Does anyone know if new posi cones can wear out on one summer?
My 9-bolt started to slip in the end of summer -11 i bought new posi cones and repaired it. I machined of the cones a little bit so they wouldnt bottom out too fast because the casing is pretty worn too. I didnt shim it... maybe that was a fault i did...

Now it seems like its bottomed out atleast VERY near bottom. if i do a burnout it sometimes locks. When im turning it doesent seems to lock.

Does anyone know if a shimming only can help? or whay should i do.

It cant be made so the cones wear out on a summer...
What did i do wrong..

 

New cones don't have the recessed ends the old ones do. Did you machine the case halves or the cones? They will bottom out against the case very quickly if not done.

 

Depends on how you use it. I've seen more than one new Auburn differential wear out in 9 months or less because the owner did a lot of burnouts while holding the brake. Water brunouts will also kill one pretty quick. Shimming the gears is more to keep the gears in the correct contact than it is to help it lock up. If the gears are not in contact correctly they will be weaker.

 

I machined the ends of the cones so it would not bottom out quickly.

 

Well.. i have done many burnouts but i have seen these rear ends in more action than mine. What kind of axle should i use to be able to do burnouts?

 

If you just stab the gas and let it go it won't hurt it. If you hold the brake then you are going to put more stress on it than it can handle. If you are going to do this or do a lot of water burnouts then you need a locker instead of a clutch or cone type differential.

 

I have done some burnouts holding my brakes..
But it feels like it has worn out very quick...

 

limited slip additive?

 

The additive doesent matter in a posi? or am i wrong?

 

the additive is for a clutch style posi to keep the clutches from chattering/hammering. Don't need or want it in a cone style.

 

That might be partly true for the Borg Warner, but the Auburn needs 2 bottles of the additive. The Auburn is also a cone type. You can not run an Auburn without the additive, and one bottle is almost never enough.

 

I don't do auburns

 

OP still hasn't said if the carrier steps were machined down. Likely not in which case the new cones without the recess would bottom out relatively quickly. Pus the case is likely worn some too and the brake plus burn outs. The carrier really needs machined too.

 

I took Twin Turbo's advice a couple of years ago and put regular gear oil in my 9bolt after I reworked it. It is working just fine.

 

Next diff for me will be a Ford 9". I know it will cost me alot of $$$.

 

I havent machined anything else than the cones, i think i mentioned that. maybe

Well i havent done that, maybe i should go for that, and maybe i have to shim it a bit too?

what do you think?

 

Dont you think axle oil is better?
90LS oil?

 

Yes, you need to shim it to get the correct gear contact. If you don't you will likely break the gears.

 

I could be wrong here, but I think he's referring to shimming the posi cones, not the gears. If that's the case, then yes, shimming to cones to where they are closer to the contact surfaces in the carrier does help them grab better.

 

That's what I'm talking about too. When the cones sit deeper in the case the axle gears move farther apart. You must shim the axle gears so that they make proper contact with the pinion gears or all of them are going to break. You have to put shims between the axles gears and the cones to restore the correct contact between the gears.

 

Go here and print off the instructions.
http://www.geocities.ws/luckyducky_9...air30Nov04.pdf
The step in the outer end of each carrier half needs to be machined flat if the cones don't have a recess in the nose.

 

This is exactly what i have done once, i bought new cones and machined them. I did not macine the carrier flat...

Maybe machining the carrier is the next step? and then i have to shim it when cones will go deeper...

I did not shim it when i used the new cones because they didnt bottom out. I had much space in the " cone window" left when i assembled it, but not anymore..

 

Without proper shimming there is slack on the gears, they do not engage each other fully and this makes them weak. Also, a little spring preload sets your static break away torque. Any gear action from 1 wheel spinning faster than the others will force the gears apart, pushing the cones into the carrier increasing break away tq. In other words, if it's all put together with slop you only have a lower break away tq rating and a weaker rear end.

Take it apart and shim it properly. I also recommend removing the ridge in the case insteaf of cutting away part of the cones, this will maximize the spline engagement between cone and axle.

 

Oh ok, I gotcha now. That makes sense!

 

were can i get the9 bolt parts in colorado

 

Randy's Ring & Pinion has a few 9 bolt parts. You might check with them.

 

http://www.9bolt.com/

 

WHAT OIL TO USE IN A 9 BOLT

The 9 bolt gearsets will run fine with standard 80w90 hypoid gear oil. If you are running a posi unit you will need 90w posi gear oil. Friction modifier is optional if you experience clutch chatter. For heavy duty use (towing/race or short ratio gearing >3.45) I recommend 85/140 gear oil for it's better lubrication properties under extra load and heat. This is the case in both posi and non posi setups!.


I used the 85/140 hypoid gear oil.

 

With regard to the additive, it's not "clutch vs cone" (shape); it's the material. METAL vs COMPOSITION.

The purples of the additive is to make the composition material behave better, and not chatter / groan / grab / otherwise behave unevenly. It has no effect on brass, or that sintered cast iron or whatever it is, that the 9-bolt cones are made of. Therefore they don't need it.

I generally avoid the old advice from back in the day about the thick gear lube. Modern lubes are MUCH better than the stuff that was around when that truism got started. 75W-90 Mobil1 is VASTLY better than the 90W-140 mineral oil we all used 40 years ago.

 

The additive has been used far longer than any composition clutch material has been around. It was used back in the '50s with the Dana Power Lock in the '55 to '64 Chevys and starting in '65 through the '80s in the Eaton Posi and Traction Lock in the Chevy 12 bolt and GM 8.5 10 bolt. All of these had steel clutch discs. Chrysler used it with the Auburn Sure Grip, which also has steel cones.

The bottom line is, if the differential chatters and pops when you turn tight corners then you need the additive. If it doesn't chatter and pop then don't use it. The additive only makes the clutches slip smoother. The more the clutches slip the less affective the limited slip differential will be. For drag cars I recommend using an oil with no additive in it at all. This will help keep both tires spinning while doing the water burnouts.

 

^^ Exactly. I once set up a 9 bolt for a guy that wanted his set up tight. It was set up tight enough that it would start to pop and ping when the diff was very hot. I added 2 bottles... some driving and gone. I will not use it otherwise although I do use it in eatons and danas (for corvettes)

 

So mine groans when I do a burn out on uneven pavement. Ok I start off with a little brake both then spin I let off and one spin only on unlevel pavement. Like down a narrow street. 3.27 with royal purple

 

You are destroying your differential by doing that.

 

 

I know it only did it twice, I was looking for a answer