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View Full Version : Howling from the drivetrain.



TbirdSCFan
11-09-2004, 11:41 AM
I might not make it with the original differential to 200000 miles. I'm getting this moderate howling noise which is fairly constant and varies with vehicle speed, rather than engine speed. Its hard to tell but pretty sure its coming from the back. differential? I suppose it could be the CV joints, anyone ever have those go out? Any of you local fellows have a spare differential for sale? Can I just pull the plug an pump it full of gear oil to fix it up? :)

FearThis SC
11-09-2004, 02:51 PM
Its one of the Half-Shaft, trust me! I had the same thing, turn out to be the joints in the half-shaft were TOAST!

TbirdSCFan
11-09-2004, 07:57 PM
Is that an easy fix?... or should I seek out a 1/2 shaft from someone with a few spare SCs sitting around?

FearThis SC
11-10-2004, 09:35 AM
Is that an easy fix?... or should I seek out a 1/2 shaft from someone with a few spare SCs sitting around?
Very easy fix, just need a NEW axle nut. Unbolt the bottom bolts from the spindle, then angle it upwards so you can pop the axle out!

Jack it up and check to see there is any play in the half-shaft before. You will know if one of them is bad.

Yes, I would seek one from a member parting out an SC! As long as their is no play in the joints.

TbirdSCFan
11-13-2004, 10:04 PM
Well, I finally got around to propping the back end up and spinning the wheels. The noise wasn't coming really from either side, so I decided to check the diff fluid... it was bone dry :eek: So I pumped in about 24 oz of 90 weight hypoid gear oil and I guess I'll find out if it was in time to do any good. :D

Update: OK.. For anyone following the thread, adding diff oil made no difference. :( Still making this faint ghostlike howl noise. At around 35mph, you can hear it pretty good. When I had the rear jacked up and ran it to the same speed, it didn't seem nearly as noisy. I don't have the nerve to crawl under the car with the wheels spinning and stick my broom handle stethoscope up to the differential to narrow it down.

Guess I'll dive in on the the 1/2 shafts this Friday. Either that or maybe I'll swap out the transmission instead. Decisions decisions.. Its supposed to rain and it'll probably be cold as well.

FearThis SC
11-16-2004, 09:57 AM
So your rear differential was the problem? Did you get around to checking out the half-shafts? I need closure :) LOL!

TbirdSCFan
11-16-2004, 11:33 AM
I don't think its the differential because even as dry as it was, adding oil should have changed something.. which it didn't. So, I'm going to check out the 1/2 shafts this wknd. I was hoping when I had the rear wheels up and running that it would be easy to pin down, only it just sorta moaned through the whole back end. :( And I didn't have the nerve to crawl under the back with the wheels spinning and my wife working the gas and brake pedal :rolleyes:

One of our members has some 1/2 shafts for cheap; I may go ahead and get the knuckle/bearings off him while I'm at it. I've never heard a bearing go with this sort of noise but I guess there's always a chance. Usually, they make a constant groan thats louder and sounds like something out of balance.

FearThis SC
11-16-2004, 11:50 AM
Did you check for play in the half-shaft while you were under the car? They shouldn't move at all. If one side it moving more than the other one, I would change that one out first.

TbirdSCFan
11-17-2004, 01:05 AM
Did you check for play in the half-shaft while you were under the car? They shouldn't move at all. If one side it moving more than the other one, I would change that one out first.Not yet. I have Friday off, so I intend to check it out then. I'm going to swap out the U joints also because I was going to do it when I swapped the tranny out anyway. They're original parts and I can't say they aren't the culprits either. Before this is all over, I may end up refurbishing the entire drivetrain. ;)

FearThis SC
11-18-2004, 01:09 PM
When I did my tranny, I had the driveshaft balanced and had new U-joints installed as part of the service. It was roughly 70 bones for the service. Let us know what you find.

FearThis SC
11-19-2004, 01:34 PM
What did you find? Inquiring minds want to know......

TbirdSCFan
11-20-2004, 01:54 AM
What did you find? Inquiring minds want to know......Well. All I got to was the rear ujoint which was tricky without removing the driveshaft or the diff yoke but I managed. Seems slightly better, but I can still hear some of the noise. Could just be humidity. However, found out that as I would rotate the rear wheels to move the yoke around as I was working on it, I heard this squeeking from the center of the car. Sounded like the shaft seal. The front ujoint didn't have obvious play, but there was some at the back of the transmission.

1/2 shafts seemed fine. No play and the boots are solid. One of the noises, a low growl when I come to a stop, does seem to come from the center of the car. I think at this point, I'll just see what happens with the newer tranny. :cool:

huckleberry
11-28-2004, 11:30 PM
if you added that much gear oil to the diff chances are the pinion bearing is doing the howling . you will need to replace it soon. it will start to leak very soon. the bearing is to high to get oil when the level is low. it is the first thing to cook

kenshi
12-01-2004, 06:20 AM
That sounds just like my differential when it was going bad. It howled for a very long time, and then when it started chattering, I figured I better do something. Check your oil again and see if there's metal in it.

TbirdSCFan
12-01-2004, 12:58 PM
The coating on the plug was silver-ish, but if there are shavings in the bottom of the diff case, I wouldn't be able to see them w/o pulling it apart. Anyone know if rebuilding the diff is easy/hard? Can you just replace the main bearing? I've seen the kits referred to from MN12performance, but didn't see them listed for sale. This'll be a springtime project as I need to do some minor other things first such as plugs & wires, replace head gaskets, swap out transmission, etc. ;)

TbirdSCFan
12-01-2004, 01:02 PM
if you added that much gear oil to the diff chances are the pinion bearing is doing the howling . you will need to replace it soon. it will start to leak very soon. the bearing is to high to get oil when the level is low. it is the first thing to cookI can believe it. Of course, the seal has been leaking for quite a while now which is why the oil was gone. If its the case, I only have myself to blame, I caught a whiff of diff oil a year or 2 ago and said "I probably oughta check it out" thinking it was no rush, and then never did until recently. :(

FearThis SC
12-01-2004, 02:48 PM
Anyone know if rebuilding the diff is easy/hard? Can you just replace the main bearing? I've seen the kits referred to from MN12performance, but didn't see them listed for sale.
I would leave rebuilting your diff to a trained professional. I've heard horror story from ppl that have done it themselves, needless to say, they howled and chewed up their brand new gears. There are very special tools need for the correct aligment of the gears, not a lot of room for error. I say take it to a drivetrain shop and have them do it.

Doug Franklin
01-17-2005, 06:56 AM
"Standard Transmission" in Ft Worth.

They only work on std trannies and rear ends. They prefer you remove it and bring it in. If you want changes they can do that too.

My old Dodge truck was $600 a couple of yrs ago with all new bearings gears and spider gears and seals, but then they had bought out a Chrysler dealership stock of parts.

Maybe a good place in Dallas but even when I was in Dallas HS 30 yrs ago we came to FW for stuff like this.

Doug Franklin
01-17-2005, 07:01 AM
For much less you may find a used posi track in a Yard with what ever ratio you want. One Yard had 10 rear end subassemblies and I found a 3.27 trac lock. Of course never know what your getting.

TbirdSCFan
03-01-2005, 02:56 PM
Last wknd, I swapped out the transmission and differential for 2 newer ones. The trans was from a 92 w/ less than 80,000, going by what I was told from David Niebert, and the diff was from from an 89 w/ about 105,000 that I got from Dan Smith.

The trans seems to be working great so far, and my wail/faint groan is gone. Although the newer diff is not whisper quiet as I would prefer, at least its quieter. :D

So with my head gaskets, and driveline issues solved, I should be able to travel to any part of the US for a meet. :cool:

I'm going to hold onto the old AOD until the weather heats up and I'm sure my newer one is solid and then I'll dispose (sell or give away) of it. With an extra cooler, it should work perfectly as is w/o any repair. In fact, I probably could have installed a cooler and not swapped the trans out to begin with, but the opportunity to get a new one was just too good to pass up. :D