[MITOK]

Hi y'all. After searching for and reading every thread on the forum with the word "backlash" in it without finding an answer, I figured it's time to see if anyone here can help me.

Ever since I bought my 2wd 04 CC a month or so ago, a very pronounced whine has emanated from the rear differential (C200 4.6) upon acceleration and as I come to a stop. If I try to maintain a constant speed, it changes into a grinding/rattling noise.

At first, I thought the differential pinion bearings were in need of replacement, but now I'm not so sure. After noticing a clunk when putting the truck in gear (A/T), I crawled underneath the drivetrain while a buddy shifted the transmission between D and R. I discovered ~10 degrees of backlash (a substantial amount) at the differential pinion. I did not observe play or backlash at any of the three U-joints.

If I tighten up the backlash, will the diff whine/grind go away?

If the answer to this question is "PROBABLY NOT,"
What should I inspect/repair/replace in order to eliminate this problem?

If the answer to this question is "PROBABLY SO,"
Should I adjust backlash by pulling the third member and adding a shim on the left side to push the ring gear toward the pinion, or should I shim the pinion to push it toward the ring gear?

Also, if you think I should just swap in a stronger rear axle because this repair is too involved and the C200 is wimpy, please let me know.

I'm really looking forward to hearing what y'all have to say about this, especially because I have to drive 2,000 miles here in a few days. Any and all help is more than appreciated.

 

[NissanPowerBaby!!!]

I'm not sure how much 10 degrees translates into in thousandths of an inch, but it still sounds like a fair bit. Make sure you consult your factory service manual though because there's large discrepancies when it comes to backlash tolerances between vehicles. I've seen everything from 0.004" to 0.020". If the backlash is out of spec, do a pattern check: this involves putting some form of marking (preferably with paint) covering both the leading and trailing sides of your teeth on the ring gear. Then rotate the pinion gear around several times in both directions to make sure you get adequate pressure. Then examine and see where the paint has been worn off. This will not only give you an idea of backlash, but also the toe or heel relation the pinion gear has with the ring gear.
If you decide that the backlash is too much by referring to specs, then bring the ring gear closer to the pinion by the use of shims. Of course this will also change your heel/toe relation with your pinion to your ring gear, so make sure to do the pattern check again to ensure the tooth contact is in the middle of the face.

 

[MITOK]

Thank you so much for the thoroughness of your response. :udaman: If I'm reading your post correctly, the following steps should be sufficient to tighten up the diff:

1) pattern check
2) shim until backlash is within spec
3) pattern check
4) if needed, adjust pinion spacers until heel/toe is centered
5) pattern check
6) check preload, etc.

Please don't hesitate to correct me if I got this mixed up.

 

[nissanmadness]

Hi y'all. After searching for and reading every thread on the forum with the word "backlash" in it without finding an answer, I figured it's time to see if anyone here can help me.

Ever since I bought my 2wd 04 CC a month or so ago, a very pronounced whine has emanated from the rear differential (C200 4.6) upon acceleration and as I come to a stop. If I try to maintain a constant speed, it changes into a grinding/rattling noise.

At first, I thought the differential pinion bearings were in need of replacement, but now I'm not so sure. After noticing a clunk when putting the truck in gear (A/T), I crawled underneath the drivetrain while a buddy shifted the transmission between D and R. I discovered ~10 degrees of backlash (a substantial amount) at the differential pinion. I did not observe play or backlash at any of the three U-joints.

If I tighten up the backlash, will the diff whine/grind go away?

If the answer to this question is "PROBABLY NOT,"
What should I inspect/repair/replace in order to eliminate this problem?

If the answer to this question is "PROBABLY SO,"
Should I adjust backlash by pulling the third member and adding a shim on the left side to push the ring gear toward the pinion, or should I shim the pinion to push it toward the ring gear?

Also, if you think I should just swap in a stronger rear axle because this repair is too involved and the C200 is wimpy, please let me know.

I'm really looking forward to hearing what y'all have to say about this, especially because I have to drive 2,000 miles here in a few days. Any and all help is more than appreciated.

First off you just CAN'T tighten a differential. Excessive slop usually means bearings are wearing out. This changes the pinion and ring gear tooth contact and wear pattern. When you drive the vehicle at a certain speed, does the whine go away when you let off the gas? If the whine comes back when you give it the gas again, your diff is worn out. If the noise is constant, you may have a bad U joint or axle bearing. Bearings growl and differentials howl. Look to see what color your gear oil is. If there is any silver tinge to it, thats where your problem will be. Lotsa luck.

 

[NissanPowerBaby!!!]

Thank you so much for the thoroughness of your response. :udaman: If I'm reading your post correctly, the following steps should be sufficient to tighten up the diff:

1) pattern check
2) shim until backlash is within spec
3) pattern check
4) if needed, adjust pinion spacers until heel/toe is centered
5) pattern check
6) check preload, etc.

Please don't hesitate to correct me if I got this mixed up.

Sounds like you have the idea. If you're in there ripping everything apart, it probably wouldn't be a bad idea to do seals (axle and pinion) if you haven't done them in a long time. Also, as mentioned before take a close look at your bearings...because if you have bad bearings doing all these adjustments will be for not, because they will cause improper preload.

 

[penski61]

you shouldnt have to adjust anything , if you are getting those noises you have bearing issues

 

[atroader]

Personally, I'd change the fluid and inspect for shavings / debris. Then jack up one tire, put tranny in neutral and turn through the gears by hand w/ both the tire and the dshaft- check for any 'catches' in the gears or a lack of smoothness when turning. I've driven trucks for years with a whine and they can be fine for general driving.

If the fluid is good and the gears feel smooth (no 'catching')- I'd drive the trip. (Assuming the previous owner didnt change it recently).

If its a daily driver etc., rebuild the gears. If you plan to push it, mod it, offroad, etc., adapt in a currie 9". At least that's my plan.