Diff issues 489/3:55

[euroz06]

Hi all,

When a bought my charger (68/383) it had granny diff (long gears/open). I went ahead and bought a 489 case, and bought new gears for 3:55 posi. I then found a shop, and the older gentleman said he can put it all together no problem. He also told me that he is closing shop and this is his last job.

Since day 1, the diff whines, at first it was just a bit, but it has gotten louder over the 7 years/6k miles (though for passengers, they dont notice it unless i point it out, so its not obnoxious) . It doesnt always whine, it wines when im cruising, under accel and off gas it doesnt whine. Another big item that really bothers me (more so than the noise) is when i put it in drive or reverse, i get a “hit”, and that has gotten progressively worse (passengers notice it quite a bit). When i was doing a brake job, and had the car on the lift, there is quite a bit of play from when i turn the wheel and the driveshaft engagement.

So it seems like obviously it wasnt set up right, but my questions are:
Can it be fixed or do i need to get all new gearing? It has about 6k miles.
Is it better to buy a new one (saw a few on ebay, but really expensive, like 1300-1500)? Is it safe to buy it used somewhere?

 

[pnora]

7 years its taken a set and I seriously doubt it can be fully corrected. Sounds like its time to start over.

 

[493 Mike]

A new gear set should fix you up, properly installed of course!
Mike

 

[padam]

I hear a lot of people say it’s hard to get a quiet set up using current production gears.

 

[steve340]

Most gear sets will have a little noise at some speed or other.
And I agree with earlier post the sets are not as good as they were - but at least you can still buy them.
I believe it is down to were does it make noise - and can you live with it.

 

[khryslerkid]

I'd want to find out why it has play whether it's normal or too much. 489 is normally a crush sleeve to set the bearing preload unless the crush sleeve eliminator was used. It needs to be evaluated and probably will need a new gear set installed along with bearings. When it's removed you can check for metal in the lube. The wear pattern is permanent now and changing anything to correct the wine and play probably won't work. They're cheaper to rebuild then to buy a new center section. Providing the person who sets it up knows what they're doing.

For parts and info there's no one better than Cass (Dr Diff) DoctorDiff Drivetrain Components

He's good about answering your emails.

 

[#41]

Buying used is always a little bit of a crap shoot, especially if you don't know hoe to read the wear. Check to make sure the "hit" is not just your U-joints. Otherwise, I'll be the contrarian and say that at 1000 miles per year of use, another alternative is to just keep driving it.

 

[AR67GTX]

Do you know what gears are in it (manufacturer)? I‘ve been through 3 new gear sets (3.55) and two driveline shops before I just took matters in my own hands and set up the last set myself. My effort was more successful than the others but I still have a bit of float whine (light throttle cruise) over a brief road speed range. The last gears I used were US Gears as they were supposed to be US made. But now I read that none of them are made in the US anymore so I’m not sure if they were or weren’t. The 2 shops I used seem to concentrate on getting a good drive side pattern but appeared to pay zero attention to the coast side. Getting a set of quiet gears installed now seems to be a near impossibility. I don’t know how the new car manufacturers manage it. Some of the differential shops that advertise complete, ready to go units may have figured out what to do. I don’t know how well most of them perform for quiet running.

 

[euroz06]

I live in Miami, so im not sure i can find someone to build it correctly.... or would have to pay more than buying a brand new dif. But, still would like to explore some options.
I see on the Dr diff site a few options:
1. a brand new diff. It asks if i have green non-adjustable ball wheel bearings? how would i find this? Then it asks if its 6-hellical gear sure track or 30 spline spool or 35 spline spool? how would I know which one i'd need? I know I have LSD, but not sure which one.
2. There is 8 3/4 bearing rebuild kit. I assume my issues are not bearings, but gears? I feel like some of the cost of a new diff is the 489 case, which in my case should be good to.

How do I check if its the u-joint? If i recall, i was turning the wheel, and there was slack before the u-joint, i.e. i could move the wheel about 1-2 inches before it would engage the driveshaft.

 

[69Bee]

The radio has a volume knob. It fixes most noise problems...

 

[ruffcut]

I want to know if he's willing to share the LSD! LOL Ruffcut

 

[euroz06]

Yea, thats why im afraid to even try to rebuild it… or even with new one, no guarantees huh.

 

[euroz06]

I want to know if he's willing to share the LSD! LOL Ruffcut

If i do get a new one, ill be happy to sell it locally. Im not sure if its posi or suregrip or whatever the name for it is.

 

[Orig69]

Check the nut on the pinion yoke to see if it's loose.
I have always bought used ones.

 

[euroz06]

Check the nut on the pinion yoke to see if it's loose.
I have always bought used ones.

oh, will do, thank you!

 

[euroz06]

oh, will do, thank you!

Check the nut on the pinion yoke to see if it's loose.
I have always bought used ones.

Do you know the torque spec for it?

 

[hunt2elk]

Do you know the torque spec for it?

240 ft lbs for the pinion nut on a 489. Honestly, if you are not at all familiar with these rear ends, and there is nobody around you that you trust to rebuild them I would recommend just getting ahold of Cass and buy a new chunk. He is a great guy to deal with and it would be a plug and play for you.

 

[euroz06]

240 ft lbs for the pinion nut on a 489. Honestly, if you are not at all familiar with these rear ends, and there is nobody around you that you trust to rebuild them I would recommend just getting ahold of Cass and buy a new chunk. He is a great guy to deal with and it would be a plug and play for you.

Id love to just buy all new dif, but its pricey. My ac condenser just broke, so i also have to get that fixed (also debating if i should put a new style compressor, whereas a kit is like $1500). This issue at this point is more of an annoyance, that id like to resolve at the lowest price point, so if i could tighten some nut, maybe change to some “super duper” diff oil, id love it (id love it if i could improve the current situation by 40-50%).
Its the nut thats behind the ujoint on the outside, right?

Who is Cass?

 

[steve340]

Dr Diff

 

[Orig69]

Id love to just buy all new dif, but its pricey. My ac condenser just broke, so i also have to get that fixed (also debating if i should put a new style compressor, whereas a kit is like $1500). This issue at this point is more of an annoyance, that id like to resolve at the lowest price point, so if i could tighten some nut, maybe change to some “super duper” diff oil, id love it (id love it if i could improve the current situation by 40-50%).
Its the nut thats behind the ujoint on the outside, right?

Who is Cass?

Yes.