31 Spline Build

musclemerc

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FFRP 4:10s
04 Cobra 31 spline CF diff
Yukon 31 spline forged axles
Motive master bearing kit
Lube Locker diff gasket
Aluminum stud girdle
Bearings/seals/wheel studs
Mobil1 synthetic oil




Yukon axles with the ABS rings



03~04 Cobra 31 spline CF differential


Lube Locker gasket




I also fabricated some custom axle tube brackets to prevent deflection from the center housing. :biggthump
 

Da Dark Jedi

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You didn't mention price for parts. What's the cost??? Look into Torcousa .com for a better gear oil (SGO Gear Oil).
 

musclemerc

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As usual I got EVERYTHING on the cheap

New Cobra diff $190.00 shipped
New Yukon axles w/ABS rings $155.00 ea
New FRPP 4:10s $100.00 shipped
New Motive Master bearing kit $60.00 shipped
New Aluminum stud girdle $79.00 shipped
Lube Locker gasket $27.00 shipped

Sticking with the Mobile1 oil, I already have it on hand.
 

Zack

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Whats the story with Yukon?

Are those 24k ABS rings...or fools gold?

:D
 

musclemerc

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^^^^ I looked at all options for 31 spline axles (which at the time only 2 Moser and OEM) I didnt want another set of OEMs (Im on my second set) and didnt like the fact that Moser did'nt include ABS rings for their axles.

Yukon had exactly what I was looking for.
1) Something stronger than OEM
2) ABS rings
3) Alloy mix in the metal

Besides, no one has installed a set of these axles on their MM so its another first by Musclemerc.....LOL!!!!
 

Zack

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Good price on the axles compared to oem.
Id bet the same company makes them for ford and Yukon.
 

musclemerc

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Good price on the axles compared to oem.
Id bet the same company makes them for ford and Yukon.
They retail for ALOT more, so yes I got a deal.

IDK if they are made by the same company. Whats the warranty for OEM?

Yukon provides a 5 year warranty on axles.

Here is a pic of what my front axle tube bracing will compare to:
These are from UPR, mine will not have the rear heim joint or the brackets. They will weld straight to the axle tube



Here is what the rear bracing will compare to:
http://www.lpwracing.com/Axle_Tube_Brace_Kit/axle_housing_brace.html

The bracing may not be needed but I figure why not, It gives me a reason to break out the welder to fabricate something
 

Zack

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Those brackets will do nothing....but have fun welding!
If anything do 3 stitch welds around the tubes and call it a day.
 

musclemerc

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I want to stay away fron welding the tubes to the housing. You do know the housing is cast steel? It takes a totally diffrent welding process to do it right. Although I do have the right equipment to weld cast (both a TIG and ARC welder)

I think the brackets will look pretty cool and it will give me something diffrent from the rest of the MMs out there.
 

Burt Ragio

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At what power level would you say it is a good idea to upgrade the oem axles ?
 

4DoorBlackTop

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I will have to do this before my next track time. Let us know how it holds together.
 

musclemerc

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Where do I get these axles for what you paid?????
:)

PM sent :D

I dont know if this site will allow me posting the info on these axles so if anyone is interested shoot me a PM.
 

musclemerc

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Here is a how to on swapping axles:

Jack the car, block the front wheels, and remove the rear tires.

Use a 10mm ratchet wrench to remove the brake caliper


Tie the caliper to the shock mount with a piece of wire to keep it out of the way. DO NOT LEAVE IT HANGING BY THE HOSE



Use a brake spoon to loosen the emergency brake and remove the rotor. After you get the rotor off you need to remove the clips that hold the e brake pads in place. Press in on the holder with a flat screwdriver and slide the retainer out


Remove the brake assembly and set them aside. Now you need to rermove the ABS sensor. Take a 10mm socket and remove the bolt from the back side of the dust shield



Set the ABS sensor aside on the axle and remove the diff cover with a 1/2" socket.



Place a pan under the diff and crack the cover from the bottom to allow it to drain




Rotate the carrier until the cross pin retainer bolt is accessable, remove the bolt with an 8mm socket



After you remove the cross pin retainer remove the cross pin with a blunt chisel and a few light taps with a hammer



Use the retainer bolt to pull the cross pin out of the carrier



You will need an extra pair of hands to push in on the axles so you can remove the C clips. While they press in on the axle use a flat screwdriver to push the C clip out



Here is a pic of the C clip



Loosen the carrier bolts and remove them along with the hardware, and shims. Be sure to keep them EXACTLY in the order they were installed. After you set the hardware aside you can pull the carrier



Remove the axle seals with a small chisel and a few soft taps with a hammer, then install the bearing puller and tighten it down.



After a few slides of the hammer the bearing will come out



Time to get dirty, you will need ALOT of shop rags and several cans of brake cleaner. Clean through the axle tubes into the carrier housing. When things are starting to come clean roll up a towel and use one of the old axles to push it through the axle tubes to ensure all the old grease is removed





After you get the tubes done, clean the carrier housing, and dont forget to clean the axle vent tube. After everything is squeeky clean time to start putting everything back in place

I use a 1-1/4" galvanized pipe cap to drive the bearings in. It fits perfect for both the bearing and the seal. Tap lightly until they are seated





At this point you can install the new axles, reinstall the carrier and fill with new fluids.

When you reinstall the carrier follow the TQ sequence on the carrier caps, cross pin retainer bolt, and the diff cover
 

musclemerc

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If your installing a 31 spline setup and new ring/pinion here you go:

If your not installing a new ring/pinion then remove the ring from the old carrier with an impact wrench then reinstall on your new 31 spline carrier. Remember to TQ to spec and use red thread locker on all ring bolts



To install your old ring on a new 31 spline diff DO NOT USE A HAMMER. Take 5 of the ring bolts and use them to walk the ring onto the carrier tightening as if it were a wheel on the car (cross pattern). Be sure to wipe down both the carrier ring flange and the back side of the ring gear with break fluid and a shop towel. Nothing can be between the ring gear and the carrier of your runout specs will be way off. (runout is .004 max total). You may need a set of carrier shims due to the fact that the 31 spline carrier may be a little diffrent

If your installing new ring/pinion then remove the drive shaft with a 12 point 12mm boxed in wrench. Try to find a piece of pipe that will fit over the wrench for extra leverage. Tie the drive shaft up on the chassis of the car to keep it out of the way.

Remove the pinion nut with an impact wrench. Notice I used 2 long bolts to keep the pinion flange from spinning while removing with the impact wrench



Now is a good time to remove the pinion flange. A few light taps round with a dead blow worked great for me


TBC......Heading out to the garage for more wrenching
 

guspech750

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There's the Travis I remember!! Nice write up Travis.


---
- Sent from my iPhone
Eaton Swap + 4.10's = Wreeeeeeeeeedom!!
 

blck10th

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Here is a pic of the brace I have. It is 1 1/4" chrome molly bent and welded from end to center to end. I will try to find some better pics.



Found a couple more:


 

musclemerc

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I decided against finishing up on the write up the ring and pinion install because the installation is too time consuming, requires a good bit of wrenching abilities, and most of all too many things can go wrong.

Here is the some info I compiled on doing the swap, it was very helpful in getting my project done maybe this info can help others.

http://www.corral.net/tech/drivetrain/gears.html

http://www.explorerforum.com/forums/showthread.php?t=144780

http://www.youtube.com/watch?v=8APYO2sZyJU

There are a few tips I can add to the info above.
1) I cant stress enough you have to keep the bearing caps in the exact order they came out on the teardown.

2) When you start, use the same width pinion shim that came out of the stock setup. More than likely going from 3:55 to 4:10 will require the same pinion depth.

3) Do not install the new crush sleeve or pinion nut on the test fit for pinion depth, instead take your old crush sleve and place it between the oil slinger and the pinion nut. Tighten to 20lbs, thats all you need to preload the pinion bearing

4) Leave the carrier caps inplace while shimming the carrier. It will make it ALOT easier and will save you fighting with the carrier falling out.

5) Get a hand pump to fill the rear end with grease

Here are a few must have tools to do the job.

A set of feeler guages to measure the shims, brass mallett, plastic mallett, dial caliper with magnetic base, misc scribes, IN LB wrench, crow bar, bearing race installer, and a small fish scale

A small fish scale??? Yes, if you dont have access to an INLB wrench then get a small fish scale from Walmart and put string around the pinion flange and tie the scale to it and pull till you get 1.66 lbs on the scale. Sounds crazy but it works!

here is a shot of the axles before installing them:



here is a shot of the splines:



My rear end is super quiet and I saved ALOT of money by researching and doing the work myself.

Good Luck! :biggthump
 
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Zack

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Good stuff Travis.

This is something I have never done and never plan to.

I have a 'guy' who can swap gears/axles in a bit over 2 hours with fluids for $250. I cant beat that price with a stick.
 

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