Rebuilding 9" 3rd Member
 

Has anyone rebuilt their 9'' third member? I have a spare in the shed and the one installed is leaking so it needs repair. I figure I would rebuild the 4.10 in the shed to replace the 3.83 in the truck. I am also contemplating replacing the 4.10's with higher gearing like 3.55. any information, advice, experiences, do's don'ts would be appreciated. plus a good place (trustworthy) to get parts.. I have done the internet searches and see there are a number of places to get parts. I also know you can buy already assembled units but that will take all the fun and learning out of it..

thanks

Most folk swap them rather than rebuild. The center chunk can be swapped in under an hour from start to finish.

It takes some specialized tools to complete the gear swap, and if you want to take it on as a project I'm sure you can find how toos on the net.


have fun



John :-X06

Seems like a rebuild unit would cost around $500.00 when a rebuild kit costs about $100.00. I have two 3rd members, one installed and one in the shed so for me the rebuild kit would be best. If you buy a used one for a swap and just install it you are taking a chance that it is in worse condition than the one you currently have installed. To me 'swapping' without rebuild is a mistake and $500.00 is too much for something I can do myself.

I have found a few 'how tos' on the net, none of them have mentioned special tools but if some are needed I can either make them, buy them or make do without them if possible.

I may be different but I do get enjoyment out of working on my truck. I also know when I am finished with a repair that it is better than any shop would do.

i rebuild mine and it went very easy. i used bearings from napa and reused all the existing shims. the only thing to keep in mind is there are two different 9" there's a big bearing and a stranded bearing rear diff. the special tools you need are: press, a Dial Indicator With Magnetic/Static Base. so you can measure the back lash, and youll need something to mark the gear to check for teeth alignment i used red grease to look at mine.

don't know if you say this but its a good step by step right up on how to do this
https://www.ford-trucks.com/article/...ear_Setup.html

good luck and let use know how it goes.

Will do.. Thanks I have the tools needed then and this is a not big bearing rear end I believe or at least I am about to install normal axle bearings in it.. My spare came out of the truck originally and the installed one is out of a 72' F250..
I will take photos and post some type of review of the project. I will be a few months as at work we are about to enter a 3 month outage replacing some heavy duty equipment.. For me this equals 14-16 hour days 6-7 days per week..

F250? What F250 had a 9 inch rear end? None.

F250's used Dana 60's from 1953 thru 1985.

1968/72: There are two different 9 inch rear ends. *

9 inch:

Ford changed the differential bearings/races midyear 1969, going to the "slim line" tapered roller design.

The pinion bearings/races are the same for all 9's from 1957 thru 1986.

There are two different pinion seals, depending on what year the rear end is from.

Axle bearings: It depends on what year the 9 is from. Some 1974/86's used tapered roller bearing assembly's, which includes the seal.

Otherwise the bearings are the large ball type used beginning in 1957.
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* 1968/72: Ford offered an optional Heavy Duty 9 inch that has a 9 3/8" RING GEAR.

There are two versions: With or without Limited Slip. With L/S, the axle shafts have 31 splines. Without, 28 splines.

Depending on which 9 3/8" rear end it has, only 5 parts are shared with the 9 inch: Housing gasket, 2 pinion bearings, one pinion race, the retainer for the pilot bearing.

EVERYTHING else is different.

9 3/8" The axle bearing is stamped 1580 and is 3 9/64" O/A diameter.

NumberDummy, Thank you very much for the reply and information as this is exactly what I needed.
A quick question, I no longer have the original axle bearings to make sure my repalcements are the correct size. Will the difference be obvious upon installation (I will also measure the ID of the axle housing).

The previous owner had two trucks this F100 (70)and an F250 (72) he used for parts. He told me he took the 3rd member in the F100 from the F250 and then threw the 'original' in the bed of the F100 before I pulled out, along with a bunch of other stuff. So it sounds like he way full of crap. I went to get universal joints for my truck and had to go back to get the correct rear one, I ended up requiring one from a 72 F250.. So at least the Yoke if off a F250 or somehow stuff got mixed up..

The Axles had sealed ball bearings pressed on. I also have 28 spline axles and do not have limited slip but would like to replace the open carrier with a limited slip when I rebuild the 3.83 gears, I am assuming you can get limited slip with 28 spline. But first I need to rebuild the 4.10 gears.

Thank you again for all the useful information. One day I will figure out what I have and this forum will be the driving force behind that.

Dana 60's do not have "drop out" third members.

There's no such thng as 3.83-1 gears, regardless of what the rear end is.

1967/72 F100: Common 9" ratios: 3.25-1 / 3.54-1 / 3.73-1.

Axle ball bearings:

9 inch: 3 9/64" O.D. / 1 17/32" I.D. / 1 5/64" thick / Bearing Industry # 88128

9 3/8 inch: 3 9/64" O,D, / 1 5/8" I.D. / 1 5/64" thick / Bearing Industry # 1580

Axle seals:

9 inch: 2 1/2" O.D. / 1 1/2" I.D. /// 9 3/8 inch: 2 1/2" O.D. / 1 19/32" I.D.

Bearing industry numbers are what autoparts go by.

Some F250's use the same u-joints as F100's.

I am sorry for the error, I believe he told me that they were 3.89:1 gears and the spare has 4.11:1 gears. And I will confirm if I rebuild them.

Yes, I know dana's don't have drop out 3rd members. I was just attempting to relay the info I was given when I purchased the truck. So now we know that since NO 1972 F250 2WD ever had a for 9" my installed unit did not come out of a F250.. This is not a surprise as I find many thing the previous owner told me to be false. Again Thank you for helping me understand.

The Axle bearings I purchased 514003 (no idea what the BI # is this was the only number on them) fit the housing and the axle, the seals (1 1/2 ID) I purchased fit the housing and the axle, so I am guessing I have a 9". Again Thank you for this additional info as this clears up many things.

I have an additional question.
Say I want to pull the Pinion ONLY and replace the seal and 1 bearing (unless both are accessible) Can I do just this and not mess up my spacing (assuming I use the same shims in the same place)? I am thinking about doing this as I would like to fix my leak without investing in the time to rebuild for now. I will rebuild it this winter.

Thanks again for all the help and straightening out my confused mind.