Center section swap issues

74delta

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Ok guy need your help as I am out of my element when it comes to differentials. I picked up a fresh rebuilt 489 case with a cone style suregrip to replace my open 742 case, Both 3.23 gears in my 65 300. The guy who sold it to me was a hard-core mopar enthusiast with lots of nice parts/cars. The swap went super easy. Unfortunately I have a real bad howl when coasting. My question is could this be caused by the axel adjustment on the passenger side. I did not mess with that at all and just put it where it was previously. Ill attach a picture that shows the paint markings on the gears but from my research they looked good so I'm hoping its not a pinion preload issue and its just me being stupid and assuming that adjustment on the axel would have been the same. I only drove the car about 1/2 a mile since the install.

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Not likely. If your axle bearing adjustment was fine before it’s fine now.

Did you look at your axle bearings? Did they have any grease on/in them? Sometimes taking them out and back in disrupts the little grease left and they make noise.

always good to clean and repack rear axle bearings.
 
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Not likely. If your axle bearing adjustment was fine before it’s fine now.

Did you look at your axle bearings? Did they have any grease on/in them? Sometimes taking them out and back in disrupts the little grease left and they make noise.

always good to clean and repack rear axle bearings.
I did not disturb them. Still looked like they had good grease.
 
Since you didn't touch the bearing adjustment, I assume you didn't check it either. That is an easy thing to check... Basically, the axle has to have just a touch of end play. Look in the FSM for more clarity on that... Just grab the axle and see if it moves .010-.015 (or whatever the FSM says) It would probably only be noisy if it was wrong, and then all the time, but just pull the wheel and check it so you can check that off as not being the problem.

That said, most likely the gear lash is set wrong or the gears are junk. This is the risk of buying used gear sets.
 
too loose.
Is there a potential way ro rectify it being too loose without complete disassembly? I bought a rebuilt one with the hopes of not having to pay someone to set it up. Was really hoping that not having messed with that axel adjustment was my problem haha
 
Was really hoping that not having messed with that axel adjustment was my problem

That's easy to check... I'm all about doing the simple stuff first before tearing into it.

Did the seller rebuild it? After checking the axle adjustment (so you can say "yes" when he asks) give him a call.
 
That's easy to check... I'm all about doing the simple stuff first before tearing into it.

Did the seller rebuild it? After checking the axle adjustment (so you can say "yes" when he asks) give him a call.
The seller didn't rebuild it. Unfortunately he had it rebuilt awhile ago for one of his cars but it never made its way in. He had some nice hemi 4 speed cars.
 
Sounds like it is either one of two things. First of all the preload on the pinion may not be tight enough allowing the pinion to move in and out depending on whether your accelerating or decelerating. This moves the pinion in and out of contact with the crown and the adjustment is lost.
Secondly it could be that the backlash was never set properly. You can check this with a dial indicator or marking paint. It looks like they have done this by the look of the yellow paint. If it is incorrect it is a matter of adjusting the bearing caps on either side of the crown.
You can probably check the pinion with the housing installed. Take the driveshaft off and move the pinion back and forth. Watch for end play. To adjust the crown would require removal of the unit.
 
85w90 and friction modifier

That oil should work. I am inclined to agree that the set up is wrong. Most likely the pinion shaft has excessive end play as noted above. Try removing the drive line and have a helper turn a wheel back and forth in short movements. If the pinion shaft is too loose, you should be able to see it move in and out as the direction of rotation on the wheel is changed.

Dave
 
The seller didn't rebuild it. Unfortunately he had it rebuilt awhile ago for one of his cars but it never made its way in. He had some nice hemi 4 speed cars.
Sorry that happened. Whether "rebuilt" or not, usually bad axle bearings make a lot of noise on turns, not deceleration. Pinions don't go out of adjustment sitting on a shelf. Advise you pull the 489, check with friends and clubs in your area on who is knowledgeable, and have someone with good references properly rebuild the 489. Unfortunately, that may be a $600-$700 hit.

Another option, take the 489 back and see if the guy will return your money. 742 is a good case. Use the $ to rebuild that.
 
Sorry that happened. Whether "rebuilt" or not, usually bad axle bearings make a lot of noise on turns, not deceleration. Pinions don't go out of adjustment sitting on a shelf. Advise you pull the 489, check with friends and clubs in your area on who is knowledgeable, and have someone with good references properly rebuild the 489. Unfortunately, that may be a $600-$700 hit.

Another option, take the 489 back and see if the guy will return your money. 742 is a good case. Use the $ to rebuild that.
You are correct in saying pinions don’t go out of adjustment however if it was never set properly that could be the problem. Either way this will require some work to reset and repair. The unit could still be salvaged but needs to be set properly right away.
 
Sorry that happened. Whether "rebuilt" or not, usually bad axle bearings make a lot of noise on turns, not deceleration. Pinions don't go out of adjustment sitting on a shelf. Advise you pull the 489, check with friends and clubs in your area on who is knowledgeable, and have someone with good references properly rebuild the 489. Unfortunately, that may be a $600-$700 hit.

Another option, take the 489 back and see if the guy will return your money. 742 is a good case. Use the $ to rebuild that.
Honestly I didn't check any specs on it before the install. Later today I'm going to throw it 9n the lift and check the pinion bearing preload. Based off of reading forums and watching videos all morning that seems to be a very likely suspect.
 
It
Honestly I didn't check any specs on it before the install. Later today I'm going to throw it 9n the lift and check the pinion bearing preload. Based off of reading forums and watching videos all morning that seems to be a very likely suspect.
will be hard to check at this time. Preload is set with only the pinion in place. It’s worth trying though.
 
It

will be hard to check at this time. Preload is set with only the pinion in place. It’s worth trying though.
My thought is to check it and see where its at and if it seems to loose to snug it up 1/ 8 or 1/4 turn and see if it affects the noise at all. Rinse and repeat. If it doesn't do anything probably drop it off to someone to be gone through.
 
Should have just put a sure grip in the 742 case. Probably cheaper you have a new sure grip and if you match the backlash with what it was before the swap you will have no noise. Oh well, good luck.
It's not the pinion, check if you like but if they screwed up a crush sleeve rear that bad you need a different center.
 
Should have just put a sure grip in the 742 case. Probably cheaper you have a new sure grip and if you match the backlash with what it was before the swap you will have no noise. Oh well, good luck.
It's not the pinion, check if you like but if they screwed up a crush sleeve rear that bad you need a different center.
Hey Dave,
This is new for me. Thought the crush sleeve could be removed and replaced, especially if the pinion set up was loose. How would the crush sleeve set up damage the 489 case? Thanks, Ben
 
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