The new 14 bff full rehab questions and conversation thread

As I've shared elsewhere, I had a funny noise from the rear end and upon closer inspection, it appears that previous owners had let the gear oil run low for an extended period of time. I'm pretty sure this truck lived a life of heavy hauling and being a true camper special. Someone prior to my ownership put all new rear brakes on, including new hub bearings/seals and it's obvious that no one bothered to look at the center innards, or they might have noticed the forbidden glitter, broken magnet, cage remnants and missing rollers from the pinon extension bearing. The "new" wheel bearings appear to be toast; you can see the odd wear, a burnished look with shiny at the very ends. Pictures of this to follow on later. They're getting changed, as well as all the rest of the bearings in the unit.

I'm in the parts procurement phase and boy howdy, do I have a series of questions to all who have completely gone through a 14bff; bearings, seals, ring gear/pinon, the whole enchilada. What part manufacturer preferences were considerations for your project. Like the choices of Timken, Koyo or others for bearings and whose ring/pinon did you go with? Where did you get them? What ratio did you use and why? Locker or not to locker? What did you do? How has it held up?

I am thinking a 3.42 ratio will play best with a 3 speed transmission at highway speeds and still be able to pull most loads from a standstill. It's 4.10 now but the with the end play now it seems like it's fried. Good a time as any to change, no?

All this for a C20 big block, that may get turned up some day. Mostly to use as a tow pig, but not going to patently disregard a mild to medium go-fast future. Not a seven second rocket, but a fun ride that likes to smoke both wheels.

The whole reason for creating a new thread is mainly to not hijack anyone else's thread and focus specifically on what you would consider important to do this job for long life and reliability. And to see if this is a job you did while the housing was still attached, or did you pull it off for ease of accessibility? Basically, a what did you do and why thread.

I appreciate your input and experience doing this particular job. This will be a first for me, but I'm not skeered. Maybe I should be... what do you think? Thanks folks, I appreciate your input. It's better than You Tube videos for the win. And the guy I used to have (who was exceptional) has retired and is no longer available. I don't know now who to trust, and call me crazy, but it seems like a 14 bolt is easier to do than other GM differentials. Am I nuts thinking that?

Getting ready to pop the center section out so I can include more pictures beyond the preliminary ones here. Should be interesting.... welcome aboard.

I haven’t done a 14B FF myself, but for the other rears I’ve done I’ll list my preferences.

Timken or Koyo are both quality bearings, I’ve used both without issue.

Gear sets, I’d recommend AAM, Revolution. However a quick search suggests no 3.42 ratios offered by either for the 10.5. You’ll probably be stuck with a gear set from the Yukon/Standard/Randys conglomerate (not necessarily a bad thing, just how the availability lands).

For a 14B you’ll need a spanner for the side adjusters (you can use a punch, but no one like a primitive Pete), and you’ll be working “backwards” with the pinion depth, as you add shim to between the cartridge and housing to move the pinion away from the ring gear, whereas a 10/12/14bsf you add shim to move it closer.

You’ll need a good dial indicator and base, inch lb beam torque wrench, means of R&Ring races and seals, lots of brake parts cleaner/solvent, a small stone to hit mating surfaces, and the regular assortment of hand tools.

I don’t even know enough to be dangerous, but I thought that for many GM axles there are two different carriers, based on the ratio. However, I may also be really off in left field.

I have not read through up this posting, but it looks like it could be very useful.

75gmck25 said:

GM axles there are two different carriers

Click to expand...

You are correct, depending on the axle it can be almost a non factor though, for example an 8.5” 10 bolt break is 2.56 and down, 2.73 and up. For 99% of people they are going from 2.73 to 3.42/3.73/4.10/etc, not 4.10 to 2.56.

The 14b FF break should be 4.10 and down, 4.56 and up iirc.

Or if you are an unlucky person and bought a Dana “X1” series axle (61,71, offset pinion) on the premise it was a 60/70, wanting to regear you get to pull out all of the tricks to do so. Wrong carrier, ring gear spacer, mismatched carrier bearing and race just to get the new gears to mesh.

75gmck25 said:

I don’t even know enough to be dangerous, but I thought that for many GM axles there are two different carriers, based on the ratio. However, I may also be really off in left field.

I have not read through up this posting, but it looks like it could be very useful.

https://www.gmsquarebody.com/threads/%E2%80%9Cthe-14-bolt-full-float-bible%E2%80%9D.48189/

Click to expand...

That is an excellent resource, one I've been digging into for a while now. Thanks for bringing it up, I slipped. One that gives me inspiration. Good catch.

Yes, from what I've read the carrier break is 4.1 and lower numerically and 4.56 and higher numerically. This one is supposed to be 4.1 according to the glovebox sticker.
And like I've mentioned in another thread, I would rather use the funds a GearVendors unit represents for better heads and intake/exhaust so a 3.42 gearset makes sense for me, much like a static drop would over bagging it.

legopnuematic said:

I haven’t done a 14B FF myself, but for the other rears I’ve done I’ll list my preferences.

Timken or Koyo are both quality bearings, I’ve used both without issue.

Gear sets, I’d recommend AAM, Revolution. However a quick search suggests no 3.42 ratios offered by either for the 10.5. You’ll probably be stuck with a gear set from the Yukon/Standard/Randys conglomerate (not necessarily a bad thing, just how the availability lands).

For a 14B you’ll need a spanner for the side adjusters (you can use a punch, but no one like a primitive Pete), and you’ll be working “backwards” with the pinion depth, as you add shim to between the cartridge and housing to move the pinion away from the ring gear, whereas a 10/12/14bsf you add shim to move it closer.

You’ll need a good dial indicator and base, inch lb beam torque wrench, means of R&Ring races and seals, lots of brake parts cleaner/solvent, a small stone to hit mating surfaces, and the regular assortment of hand tools.

Click to expand...

Looks like all I need is the spanner and a decent inch pound spanner type torque wrench. Although I do have quite the assortment of pin punches in a pinch.

What is the small stone for? Deburring the pumpkin? This is a part of the procedures I must have missed.

Wheel bearing pictures later on, after the farm animals maintenence and the rain lets up this afternoon.

You can use a small fine cut file as well. I always run over the mating faces of the carrier and ring gear with a stone or file to knock any dings or high spots down, that way you don’t accidentally introduce runout from it not mating squarely. There is almost always one or two imperfections from shipping/handling. I also will hit lightly the mating faces of the carrier bearing caps, on a 14 bolt I’d hit the mating face of the cartridge to the housing.

Only takes a minute to do so I always do it.

Thank you Spencer, that is awesome advice and I understand the why behind it. Will do.

Here's a representative look at the wheel bearings as I promised yesterday. Notice the wear patina

Shows up better under flash


Races, plain and flash



That doesn't look serviceable to me. At least not on anything I want my name on.

I can only imagine what the carrier and remaining pinon bearings look like. More photos to follow upon disassembly, hopefully by the end of the weekend.

Pictorial step by step r and r 14ff starts o post 35

If youre still buying parts I've bought most of my stuff from Summit and East Coast Gear Supply....they should be running a 10% off Memorial Day sale next week.

I’ll give a +1 on ECGS, very good pricing on what I got from them.

C&M Gearworks is another good vendor.

I got my 12 bolt rebuild stuff from quick performance. Got 3000 miles on my first self rebuild and it's been quiet. Break in oil looked great.

Timken bearings, unsure of the axles and ring and pinion brand.

You guys are the best. Thanks Matt for the heads up, very much appreciated.

I am still waiting to pull the trigger on parts and a discount is icing on the cake. That keeps Mrs Radiohead happy too; happy wife, happy life. Easier to "sell" heads, intake, etc later on.

And Craig, thanks for the link. I am off to see what you did and appreciate your putting what you did down as a learning tool for the rest of us.

Did I mention that you guys are the best?
Thanks again folks. I just hope I have enough hutzphah to lift up the new carrier assembly. Might have to recruit some nephew's... details and pics to come!

Love how life gets in the way of side fun.

Did manage to verify 30 spline shafts and 1350 U-joints today. And start the thorough soaking of swaybar fasteners with AeroKroil so it can be moved out of the way.

Along with 3.42 gears, going with a new u bolt yoke and Grizzly locker, all bearings and acqutrements (sp?). Just waiting to see if they have a holiday sale.

Get some more honey do's done this week and then I can dive in, cannonball style without guilt. Lol

I haven't seen an email on a promo code from them yet. If theyre not gonna do it you've got enough in your cart to at least get free shipping.