I thought a 2003 F250 would have a 10.5" not a 10.25 what gives here?

 

bump to the top. I don't recall when it changed exactly.

 

Carrier? The differential carrier? Got any photos? I don't think this is right.

 

This information was provided to me years ago (june 2005) when I was trying to find a posi for my 96 F350 7.3 dually.....hope it helps

The differences between the 10.25"-10.5" are the length of the pinion splines (short vs long), pinion shaft lengths (10.25 = 8.250" 10.5" = 8.00") , inner pinion bearings (tall vs short 10.25 uses a taller bearing 10.5 uses a shorter bearing.) Both inner pinion bearings share the same OD 4.125", same OD as the carrier bearing race it is also very easy to install a carrier bearing race into the inner pinion bearing hole, you won't notice it till you try to crush the sleeve. The outside diameter of the ring gear is 10.375" on the 10.25" and 10.625" on the 10.5" the difference is .188" on a radius more or less, these are nominal dimensions based on my experience I did not get these numbers out of shop manual.

You are correct about installing 10.25" gear sets into 10.5" differentials, as you well know you will need a long spline pinion in a 10.5" application. The long spline pinion first came out on the 10.25" in 1993, from what I heard and from what I have experienced here at my shop there were a lot of problems with loose pinion yokes. I was told that the longer splines would make better contact with the pinion and would have less tendency to come loose. I have seen a lot of loose long and short spline pinions and I have torn down thousands of long and short spline differentials, they all had one thing in common...the inner pinion bearing was loose on the pinion shaft. If the pinion yoke was tight the inner pinion bearing was also tight. My theory...loose pinion bearing = loose short or long spline pinion yokes.


When you install a 10.25" gear set into a 10.5" you must use a 10.25" bearing kit, you cannot use the 10.5" inner pinion bearing on the 10.25" gear set, everything else is the same. I did try one time to install a 10.5" 3.73 into a 10.25" the problem that I had was ring gear interference with the inside of the housing it may have been just the housing I don't know I have never tried it again since then. I don't see why you couldn't use the 10.5" in a 10.25, just use the 10.5" inner pinion bearing everything else is the same.

The 10.25" and 10.5" carriers share the same ring gear bolt spacing and the same ring gear ID, if you are swapping out complete carrier assemblies you won't have any problems. The very first 10.5" Trac-loks were actually 10.25" Trac-loks (Mfg by Dana) you can identify them by the up raised numbers 10.25 on the ring gear side of the case, early model Trac-loks did not have any numbers. The later 10.5" Trac-loks ( I believe 2000 and up) are all three pinion carriers (vs two pinions on the 10.25" T/L). All of the three pinion carriers are of a two piece case design, please note that three pinion carriers were also available as open carriers (non posi) if you are looking at them on a computer they are virtually identical.

If you find a less expensive 10.5" Trac-lok you may want to consider buying it because it will also work in your 10.25" full floating differential, the three pinion Trac-lok will not work with a semi floating 10.25" differential ( there are no provisions for C-clips). The part number for the three pinion clutch kit is F81Z4947AA, the part number for the two pinion is 72960X. The three pinion kit will have to come from your local Ford dealer, the two pinion kit will come from a Dana dealer (its a lot cheaper too.) Ford actually had Dana discontinue the Trac-lok because Dana was selling them too cheap to the walk in public.

You can also use pre '93 gear sets in all 1993-1997 10.25" applications, ll you will need is a short spline pinion yoke with the same size u-joint. The pinion splines on a 10.25" and 10.5" are both 31 spline, the crush sleeves are also the same (ditto for Ford 9" 8.8 7.5).

 

Here is an old article that shows some of the differences. Ford 10.25 & 10.50-Inch Axle Tips - Axle Examination

 

Outstanding information Larry, tried to rep you.

 

Yes the carrier is stamped 10.25, I am installing a brand new loaded Ford open carrier in place of the original trac loc. I am hoping Larry is correct that it will go in with no issues..

 

I got him Tom..

 

Just a update, got the new Open Ford three pinion carrier installed and everything went great, it replaced my 10.25" Dana trac lock 2 pinion carrier that was making all kinds of noise when I would take off from a stop and turning left or right. Thanks for all the info guys..

 

Bump...... 😁

 

Really? Bump for what reason?

 

do you have information on where to source 10.25 ls clutch packs? If not, just find a 10.5 carrier?

 

10.25 2 pinion
https://eastcoastgearsupply.com/i-20...-kit-late.html

10.5 3 pinion
https://eastcoastgearsupply.com/i-20...build-kit.html