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WANTED:Gear lash specs for 11.5" AAM Duramax rear axle.	View previous thread :: View next thread
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seedcleaner

Posted 2/6/2010 20:31 (#1061736)
Subject: WANTED:Gear lash specs for 11.5" AAM Duramax rear axle.

Mid-Missouri

Putting together the ring, pinion and carrier housing. It has the adjustable nuts for gear lash instead of shims beside the carrier bearing. Don't want it too tight or loose. Thanks.

Phred

Posted 2/6/2010 20:46 (#1061757 - in reply to #1061736)
Subject: RE: WANTED:Gear lash specs for 11.5" AAM Duramax rear axle.

NE Mo

Backlash, although important, the tooth contact is more important. When I was in school, the instructor's instructions were if the tooth contact was right, the backlash was right.

seedcleaner

Posted 2/6/2010 20:59 (#1061780 - in reply to #1061757)
Subject: RE: WANTED:Gear lash specs for 11.5" AAM Duramax rear axle.

Mid-Missouri

Could you explain the difference?

tmrand

Posted 2/6/2010 21:06 (#1061799 - in reply to #1061736)
Subject: Re: WANTED:Gear lash specs for 11.5" AAM Duramax rear axle.

Southeast Colorado

If you haven't had your pinion gear out then the tooth contact will remain where it was. If you have had it out you will have to check where your teeth on the pinion contact the ring gear. This will change depending on how deep you shim your pinion gear in or out. It is a little difficult to get it back where it was, and if you change it any your differential will really howl at certain speeds. If you haven't touched the pinion just set your backlash to specs by adjusting the ring side to side and you'll be good to go. I'm not sure how to find the spec. Back when I mechaniced alot I could pretty much set them by feel. EDIT after re-reading your post if you are putting all new parts in you will have a little more lee-way. You still want to use prussian blue to see where your teeth are contacting to make sure they are centered in the ring gear. However it is better then trying to re-use old parts. That is where the annoying howling would come from.

Edited by tmrand 2/6/2010 21:09

Indianajones

Posted 2/6/2010 21:09 (#1061809 - in reply to #1061736)
Subject: RE: WANTED:Gear lash specs for 11.5" AAM Duramax rear axle.

Here is the GM proceedure for adjusting carrier bearing preload.
Bearing preload is an important and backlash adjustment.
INDY
Important:

• The differential side bearing preload is adjusted by the 2 adjusting nuts in the bearing bore. The bore and the bearing cap provide the mating threads for the bearing nut.

• The differential must be initially preloaded in order to determine the backlash of the gear set. After the backlash is set, the final bearing preload is set.

• The rotating torque of the drive pinion must be within specifications before the pinion gear bearing retainer can be installed.

Install the pinion gear bearing retainer (10.5 in axle) or the drive pinion . Refer to Drive Pinion Housing and/or Seal Replacement .
Important: The rotating torque of the drive pinion must be within specifications before installing the differential case assembly.

Install the drive pinion (11.5 in axle). Refer to Drive Pinion and Ring Gear Replacement .
Install the differential side bearings, if necessary. Refer to Differential Side Bearings Replacement .
Install the differential side bearing adjuster nuts.
Important: Before installation of the differential case assembly, ensure that the side bearing surfaces in the carrier are clean and free of burrs. If the original bearings are to be reused, the original bearing cups must also be used.

Install the differential case assembly.
If the differential case assembly cannot be installed, turn the differential side bearing adjuster nuts into the axle housing until the differential case assembly can be installed.

Install the differential bearing caps.
Install the differential bearing cap bolts.
Tighten the bearing cap bolt finger-tight. Do not torque the bearing cap bolts at this time.

Important: Do not force the ring gear into contact with the drive pinion.

Slide the differential case assembly towards the right side axle housing until the ring gear contact the pinion.
This is the zero backlash point.

If the zero backlash cannot be obtained, turn the right side differential bearing adjuster nut in towards the axle housing until the ring gear fully contacts the pinion to obtain the zero backlash.

While holding the ring gear against the pinion, turn the left differential bearing adjuster nut out from the axle housing using the J 24429 until it contacts the differential side bearing.
Turn the right differential bearing adjuster nut out from the axle housing using the J 24429 until it contacts the differential side bearing.
Back off the left adjusting nut approximately 2 slots using the J 24429 in order to obtain the initial backlash adjustment.
Install the left adjuster nut lock and the adjuster nut lock bolt.
Do not torque the bolt at this time.

Firmly tighten the right differential bearing adjuster nut using the J 24429 in order to force the differential case assembly into solid contact with the left differential adjuster nut.
Rotate the pinion several times in order to seat the bearings.
Loosen the right differential bearing adjuster nut using the J 24429 until the nut is free from the differential side bearing.
Tighten the right differential bearing adjuster nut using the J 24429 until the differential bearing adjuster nut contacts the bearing.
Once the right differential bearing adjuster contacts the differential bearing, tighten the differential bearing adjuster nut using the J 24429 the following additional amounts:
Tighten

• For used bearings, tighten the differential bearing adjuster nut an additional 2 slots.

• For new bearings, tighten the differential bearing adjuster nut an additional 3 slots.

Install the right differential bearing adjuster nut lock.
Install the right differential bearing adjuster nut lock bolt.
Do not torque the bolt at this time.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

Tighten the bearing cap bolts.
Tighten

• For the 10.5 in axle, tighten the bearing cap bolts to 185 N·m (136 lb ft).

• For the 11.5 in axle, tighten the bearing cap bolts to 207 N·m (153 lb ft).

Tighten differential bearing adjuster nut lock bolts.
Tighten
Tighten the differential bearing adjuster nut lock bolts to 27 N·m (20 lb ft).

Measure the ring gear to pinion backlash and adjust, if necessary. Refer to Backlash Adjustment .

Indianajones

Posted 2/6/2010 21:11 (#1061811 - in reply to #1061736)
Subject: RE: WANTED:Gear lash specs for 11.5" AAM Duramax rear axle.

•Proceedure for adjusting backlash per GM manual. I have done a lot of differentials and it sounds worse than it is.
Good Luck
INDY

J 8001 Dial Indicator Set

• J 24429 Side Bearing Backlash Spanner

• J 25025 Guide Pins

Important:

• Ensure that the side bearing surfaces in the axle housing are clean and free of burrs. If the original bearings are to be reused, the original bearing cups must also be used.

• The differential side bearings must be initially preloaded in order to determine the backlash of the gear set. After the backlash is set, the final bearing preload is set.

Measure the rotating torque of the drive pinion and differential assembly using an inch-pound torque wrench.
Specification
The rotating torque of the drive pinion and differential assembly should be 3.4-6.2 N·m (30-55 lb in) for new bearings or 2.8-5.1 N·m ( 25-45 lb in) for used bearings.

If the rotating torque is too low, tighten the differential bearing adjuster nuts in 1 slot increments until the specified rotating torque is obtained.
If the rotating torque is too high, loosen the differential bearing adjuster nuts in 1 slot increments until the specified rotating torque is obtained.
If the specification for the rotating torque of the drive pinion and differential assembly cannot be obtained by adjusting the differential bearing adjuster nut, remove the differential assembly, measure the rotating torque of the drive pinion and adjust as necessary. Refer to Differential Replacement and Drive Pinion Bearings Replacement .

Install the J 25025-1 and the J 8001 to the axle housing as shown.
Place the indicator stem of the J 8001-3 at the heel end of a gear tooth.
Set the J 8001-3 so that the stem is aligned with the gear rotation and perpendicular to the tooth angle.
Preload the dial of the J 8001-3 .
Align the needle and the dial face of the J 8001-3 to ZERO.

While holding the drive pinion stationary, move the ring gear back and forth.
Measure and record the backlash.

Repeat the measuring procedure at eight points around the ring gear.
Specification
The difference between the backlash at all of the measuring points should not vary by more than 0.05 mm (0.002 in).

If the difference between the backlash at all of the measuring points varies by more than 0.05 mm (0.002 in), inspect for the following conditions:
• Burrs

• A distorted case flange

• Uneven bolting

If the difference between all the measuring points is within specifications, the backlash at the minimum lash point measured should be:
Specification
The backlash between the ring gear and the drive pinion should be between 0.08-0.25 mm (0.003-0.010 in) with a preferred backlash of 0.13-0.18 mm (0.005-0.007 in).

If the backlash is not within specifications, adjust the backlash by performing the following steps:
13.1. Remove the differential bearing adjuster nut retainers bolts.

13.2. Remove the differential bearing adjuster nut retainers.

13.3. Remove the bearing cap bolts.

13.4. Remove the bearing caps. Mark the bearing caps left and right.

13.5. If the backlash is too small, increase the backlash by turning the left differential bearing adjuster in one slot and the right differential bearing adjuster out one slot using the J 24429 until the correct backlash is obtained.

13.6. If the backlash is too large, decrease the backlash by turning the right differential bearing adjuster in one slot and the left differential bearing adjuster out one slot using the J 24429 until the correct backlash is obtained.

Install the bearing caps.
Notice: Refer to Fastener Notice in the Preface section.

Install the bearing cap bolts.
Tighten

• Tighten the bearing cap bolts to 185 N·m (136 lb ft) (10.5 inch axle).

• Tighten the bearing cap bolts to 207 N·m (153 lb ft) (11.5 inch axle).

Recheck the backlash following the steps above to verify that the backlash is within specifications.
Install the differential bearing adjuster nut retainers.
Install the differential bearing adjuster nut retainer bolts.
Tighten
Tighten the differential bearing adjuster nut retainer nut bolts to 27 N·m (20 lb ft).

Measure the drive pinion and differential case side bearing preload and adjust, if necessary following the steps above.
Once the backlash and bearing preload is correct, perform a gear tooth contact pattern check in order to ensure proper alignment between the ring and pinion gears. Refer to Gear Tooth Contact Pattern Inspection .

seedcleaner

Posted 2/6/2010 21:25 (#1061841 - in reply to #1061736)
Subject: Re: WANTED:Gear lash specs for 11.5" AAM Duramax rear axle.

Mid-Missouri

I should clarify: The original gears are all shot. The carrier is broke in half, even bending the 1"+ shaft that holds the spider gears. Ring and pinion are not worth reusing. We got a good used ring, pinion, and limited slip carrier from another rear axle. Can I reuse the crush washer on the pinion shaft?

hillfarmer

Posted 2/7/2010 07:05 (#1062245 - in reply to #1061841)
Subject: Re: WANTED:Gear lash specs for 11.5" AAM Duramax rear axle.

no
for all the work

just put a new crush in

Indianajones

Posted 2/7/2010 07:19 (#1062251 - in reply to #1061841)
Subject: Re: WANTED:Gear lash specs for 11.5" AAM Duramax rear axle.

No, you ALWAYS use a new crush sleeve everytime you torque the pinion nut. (Well sorta)
I would also use the pinion shim that is on the original pinion under the rear bearing. It is more likely to set the pinion depth correct in your housing.
Better eat your wheaties when you get ready to set the pinion. I was surprised on my first one how hard they were to tighten.
INDY

Edited by Indianajones 2/7/2010 07:24

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