Differential / ARB Issues, Need Advice **BINGO**

[Tedster100]

You might be on to something there!

 

[broncokak]

I've never even run the locker while it was locked. I did jump on it once hard enough to crack a u-joint but I can't see that causing this kind of failure.

So if I understand this right you've never locked the locker? But you hammered on it a little unlocked (open)?

I have had a number of people tell me that the ARB is not very strong as an open dif. They say it gets its strength from being locked. I'm not sure if that is true or not though.

 

[Tedster100]

Yup, more or less, I spun a little on the pavement in a straight line & when the tires hooked up it roached the u-joint which should be one of the weakest parts of the driveline. I've just got a 302 with a RV cam, otherwise it's stock, not like its a blower motor or anything. The fact that all the ring gear bolts were loose May have put a different type of load on the carrier as well.

 

[nlped]

WOW!!!! That's a new one on me. I've torn up a bunch of rearends, but never done anything like that. That's a bizarre failure. Sorry Man, that sux!

 

[broncokak]

The fact that all the ring gear bolts were loose May have put a different type of load on the carrier as well.

Very good point.

ARB's Tech line has great customer service. I can't remember the guys name I taled to but I can go back and find the e-mail if you like. I'd give them a call just to see what their take is. You ARB is the same style as mine and it is old and they don't make parts for it. I'm pretty sure your looking at a new unit. :-[

ARB USA (866) 293-9078

 

[bmc69]

I have had a number of people tell me that the ARB is not very strong as an open dif. They say it gets its strength from being locked. I'm not sure if that is true or not though.

I'd never heard that...And I've hammered my ARBs to the extreme while unlocked..no mercy. That said, the one that's probably taken the most abuse over the years is in a D44, not a 9".

That is the first time I've seen that kind of failure. Pretty amazing. Be interesting to get ARBs take on it...even if that is an obsolete design.

 

[Tedster100]

Thanks, I did e-mail them, haven't heard back yet. I may call later.

 

[bmc69]

I did jump on it once hard enough to crack a u-joint but I can't see that causing this kind of failure. Guess I'm gonna have to get a new one.

Speaking as an injuneer...I think I see what happened. When the dif is unlocked, and you are spinning one wheel faster than the other (or loading one up more than the other), that section that failed is under a shear load, from ring gear drive, as well as a tensile load, caused by the spider gear reaction force vector (sine of tooth contact angle, basically) that wants to push them apart when they are loaded up.

When locked, that second load goes away and its only the shear load that that has to be transmitted across that zone that fractured.

 

[Yeller]

Yep seen that failure before in the older ARB's. A 9" carrier is small and it gets thin in that spot. The issue is also agrivated if your running a stock carrier and not a nodular one, as the stock one flexes more. The ring gear bolts are aslo suspect allowing things move.

This is the best cure we have found for keeping the bolts tight, better than safety wire.
http://www.alltechmotorsports.com/MechanicsandFab.html

 

[Broncobowsher]

Thanks, I did e-mail them, haven't heard back yet. I may call later.

Phone works better with ARB

 

[Tedster100]

Well, I talked to ARB about the failure. Something they notice that I hadn't was the thread imprint from the ring gear bolts. It would seem to indicate that the ring gear was loose for a while. They also confirmed that it's an old style unit that they have no parts for. I asked about getting help with maybe just the carrier but have head nothing back for two days. Anybody got an old style air locker carrier laying around?.......didn't think so, guess I'm screwed.