8 3/4 auburn grip and loc carrier. broken parts question

[chrisf]

bought a 742 case 3.55 gear with a auburn grip and loc carrier. little too much power and it broke the button off the center pin and knocked one of the springs out.

anybody have a service manual / schematic for one of these things so i can order the correct parts? emailed auburn waiting for a reply.

 

[Dana67Dart]

Post photos of what you have.

 

[chrisf]

photos. round broken "button" was on the center pin. spring came out i assume when the button broke. you can see in the third pic where the button went on the pin.

 

[chrisf]

got it figured out. easy fix

 

[Dana67Dart]

easy fix

and what did you do?

 

[chrisf]

and what did you do?

got ahold of auburn. $200 in parts and she will be as good as new.

 

[MOPARMAGA]

You already are overpowering it, it will probably happen again, maybe step up to a better clutch type if able .

 

[Big.J.007]

It ain't broken.. The center button ejected and kicked a spring out. If your using green bearings leave the center button off. Just back the bolts off the case halfs and reinstall the spring. If needing a button salvage 1 from an open carrier they are the same. Or spend $200. The spring plates from your pics are in good condition.

 

[chrisf]

thanks guys, i bought it off a guy this way as he went to a 9" i know cone sure grips are not that tough. its a 489 with new MP 3.55's ill fix everything and keep it

 

[chrisf]

It ain't broken.. The center button ejected and kicked a spring out. If your using green bearings leave the center button off. Just back the bolts off the case halfs and reinstall the spring. If needing a button salvage 1 from an open carrier they are the same. Or spend $200. The spring plates from your pics are in good condition.

great advice. thank you. other than the case halves. haven't figured out disassembly yet. no case bolts. ill post a pic tomorrow. its one of the 22 projects i have on the go at the same time so sometimes it takes months to get the hamster back on the wheel.

 

[33IMP]

Case bolts on a clutch type are opposite the ring gear.
The cone type has the assembly bolts on the same side of the carrier as the ring gear.

 

[RustyRatRod]

thanks guys, i bought it off a guy this way as he went to a 9" i know cone sure grips are not that tough. its a 489 with new MP 3.55's ill fix everything and keep it

That's incorrect. The newer Auburn units, which is what that is, are much stronger than their factory counterparts. They will handle a good bit of power. IMO, power output had nothing to do with that failure.

 

[chrisf]

so what caused the failure? i did not do the damage. i just bought the aftermath. lol

 

[Dave999]

does that cross shaft have a dowel to pin it or does it depend on the ends of the axle shafts riding on the button to keep it still?

if the shaft has spun, gotta find out why.

usual failure is the cones bottom out in the case leading to a 1 wheel burnout that puts the full torque through the pinion/spider gears to the side gear/cone and axle with no traction, which spins very fast. in that scenario your little spider gears are spinning excessively fast on their cross shaft. they just ride on the shaft, the chances of a seizure are large. if one of them grabbed and twisted the shaft that would bust your button

the other option would be that if the axle ends are supposed to butt up against the button to stop the shaft turning and the axles were too short or a wheel bearing collar moved. the space gets too great and the button twists against the axle shaft end and gets hammered at the next corner you take

no experience with the Auburn units but quite a lot with the borg warner separate cone and side gear set up that spawned this design. kinda universal on 60s to 80s Australian and south african bigger cars as both had big Borgwarner factories that supplied everyone...

Which is why i'm asking about dowel pins for the cross shaft (single shaft 2 spider gears designs usually have dowels) the 4 pinion/spider gear type doesn't need that, because it has a 4 leg cross pinned into the case by its 4 legs and 4 pinion/spider gears. different spring pack

with a spring pack like that its a 2 spider gears and cross shaft only rather than 4
and an auburn unit is usually integral cone and side gear so loosening the case halves will not result in spline misalignment if the axles are out. i.e easier to work on

these are great on pebble mud sand uncapped roads farm tracks etc because they don't take much torque to actually start working but never truly lock up, there is always some differential action...

Dave

 

[Desoto291hemi]

Since you purchased it already hurt you don’t really know what happened .
I agree with a few others that it was most likely already worn and after it broke loose on a one wheel burnout that it hurt itself .

But now,,since you purchased the repair parts,,,,I’m assuming that new cones came with it for 200 bucks,,,you should be almost as good as new now .

They are a very sure grip,,,you won’t hurt it unless you are making a lot of power and using slicks .

Tommy

 

[MiradaMegaCab]

Did the pin bolt shear?

 

[Dave999]

ahhhh no dowel but a pin bolt.... must have done... which makes me think seizure

 

[RustyRatRod]

View attachment 1716425480Did the pin bolt shear?

If it did, the only way that could have happened is from extreme abuse by hanging one tire off the pavement and standing on the gas. That would over heat the two center pinion gears, weld them to the cross pin and snap the pin bolt. But normally that does more damage. It usually breaks the case around the pin bolt hole and also wallows out the holes the cross pin goes through in the case, completely ruining the case, so if that happened, there will be ample evidence.

 

[Dave999]

might find mr bolt in the bottom of the housing, if it is complete all is not lost

 

[MiradaMegaCab]

The ample evidence is that the “buttons” pin sheared.

 

[Dave999]

well if the case is alright everything else can be machined/shimmed to make a worn out one work for another 50-80K miles.... won't know till you look. does the cone end of the case at each side have windows to let oil in, through which you can see cone depth of engagement with the case, any space between cone end and outer bearing end of case and its got life in it.
here is a grubby Aussie one i messed with a few weeks ago, fresh from my stash of rusty old junk.
still has a reasonably long service life left in it
see the little window

this is a cast steel one out of a Gen III camaro or 5 litre holden i think.... these things get everywhere...

Dave

 

[MiradaMegaCab]

We shouldn’t see the hole in the pin as pictured. The hole should be parallel to the axles to retain the buttons dowel pin.

 

[Dave999]

yeah which means that pin has turned through near 90* but there should be a bolt close to one end of the pin that stops it turning it bolts in from one side of the case. that bolt must be snapped or missing i.e backed out due to vibration. allowing the pin to turn and put pressure on the central button until its small mounting stud snapped

what caused the twist in that shaft? it will dictate what work you need to do.
i have seen the type like my one above have the dowel hole that they use instead of a bolt wallowed out. and signs of smearing of spider gear onto shaft i.e a semi seizure.
was on a one for 2.77:1 gears so useless case hemispheres for any other application. the good parts became spares

you won't know till you pull it apart. but they are simple units, it will be obvious
lets hope the bolt just fell out
it should be in the bottom of the axle housing unless it got pinged down one axle tube or the other

Dave

 

[MiradaMegaCab]

Assuming the case is good and these are the replacement parts the OP bought, he should be good to go but I’d run Green Bearings and eliminate Auburn’s buttons…… The Auburn is a strong unit but the buttons dowel pin retention is the weak point of their design. Maybe there’s not enough space for a conventional thrust block.

 

[Dave999]

sorry mixing your posts up with the OP apologies...