85w140 Oil Helped a bit with Vibrations?

[SwampSurvivor]

I have been chasing driveline vibrations for 2 years on the cherokee. Finally decided to do SYE this spring. Driveline angles were set properly with shims on the axle. I still had vibrations. Then, I decided to bring the double cardan driveshaft to fleetpride to have it rebuilt and balanced. They did all of thta. Still had problems. I noticed that if I would drive for extended periods of time, they would "creep" down slower and slower. IE - on the way into work in the morning, I could go 55 with no problems. But on an extended highway run, I would have problems with 45 by the time I got to my destination. I decided to dump in some 85w-140 oil to see if that helped. Oddly enough, It seemed to help a bit. I can now run 65/70 with minor vibrations. Last night I drove it at 70 for probably 15 or so miles and the vibrations didn't get to the point I thought I was going to get an inner ear infection or have something let go. Guess my rear end is toast. Apparently something is so worn out that the 80-90 would get too "thin".

 

[Doog]

Try putting a microphone on the rear diff and driving on the freeway. That might give you a better indication if you have an issue with the diff.

 

[Rand]

might be a good time to upgrade to a 8.8 from a ford exploder.

 

[NHGUY]

The Chrysler 8-1/4 and Dana 35 is well known for bearing/gear failures.Parts stores sell a ton of Cherokee/Grand Cherokee bearings/seals due to the problems they have.

 

[SwampSurvivor]

Originally Posted By: Doog

Try putting a microphone on the rear diff and driving on the freeway. That might give you a better indication if you have an issue with the diff.

Interesting. I'll have to try that!

Originally Posted By: Rand

might be a good time to upgrade to a 8.8 from a ford exploder.

I'm trying to figure out how to make that work. They are somewhat readily available in 4.10s. All I would need to do is weld on some leaf spring perches and upgrade the parking brake cables and brake proportioning valve to get it under there. Viable option as I can get a good 8.8 for $100. The only downside is the 8.8 is a bit narrower than the 8.25'' axle.

Originally Posted By: NHGUY

The Chrysler 8-1/4 and Dana 35 is well known for bearing/gear failures.Parts stores sell a ton of Cherokee/Grand Cherokee bearings/seals due to the problems they have.

The Dana 35 is a pretty bad rear end - not just pinion bearings. This 8.25 has always howled on deceleratin. I have a 6* shim in the back and I ran it low on oil for an unknown amount of time. I checked it back in May (for the first time ever) and it only had 1/2 quart in it (full capacity is 2.2 quarts). My guess is not only did it starve the pinion bearing but lots of other things.

 

[artificialist]

I'm glad you were able to quiet it down with just oil, because my dad knew some people who had to fill the rearend with grease because of a lousy design.

 

[SwampSurvivor]

Originally Posted By: artificialist

I'm glad you were able to quiet it down with just oil, because my dad knew some people who had to fill the rearend with grease because of a lousy design.

That may need to come next! I need this to hold out another 6 or 7 months.

 

[Greasymechtech]

Amsoil SAE 190 or 250 Torso SAE 250 Lucas SAE 250 Go thick typically means that it's broken

 

[SwampSurvivor]

I'm doing the equivalent of putting 20w-50 in an engine because it has low oil pressure and knocks ...

 

[andyd]

Heh heh, 80/90 was keeping the rods attached on my first car. I was 10 and the car was a 53 Ford I paid 5$ for. PS, my 528e owner's manual suggests 20w50 for my temperature range. It does the job quite well.

 

[MolaKule]

"double cardan driveshaft " Are you referring to an actual vibration that seems to run and up and down the driveshaft, or a noise that is coming from the differential? Are the U-joints "phased" properly?

 

[SwampSurvivor]

Originally Posted By: MolaKule

"double cardan driveshaft " Are you referring to an actual vibration that seems to run and up and down the driveshaft, or a noise that is coming from the differential? Are the U-joints "phased" properly?

It's coming from something either in the driveshaft or rear end. It goes away when I remove the driveshaft. The same was true when the pinion bearing failed in the front differential. Wasn't the driveshaft, but problem would go away when the driveshaft was out. U Joints are phased properly.

 

[MolaKule]

If there is any wet areas around the drive pinion bearing seal you most likely have 1.) a drive pinion bearing going out. Other possibilities are 2.) a chipped or missing tooth on the drive pinion gear or the ring gear, or 3.) an axle bearing. Usually it's 1.

 

[SwampSurvivor]

This seems to be eerily similar to what happened in the front. Seeping oil through the pinion (yes, I'm a dumb --- for not checking the leaking differential for two years) and vibrations. Eventually they got worse and I could wiggle the pinion yoke around. The 80w-90 seeps through the pinion. The 85w140 does not ... yet. This particular rear axle is known for pinion bearing failure. It's going to get expensive, that's for sure. I'm not going to pay the labor to have a new pinion bearing put in and end up with 3.55 gears; if I am paying for that labor it's getting lower gears. Which, of course, means the front needs it as well.

 

[artificialist]

Originally Posted By: Miller88

It's going to get expensive, that's for sure. I'm not going to pay the labor to have a new pinion bearing put in and end up with 3.55 gears; if I am paying for that labor it's getting lower gears. Which, of course, means the front needs it as well.

Did the vehicle have a factory option for 3.55 gears? If so, getting a good 3.55 gear front differential may be a cheaper and simpler option.

 

[SwampSurvivor]

Yeah it has 3.55 gears right now front and rear. I just don't want to spend $500 and end up with factory gears. That's what lead me to buying an entire junkyard axle and swapping it in last year; I didn't want to spend the money for a regear and end up with factory gears.