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Author Topic: Differential Overhaul Procedure - Chrysler 8.25" used as test case  (Read 12861 times)
Joel5.0
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« on: November 25, 2012, 11:45:16 am »

What follows is a little overhaul procedure I did months ago of a Chrysler 8.25" differential to show the steps common in any differential overhaul.

Patient:

1998 Jeep Cherokee 4.0L I6 with a 8.25" Chrysler open style differential




Symptom/Complaint:

This unit had a little incident where the pinion nut became loose while driving in the highway, loosing it and causing the driveshaft to drop. The unit was towed to the shop and a new pinion nut was installed. The internals were not checked and a test drive showed the differential did suffer from a bat mesh pattern due to the whine sound from it.

The Cherokee was used for a week by the customer and brought back for a full differential overhaul after the real damage was assessed. This is what I found:





As you can see, the pinion did a number on the carrier unit even though no major damage to the pinion or ring themselves was noted. I then proceeded to check the existing mesh pattern to see where it was for reference and here is the result:



Definitely not the optimum or the typical after a little over 190k miles.

Unit Removal:

So..... removing the unit internals begin:



As you can see, this unit is different from the 8.8 Ford unit because the carrier uses adjustable rings on each side instead of shims to adjust backlash.

« Last Edit: December 07, 2012, 07:07:39 am by Joel5.0 » Logged

ACRONYMS:
LUK  LMK  JIC  BTSTDTRT  YCYDYP  NFI-YTM  SPOBI, and the classic... DILLIGAS

'86 Mustang GT, X-303 cam, Holley DP 700, RG Tran., 289 Heads   Ford Smilie 2


Quote from: Joel5.0
The right to be stupid is inalienable for sure however, there is no such thing as a right to impose stupidity onto others
Great Thoughts will Overwhelm a Feeble Mind
There is never money to do it right, but there's always money to do it over.
Knowledge based on external evidence is unreliable.
He, who doesn't ask, does not deserve an answer.
A mind is like a parachute it only works when it is open.  (oldmanjoe)
If you can't explain it simply, you don't understand it well enough. (Albert Einstein)
Tuning on a Dyno for the track, is like swim practice in a bathtub.
I can explain it for you, but I can't understand it for you. (90lxcoupe)
The proof of understanding is the ability to explain it. (H. Torruella)
Ignorance is bliss, but stupidity is orgasmic.
Fraud and falsehood only dread examination. Truth invites it. (Samuel Johnson)
The chaotic resistance of the opponents leads to the conclusion that they are not prepared to meet the challenge. The problem is already much more psychological then technological. [Bojidar Djordjev]
Individuals are rational and humane... Crowds are reactionary and barbaric. (Jason)
The person who says it cannot be done should not interrupt the person doing it. –Chinese Proverb
Nothing sways the stupid more than arguments they can't understand - Cardinal de Retz
Joel5.0
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« Reply #1 on: March 29, 2013, 07:10:16 pm »

Carrier Damage Assesment:

The following pictures shows the damage the pinion inflicted to the carrier housing. To my surprise, the pinion did not show any signs of damage, nicks or cracks.





Carrier Housing Damage Repair/Fix:

Since a thorough inspection did not show any major problems, it was decided to deburr the indentation marks to prevent any metal filings/material to fall into the mesh or bearings and reuse it.



Parts Ordered:

Initially I made the mistake of identifying the differential as a Dana 35 unit w/out looking at a specific clause regarding Jeep Cherokee rear differentials and the following kits were ordered w/out having the vehicle at the shop:


Unfortunately, the unit turned out to be a Chrysler 8.25 after a physical inspection and wasn't a 3.73 ratio unit ....  .

Anyway, I have to recognize and give credit where it's due......  Summit Racing customer's service was very understanding and helpful in providing the correct components + helping us fix my Oops! understanding how expensive shipping costs are from/to my neck of the woods. My hat is off to them and this 20+ years customer will stay loyal.

The parts ordered were Richmond Gear RMG-4900741 with the correct 3.55 ratio and Ratech Deluxe Ring and Pinion Installation Kit RAT-3022K. Since the vehicle owner was getting his certification as a US Army SCUBA Instructor..... time pressure for the repair was not a problem on this side..... Phew.

Tools and Equipment Used:

Aside the classic wrenches, sockets, torque wrenches (in Ft-lbs and In-lbs), the Pinion Depth Setting Gage. I have the Central Tools 6470 unit.




Next.... I'll explain how it is used and even though finishing this might take a little more time due to activities and other stuff, hang in there. If you do want to check the instructions for the Pinion Depth Depth Gage though, check the PDF file at http://www.centraltools.com/pdf/6470.PDF.

Under Construction
Logged

ACRONYMS:
LUK  LMK  JIC  BTSTDTRT  YCYDYP  NFI-YTM  SPOBI, and the classic... DILLIGAS

'86 Mustang GT, X-303 cam, Holley DP 700, RG Tran., 289 Heads   Ford Smilie 2


Quote from: Joel5.0
The right to be stupid is inalienable for sure however, there is no such thing as a right to impose stupidity onto others
Great Thoughts will Overwhelm a Feeble Mind
There is never money to do it right, but there's always money to do it over.
Knowledge based on external evidence is unreliable.
He, who doesn't ask, does not deserve an answer.
A mind is like a parachute it only works when it is open.  (oldmanjoe)
If you can't explain it simply, you don't understand it well enough. (Albert Einstein)
Tuning on a Dyno for the track, is like swim practice in a bathtub.
I can explain it for you, but I can't understand it for you. (90lxcoupe)
The proof of understanding is the ability to explain it. (H. Torruella)
Ignorance is bliss, but stupidity is orgasmic.
Fraud and falsehood only dread examination. Truth invites it. (Samuel Johnson)
The chaotic resistance of the opponents leads to the conclusion that they are not prepared to meet the challenge. The problem is already much more psychological then technological. [Bojidar Djordjev]
Individuals are rational and humane... Crowds are reactionary and barbaric. (Jason)
The person who says it cannot be done should not interrupt the person doing it. –Chinese Proverb
Nothing sways the stupid more than arguments they can't understand - Cardinal de Retz
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