Stevo1971

agreen

Oh I get what you were saying now. Your rear main was leaking engine oil and might be blowing back to look like it's a bad transfer case seal. Looking at the pictures it definitely looks like it's more concentrated around the transfer case seal, so I'd go ahead and change it.

Try this: Transmission in park, transfer case in 4H. How much can you rotate the front yoke on the transfer case?

Stevo1971

Will do this after work today or this weekend. will report what I find.
Thanks 👍

lawsoncl

That sounds rpm dependent, not speed or throttle dependant? To me at least, that points to the trans or engine. Not xfer case or anything downstream. Any vibes just reving in the driveway in park, or in gear with foot on the brake?

Chick-N-Picker

It's kind of hard to diagnosis the transmission mount by just looking at it. It can appear to be ok but be wore out. Also you should fix the exhaust hanger.

I'm just saying I have had, and currently have the exact issue you describe. A vibrated/knock/whatever you call it when starting from a stop that smoothes out and goes away once I reach enough speed. The longer you wait the worse it will get. Mine now knocks sometimes when sitting at idle and my foot on the break. It doesn't do that at first.

I've already changed my transmission mount once and it solved it for a very short while. Maybe 1 week. Then it came back, and has only gotten worse over time. Guess what though, it still looked new, it was only a week old.

Now I have a Mopar transmission mount instead of the cheap after market and am hoping when I put it in it stays resolved. Based on my research and others the after markets are junk and they only solved their issue when going to a Mopar. I can confirm that Mopar does appear to have thicker rubber so I'm really hoping it fixes it.

Crazy that the original Mopar one I took off in 2019 was 30 years old at the time and looked it but still did not allow in vibration/knock of the exhaust.

Stevo1971

Well, what a nightmare. I went to Advance for the seal. He understood I needed the rear seal. I went home, took drive shaft off, pulled leaky seal out with flat head screwdriver, took new seal out of the box and ……oh man. Wrong part. Gave me the front seal. Called them but they don’t have the rear seal. Three other stores have it and all are at least 25 miles away.
Called the Zone. They have it. Drove 15 miles to store, stopping at Advance to return wrong part. Got to the Zone. They don’t have the part they just told me an hour ago they have. FML
Quit for the day.
Next day call one of the three stores that supposedly have my seal. Tried getting the girl to use a caliper to check against mine. She doesn’t know how to use a caliper. Drove 25 miles to the store. As luck would have it, they don’t have the seal they said they had. FML
The guy pulled a bunch of seals trying to find mine. No deal. He suggested PEPBOYS.
Went to PEPBOYS another 15 miles. They had the part. Finally.
Got home, put in seal. It was pretty snug but it’s in. Put everything back together, filled with new atf.
Took it for a drive. Vibration is still there. And now it seems to be heard even after switching gears. This leads me to believe the next step is drain, clean and fill Dana 35 with new fluid and gasket. It’s hot to the touch after driving which I guess is normal.
Checked motor mounts. No cracks. Look solid.
If the Dana rear isn’t the culprit then I guess transmission mount is next.

Stevo1971

No vibration in park or idle except for exhaust, which has made this noise for years. Having a really hard time excepting possibility that a noise I’ve been hearing for years has turned into this. But what do I know?
In order to fix broken hanger issue I would have to replace that section of pipe and I just spent time and money putting exhaust back together, cat and all, for inspection. Was straight piping it for a year.

lawsoncl

How did the rear driveshaft u-joints feel when you had it out? Floppy loose, tight and binding at an angle. Slip joint not real sloppy? I probably would have had a few spares in hand before pulling the shaft, just because Mr Murphy would rear his ugly head if I didn't..

Stevo1971

U joints were still good. No slop or play.
Swapping them out at same time would have been a good idea they don’t look deteriorated or at least the caps didn’t fall off. It’s easy enough to remove the shaft if need be in the future. As expected for an older vehicle they weren’t exactly clean.