[East]

I am working on a 12 bolt differential.

One of the springs separated from the preload pack. I recently purchased a complete kit as I misplaced the spring and I could not obtain a single spring.

The preload pack is a 400# kit that is the same as the original.

I have watched a couple of videos on Youtube for getting the high tension parts back in but would like to hear from people who have experience with this to provide their insight and/or hindsight.

I always find a better way to do things only after I finish the task. I have never done this so I am without the better way.

[400 Lemans]

Compress the two halves with the springs installed in a vise and then zip tie them together. Slide it in the carrior and then cut the ties. Its a little tricky but its about the easiest way. It takes some pretty stout zip ties also.

[East]

Maybe more than one each for each spring?

I shall give that a try. I will test it in a vise... s l o w l y. My zip ties are kept in the garage. I live in Las Vegas. You know the rest.

This method is very easy. I would have never imagined 400 # tension against zip ties. But I like easy very much.

Thank you!

[400 Lemans]

Just zip tie around the center of the plates a few times and not the individual springs. Makes it easier to get the ties back out after you cut them.

[steve25]

Pick up a roll of mechanic’s wire to use in place of the cable ties.

It’s far safer!

You can braid two lengths of them together with the help of drill and your vise.

[blueghoast]

Wish I would of known that a long time ago when I did mine.
Man what a pain. that is a great tip.

GT

[sdbob]

When Tom Watt helped me with my 8.5. He said dont use the preload springs. This is in a drag application. Also no crush sleeve. Been working in my car for years also my street car.

[East]

I am only replacing the preload pack and not rebuilding.

I will have to use the preload pack and will not be able to omit.

All suggestions are great.

I feel a lot better taking on this task because I had planned on only replacing springs with most major components left in place.

I would have preferred to pour all the liquids in and install cover, but small price to pay for less steps.

Thank you all for that.

[mgarblik]

I hope this description makes sense. Get 2 pieces of scrap sheet metal about 1/8" thick. wide enough to span the pre-load plates and a couple inches longer than the pre-load plates. Make a sandwich with a scrap metal piece on each side of the pre-load plates. Use a 3" C clamp to compress the sandwich enough to close the hole where the pinion pin passes through until the 2 plates almost touch. insert the sandwich into the opening in the case until the C clamp stops against the case. Then use a brass drift and a small ball peen hammer to carefully tap the plates, top and bottom, as they go into the case, sliding out from the scrap metal and into the case. Wear safety glasses, just in case. It's really simple and this is the way I have been doing it for decades. This procedure is spelled out in factory service manuals as well.. No zip ties needed! Good luck.

[AG]

It would be a good time to check the backlash between the side gears and pinion gears and shim your clutch packs if necessary.

[East]

That is a quick question. I will find out the procedure in depth.

I have no hands-on time working on differentials. I have always depended on Dan's Driveline Repair to perform any work that was necessary.

I purchased the 12 bolt rear end from a coworker with a 1969 Camaro back in the 1980s. It was equipped with 4.88:1 gear ratio. I then purchased a Moroso Brute Strength posi unit.

I had planned on using 3.90:1 ratio but Tom Watt recommended using 4.10:1 instead because of 3.90:1 being noisier. He was a little miffed with me on the phone because I didn't know what I was working with as far as knowing the difference between an Eaton or Auburn when I was ordering gears. Totally understandable.

The second time Dan worked on the rear end was to swap in a 3 series posi and 3.08:1 gears. That's what is currently in place.

[AG]

You'll need a dial indicator and mag base to measure backlash.

[mgarblik]

The only change I make when I take these measurements is I use motor oil, 30W, or 20W-50, rather than 90Wt. on the discs for lube. This is just for these measurements. In my experience, using 90 wt. artificially reduces the backlash and it's hard to get a good measurement. Meaning when you get it assembled and operating, the backlash is too much. Try to get the stylus in the dial indicator as straight as possible on the pinion gear when measuring. In my experience, all new clutches will restore the backlash unless the gear teeth are really worn. Good luck.

[East]

This is one tool that I do not have.

I see Mitutoyo and Starrett sold on Amazon.

I don't know what features to desire or appreciate when shopping for this tool.

The magnetic base seems easy to figure out.

[Formulas]

If your disassembling and reinstalling the center section you don't need a dial indicator all you have to do is keep your side shims and caps going back in where they came from, To shim the clutches themselves is easy one side at a time on the bench set empty carrier on one end drop in the clutch pack shimming up until axle / spider gears and cross shaft start to be difficult to install.. no preload and almost no looseness.. repeat other side keeping axle gears and clutches going together for last time in same spot

I would be wondering why the first spring sprung from its spot to make sure it doesn't happen again

I would also apply proper torque to ring gear bolts.. not backing them off just hit them with proper torque to ensure nothing is loose easy peasy keeps murphy away

[East]

Originally Posted by Formulas

If your disassembling and reinstalling the center section you don't need a dial indicator all you have to do is keep your side shims and caps going back in where they came from, To shim the clutches themselves is easy one side at a time on the bench set empty carrier on one end drop in the clutch pack shimming up until axle / spider gears and cross shaft start to be difficult to install.. no preload and almost no looseness.. repeat other side keeping axle gears and clutches going together for last time in same spot

I would be wondering why the first spring sprung from its spot to make sure it doesn't happen again

I would also apply proper torque to ring gear bolts.. not backing them off just hit them with proper torque to ensure nothing is loose easy peasy keeps murphy away

I figured someone would question as to why the spring left its location, and I don't have a clue. If the preload pack has a defect, it will be corrected with the new parts.

I have a torque wrench that I will be able to check proper torque.

I just had an epiphany:

I always wondered why whenever i seen a nice classic car, there was an old guy driving it. I'd think that a lot of old guys like fast classics.

I'm 62 and have owned my car over 40 years. I'm only just now getting around to trying to finish it.

I always told myself I'll get some money and work on it this weekend. Time flies.

I want to thank everyone for their valuable insight that is greatly appreciated.

-----Kevin

[Formulas]

Every bit of clutch and spiders, axle gear wear increases the gap the spring sits in ( could of lost some preload ) also decreases tooth engagement on spider / axle gears.... That's why they used to say Happiness is a tight Posi

To gage how much a Posi clutch is worn measure thickness at the ears where they don't rub compare to where they do rub, You may find they don't wear much,