Dana 20 Whine on 45-50 MPH Acceleration

D

Desertratsocal

New member
I have a 1972 Scout II with a big block Chevy 396, turbo 350 and novak adapter Dana 20. I am running Dana 44's front and rear with disc brakes all around. The bbc is fired by an hei system and fed by a 770 Holley carb. The exhaust is novak block huggers designed for a Jeep application. The motor mounts are novak Jeep mounts for a older commander. When I adapted the transfer case, I went from a (tf 727) 18/8/56 bull gear to a 18/8/55 6 spline bull gear (Jeep t150). Also, the engine and transmission is offset by 1 1/2" to the driver's side for front driveline clearance for the turbo 350 pan.

Now the issue: when driving the Scout at highway speeds, I get a distinct whine/howl at starting at 45 mph on light acceleration. It doesn't do it on hard acceleration. When I back off the pedal, I get moderate gear noise which goes away as the speed decreases at around 40 to 35 mph. It does it as well during even throttle at 50 to 55 mph, but won't do it at lower speeds.

I have new drivelines. The transfer case functions properly and is full of 85/120 lucas gear lube. Both front and rear differentials have been rebuilt. The transmission and engine have been rebuilt. I have tried two different Dana 20's and they both did the same thing. I am running a twin stick on the transfer case.

The only thing I can think of is that the bull gear isn't torqued to the 150 ft. Lbs.? Would that cause the issue I am describing? Or does my Dana 20 need rebuilt?

Thanks!

Scott - usmc(ret.)
 
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It is absolutely coming from the transfer case. The gear sets are identical. The first one I tried I have torn down now and the bearing are shot.

Yesterday I unbolted the second transfer case and retorqued the bull gear, replaced the gasket and bolted it back on. I filled it with gear lube (85/120 lucas) and took it for a spin. It is moderately quieter but the noise is still there.

When shifting from reverse to drive and back to reverse there is quite a bit of what sounds like "gear" play coming from the transfer case. So I suspect the whole thing needs rebuild.

I think I am going to opt for bolting a NP205 to my th350.
 
Were the drive shaft/ u-joint angles checked, and are they equal and opposite front to rear? U-joints that are borderline or working out of spec can transmit noise that we hear as something else, and also cause premature wear on things close to them like transmission output bearings or differential pinion bearings.

The speeds and noise you describe usually point to a worn slip joint on the drive shaft, but you say the shafts are new. Sometimes the slip joint gets re-used.

I would check the the d20's rear output shaft end play. It should be between .001" to .005".



Lucas in the right application or dilution like they suggest does help as a viscosity modifier, but usually a good gear lube is better.

These are the things I would check if it was my rig.


I confused the lucas 85/120 with their stabilizer.

Ret. Marine? Very cool!
 
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The driveline angle is 2 degrees from left to right and 5 degrees up and down. I had to off set the engine and trans/transfer an inch and a half to the driver's side for front shaft clearance so it did give me that 2 degree left to right angle on the driveline. The driveline was build with all new part by ihonlynorth and is 37 1/2" long sitting length. I went with 1310 u joints rather than cv's at the transfer case yoke. Maybe I should have gone with a cv driveline with the 2 angles and that would eliminate this weird noise that is driving me nuts. After the western regionals, I have a NP205, fresh and new, sitting in my garage, and I am tempted to just complete to GM conversion and sell my novak adapter and two Dana 20's.

Thanks guys ---------

semper FI.
 
Not having a cv in it with those angles might. You’re sure it’s not just a gear whine in it? Although, you do have two, unless they are from the same company. Some could be noisier than others.
Hmm, Dana 20 for sale… in our yahoo group the ‘joke’ of making offers on parts and for rigs is "$50 and a tub of chocolate pudding".
 
With a 2* horizontal and 5* vertical, the compound angle figures out to an included 5.4* and well within u-joint tolerance.

The only thing I could say without being there is maybe a u-joint cap u-bolt was too tight, or a joint ain't lubed and now the trunnion has ridges or the rare occasion the drive shaft is not 100% true. I've had one new shaft that had to go back and get trued, even though it was guaranteed when it left.

I look for simple stuff, root cause of failure if I can find it before stuff gets swapped.

Being so speed/throttle related, to my mind it is something in the driveline and not so much the transfer case.
 
I will try a cv rear driveline before I spend the money on a full rebuild of the Dana 20 which worked fine before, or even a np 205.

Thanks for the advice.
 
desertratsocal said:
...the transfer case functions properly and is full of 85/120 lucas gear lube...
Click to expand...

Is that a gl-5 gear oil? If so, that grade is not recommended for use in the vintage Dana transfer cases (look it up - the topic has been discussed here before). Most use sae 50 motor oil. An sae 90 gl-1 gear oil is good, but May not be as easy to find.
 
I ran it hard at the ihwr and it ran just fine. As it turns out, I May just be whining about my Dana whining. Actually I put a cv rear drive line on and that did the trick. It had to be the 1 1/2" offset to the driver side for the big block Chevy and the lift size that threw the geometry off. Once I went with the cv I had virtually no more whine. Thanks again and I do appreciate it.
 
Do consider my (and many other IH enthusiasts') recommendation of a non-gl5 gear lube for your older Dana transfer case. I, too, made the initial mistake of using the typical off-the-shelf gear oil (gl-5 ep/hypoid type) in my t-case. When I switched to an sae 50 motor oil in my Dana case, the shifting quality became much smoother. I would also think it would make a 'slight' improvement in fuel economy, too.
 
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