The Stovebolt Site Forums The Shop Area Driveline Bad noise

Hi All,
Well I drove the 65 Chevy Grumman project van home yesterday . Wow... I didn't think it was going to make it .
There's a howling that's either from the trans or the diff . I can't tell which .

The noise is worse at lower speeds, like between 20-30 mph and is less once the truck gets going 40 or better . The noise is not as bad when backing off as it is when the truck is gaining speed . When on a flat road with little to no load the noise is gone .
There's some play in the pinion gear , but I've seen worse cases of excessive gear lash that didn't produce the noise this think makes.
Any ideas of what to check ? It almost sounds like a bad bearing in the trans . Has a bad trans bearing ever caused a howling noise?

I'm really starting to wish that I'd walked away from this nightmare .

Thanks again for all the support !

Oh yeah, 292 with a 4 speed and a front loading "pumpkin" type 1 ton diff.

There is very little in a transmission that can make noise like you describe. However, it is typical of a rear end. Does the rear end have oil in it? Not that it really matters. Once they howl, they have had it. Something like sawdust or banana peels in the rear end will be a temporary fix. One other thing that can make noise is the center bearing. If you are lucky, this might be all it is.

How long have ya had the nightmare? Some enjoy the challenge these old trucks give us. When it gets to be a nightmare we do something else for awhile, I like to crash RC airplanes, then I have two projects to challenge me.

Sounds like rear end to me. Pull the cover & have a look. If the pinion brg is tight & the carrier brgs sre loose you can adjust them up & help it some. It is easy to change the center section if you find a good used one.
Those old aluminum Grummans are great trucks. That's practically all I worked on back when I had a shop.
Have you posted a photo in the Gallery?

You've got a bad pinion bearing, probably the big one right in front of the pinion geat teeth. Don't run it long that way, or you'll shell out some gear teeth. Fortunately, it's not terribly difficult to change out the pinion bearings. I'd reccomend swapping the bearings on both sides of the ring gear carrier while you're in there.
Jerry

Thanks guys.
I was thinking ring and pinion . The center carrier bearing is a good thought . It seemed tight when I checked it , but it could be bad .
I just bought the van about a month ago and thought it would be a pretty easy fix as for the drive line . I think that I've just tried to do to much at one time and now I'm a little burned out . Nothing has worked as one would expect it to . Fix this and then that breaks, if you know what I mean .

The diff in this truck doesn't have a removable rear cover . It's the old style diff that the whole carrier is removed from the front . I think its an Eaton...does that sound right?
The only diff that I recall that was like this ones design was my 63 Impala.
I'll check that center bearing again . The PO did say that it was howling for quite awhile before it was parked, which was 7 or 8 years ago . I did check the diff oil and it was down about a half a pint . No big deal . And the oil was clean as well .
This problem may or may not be a simple fix. The trip to my home is was just over 20 miles. Wouldn't a bad bearing fail in that distance?
I do like the idea of the center bearing being a cause of the noise because the noise seems to be in between the trans and the diff .

I'll try to post some pictures in the gallery , but I'm not the best at uploading things .

Again, thanks for all of the tips . You folks are the best!

I think you're misunderstanding my terminology. The carrier bearings (plural) are the ones inside the housing, on each side of the ring gear. They support the differential assembly. That Grumman van will probably have the same Eaton rear end as the 3/4 ton and 1-ton trucks. If it's one of the bigger van bodies, it might step up to the 1 1/2 ton chassis with an upsized version of the same type of rear axle. Either way, it's time to pull the axle shafts, drop the center section out, and start looking for trashed bearings. You might be able to get an idea of what's going on by draining some of the grease out of the rear end, and check for a metallic shine, or even chunks of metal.
Jerry

If it doesn't have a cover on the rear it must be a 1 1/2 ton chassis or a heavy duty 1 ton. It probably has 10 hole wheels or 6 hole Bud wheels. You can check the pinion brgs by grabing the yoke. There should be no up & down play. Naturally ther will be some turning play.

Your right Jerry , I did think you were talking about the drive shaft carrier bearing . I should have known better , and that would be just way to easy. lol.
The hubs are 8 hole so I don't think its anything more than a 1 ton axle .
Can't say that there's any up and down ,or side play on the input bearing , but the drive shaft has a little better than a 1/4 turn of free play in the ring and pinion .

I did do a little research on the diff and was told that for the most part, no parts were to be had for it . Is this true ? Am I in for a lot of work trying to fit a newer Dana into the van ?

With the free play that's in the ring and pinion,if the carrier bearings turn out to be bad, could the ring and pinion still be good if the carrier bearings were replaced ?

I'll try and get the carrier out this week . I still can't figure out how to upload pictures . Must be a big secret.
Thanks again guys .

There are parts available for the Eaton, but the available gear sets are limited and the parts are expensive.

Before investing in that rear I'd want to consider carefully what gear ratio is going to make the most sense. If its not one of the three available Eaton ratios then you need to consider an axle swap.

You have more options than just the Dana. I'm using a GM 14-bolt under my 1-ton. The 14-bolt was GM's successor to the Eaton and is pretty stout.

Thanks Old Sub,
Ya know, I put a diff from a 73 K2500 into my 76 K1500 short box that I built into a light duty 3/4 ton some 30 years ago now . I never had a problem with that diff . It was either towing cars or pushing snow. I think the diff was a Dana 60 , does that sound right?
Would it be a lot of work to fit a diff like that into this van?
Any idea if a diff from like 73 - 80 would be a direct fit , or would the spring seats need to be repositioned ?
Its a bit8h getting old . Thirty years ago this would be a walk in the park for me.I just can't believe that I've forgotten so much about building plain old Chevy's.

Well, thanks again. You guys are filling up the old dead space in between my ears with lots of options. All are greatly welcomed.

Hello again,
Well this is a little embarrassing to say the least.
After blasting all of the crud off of the diff...it turns out that it does have a removable rear cover, as well as the removable carrier . So now I'm back to wondering what diff this old P30 has .
It sounds like it has bad bearings , either pinion , or carrier bearings . Seeing as to how the rear cover can be removed , will this increase the chance of being able to repair this diff ?

It was thought that if it was an Eaton without a rear cover, it was kind of toast. Since both the front and rear can be accessed, is there a chance this diff can be saved ?

Thanks for any information. I'd really like to avoid changing the whole diff .

First find out what you got.
Clean whole axle assy to find casting or part numbers.

2. Send good photos of everything here to get help on identification.

3. Buy manual "books4cars" in Seattle are one source.

4. Inspect axle differential see what may need done

5. Find parts supply - at minimum I would say wheel bearings and seals - may as well get brake parts while you are there.

Dan Bentler