, your results may vary.

So i wanged it all down had between 20 to 25 inch pounds of pre load, time to send it.
Also, dug around my vault and found an old Torsen, which I'll be adding to the project

 

[blacksheep-1]

dropped the Torsen in using the old shims and it was dead on, checked the run pattern on the gears, and put it in the car.

 

[Fabman]

A super easy way to check for a bent housing is to put a complete differential with the wheels on it on two milk crates, one wheel in each. Mark the center of each tire with chalk. measure between the marks and have someone rotate the housing 360* while you have the tape on those marks and if its bent you will see that distance grow and shrink big as sh!t.
You can also tell which way its bent-toe in or out or cambered.

 

[blacksheep-1]

A super easy way to check for a bent housing is to put a complete differential with the wheels on it on two milk crates, one wheel in each. Mark the center of each tire with chalk. measure between the marks and have someone rotate the housing 360* while you have the tape on those marks and if its bent you will see that distance grow and shrink big as sh!t.
You can also tell which way its bent-toe in or out or cambered.

I'm a one man show..

 

[bob]

Maximum force adjustment tool is also called "BFH"

I also beat myself up today working on my racer. I'm just not a Ford fan. I have never worked on a more painful car and I work on Italian cars too.

 

[Fabman]

I'm a one man show..

Yeah me too.....hook the tape in a tread.

 

[blacksheep-1]

Yeah me too.....hook the tape in a tread.

You still have to determine which side is bent, to do that you'll need dead center.
I tried the wheel methadone awhile back, maybe I'm a klutz but it took 2

 

[blacksheep-1]

So when I build a diff, I like to use one of these covers, they're cast. so their value is a bit dubious, but I've been running them since the Camaro stuff back in the 80s. Maybe they give the bearings a bit more strength.




So I'm back to cutting springs again, since I can't find one in both the right height and rate, the problem with this is that ford uses a "beehive" spring that is of smaller diameter at the ends, but.. and this is a big but, there is no way to index the springs in the perches once they are cut because of the bigger diameter.. here's the fix.



I located some pipe in 3-3/4 diameter that will just barely slide into the springs, cut them at 3/4 inch length, then squared the ends of the tubing in my lathe.
I then located some roll bar plate in 1/8 inch.


I welded the tubing to the plates, trimmed them and chucked them up in the lathe.
I'm going to tell you right here and now, this can get out of hand real quick, anytime you put something like sheetmetal or plate in a lathe it can be deadly. So wear eye protection, some thick gloves, body armor and maybe a condom just to be sure.



Once the plate was now the correct diameter, I used the lathe to find the exact center, then ran a hole saw through it, and had to cut it a bit bigger in the lathe.



and now I have a way to index the larger diameter spring in the stock spring pocket.




and I already know what some of you cheaters are thinking, I'm about an hour's work from turning this into a weight jacker that would slide by an unsuspecting tech guy.

 

[TMSBOSS]

I already know what some of you cheaters are thinking, I'm about an hour's work from turning this into a weight jacker that would slide by an unsuspecting tech guy

If you wanted to be a bit less conspicuous you. Could make the bottom plate from different thickness plates.

 

[blacksheep-1]

make the ring a bit longer and just throw shims behind it.

 

[blacksheep-1]

So, I installed the new studs from OP Tim and pressed them in, so make sure they are straight, I used an old wheel, greased the lug nuts and ran all the nuts down tight, real tight, so they are not only seated, but straight as well.