Dodge Viper Dana 44 Rear - Pinion bearing going?

[Ron-Indy]

Diagnosed a bearing noise to the pinion bearing and to get a second opinion pulled an oil sample. Unfortunately seems inconclusive but perhaps given the fact that I caught it early maybe better this way. Any opinions as to whether this UOA helps confirm or deny?

Thanks

 

[INDYMAC]

Is this a SAE 110 or 140?

 

[Bror Jace]

Ron-Indy,
As INDYMAC asks, the viscosity of this oil ... and the range provided by Blackstone ... seem to indicate a 75W-110 oil instead of the 75W-140 stated. I'd say the range for a 75W-140 at temp should be 22-40+ cSt with most formulated around 25-28 when new.

Can you state the brand?

It could also be that you used a 75W-140 and it sheared mightily ... in which case the noise is just an indication of the condition of the oil. Time to drain and replace.

If the application calls for a 75W-140, it appears your oil change interval is 10,000 miles, max (at least for this brand of gear oil). Wear is higher than it should be IMHO, but not so high as to produce sudden, catastrophic wear that would induce a noise all by itself. A true failure would result in visible debris in the oil and (I suspect) element values a few times higher than what's currently showing.

I agree with Blackstone that bearing wear typically shows up as bronze wear (copper and tin in UOA) unless the bearings are roller bearings.

Replace with new, quality 75W-140 gear oil and I bet the noise goes away or diminishes greatly.

 

[SteveSRT8]

And the other side is many rear ends simply make noise. You may alter it slightly by oil choice, but I have a hard time believing you hurt that rear end at only 26k.

 

[Ron-Indy]

The oil type is Mopar and it is indeed a 75W-140 synthetic. The noise started earlier this past summer and has gotten more noticable over the past 3,000 miles. Other Viper owners that have ridden in the car immediately notice the noise as being odd. Noise occurs regardless of gear selected, load, or engine rpm but is proportional to road speed and continues right down to a full stop.

Agree completely that a non-abused spirited driving shouldn't kill a rear at 26K, especially a supposed heavy duty one. Expected more metal but stupidly took the sample cold so maybe that minimized the readings. Oil looked just like new color and clarity wise. Rear holds 41 ounces of oil plus 4 ounces of friction modifier.

 

[Bror Jace]

Ron-Indy,
Thanks for the update. I am sticking with my original theory that the rear has sheared this oil down, accelerating wear and causing excess noise.

But if other Viper owners are saying it's not common, perhaps your diff was not properly set-up by the factory? Perhaps it's not shimmed correctly and that is causing the shearing, extra wear and noise? All these symptoms seem to go hand in hand.

In the short term, I would change the oil and see how quickly the noise comes back ... say another 6,000 - 7,000 miles? That will buy you some time to find someone who really knows their Dana 44 diffs to open up the rear end and check to see if it is set-up properly.

I'd switch oils ... but that's up to you. If other owners have good luck using the same stuff, I doubt switching oils is going to make a world of difference.

Sweet ride, by the way. The 1st Generation hard top Vipers are some of the most gorgeous cars ever made ... taking after the 1965 Shelby Daytona Coupes, of course.

 

[Ron-Indy]

Thanks Bror,

I'll take your advice and change the oil tomorrow and let you know if the sound changes - Given the work and expense involved for a mechanical repair, worth the effort to try this first. Thanks for the input and yes, it's a great car. Was my dream car and still is.

By the way, do you have a recommendation for a more stout gear oil? Proximity to exhaust generates fairly high temps. Thanks again.

 

[INDYMAC]

I agree with Bror, and think that you probably have a rare gear or LSD defect probably caused by improper gear installation. It's also possible that the metallurgy was defective in the first place too.

Since you only have 26K miles, why don't you take it to the dealer and have them fix it? A rebuild would be better on their dime than yours, and keep your power train warranty intact. Also, stay with the factory recommended gear oil/additive until warranty has expired. If for some reason your warranty does not apply and the rebuild is on your dime, then try a better gear oil. I'm a fan of Lubrication Engineers gear oils, but think AMSOIL and Schaeffers have excellent offerings too.

Good luck and keep us posted on how you fix your wonderful car.

 

[Bror Jace]

"If for some reason your warranty does not apply and the rebuild is on your dime, then try a better gear oil. I'm a fan of Lubrication Engineers gear oils, but think AMSOIL and Schaeffers have excellent offerings too."

I agree with INDYMAC's brand recommendations. Very solid performers each.

I am currently trying Chevron's Delo 80W-90 gear oil in the overtaxed torsen diff of my S2000 ... but it will be years before I will accumulate enough miles to do a UOA and be able to recommend it with the same degree of confidence.

 

[Ron-Indy]

Thanks guys...

Unfortunately original warranty is long since expired as is the extended. It's a 1996 GTS, the stereotypical blue w/ dual white stripe.

Up until this discussion, I was planned on pulling the rear and bringing it to a shop to replace all bearings and reset all critical dimensions. Cost is very reasonable; $100 plus parts. Forunately with some of the proceeds of a 1970 Trans Am I sold years ago, way before the values rose I invested in a full rise scissor lift so the removal and replacement shouldn't be too bad.

New plan is to record the sound as is, change the oil, ride and record again for future reference. If sound diminishes to normal levels, run for a few months and change again with an upgraded fluid. If sound is still noticable, I'll pull it and have it opened up for observation. Either way, will report back....

 

[INDYMAC]

When you change the oil, you might be able to inspect the ring and pinion gears through the drain and fill holes with a flashlight. You might be able to see the source of your problem.

Good luck.

 

[Ron-Indy]

Well, experiment concluded. Changed out diff oil for a fresh dose and sound is exactly the same. Then changed out trans oil as it was time anyway. Since I was changing back to ATF from a Mopar gear oil (Castrol Syntorq), if the sound changed at all it might indicate a trans issue rather than diff, but the ATF had no affect on the sound either. I recorded it each time but since it didn't change I won't bother posting here.

Though I have a borescope, it really isn't high quality enough to examine the innards of something that oily and if it is the bearing they'd be no way to get back there anyway, so time to pull the diff. I'll let you know what the bearings look like once I have them out. Thanks again for the advice.

As a side note, GEN I & II Viper's came installed with Dexron III as the factory trans fill (Borg Warner then Tremac T-56). After some wimpy owners complained about neutral gear rattle, a TSB allowed switching to a higher viscosity Mopar sythetic gear oil as a remedy and the factory fill changed accordingly. I tried it but at a $100 a fill, felt frequent changes were better than high dollar oil that I was too cheap to dump and reverted to ATF+4 since Dexron III is long gone.

 

[gomes512]

Did these use the 44a rearends or was this a full iron?

Not sure how big of a pain it is but I'd crack open the cover and look for debris between the housing and cover indicating abnormal wear. If its a 44a then my first thing to check would be the wheel bearings.

 

[Ron-Indy]

If by "A" you mean aluminum, yes it's an aluminum cased rear. Unfortunately I can't open the diff cover as the cover and mounting arms are all one piece and it's pretty deep up inside the frame. Cover off requires removal. The unmounted diff is a 2008, similar but not exact. Oddly, I never thought about wheel bearings. Worth a listen... Thanks

.

 

[Jim Allen]

Sometimes parts just fail and there's no rhyme or reason to it.

Does it make the noise coasting in neutral? If so, it may be a wheel bearing instead of something in the diff. Also, a wheel bearing may get noisier or quieter in a turn (coasting around the turn so you can hear better). Try turns in both directions.

Does it change pitch with speed or load... can you get the noise to change significantly by manipulating the throttle? If so, that 's more an indicator of diff problems. Also, pinion bearing noise will change pitch with the load, sometimes even more noisy on decel (depending on which bearing has failed). RIng and pinion noise is usually very speed and load sensitive, reaching a crescendo at a certain speed. If the noise goes away in reverse, that may also be an indication of a diff (ring and pinion) problem.

If the true cause does not become apparent, before you start needlessly throwing parts at it, you may let things develop a bit until it becomes more clear.

 

[Jim Allen]

By the way, there are no bronze/copper parts in a rear axle, so I don't know why a roller bearing failure would be indicated by that. Roller bearings are all steel or alloys, so the indication would be in that area. maybe nickel. I haven't seen enough diff oil UOAs to draw any conclusions but that 174 PPM does seem a bit on the high side but only for the 10K mile interval.

 

[Ron-Indy]

Hi Jim,

Thanks for the input - It's noisy under all conditions, with the only variable being speed which it's directly proportional to. I did the definitive test today and am confident that it's the diff. I put it up in my lift and had my son run it at about 60 mph in 4th gear - Obviously a wheels free lift

Anyway, with a mechanic stethoscope, I found that the rear wheel bearings were dead silent, the trans quiet and the rear somewhat noisy, but how much is too much? Then I got in the car, had my son raise the lift to verified the sound and found it quite prominent on acceleration and steady state and even more noticeable while coasting but more likely because everything else was quiet not that it was significantly louder.

Next, removed the driveshaft and repeated – Dead silent under all conditions. 2 hours later, the Diff is on the floor waiting to be cracked open.

Didn’t want to let it go further as I drive a bit over the limit on rare occasions and kinda like to keep everything in tip top shape especially for those situations. Secondly, I pull it off the road for the winter so I have the time to get it done without impacting my drive time.

Will share the results of the overhaul later in the week.

 

[REDDOG]

Good stuff here guys! Thanks to all for sharing!

REDDOG

 

[Ron-Indy]

In deciding on my next diff fill oil I noticed this UOA from the board:

http://bit.ly/hQLnid

Same mileage and very similar iron. Major differences seem to be phosphorus (mine higher = good) and viscosity (mine lower = bad)

Could the lower viscosity be because of the 4 oz. of low viscosity friction modifier I added rather then the shearing that was inititally suspected? The FM is required for smooth operation of the limited slip clutches. 4 ounces doesn't seem like much, but it's about 10% of the total fill volume (45 oz.)

Thanks

 

[Jim Allen]

From my research, the FM does reduce the viscosity a little but also reduces the oxidation resistance of the oil in a way that I'm not clear about. The Dana engineer I spoke to about it said to use only the amount that was absolutely necessary. Some synthetics have friction characteristics compatible with the unit, so that additive isn't needed, but you really don't know what will work until you try it because the friction material in each LS unit is somewhat different.