Intermediate Shaft Noise?

Hi all. It's been a looooong time since I posted. I've been toying with the 67 CJ5 after years of only occasional driving (mostly sitting), and I've decided to address the excessively loud T90J/Dana 18. I rebuilt the 18 in 2010, and the T90J in 2013/14. I'm pretty sure I put in a Novak shaft, but I can't really remember. Does this sound like only intermediate shaft, or should I just start from scratch and rebuild them all? It gets really loud at higher speeds, but disappears when not under load (but there is still a different roar). I still have all my Rick Stivers kit I made for the countershaft. I'm definitely going to do new gaskets and try to stop the drip again.

There's also kind of a helicopter sound as well that gets louder with speed. You can kind of hear it in the video. That sound has been there for years.
Thanks in advance!

 

You can remove the gear and shaft for inspection while leaving the transfer case intact.
Not necessary to remove transfer case.

 

Id say it sounds normal but maybe its not. Sometimes mine is loud and other times its not. Maybe try some different oil.

 

Just finished doing a second rebuild on my D18. First one was done with a Kaiser Willys rebuild kit. Had about 60 miles on it and it made the same noise as yours. Ordered a Novak kit and did the second rebuild. It sounds the same. I don’t know how it sounded before I did the restoration, I am thinking it was likely the same. At least that is what I’m telling myself, I am NOT taking it apart again!!

 

JMO - the Dana 18 is noisy. When the Dana 20 was introduced, it was called the "new silent transfer case" (quieter but hardly silent) because ... the Dana 18 is really noisy, as well as wearing out rather quickly. Considering the expectations of modern drivers, I would not be surprised if new owners found a normal-sounding Dana 18 to be alarmingly loud.

I'd point out, that the intermediate shaft is connected to the rear driveshaft always, so the speed it turns is proportional to the speed of the Jeep. Thus noise should increase with speed and the pitch of the noise should not change as you change gears. Same thing in low range, except the straight-cut low range output gear is now meshed with the intermediate gear, plus the intermediate gear speed is then 2.42x faster for a given speed. Now, straight cut gears are LOUD; reverse in cars is typically straight cut, and makes the characteristic whine.

What I would do - there must be a dB app for your smart phone. I would find a quiet stretch of road for a test, and make some measurements. Then I would drive the Jeep for another 1000 or 2000 miles and see if it gets any louder. You'd need to make everything about the measurement the same for the testing.

About 20 sec of searcing - https://www.healthyhearing.com/report/47805-The-best-phone-apps-to-measure-noise-levels#:~:text=Apps for both Android and iOS 1 Decibel,and decay rates. 3 Too Noisy Pro.

Realize that tires wear down and (typically) get noisier with time too. I would try and position the phone so the majority of the noise it samples comes from the transfer case.

Also JMO - insulation on the floor will reduce noise a lot. I realize that many like the all-weather character of their interiors (ie bare floors), but a couple of thicknesses of jute carpet padding and indoor-outdoor carpet will lower interior noise substantially. Plus it feels nice on your bare feet, should you choose to drive in your sandals or bare.

 

My M38a1 is a little quieter. You may need a new intermediate shaft and bearing.

 

Video is unavailable.

 

If there wasnt a picture I would have thought it was my Jeep. My 18 is pretty fresh and sounds the same. Turn up the radio...

 

Herm the Overdrive Guy did my last rebuild when I lost the needle bearings in June, as I didn't have time to rebuilt it and just wanted it done. I've rebuilt several, and have a pile of rear bearing shims, extra seals, gaskets, etc., but I needed to focus on rebuilding both axles and swapping the ring/pinion in my D25, so divide and conquer. Herm's rebuild is probably the quietest D18 I have ever had. I also ordered the Advanced adapter cone bearing kit and sent Herm my old intermediate gear so it could be machined for the different bearings since the inside was damaged when the needle bearings went south. New gear should be here in a few days (along with the parts to move the ebrake to my 11 inch brake drums), but now I'm not sure I want to install it and mess with my now very quiet D18. I hate to think that I spent money on an upgrade I won't be using right away...

 

Let it sit in a box on the shelf then.
Use it another time.

 

Here is mine, it used to be quieter but the inside of my intermediate gear isn't great and I managed to flat tow 200miles without oil in the rear axle.
Seemed fast at the time

This one is a bit faster

 

Should work now. Forgot to check a box when publishing.

 

Scott - I can hear your music which tells me a lot. That's loads quieter than mine. Max volume on my Bose bluetooth speaker is almost drowned out by mine....you can hear my voice when I push the clutch in and out.

Thanks everyone for the replies. I pulled it all and am going to go through it, including the T90.
Now....how much pitting is too much pitting on the gears? I have another T90 laying around that I could swap parts if they are in better shape.



cj2atruck - Herm rebuilt my overdrive for me, but the shipping was huge from KY. I'm going to try to do what I can on this end before sending off my transfer case.

 

Hmmm, that's a lot of pitting. If you have better gears in your other transmission, I would mix and match to get the best transmission back into the jeep so you reduce the risk of messing with it again in the near future. If you don't have better spares, I would just run them and be easy on the throttle.

Back in the day when I was running T90s behind small block Chevy motors, I had three transmissions in my garage, and always one ready to install, as I kept losing the needle bearings between the input and main shafts. After a few swaps, I started shimming the main shaft at the rear bearing to reduce the play between the two shafts, which helped them live longer.

 

Yes, those look quite bad to me. I know that bearings with pitting are noisy (whine), thus I would expect pitted gears to be noisy too. I would be inclined to replace those with better used gears if I had them, or with new production if not. The sliding gearswould not concern me, since they are only in contact when that gear is selected. Second and the cluster gear are meshed and spin constantly when the main shaft is turning.

 

As mentioned previously, replace those gears.

 

Thanks all. I tore into it tonight. Needless to say...it is ugly. I'm going to put it all in my build thread http://www.earlycj5.com/xf_cj5/index.php?threads/94558/page-5