The Stovebolt Site Forums The Shop Area General Truck Talk rear differential ?'s...

Good Lord... So, here I am getting ready to order the parts to convert my 65 Chevy 12-bolt with 4.10's to 3.42's and the parts guy says he thinks I need to change the carrier too...? He said when you jump from 4's ot 3's in ratio, the original carrier is too thick or big. Does anyone know? My god, I'm already up to around $300 in ring/pinion/bearing kit, and NOW it's another $100 or so for a carrier? Does all this sound right? Any suggestions or answers? thanks, randy

He's right, and that 4-something carrier you've got is what the roundtrack or offroad racers are all looking for! Put the carrier on ebay with a reasonable reserve, and watch the bidding war start! The 3-something carriers are very common, so don't let your wrench rip you off. The local salvage yard should have lots of carriers from "core" rear ends with bad gears or bearings that would be scrap iron otherwise.
Jerry

No kidding...? So, I ACTUALLY have a part that might have some value it it??? That's got to be a first! Normally I buy super high and sell super low... What the heck IS this carrier thing anyway? When he first said I would need a smaller carrier I thought he was talking about the differential center / housing, but it doesn't sound like that now...

The carrier is the part the ring gear bolts onto, the big round casting where the spider gears and axle gears mount. The position of the flange where the ring gear bolts is in a different place on the low-geared models, so when you change to a higher ratio, the new ring gear doesn't mesh with the pinion properly unless the carrier is also changed.
Jerry

Well for chrissakes... that all makes sense! HR Lincoln, I appreciate your taking the time... Now, I better go sell ANOTHER dang gun to pay for the additional parts (and THAT just doesn't seem right!!!) Thanks again!!! randy

Hmmmmm- - - -that's my OTHER passion, building custom rifles! Too bad you're not a little closer to Tennessee, if you're in the mood to unload some firepower!
Jerry

Yeah, but isn't your WEATHER a bit treacherous right now? We're hoping and praying for another 1/8 inch of rain just to keep our lawns from bursting into flames out here in the desert! I just bought an 1100 remington in .410 for dove/pheasant/duck hunting AND an 11-48 in .410 for.... uhhhh... hmmmmm... what did I tell the ol' lady it was for again.... INVESTMENT I think... Yeah, if we were closer we could do some swapping! (Guns for parts I mean, the ol' lady is a bit closed minded on the other 'swapping' I think...)HA!

School's out today, but other than a little heavy rain, we got out pretty easy. I've got another problem, my wife hunts and shoots, and trains bird dogs, so it's hard to sneak a new purchase past her. "I like this one- - - -it's mine!" So far, I've lost a nice custom Mauser .30-06 and a stainless Ruger Blackhawk .357 that way! At least when I build or buy a replacement she doesn't gripe! She shoots a 3" magnum Mossberg 500 for turkeys, and a Remington 1100 16 gauge for sporting clays and quail.

Gun swapping, definitely! Anything else, and I'd be the target of that Mauser!
Jerry

HA! Well, lemme AXE you this... Am I on the right track with this rear gear swap? It sounds like what I'll need is the new 3.42 ring and pinion, the new carrier, some gear lube and a 'bearing kit' to complete ths swap out. Does that sound about right? Everything that is currently in the truck rear end is still solid, quiet and looks good with no excessive slop, do I need to change anything else? I just don't wanna tear it down and get halfway thru and learn that the shlpitzer shank won't fit with the new gear or the crabnagger needs to be upgraded... You sound like somebody that knows, so I'm asking before hand. THANKS! randy

It sounds like you've covered all the bases. The ring & pinion and the carrier will get everything aligned properly, and the "bearing kit" will have all the small parts like bearing shims, seals, and a "crush sleeve" that sets the pinion bearing preload as the pinion nut is tightened. Now, all you need is an installer who really knows his stuff to assemble it. Hypoid gears are lapped to a perfect, noise-free fit during manufacture, and they MUST be assembled in exactly the right relationship or you'll have a whine as they run. Just a slight out-of-position installation will still run and pull OK, but the whine will out-scream a siren. Make sure the tech who installs the gearset has the tools and the knowledge to do it right the first time!
Jerry

I asked my differential guy who just finished up rebuilding my new 3.40, 12 bolt that I got today. He said the 2.76, 3.08, 3.40 or 3.42 use the same carrier, and that one is now remade but expensive. It has been hard to find in the past. the 2.56 and 2.73 use another carrier. The 3.73, 4.11, 4.56, 4.88, and 5.13 use another carrier.
It is a little more complicated than this and so as HRL said the set-up is best left to the guys in the know.
some thick, some too thin carriers: (mismanufactured) were made sometime ago (70's) that got out into the system. You should not have to worry about those now.

trucks and autos:
diff's have different offsets.

I'm just passing on what he knows.

How do you tighten the carrier bolts? the book says 85-90 ftlbs but HOW....? How do you hold it to torque it. I don't think it's wise to torque it against the pinion gear.

Jeremy

(Editor's note: This old post has way too much off topic content for me to try to clean up. Please post your question in a new post. Thanks)