Will a worn carrier pin cause noise?

[zdillinger]

I have a rather annoying noise coming out of the rear of my '73 (318, 904, 2.71 8 1/4). It almost sounds like a dragging brake, but I'm certain that this isn't the problem. The pinion moves freely, no noise / sloppy movement so I don't suspect this. I've never moved the pinion or the ring gear, so the backlash / pinion depth are unchanged. However, there seems to be a fair amount of slop between the axle shafts and the carrier (i.e. the ring gear spins a bit before the axles start to turn). I don't see a spec on this, so I'm unsure if this is ok. Also, it appears that the spider gears move a bit laterally when the pinion yoke is spun in one direction and then the other (the source of the slop?)

So, my question: if the carrier pin that passes through the spider gears is worn, could this create enough slop in the gears that a gear-slop noise would be present (quite loud)? I've already replaced the axle bearings and the problem still exists. If it isn't the cross pin, I wonder if it might be the output shaft support bearing on the 904. I hope not...

EDIT: One more question: can anyone tell me where the vent for the 8 1/4 is?

 

[Supershafts]

Should be on the housings tube.

when you took the cover off and looked at the cross pin and then seen it move, there should be no movement there, it should be a nice tight slip fit, no other movement.

 

[zdillinger]

Should be on the housings tube.

when you took the cover off and looked at the cross pin and then seen it move, there should be no movement there, it should be a nice tight slip fit, no other movement.

Thanks! I definitely have slop, specifically the spider gears move up and down slightly on the shaft, which appears to be worn. I didn't think that was right, but wasn't sure if this would cause gear-like noise or just a clunk. I've ordered a new cross pin, so hopefully this cures the problem, but we'll see. If it isn't this, I'm lost, as the bearings all seem to be good (no noise, no lateral movement at the carrier, no pinion slopiness).

 

[67 coronet]

should be some tight tolerances in there.if you can see movement then there is a problem.rear diffs can make all kinds of wierd noises.if it turns out to not be the problem,then jack stand the rear and listen underneith while running to find the spot of the noise.cheep stethescopes work great for this.

 

[zdillinger]

The car is up on jack stands right now, with the rear cover pulled and the oil drained. I'm sure I can't spin it hard / fast enough by hand to recreate the noise and I don't want to spin it too much without proper lubrication (there's still some oil clinging to the gears, but not much). The only thing I can see moving around is the spider gears, which causes some slop between the axles and the ring gear. Hopefully the new pin from DTS fixes the problem. Should have it in a couple of days and I will post followup.

Have you guys ever seen a bad transmission output shaft support bearing? Would this cause a similar problem? It isn't in the rear end, obviously, but this would be in the driveline and could cause noise I think.

 

[67 coronet]

The car is up on jack stands right now, with the rear cover pulled and the oil drained. I'm sure I can't spin it hard / fast enough by hand to recreate the noise and I don't want to spin it too much without proper lubrication (there's still some oil clinging to the gears, but not much). The only thing I can see moving around is the spider gears, which causes some slop between the axles and the ring gear. Hopefully the new pin from DTS fixes the problem. Should have it in a couple of days and I will post followup.

Have you guys ever seen a bad transmission output shaft support bearing? Would this cause a similar problem? It isn't in the rear end, obviously, but this would be in the driveline and could cause noise I think.

i meant to run it with cover on and fluid in.i have seen many trans output bearings and bushings go bad.see if there is up and down or side to side play where the drive line goes into the trans.should be fairly tight.

 

[zdillinger]

i meant to run it with cover on and fluid in.i have seen many trans output bearings and bushings go bad.see if there is up and down or side to side play where the drive line goes into the trans.should be fairly tight.

Once I get the new cross pin in, I'll put everything back together and road test it. If the noise is still there, i'll run it up on jack stands.

I'll check the play at the transmission end of the driveshaft a little later tonight. The noise i'm hearing sounds like its coming from the rear, but its very hard to pinpoint while driving (my exhaust is kind of loud...). I'm hoping it isn't the output shaft bearing, because the FSM says I have to unload the torsion bars and remove the crossmember to fix it, not something I'm looking forward to doing. But we'll see!

Thanks!

Zach

 

[Dodge33]

Differential carrier

Hello Z, I would say that it's the spider gear's are wore, it happen's alot in rear ends. you should not see any movement with these piece's! You could probably buy new spider's at a good drive train shop, may be Randy's ring and pinion, maybe one of the guy's here on the site know's of a better place. This is not Mopar related....... but we bought a used 90 Ford pick-up 1/2 ton truck 5-7 year's ago, and it was making differential noise's in the rear end, (maybe spider noise's) took the rear cover off and inspected it, did'nt find anything, so we cleaned off the carrier and inside the housing with brake clean, to wash of all residue, metal shaving's or whatever, and we ended up putting 85W140
gear oil in there, and we have been driving it since, no problem's. Maybe worth a try!

 

[zdillinger]

Hello Z, I would say that it's the spider gear's are wore, it happen's alot in rear ends. you should not see any movement with these piece's! You could probably buy new spider's at a good drive train shop, may be Randy's ring and pinion, maybe one of the guy's here on the site know's of a better place. This is not Mopar related....... but we bought a used 90 Ford pick-up 1/2 ton truck 5-7 year's ago, and it was making differential noise's in the rear end, (maybe spider noise's) took the rear cover off and inspected it, did'nt find anything, so we cleaned off the carrier and inside the housing with brake clean, to wash of all residue, metal shaving's or whatever, and we ended up putting 85W140
gear oil in there, and we have been driving it since, no problem's. Maybe worth a try!

I appreciate the input! The more I think about it, the more likely I think it is that the spider movement is causing the noise. I found some new spider kits at Drive Train Specialists, same place I ordered my cross pin from. My plan right now is to blast the inside of the case clean with brake clean, put the new pin in place, fill 'er back up with oil and drive it. If the noise is gone, I'm happy. If its still there, I'll try the spider kit ($123... anybody know of a less expensive source?), assuming the trans shaft bearing doesn't appear to be shot. I just want to drive my car without worrying that the rear end is going to fall apart, or that the trans is going to puke. Glad this is happening now, not in July!

 

[mopar367]

Make sure the carrier that the pin fits into isn't worn. I have had some of the 8 1/4 diffs and it was the cast iron carrier that was worn, and not the steel pin that holds the spyder gears

 

[zdillinger]

Make sure the carrier that the pin fits into isn't worn. I have had some of the 8 1/4 diffs and it was the cast iron carrier that was worn, and not the steel pin that holds the spyder gears

Crap, I hope not. If that's the case, I guess my best fix is to pull the rear end and put in another one. Might be tough to find a 2.71 8 1/4 for a '73 B Body, I suspect...

Zach

 

[Supershafts]

You just need to buy a carrier, and pay attention to what the set up is at right now, measure it now and put it back the same way

 

[zdillinger]

You just need to buy a carrier, and pay attention to what the set up is at right now, measure it now and put it back the same way

Fair enough. This is my first time ever messing with one of these (outside of replacing a broken crosspin on a Datsun 280ZX), so I'm hesitant. But I figure I can do pretty much anything, as long as I use a little care and common sense. If the carrier is fragged, I'll try the swap, but I'm hoping its just the shaft / spider gears, since the pin doesn't seem to move in the carrier, only the gears are moving on the pin. We'll see!

Zach

 

[Supershafts]

The pin can be worn at the spider section, take it apart carefully and if you need a new carrier make checks of the backlash measurement before you pull anything else, this way you can set that back as it was

 

[mopar367]

Personally I would just swap it for a 9 1/4 or a 8 3/4. with anything more than a mild 318 they just break. I broke 2

 

[Cranky]

Make sure the carrier that the pin fits into isn't worn. I have had some of the 8 1/4 diffs and it was the cast iron carrier that was worn, and not the steel pin that holds the spyder gears

Same thing with a 79 D 150. The pin didn't look too bad but the carrier was hosed and it did the same thing as zdillenger's is doing. Had plenty of play before the axles would rotate. I junked the thing and popped in an 8 3/4 from a 68 pickup. It was pretty much a bolt in. The E-brake cables were different but I was able to use the ones that were on the 79 originally.

zdillenger, did you pull out the old cross pin to inspect it and the fit it goes in before spending the money on new parts?

 

[zdillinger]

Same thing with a 79 D 150. The pin didn't look too bad but the carrier was hosed and it did the same thing as zdillenger's is doing. Had plenty of play before the axles would rotate. I junked the thing and popped in an 8 3/4 from a 68 pickup. It was pretty much a bolt in. The E-brake cables were different but I was able to use the ones that were on the 79 originally.

zdillenger, did you pull out the old cross pin to inspect it and the fit it goes in before spending the money on new parts?

Yup, there is some noticeable wear on the cross pin at the spider gears. That's why I was wondering if that could cause my noise. I didn't shoot pics, but I will snap a couple tonight and post 'em up, see what you guys think.

Zach

 

[zdillinger]

Just an update. I got the new cross shaft pin from DTS and got it in. Replaced the cover, filled with oil, etc. The noise seems to be gone! So I guess the pin fixed it! Now, time to put some miles on her!