DIY Rear end gear install?

[Andy@SquashPerformance]

I know a few people have bought Aussie housings already loaded with the gears they want and that's an easy swap. It is also the most costly. I would like to install 3.45 or 3.70 gears in my existing housing. Does anyone have a procedure for it? I mean I have no specs, does it have a crush sleeve? Preload? Is the carrier different?

And correct me if I'm wrong, but the going price for a compete diff (less shipping) is $1500AUD, gears alone seem to be $800AUD, that comes from ebay.com.au. Is there a better place/way to get them?

Andy

[Devilish34]

Gears and parts will cost you almost as much $$$

[Andy@SquashPerformance]

Gears and parts will cost you almost as much $$$

Gears cost 1/2 as much, so what else is needed?

Andy

[Greg@PacePerformance]

Just a copy and paste with no pictures
Rear Axle Disassemble
Tools Required
• E-308 Seal Remover.

• 205-116 Carrier Bearing Puller Including Plug.

• DT-48805 Pinion Tail Bearing Cup Remover.

• DT-48725 Pinion Head Bearing Cup Removal Kit.

• DT-48726 Pinion Head Bearing Cup Remover.

Caution: Refer to Safety Glasses Caution in the Preface section.

Caution: Refer to Vehicle Lifting Caution in the Preface section.

Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
Drain the differential fluid. Refer to the draining procedure in Differential Oil Replacement .
Remove the differential from the vehicle. Refer to Differential Replacement .



Important: The holding device must be able to rotate.

Mount the differential assembly (1) to a suitable holding device (2).



Remove the differential housing cover to differential housing retaining bolts (1).



Important: Use a soft faced hammer to aid in separating the differential housing cover from the rear differential housing (1).

Remove the rear differential housing cover (1).



Remove the left and right axle shaft seals (1) from the differential (2).
Discard the axle shaft seals.





Remove the circlip (1) from the differential (2).



Important: Mark the left shim (3) and right shim (1) before removing for correct refitting.

Remove the left shim (3) and right shim (1) from the differential (2).



Important: Remove the differential (1) using a suitable tool or with the aid of an assistant.

Remove the differential (1) from the differential housing (2).
Important: Place a suitable container to catch remaining differential fluid.

Allow remaining differential fluid to drain.



Position the differential (1) onto a suitable holding device (2).



Important: Use a suitable puller (2) and 205-116 (3) to remove the right bearing (1).

Remove the right bearing (1) from the differential (4).
Discard the right bearing.

Turn the differential (4) over on the holding tool with the aid of an assistant.
Important: Use a suitable puller (2) and 205-116 (3) to remove the left bearing.

Remove the left bearing from the differential (4).
Discard the left bearing.





Remove the ring gear to differential retaining bolts (1).
Discard ring gear to differential retaining bolts.

Remove the differential from the holding device.
Important: Make sure there is soft material between the differential and the bench top.

Place the differential onto a bench top.



Important: Use suitable tools or a suitable press to remove the ring gear (1) from the differential (2). Take care not to damage the ring gear retaining bolt hole threads.

Remove the ring gear (1) from the differential (2).



Install the universal holding tool (2) to the pinion flange (1).
Important: Hold the pinion flange with universal holding tool (2).

Remove the pinion flange to prevailing torque pinion flange retaining nut (1).
Discard the prevailing torque pinion flange retaining nut.

Remove the universal holding tool (2) from the pinion flange (1).



Important: The pinion flange (1) can be removed with a suitable puller or with a press (2). Support the pinion or place a soft cloth under the pinion to prevent damage when removing.

Remove the pinion flange (1) from the differential housing (3).
Remove the pinion from the differential housing (3).



Important: Do not damage any sealing surfaces when removing the axle shaft oil seal (1). Cuts or abrasions will damage the assembly and result in lubricant leakage from this area.

Using a E-308 (2), remove the pinion flange oil seal (1) from the differential housing (3).
Discard the pinion flange oil seal.

Remove the tail bearing from the differential housing (3).
Discard the tail bearing.





Important: Use a suitable press and DT-48805 to remove the tail bearing cup.

Position the DT-48805 (1) to the differential housing (2) and press out the tail bearing cup.
Remove the tail bearing cup from the differential housing (2).
Discard the tail bearing cup.





Important: Use DT-48725 (1, 2) and DT-48726 (3) to remove the head bearing cup.

Position DT-48726 (3) to the differential housing (4) and pull out the head bearing cup.
Remove the head bearing cup from the differential housing (4).
Discard the head bearing cup.





Important: Do not reuse the collapsible spacer (1).

Remove the collapsible spacer (1) from the pinion gear (2).
Discard the collapsible spacer.





Important: Use a suitable press and press plates to remove the pinion head bearing (1).

Remove the pinion head bearing (1) from the pinion gear (2).
Discard the pinion head bearing.

Remove the pinion shim from the pinion gear (2).
Clean loctite from the pinion gear thread.

[Devilish34]

Greg whats the approx cost on all of those parts and tool?

I remember looking into this and with parts and labor it was real close

[Andy@SquashPerformance]

Thanks Greg! So it looks like I need ring gear bolts (easy), pinion nut (I'm guessing it's self-locking), and a crush sleeve in addition to the ring and pinion. Might be smart to get seals as well.

Greg, does Pace sell any of this stuff? R&P included? Do you know if the Camaro gearset is the same?

Andy

[Greg@PacePerformance]

After looking at the install instructions I would rather pay for a drop in unit.
Let me price the parts and see what I come up with.

Pinion nut - 92194936 - $12.78
Crush spacer - 92191328 - $14.70
Ring gear bolt - 92191339 - $18.51 each x 10 = 185.10

[Greg@PacePerformance]

Another quick and dirty post.

Rear Axle Assemble
Tools Required
• DT-48721 Right Axle Seal Installer

• DT-48722 Left Axle Seal Installer

• DT-48723 Pinion Head Bearing Cup Installer

• DT-48725 Pinion Tail Bearing Cup Installer

• DT-48727 Pinion Seal Installer

• DT-48728 Differential Bearing Installer

• DT-48806 Pinion Bearing Measurement Spacer

• DT-48807 Pinion Head Bearing Installer





Important: Use DT-48806 otherwise bearing height cannot be measured correctly.

Measure the thickness of DT-48806 (1) using a depth gauge (2) (e.g - 3.67 mm).
Record the thickness of the DT-48806 (1).



Important: Rotate the pinion head bearing (2) to settle for correct measurement.

Measure the thickness of the DT-48806 (1) and the pinion head bearing (2) with the depth gauge (3) (e.g - 33.925 mm).
Record the thickness of the DT-48806 (1) and pinion head bearing (2).
Subtract the thickness of DT-48806 (1) 3.67 mm from the total thickness of the pinion bearing measurement spacer (1) and the pinion bearing (2) 33.925 mm to determine the pinion head bearing (2) thickness.
Example - The pinion head bearing (2) thickness is 33.925 mm - 3.67 mm = 30.255 mm





Record the serial number (1), set number (3) and size (4) which are stamped into the pinion gear (2).
Example:

• Serial Number A0200008 (1)

• Pinion Size 106.475 mm (4)

• Set Number 260125 (3)





Check that the serial number (1) and set number (3) which are stamped into the ring gear (2) match those of the pinion set in step 7.
Example:

• Serial Number A0200008 (1)

• Set Number 260125 (3)





Important: The identification number (1, 3, and 4) is stamped into the differential housing (2).

Identify the differential housing.
• Manufacturing date (1).

• Item number (4).

• Size equals 138 plus the number on the housing. Example - 138.180 mm (3).

Record the differential housing size. Example - 138.180 mm
Determine the thickness of the pinion shim.
• Add the pinion plus the bearing Example - 106.475 mm + 30.255 mm = 136.730 mm.

• Subtract the pinion plus the head bearing from the housing size, also subtract the correction factor. The correction factor is.05 mm. Example 138.180 - 136.730 - 0.05 = 1.40 mm thickness shim required.

Position the correct shim onto the pinion head.



Important: Use DT-48807 (3) to aid in pinion bearing (2) installation.

Important: Position the pinion gear (1) onto an aluminium plate in suitable press (4) before pressing the pinion head bearing (2) to prevent damage to the pinion (1).

Position the NEW pinion head bearing (2) onto the pinion gear (1).
Important: Use a suitable press (4) to install the NEW differential pinion head bearing (2).

Press the NEW pinion head bearing (2) onto the pinion gear using DT-48807 (3).
Clean the ring gear and the contact area of the differential.
Caution: Refer to Safety Glasses Caution in the Preface section.





Important: To make fitting easier cool the bearing cups (2).

Position the NEW head bearing cup (1) into the differential housing (2).



Press the NEW head bearing cup in with DT-48723 (1) and rotate until it fits tightly in the front differential housing (2).
Use a feeler gauge to make sure the NEW head bearing cup is seated correctly.



Important: To make fitting easier cool the bearing cup (2).

Position the NEW tail bearing cup (2) to the differential housing (3).
Press the NEW tail bearing cup in with DT-48725 (1) and rotate until it fits tightly in the front differential housing (2).
Use a feeler gauge to make sure the NEW tail bearing cup is seated correctly.



Important: Warm the ring gear (1) evenly using a hotplate until it fits over the differential (2).

Position the ring gear (1) to the differential (2).
Important: Do not fully tighten the NEW ring gear to differential retaining bolts at this stage.

Important: The ring gear has to cool before the ring gear to differential retaining bolts can be tightened.

Install two NEW ring gear to differential retaining bolts.
Notice: Refer to Fastener Notice in the Preface section.





Important: The ring gear has to cool before the ring gear to differential retaining bolts (1) can be tightened.

Important: Tighten the ring gear to differential retaining bolts (1) working diagonally.

Install the remaining NEW ring gear to differential retaining bolts (1).
Tighten
Tighten the bolts to 125 N·m (96 lb ft).





Important: Use a suitable press (4) to install the right differential bearing (1).

Press the right differential bearing (1) to the differential (3) with DT-48728 (2).
Important: Use a suitable press (4) to install the left differential bearing.

Rotate and press the left bearing to the differential with DT-48728 (2).



Important: Position the differential (1) to the differential housing (2) using a suitable tool or with the aid of an assistant.

Position the differential (1) to the differential housing (2).



Position the left shim (3) and right shim (1) to the original position in the differential housing (2).



Important: Do not fully tighten the bearing bolts (1) is stage. The differential has to be able to move freely within the differential housing to allow fitment of the circlip.

Position the differential housing cover to the differential housing and retain with the 4 bearing bolts (1).
Turn the differential assembly left through 90° for the differential to slide down in the housing.



Important: Align the opening of the circlip (1) with the opening on the differential housing.

Install the circlip (1) to the differential (3) with circlip pliers (2).
Make sure the circlip (1) is fitted correctly.



Important: Tighten the differential housing cover to differential housing retaining bolts (1) working diagonally.

Install the remaining differential housing cover to differential housing retaining bolts (1).
Tighten
Tighten the housing bolts to 53 N·m (39 lb ft).

Tighten
Tighten the bearing bolts to 153 N·m (112 lb ft).





Position the backlash tool (1, 4) to the differential assembly (3).
Secure the backlash tool (1) to the differential assembly (3) by adjusting the spreading nut (4).
Mount the turning torque gauge (2) to the backlash tool (1).
Rotate the turning torque gauge (2) clockwise and record reading.
Important: This figure is for NEW bearings only.

Turning torque should be between 2.0 to 3.3 N·m (27 lb in).
If the measured turning torque is outside the tolerance:
• Remove the rear differential housing.

• If turning torque is too high or too low, fit a thinner or thicker shim respectively.

• Repeat from steps 5-11 from the disassembly procedure then from step 27 onwards in the assembly procedure.

• Check turning torque. Repeat until the turning torque is correct.

Remove differential assembly. Repeat steps 5 through 11 from the disassembly procedure.



Position the pinion (4) on DT-48728 (3) in a suitable press (2).
Important: The differential housing (1) must not rest on the press (2). Use a suitable supporting tool (3) to elevate pinion (4).

Position the differential housing (1) over the pinion gear (4).



Position a NEW collapsible spacer (1) to the differential (2).



Position the pinion tail bearing (1) to the differential housing (2).



Important: Take care to only press the tail bearing until it rests on the collapsible spacer so that it is not damaged.

Use a suitable press (2) and DT-48723 (1) to press the tail bearing until it rests against the collapsible spacer.
Remove the supporting tool so that the differential housing rests on the table.



Lubricate the NEW pinion flange seal (1) with correct grease. Refer to Adhesives, Fluids, Lubricants, and Sealers.
Important: Use DT-48727 to install the seals to correct depth.

Install the pinion flange seal (1) to the differential housing (4) with DT-48727 (2) in a suitable press (3).
Mount the differential housing (4) on a suitable holding device.



Position the pinion flange (2) to the differential (3).
Lubricate the contact surface of the prevailing torque pinion flange retaining nut (1) with correct grease. Refer to Adhesives, Fluids, Lubricants, and Sealers.
Apply correct Loctite to the thread of the NEW prevailing torque pinion flange retaining nut (1).
Important: Do not fully tighten the NEW prevailing torque pinion flange retaining nut at this stage. Overtightening will require disassembly and fitment of a new collapsible spacer and possibly bearings.

Install the NEW prevailing torque pinion flange retaining nut (1) to the differential (3).



Install the universal pulley holder (3) to the pinion flange (1).
Tighten the prevailing torque pinion flange retaining nut (2) carefully until it has no play.
Remove the universal pulley holder from the pinion flange (1).
Turn the differential assembly through 90°.



Position the turning torque gauge (1) to the prevailing torque pinion flange nut.
Turn the turning torque gauge (1) in a clockwise direction and record reading.
Important: This torque figure is for NEW bearings only.

Turning torque should be between 2.2 and 2.7 N·m (20-25 lb in).
If the turning torque is below specified tolerance, tighten the prevailing torque pinion flange retaining nut in small steps and check turning torque until specified turning torque is reached.
If the turning torque is above specified tolerance disassemble, fit new collapsible spacer and repeat until correct specification is achieved.



Position a dial gauge (2) to measure the concentric running on centering while turning the pinion (1).
If the measured value is above.1 mm remove the pinion flange and re-install at a different angle. Repeat steps 52-66 in the assembly procedure. Make sure the turning torque is 0.1-0.2 N·m higher than recorded in step 63 but not higher than 2.7 N·m.



Position the backlash tool (2) to the differential assembly.
Important: The location of the dial gauge on the backlash tool (2) arm corresponds to the edge of the ring gear (210 mm)

Position the dial gauge (1) to the backlash tool (2).
Use a suitable tool to move the backlash tool (2) within the backlash and record the reading.
Backlash must be between.07 and.18 mm.
If the backlash is not between the specified tolerance, it must be adjusted with differential shims otherwise turning torque set during steps 38-43 will be changed.
If a.05 mm thinner shim is used on the right a.05 mm thicker shim has to be added to the left.
Remove the rear differential housing. Refer to steps 5 and 6 in the disassembly procedure.



Clean the mating faces of the differential housings (2).
Important: Apply a 1 mm liquid seal bead (1) to the differential housing. Use the graphic as a template.

Apply a 1 mm liquid seal bead (Loctite 5910) (1) to the mating face of the differential housing. Refer to Adhesives, Fluids, Lubricants, and Sealers.
Install the differential housing cover to the differential housing. Refer to steps 26 through 33.



Important: The left and right rear axle shaft seals are different sizes so there are 2 different size installers. Make sure that the correct seal installer is used for the correct seal.

Important: Fill the space between the dust lip and the seal lip with the correct grease.

Install the left and right rear axle shaft seals (1) using DT-48722 and DT-48721 (2).



Install two rear axle flanges or two sealing plugs (1) to seal the differential (3).
Important: Set the air pressure regulator to.4 bar before connecting.

Remove the oil drain plug and install the air pressure regulator (2).
Connect the air supply to the regulator (2) and pressurise the differential (3) to.4 bar.
Disconnect the air supply from the regulator (2).
The pressure should not decrease from.4 bar within 3 minutes. If the pressure decreases, locate and repair leakage.
Install the differential (3) to the vehicle. Refer to Differential Replacement.
Fill the differential fluid. Refer to the filling procedure in Differential Oil Replacement.

[edmanet]

Greg whats the approx cost on all of those parts and tool?

I remember looking into this and with parts and labor it was real close


I agree. Its easier to just buy the entire diff. And its even easier if you pay
someone to install it. Some things just aren't worth the hassle.

[Andy@SquashPerformance]

As "daunting" as these instructions look it seems like a pretty standard swap other than a few non-expensive steps (heating the ring gear for example). Those ring gear bolts are way too expensive from GM! I'll have to look for alternatives. Hmmmm.... Thanks again for all of the info.

Andy

[wagon540]

My tranny guy did my 3.90s, said it was a lot of work but it was his first G8 and he made some fixtures as he did mine so future installs would be easier. I can't tell you a price since the gears are prototypes and we traded labor as we're restoring his 66 Nova.
Don't know if i'm allowed to post his phone # as he's not a vendor but i could call and ask him or PM me for phone#.
I do know he's done Robin Lawrences Camaro (Hot rod magazine test car) since then also.

[Mlozano]

Talk about some serious DIY'ers

[Andy@SquashPerformance]

My tranny guy did my 3.90s, said it was a lot of work but it was his first G8 and he made some fixtures as he did mine so future installs would be easier. I can't tell you a price since the gears are prototypes and we traded labor as we're restoring his 66 Nova.
Don't know if i'm allowed to post his phone # as he's not a vendor but i could call and ask him or PM me for phone#.
I do know he's done Robin Lawrences Camaro (Hot rod magazine test car) since then also.

PM on the way...

Andy

[GeorgeInNePa]

My tranny guy did my 3.90s, said it was a lot of work but it was his first G8 and he made some fixtures as he did mine so future installs would be easier. I can't tell you a price since the gears are prototypes and we traded labor as we're restoring his 66 Nova.
Don't know if i'm allowed to post his phone # as he's not a vendor but i could call and ask him or PM me for phone#.
I do know he's done Robin Lawrences Camaro (Hot rod magazine test car) since then also.

Did he make the gears or buy them elsewhere?

[Andy@SquashPerformance]

I haven't heard of a 3.90 so maybe he made some others work in the diff housing. I've read some things about some kinda Ford gear fitting?

Andy

[SpeedRacerX]

I believe it was a Camaro prototype 3.90 gear that didn't fit but it did fit in the G8. He has a good set of friends.... :woohoo:

[Tjay74]

$18.50 each for the ring gear bolts...

I mean come one, the parts for the g8 are almost as bad as the new shelby kr500 mustang and its $21,000 hood.

[Chewy]

My tranny guy did my 3.90s, said it was a lot of work but it was his first G8 and he made some fixtures as he did mine so future installs would be easier. I can't tell you a price since the gears are prototypes and we traded labor as we're restoring his 66 Nova.
Don't know if i'm allowed to post his phone # as he's not a vendor but i could call and ask him or PM me for phone#.
I do know he's done Robin Lawrences Camaro (Hot rod magazine test car) since then also.

Post away Kim! No issues here with that. We don't have those gay rules.

Chris

[wagon540]

My gears are a prototype set from Motive gear, Speedracerx is correct, they were sent to him for the Hot Rod test Camaro thinking at the time were the same as the G8. Obviously they didn't fit but they still needed to try them in something so he called me and we put them in my car.He said fit just like they should which i took to mean not too many shims or problems.
His name is Bob Alexander at Performance Transmissions in Clinton Illinois. 217 935 5352.
Been going to him for years, never had a single problem. If the tranny goes out in the G8 i won't even mess with warranty it's going straight to him to get beefed up.
He did say it's quite a bit of work doing the gears and he made some fixtures along the way to make future installs easier, i have no clue what those are or what is needed for a DIY swap. I do know i wouldn't trade these gears for anything else.
BTW he also mentioned a 4.10 set too.

Kim.

[Mlozano]

What in world does is it doing for your daily driving? 3.90 is kinda nuts on DD don't u think?

[wagon540]

What in world does is it doing for your daily driving? 3.90 is kinda nuts on DD don't u think?

Well it's not my daily driver but i drive it as much as i can. I've done several road trips in fact i'm driving 2 1/2 hrs tomorrow to the Rt 66 cruise in springfield, it's basically like holding it in 5th with stock gears, around 2400 at 75, but in town is a whole lot more fun especially with the 3600 Yank converter.

[G8 GT V8]

What in world does is it doing for your daily driving? 3.90 is kinda nuts on DD don't u think?

With our overdrive tranny, a 3.90 would be like having a 2.60 rear gear in a car with a 1:1 final gear ratio (non-overdrive tranny) which would be very DD friendly.

I bet 1st gear goes by real fast with our 4.03 1st gear ratio...

[edmanet]

I know 1st goes by fast with a 327 diff.

[GeorgeInNePa]

My gears are a prototype set from Motive gear, Speedracerx is correct, they were sent to him for the Hot Rod test Camaro thinking at the time were the same as the G8. Obviously they didn't fit but they still needed to try them in something so he called me and we put them in my car.He said fit just like they should which i took to mean not too many shims or problems.
His name is Bob Alexander at Performance Transmissions in Clinton Illinois. 217 935 5352.
Been going to him for years, never had a single problem. If the tranny goes out in the G8 i won't even mess with warranty it's going straight to him to get beefed up.
He did say it's quite a bit of work doing the gears and he made some fixtures along the way to make future installs easier, i have no clue what those are or what is needed for a DIY swap. I do know i wouldn't trade these gears for anything else.
BTW he also mentioned a 4.10 set too.

Kim.

Does he have access to gears besides 3.90 and 4.10s?

[jeff]

Where can I find the 2 axle seal installing tools?