View Full Version : Something in drivetrain is growling
10-13-2009, 03:03 PM
Started 2 weeks ago, out of the blue. It sounds like a bad bearing. It's a constant growling that becomes noticeable ~25mph and increases in pitch the faster I go.
I've rotated the tires, replaced both front hubs and the driver's side half-shaft and the noise is still there. I needed to replace one of the hubs anyway because of a bad ABS sensor, and I wanted to replace the half-shaft to try and get rid of a popping noise reported in another thread.
I've had a couple people listen to it and everyone agrees it sounds like it's coming from the driver's-side front. Any ideas as to what else it could be?
10-14-2009, 10:24 AM
I should add that the noise is the same whether I'm on the throttle or coasting, going around turns or even if I put the trans in N while moving. I've also checked to make sure nothing is rubbing. Basically it sounds like I'm running a set of mudder tires, but the noise only comes from the front. It tracks straight and doesn't pull or push to either side so it's not an alignment issue. I'm worried that it might be in the trans. I did a drain and fill and changed the filter about 5k miles ago and it doesn't leak so fluid should be good.
10-22-2009, 07:08 AM
Well I replaced the last piece - the passenger side half-shaft - and it's still making the noise. It really sounds like a bad bearing. Could it be the stub shaft bearing?
10-22-2009, 07:19 AM
Get a video... does it sound anything like this...
10-22-2009, 07:27 AM
I will try to get a recording sometime over the next few days and I'll post it up. But no, it only makes the noise when moving. Just imagine a lifted pickup with fat 36" mudders going down the highway - that's what it sounds like. My Firebird had a bad carrier bearing once that would whine when under load, this doesn't sound like that though.
Your car sounds awesome btw. It was hard to hear the noise over your exhaust. You have a fquick or cardomain page?
10-22-2009, 07:35 AM
yea i have car domain but i'm never on it, I do use streetfire though.
10-22-2009, 07:45 AM
I was just curious what all you had done to your car.
10-22-2009, 07:51 AM
Stock internals, bigger injectors, a turbo charger, that's all... still gotta get some time here and put my new LS6 valve springs in.
10-23-2009, 08:06 AM
Okay here's a vid. I made a longer one but too big to upload, I'll have to see if I can cut it down.
View Video on FQuick (http://www.fquick.com/videos/GAGT_trans_growl/9071)
10-23-2009, 08:36 AM
Here's a second clip. It gets louder when turning to the right and quieter going left. Also louder coming to a stop.
Question about the half-shafts - is there a stub shaft on both sides or only the passenger side? There's a bearing inside the trans housing for the stub right?
View Video on FQuick (http://www.fquick.com/videos/GAGT_trans_growl_2/9072)
10-25-2009, 03:11 PM
So the stub shaft is only used on the passenger side. But what's this in the housing? It looks like a pinion shaft. Is the differential on the right side of the trans?
10-25-2009, 06:17 PM
Yes, the differential is on the passenger side of the trans. It has a stub output shaft on that side and the longer main output shaft that goes from the diff over to the driver side. Don't know much about the bearings that hold those in place though. I would normally say that noise sounds like a wheel bearing, but you said you replaced those already. So unless there was some other problem that might cause a wheel bearing to wear out prematurely, it must be something else.
10-26-2009, 06:46 AM
Thanks, yes I've replaced both hubs and half-shafts now and no change. Is it possible to get to the differential without removing the trans from the car?
10-26-2009, 04:58 PM
Unfortunately no. The trans case does not have a removable nose like some automatics. The trans has to be removed and completely disassembled to remove the diff. Don't know if the diff is the problem though or if it's something else. Having replaced most of the other things already, you could probably start narrowing it down to something in the trans though.
10-28-2009, 10:05 AM
What is the parts exchange on the MN5? I'm looking for a used transmission and most of these places are stating only 99-00 are interchangable.
As long as I get a 4T45E from a V6 with the GT (3.29) ratio, should it matter what year or model it came from?
10-28-2009, 05:12 PM
No, it doesn't matter. As long as it is a 4T45E (RPO code MN5) with the 3.29 drive ratio (RPO code FR9), you can use any of those transmissions up to 2005 I believe.
I was wondering that transmission questions as well.
Because on my '99 Grand am, it Shifts in to 4th at 35. (Or 3rd if you're going 35->34)
and on my '04 Grand am, it shifts in to 4th at 40.
The RPMs are the same at equal speeds, it just revs higher on the later year car before it shifts.
(1.5k @ 50mph, etc..)
11-01-2009, 07:47 AM
Probably just a programming difference. That is all controlled by the pcm. Has nothing to do with gearing or any mechanical differences in the trans.
11-04-2009, 07:18 AM
It's gotten worse over the past week and after driving it had that burnt grease smell coming from the drivers side so I put a second hub on that side and that fixed the problem. Hard to believe I had 2 in a row or else I got overzealous with the nut one of the times I had it apart. But at least it wasn't the trans.
11-04-2009, 09:20 AM
That's a plus I suppose. What brand of hub assemblies were you using?
11-04-2009, 11:49 AM
Timken. They came with the new nuts which are supposed to use less torque than the stock ones but I don't put them on with a torque wrench, I just made 'em gutentight.
01-16-2010, 12:52 AM
I have the same problem. Is it hard to replace by yourself, or should I let a mechanic take care of that? It started on my car just after i got new tires, so that kinda threw me off
01-27-2010, 01:42 PM
Having put on 3 hubs and 2 half-shafts (which also requires removing the hub) I think I could do it in my sleep. You need a 36mm socket and breaker bar in addition to your standard set of sockets or wrenches.
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