I notice that my rear differential (D35) on my Jeep makes noticably more noise when really cold outside (like this morning 10*F). It's a little noisey in the summer but not as much as winter. 10-15 minute drive after it warms up the noise is not as bad. I'm using Royal Purple Max Gear 75W140. Would a 75W90 tone it down in winter? Kind of annoying whoosh noise that's been there for a while now and I think I may need to take to a driveline shop to look at. I serviced the rear diff a few of months ago and everything looked normal. I'm wondering if the rear needs adjusting(backlash?).
Noisey diffy
- Thread starter jeepzj
- Start date
- Status
It's a steady one that increases as I go faster but tones down after 10-15 minutes of cruising.....but can still hear it. I had both carrier bearings and the pinion bearing replaced at the dealer under warranty at 50K miles. I now have 105K so it's been 55K since the overhaul. After the overhaul my rear diff was totally silent. Starting making noise at 75K and it's been the same ever since. Why do these diff's\bearings produce noise after a short time? If I decide to replace the entire rear (ring, pinion and all bearings), should I go with Timken? I hear they are very good quality parts.
MolaKule
Staff member
Are you sure it's not your tires???
If using a 75W140 doesn't tone it down and it's not your tires, you may have an input drive pinion bearing race that is loose in the input drive pinion compartment. I have seen them loosen up, yaw and spin in the compartment and the only way to remedy the situation is to buy a new race and "stake" it in the housing.
If using a 75W140 doesn't tone it down and it's not your tires, you may have an input drive pinion bearing race that is loose in the input drive pinion compartment. I have seen them loosen up, yaw and spin in the compartment and the only way to remedy the situation is to buy a new race and "stake" it in the housing.
MolaKule,
I bought new Firestone Desination LE tires during the summer so I've had them on for a while now. Not sure if the tires make that type of noise. I guess the only way to find out if it is the tires is to replace them with a different set....which I don't have. Maybe I can air up more and see if that makes any difference. I have them aired to 32PSI. Sidewall max psi indicated 44 so maybe I'll go to 36.
MolaKule
Staff member
I would put 38-40 psi in those tires in summer and 40-42 in winter.
It's usually the tread design that creates the noise. For example, my Frontier has Glacier Grip Mud/Snow tires that are 6 times as noisy as a regular light truck tire with conventional tread.
Quite honestly, I would use a Coastal or Schaeffer's Blend diffy oil in 75W140 and not do a thing unless the noise gets louder or you encounter a vibration.
I assume your Universal joints are new or have been lubricated?
It's usually the tread design that creates the noise. For example, my Frontier has Glacier Grip Mud/Snow tires that are 6 times as noisy as a regular light truck tire with conventional tread.
Quite honestly, I would use a Coastal or Schaeffer's Blend diffy oil in 75W140 and not do a thing unless the noise gets louder or you encounter a vibration.
I assume your Universal joints are new or have been lubricated?
Never had the u-joints lubricated nor did I know I am able to. Are you referring to just the rear diff u-joint? There are no zerk fittings in the u-joints so how would I lubricate them? I have a 1998 Jeep Grand Cherokee Laredo 4.0L I6.
I cannot believe I have to challenge the mighty MolaKule on something, and I'm surprised I have the guts.
I would STRONGLY caution AGAINST putting more air in the tires than they are rated to carry. In fact, I wouldn't put more air in that they need to support the load (if the stock size tires are used, that usually means the OE pressures). I agree that for the purposes of diagnosing a noise (and yes it could be tires), pumping them up very high can eliminate or change the noise. Running them that way is asking for abnormal wear, a molar-loosening ride and possibly tire damage. Remember the tires are the first part of your suspension. Also they are designed to have a certain tread contact on the road based on pressure and the weight on that tire. When you change the pressure higher or lower from that ideal position you are altering grip characteristics probably for the worse.
I would STRONGLY caution AGAINST putting more air in the tires than they are rated to carry. In fact, I wouldn't put more air in that they need to support the load (if the stock size tires are used, that usually means the OE pressures). I agree that for the purposes of diagnosing a noise (and yes it could be tires), pumping them up very high can eliminate or change the noise. Running them that way is asking for abnormal wear, a molar-loosening ride and possibly tire damage. Remember the tires are the first part of your suspension. Also they are designed to have a certain tread contact on the road based on pressure and the weight on that tire. When you change the pressure higher or lower from that ideal position you are altering grip characteristics probably for the worse.
Either you have an mechanical problem (bearings, diff, R&P, etc.), in which case it will get worse and become clearly diagnosable, or you just have a noisy axle and it will be that way for next 150K miles. Making adjustments to the ring and pinion setup at this late stage won't help. If it's misadjusted, it probably happened at the factory and it's now taken a "set." One thing you might be able to fix would be incorrect bearing preloads, but to do that you are pulling the unit completely apart. As to the noise, is it a steady one that increases as you go faster? Is it only on acceleration then stops on cruise or coast- or vice versa. Is it only on turns but not going straight. A steady noise is usually a bearing. The ones that come with acceleration or coast are usually ring and pinion setup issues. The ones in turns are often differntial related. That's the nutshellinfo anyway. BTW, the later D35s and D44s are notorious for noises and problems. Good luck.
MolaKule
Staff member
Jeepzj,
The U-joints would have to be removed or replaced.
In my experience, running tires 10 lbs. below max may give you a good ride, but also accelerates wear on the outside tread. On the othe end of the spectrum, running them over max will wear the center tread, hence the suggestion for running them a few lbs. below the max of 44 lbs., as they are rated for a max of 44 lbs.
The U-joints would have to be removed or replaced.
In my experience, running tires 10 lbs. below max may give you a good ride, but also accelerates wear on the outside tread. On the othe end of the spectrum, running them over max will wear the center tread, hence the suggestion for running them a few lbs. below the max of 44 lbs., as they are rated for a max of 44 lbs.
I aired them up to 38psi and made no noticeable difference in noise. I now have them aired to 34psi which seems like a good compromise.
MolaKule
Staff member
I would investigate the U-joint theory first.
Most diffy noise, in my experience, is a result of incorrect pre-loading (backlash adjustment), worn shims causing poor pre-loading, or the input drive pinion bearing and race or a combination of the above.
In rare cases, the wheel (axle) bearings are to blame, but the noise would be coming from one side or the other, and not from rear center.
http://auto.howstuffworks.com/differential3.htm
and
http://auto.howstuffworks.com/differential8.htm
[ December 21, 2005, 04:49 PM: Message edited by: MolaKule ]
Most diffy noise, in my experience, is a result of incorrect pre-loading (backlash adjustment), worn shims causing poor pre-loading, or the input drive pinion bearing and race or a combination of the above.
In rare cases, the wheel (axle) bearings are to blame, but the noise would be coming from one side or the other, and not from rear center.
http://auto.howstuffworks.com/differential3.htm
and
http://auto.howstuffworks.com/differential8.htm
[ December 21, 2005, 04:49 PM: Message edited by: MolaKule ]
Agree with that, the D44 in my Nissan Titan whines between 65-75 under load, for example going up a hill. It's annoying, but the dealer says its normal.
- Status
Similar threads
