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View Full Version : Need Help with 31-Spline Differential Conversion


ProfChaos
02-08-2006, 06:18 PM
Does the following look right for converting the differential from 28- to 31-spline (Ford Racing), or is there something missing or something that is redundant? (I have the stock T-45 transmission in-place):

31-Spline '96 Cobra Rear-End Conversion:
The Details:

Axles: Ford Racing 31-spline, five-lug: $256.95 pr.
Ford Racing 31-Spline Axles (http://www.mustangsunlimited.com/itemdy00.asp?T1=M4235D+01)

Rear Axle Installation Kit: $14.95
Rear Axle Installation Kit (http://www.mustangsunlimited.com/itemdy00.asp?T1=M4050B+01)

Axle Bearing Kit: Ford Racing (M1225-B): $25.00 pr.
Axle Bearing Kit for Non-IRS Cobras (http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=6006)

Differential Master Bearing Kit: $109.95
FRPP Differential Master Bearing Kit (http://www.mustangsunlimited.com/itemdy00.asp?T1=BK8881+01)

Ford Racing 8.8, 31-spllne Trac-Lok diff: $259.95
Ford Racing 31-Spline Trac-Loc for '96-'98 Cobra (http://www.mustangsunlimited.com/itemdy00.asp?T1=M4204F318+01)

Ford Racing 4.10:1 Ring and Pinion Gears: 8.8, 31-spline: $209.95
FRPP Ring and Pinion for 8.8", 31-Spline Diff (http://www.mustangsunlimited.com/itemdy00.asp?T1=M4209G410+01)

Ford Racing, Alum. Drive shaft (M-4602-J): $289.00
Ford Racing Auminum Drive Shaft for 96-98 Cobra (http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=2980)

Royal Purple Differential Lube (2 qt.) $19.90
Royal Purple Differential Lube (http://www.mustangsunlimited.com/itemdy00.asp?T1=RP01300+01)

**Sub Total: $1185.65**


Do I also need the following yoke, or is it included in the Ford Racing 31-spline aluminum drive shaft listed above?
(I don't want to be redundant in buying parts.)

Ford Racing 31-Spline Driveshaft Yoke for T-45 (http://www.mustangsunlimited.com/itemdy00.asp?T1=M4841A+01)

Thanks for your help.
--Professor Chaos

bolt-on
02-08-2006, 08:23 PM
The 31-spline yoke is included with the aluminum driveshaft. You may want new ABS rings if you do not want to have the originals pressed off and on.

tazzracing1
02-08-2006, 11:50 PM
Everything looks in order othe than your choice on the abs ring like Larry said.

InfamousSVT
02-09-2006, 05:31 AM
Looks good, but I would suggest the Moser or Strange 31 spline axles over the Ford Racing ones.

Good luck :thumbsup:


****edit****

Get a TA girdle cover too, if you don't already have one. ;)

tazzracing1
02-09-2006, 02:12 PM
I had mooser with a 2yr war. and corrosion resetant coating

ProfChaos
02-10-2006, 08:01 PM
Looks good, but I would suggest the Moser or Strange 31 spline axles over the Ford Racing ones.

Good luck :thumbsup:


****edit****

Get a TA girdle cover too, if you don't already have one. ;)


Thanks guys. I'll look into the Moser 31-spline axles, and I'll look into a girdled differential cover.

--Professor Chaos

ProfChaos
02-10-2006, 09:29 PM
On a related note, what are the advantages of going with the Trac-Lok (http://www.mustangsunlimited.com/itemdy00.asp?T1=M4204F318+01 ), as opposed to going with the FRPP "Direct Replacement" 8.8", 31-Spline, Open Differential (http://www.mustangsunlimited.com/itemdy00.asp?T1=M4204F3180+01)?

Thanks for your help.
--Professor Chaos

psycho43142
02-11-2006, 12:33 PM
The traction lok is a limited slip dif where the factory replacement says it's open meaning non-posi.

ProfChaos
02-11-2006, 01:16 PM
The traction lok is a limited slip dif where the factory replacement says it's open meaning non-posi.


OK, thanks. That's a big difference--well worth the additional $80. :starwars:

cheers,
--Professor Chaos

ProfChaos
02-14-2006, 08:05 PM
The traction lok is a limited slip dif where the factory replacement says it's open meaning non-posi.

I actually learned today--from an SVT Cobra tech who surely should know--that the "open differential" at the URL below is not OEM for the Modular Cobra, even though it would likely still fit, as it is designed for an 8.8" Ford rear end:

NOT OEM and NOT POSI:
8.8" 31-Spline Open Differential (FRPP)
(http://www.mustangsunlimited.com/itemdy00.asp?T1=M4204F3180+01 )

According to the aforementioned SVT tech (who has rebuilt many-a-Cobra), the OEM is a Trac-Lok, but is a 28-spline Trac-Lok:

STOCK:
8.8" Traction-Lok 28-Spline Differential (FRPP)
(http://www.mustangsunlimited.com/itemdy00.asp?T1=M4204F288+01 )

*****
Since I plan to upgrade to 31-spline axles, the following should do the trick (at a minimum):


8.8" TRACTION-LOK 31 SPLINE DIFFERENTIAL (FRPP) (http://www.mustangsunlimited.com/itemdy00.asp?T1=M4204F318+01 )

****
Even so, I might just "go for it" and get an Auburn 31-spline, cone-type Trac-Lok:

8.8" Auburn 31-Spline Locking Differential (FRPP) (http://www.mustangsunlimited.com/itemdy00.asp?T1=M4204A31+01)

cheers,
--Professor Chaos