[SmokinBBC]

OK guys. As you know Gary (GTR1999) did a thread on Posi Tuning....well I am the lucky SOB that he did the Blueprinting for!

First the short story of how I got this far....I noticed quite a bit of play in my yokes, so I decided to drop the halfshafts to check out the play..both sides were well in excess of .05, so I contacted Gary to get some advice. He advised dropping the diff and taking a look inside. So I did it. Four hours later and an hours worth of cleaning, I opened her up. Sure enough some mushrooming...but that wasn't the real concern. I discovered 3 cracks..2 along the shaft holes and one crack about 2 inches long in the large window. See Gary's posi tuning post for the pic. After some consultation with the master and some long hard thinking and reading Gary's paper(at least 5 times!), I decided to due the rebuild myself.....that is after Gary agreed to build the posi case I wanted.

Anyway, I am at the point where I am going to set-up the differential...but before I get going, some PICS:

Here is the new POSI unit from the ARTIST (formerly know as Gary). For better pics, see his Posi Tuning post.

Here is the master rebuild kit from Gary. I got the torrington yoke bearings as advised ...one look at them and you can tell the difference. Gary has a good pic in his Iron Differential Rebuild post.

Also notice that the old ring gear bolt (on top of the new ring gear bolts) have a shoulder..The new bolts are threaded all the way up..decision time.

Here are my new Toms 3.36 gears:

Here are my new yokes. Notice that they are 75 Rockwell..thx Gary!

As you can see in this pic, I have cleaned, primed and cast painted the housing. I also tapped and installed the 1/4npt drain plug.

While I was waiting for all my new goodies, I did a few other things as well. Rebuild halfshafts, and drive shaft. Also cleaned and painted the differential cross member, diff bracket and strut rod bracket. I know a few guys with farming experience and they suggested that I use tractor paint since it will withstand chips and weather better....only time will tell, but they look pretty good:

I also did some mild polishing and radiusing the housing with a dremel. I did not go as far as Gary does in his rebuilds.


My next step is to inspect all the parts, debur and install the ring gear and install the races in the housing.

As the thread title states, I am doing this for the first time and I am following Gary's paper and his rebuild post...so be patient and gentle with me

 

[Patrick]

That's kick ass!

Thanks for taking me along.:thumbsup:

 

[gtr1999]

Looks good Paul. You might want to take a turn on the pipe tap to set the plug just a little more. Looks like 1/2 turn might be good.

 

[SmokinBBC]

Looks good Paul. You might want to take a turn on the pipe tap to set the plug just a little more. Looks like 1/2 turn might be good.

Gary,

It is just laying in there for the pic...it does go about 1 more turn.


Here is a pic of the races installed. You can see that from the front the large race looks perfectly centered. From the other side there it looks as if there is more race over the lip of the housing on the left side than the right. Is this a concern? The race is all the way in and flush. I don't recall if it looked like this when I removed the old race.

 

[gtr1999]

As long as the races are home you're ok. Now get back to work!:laughing:

 

[SmokinBBC]

As long as the races are home you're ok. Now get back to work!:laughing:

I'm no slacker:laughing:

I stoned the ring gear, used a little brake cleaner in the holes and on the new bolts. I used 5 old bolts to draw the gear up. Locktight on the 10 new bolts, star pattern torque to 55lbs and witness marked!

I put some lapping compound on the yoke and tightened it down on the pinion a couple of times and cleaned up. Now it is snug and a little easier to get off. I also put on the old bearing which I polished a few thousands off to make it slip fit. It is a little tight, but comes off very easily with the bearing splitter. I am going to leave it this way. However, the new top bearing is very tight. I did not try to put it on..might have to polish the pionion a little to make it slip fit.

Also ground down the top of the old pinion nut......I think I am ready for the first test fit. I am starting with the old shim which is .027.

However, I have family obligations later today and tomorrow, so it will have to wait:thud: Time to wrap everything up. Till next time...

 

[SmokinBBC]

I'm Back.....installed the pinion and did some test fitting of the case and shims. I have taken some pics, but I'll post them later..for now I want to check the first pattern.

Pinion Shim .027
Left Carrier Shim .220
Right Carrier shim .245
Backlash 5-6

I'm thinking that I need to go down to .026/.025 on the pinion shim and increase the backslash a little.

 

[gtr1999]

Paul,
Got your mail. Thank you.

The pattern is too deep. Go to .022 and you'll see it come up- probably too much. Keep the BL at 5-6.

 

[SmokinBBC]

Gary,

Don't have a 22. I have a 21 and 23. Here is the pattern with the 23. Backlash opened up to 7/8 with the new pinion shim.

My patterns don't seem to show up real well...more load needed?

 

[gtr1999]

You'll have to reshim to keep the BL at 5-6. The pattern is light, mix it up like mayo and load the pinion with a leather belt so you have to apply some force to rotate the ring gear. I made a RG wrench out of a junk box wrench that I welded to a long piece of steel rod. A long box wrench also works well.

You want to get to this:

I made up this masterpiece to load the early 4 spd yokes with U bolts. I use a small strap wrench on it.

 

[tracdogg2]

Paul,
You're real close. I would go with the .021 shim and tighten up the backlash and do another pattern check. Try using a little less marking compund. Also check the pattern and the backlash in several spots around the ring gear.
Mike

 

[SmokinBBC]

Gary,

I put a few drops of oil in the marking paste..much better.

Here it is with pinion at .021 with BL at 6. Hope this works cause the 21 is the smallest in my pack.

 

[SmokinBBC]

Paul,
You're real close. I would go with the .021 shim and tighten up the backlash and do another pattern check. Try using a little less marking compund. Also check the pattern and the backlash in several spots around the ring gear.
Mike

The 21 is in...see post above..whatya think?

 

[gtr1999]

coast is getting better but I don't like the drive. The drive looks centered on the tooth between toe and heel but still looks deep and that would require a thinner shim. It is more important to get the pattern equal between the face and flank then between the heel and toe.

.021 is thin. I haven't used one under.024".- Mike have you used any under this?

Clean the paste off, go back over the set points. Are you checking the BL in several places?

Maybe take a break and go back to it?

 

[SmokinBBC]

coast is getting better but I don't like the drive. The drive looks centered on the tooth between toe and heel but still looks deep and that would require a thinner shim. It is more important to get the pattern equal between the face and flank then between the heel and toe.

.021 is thin. I haven't used one under.024".- Mike have you used any under this?

Clean the paste off, go back over the set points. Are you checking the BL in several places?

Maybe take a break and go back to it?

I just rechecked BL....lowest 6-highest 9

 

[gtr1999]

.003 varience isn't out of control, I've had them up to .005 but I was able to get the pattern in. I would reshim for 4-7 and recheck.

Also how snug are the shims? I set them so that I just need a little help with a small bar. If too loose the case will move.

 

[SmokinBBC]

Ok. I'm going to tighten the BL up a little, clean the paste off and give one last pattern check today...be back shortly.

 

[gtr1999]

Did you take a picture of the setup pattern on the gears when you opened the box? I usually do this to compare later.

 

[SmokinBBC]

Unfortunately I don't have pics of the old pattern. But I can see a pattern worn on the gear. I'll see if I can get a good pic of that.

The shims are snug. I have to slightly tap them in.

Here are new pics at 4-7 BL and 21 shim. Cleaned up the gears and didn't use too much marker. Looks better.

 

[SmokinBBC]

One more pattern with hopefully better pics.