28 spline vs. 31

[jabo731]

I need a differential. left wheel is trying to pull harder than the right. To be honest the dollars are tight, so I was wondering how does it sound to replace the stock diff with an Eaton 28 spline. And next will my stock axles be okay. If not i'll have to bite the bullet and go 31 spline axle and diff. How much stronger is the 31 and is it worth the money.

[merc]

You could purchase a upgraded LSD and use your stock 28 spline axles. I currently have a Auburn Pro on 28’s, but I have a set of 31 spline axles in reserve. The stock LSD is going to fail with abuse, lot’s of members have replaced them.

[LVMarauder]

31 is stronger all around but expensive no doubt. but plausable idea if just your diff is going south. Are you sure your 28 spline axles are ok? unless your SC and pushing lots of load all the time a 28 setup should work.

[HwyCruiser]

If you have an early '03 300A and never had the TSB done then the axles are a crap shoot. But assuming the axles are still good, the "budget" route is to have the stock traction-loc rebuilt. The rebuild kit is $50. I got a quote locally to do the R&R and rebuild for $350 including parts but I decided to upgrade.

Your looking at about $800 in parts for 31-spine axles and a new diff, so say $1100+ installed. If your not currently supercharged or planning on supercharging there's little point in upgrading to a 31-spline setup though.

[jabo731]

I didn't know there were a TSB on our axles. I didn't have it done. My car has 36,600 miles on it now.

[LVMarauder]

Mine had scoring at 10 k miles.

[BUCKWHEAT]

I have an early 300A and just changed out axles at 40,000 miles. Put in the 31 splines with an Auburn unit. My original axles were one bad, one ok. I just assume the 31's will be better with the S/C.

[FordNut]

I just dropped off my spare rear end for the 31 spline buildup to be started. Probably within a month or so I'll be swapping out units and my old one will be available.

About 2-3k miles on new FoMoCo 28 spline traction-loc diff unit, had the axle TSB done, has 4.10 gears, works great.

[O's Fan Rich]

I just dropped off my spare rear end for the 31 spline buildup to be started. Probably within a month or so I'll be swapping out units and my old one will be available.

About 2-3k miles on new FoMoCo 28 spline traction-loc diff unit, had the axle TSB done, has 4.10 gears, works great.

Spare rear, huh? Braggert!!!
Changing ratios, Brian?

[RF Overlord]

I didn't know there were a TSB on our axles. I didn't have it done. My car has 36,600 miles on it now.From Police Fleet Manager magazine:

"On the early build 2003 CVPI, all units built before January 1, 2003, the axle bearing or seal may fail due to excessive loads, higher temperatures or inadequate lubrication. In extreme cases, the bearing can cause the axle shaft to fail. If the axle fails, it is still held in place by the rotor and brake caliper.

TSB 03-05-05 has been issued which involves a complete rear axle bearing service kit. For the record, 75W-140 synthetic gear oil should be used, not the lighter duty 75W-90 petroleum-based oil.

The officer or mechanic may have a warning of this condition. The seal may leak, there may be excessive play, the check ABS light may activate, and bearing may or may not indicate a noise. The TSB includes a heavier bearing. In actual fleet service where the TSB has been performed, feedback indicates the problem has been completely resolved."

Since you're just barely over warranty mileage, you *might* get a friendly dealer to perform this TSB. If not, you should consider having the axles pulled and checked anyway, for peace of mind. Remember, this only applies to cars built before January '03.

[Jolly Roger]

I need a differential. left wheel is trying to pull harder than the right. To be honest the dollars are tight, so I was wondering how does it sound to replace the stock diff with an Eaton 28 spline. And next will my stock axles be okay. If not i'll have to bite the bullet and go 31 spline axle and diff. How much stronger is the 31 and is it worth the money.

Powertrax or Track-lock.;)
Nuff said.

[FordNut]

Spare rear, huh? Braggert!!!
Changing ratios, Brian?
Nope, just getting tubes welded and converting to 31 splines with ECTED electric locker. Already have the 4.10s and sticking with them, just replacing everything in the rear end with new stuff, so my old one will be intact after the swap.

[MikesMerc]

If you don't plan on heavy racing, save money and get the 28s. If you plan on sticky tires and the track, I'd suggest the 31s. I've seen the 28s break under racing conditions.

[SergntMac]

I'm sitting here wondering "what happened to my post"? Then I realized that you have two threads on this topic running at the same time. I posted in the other thread.

Not the way to get a solid answer, eh?

[John F. Russo]

I have a Kenny Brown conversion car. I'm not into heavy racing but I have gone to the track three times during the 54,000 miles I have driven.

I always appreciate the great ideas on this site. It is an instant source of ideas. Thank you all!

I have been noticing a minor whining noise as compared to when I first owned the car. And it appears that it is differential related.

My goal is to get to about 600 to 700 RWHP before I die! (At the rate I'm going it is an issue at my age.)

First, I just had my rims widened and getting two- 285/45ZR18TL Pirelli's (P Zero Assimetrico) on my rear. I'm going to increase the boost to about 10 to 12 psig. (This all increases the probability of blowing engine and my differential sooner than I would like.)

So I would like to ask a few questions about my plans for car failure for my daily driver.

1. Should I get a 31 spline axle now or run my stock unit it until it fails? (Of course that will cost me a towing plus being without a car unless I buy all of the parts for this impending certain event. And when it happens have the work done immediately).
2. What posi to buy? Auburn, Eaton and others mentioned before.
3. Other thoughts?


______________________________ _____________________
2003 Dark Blue Pearl 300B (Canadian) w/Light Flint (reversed traction control, mini spare, trunked 6 disc CD changer, clock-in-the-radio, heated front seats/mirrors, hood light), Born 12/10/02; converted new then used 2/28/03
ENGINE: Kenny Brown: 6th “Signature Series” conversion (450 hp), Vortech supercharger (5 to 7 psig boost; pulley), 377 RWTQ, Dennis Reinhart Cobra engine cooling kit TRANSMISSION: Stock transmission upgraded with Performance Automatic "Super Streeter" transmission version, stub shaft (defective metal) failed at 30k miles; upgraded internals (except for torque converter) to Dennis Reinhart's design; Precision, triple disc, P/N469018-3, later upgraded to 3500 rpm stall speed); Ford Racing transmission aluminum pan SUSPENSION: Metco control arms (black powdered coated), coil from each front stock spring removed to produce the “same” effect as an Eibach spring DRIVETRAIN 4.10 gears, MMX Driveshaft, Ford Racing Stud and Girdle BRAKES:14 in. BaerClaw front, (two piston, slotted rotors), TIRES: Pirelli P-Zero Asimmetrico (front 255/45ZR18 99Y, rear 255/50ZR18 102Y), ACCESSORIES: Wheel locks (Ford), godshead valve stem caps, Dead pedal, Badgeless front grille by “Zack”; Zaino waxing; RainX; Autobhanded, FordChip, Ground clearance: 5 in.; 36,000 miles MISCELLANEOUS 18.5 mpg at a steady speed of 80 mph, one tank of gas
______________________________ ___________________________
1961 Ford Galaxie, 2 dr. Club Victoria, 390CID, 375hp, 4 barrel (gone)

[MikesMerc]

My 2 cents would be to run it until it breaks, then swap in a nice 31 spline set up. If you go in early due to humming or whining noises, I'd get the 31 spline set up as well. If you plan on those power levels, I wouldn't waste a dime on 28 spline repairs.

As for the diff, I prefer the eaton, though the Auburn would be just as good.

[John F. Russo]

My 2 cents would be to run it until it breaks, then swap in a nice 31 spline set up. If you go in early due to humming or whining noises, I'd get the 31 spline set up as well. If you plan on those power levels, I wouldn't waste a dime on 28 spline repairs.

As for the diff, I prefer the eaton, though the Auburn would be just as good.

Thank you again Dave for your input.

[jabo731]

I had the TSB done on my rear axle. Actually they said my axle were fine, they did say I had a leak in my diff. When they fixed the seal the threw in the Auburn Pro for me. The thing is, I hope I did not ****** up by putting the new diff. on my stock 28 spline axles. I probally should have bitten the bullet and upgraded to 31 splines axles and a new diff. What do you guys think?

[sailsmen]

Members are running 450+RWHP w/ DR and no problems w/ 28.

I have the stock diff, 63K miles and 150+ runs down the 1,320' of which 30+run and 20K miles are w/ an S/C.

[jabo731]

thanks sailsmen, that makes me feel a little more at ease.

[1 Bad Merc]

A quick question for the guys that have changed their diffs. When you go to an eaton or auburn or detroit locker with the 31 splines do you guys get the noise like the old lockers when you turn corners? I remember the old 60's cars and you would hear a ratcheting sound when they turned the corner. This is probably a stupid question but I am curious. Thanks for the replies.

[SergntMac]

A quick question for the guys that have changed their diffs. When you go to an eaton or auburn or detroit locker with the 31 splines do you guys get the noise like the old lockers when you turn corners? I remember the old 60's cars and you would hear a ratcheting sound when they turned the corner. When it's all brand new, yes, it's a bit sticky in a hard turn. But, it all smooths out with time. I have about 3K on my rear end build up, all is quiet now.