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Discussion Starter #1
Ok, I'm no automatic transmission tech so I don't know what part of the tranny the noise could possibly be from. Whenever I turn left and accellerate, I hear a grinding noise from the tranny. This has been going on for a while but I never really acknowleged it. I think it has something to do with the speed of each tire when you're turning. When you're turning, the wheels on the the outside of the turn have to turn faster than the wheels on the inside. So I think whatever it is that lets the left tire go slower than the right might have something wrong with it. Unless this is normal, which I don't think it sounds normal. Does anybody know what the noise could be coming from? It never happens when I turn right. There aren't any codes. :hmm:
 

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Just my 2¢

I don't think what you hear is a transmission noise, but may be a hub bearing noise. The hub and bearing come as a unit assembly for about $80 each front side. It is recommended that both sides, left hub and right hub, are changed at the same time. Please follow that recommendation.

I did not, and learned the hard way. Only one of mine made noise so I changed that one. Later I was tooling along at about 70 MPH with the radio cranked up and the A/C cranked down blowing snow, when the other side made a few squeaks then sheared off one caliper bracket bolt causing the caliper to wedge inside the alloy wheel and rotor. The right front wheel locked immediately. It trashed the tire, the caliper, the rotor, the brake line and hose, well, everything but the wheel rim. The rim inside looked trashed but balanced out fine with a new tire.

The tow bill home cost more than I "saved" not buying other hub assembly. Not to mention the damage to my good shorts.
 

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Discussion Starter #3
Nope, this is definatly not a bearing noise. I've heard bearing noises before (not on my caddy). I also regularly inspect various items on my car, and that includes the bearings, because I have to drive it at least 80 miles every day for college. My bearings have no play.

The grinding is not a steady grind and you can feel it throughout the body. I am almost sure that its something in the tranny... Its almost like something is slipping while I accellerate.

Could my two bad upper motor mounts have something to do with it? (I'm waiting for the parts to come in)

I'm trying to read as much as I can find on how the tranny works now, so that I can at least have a generalized idea of what the possibilities are.
 

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Krashed989 said:
Nope, this is definatly not a bearing noise. I've heard bearing noises before (not on my caddy). I also regularly inspect various items on my car, and that includes the bearings, because I have to drive it at least 80 miles every day for college. My bearings have no play.

The grinding is not a steady grind and you can feel it throughout the body. I am almost sure that its something in the tranny... Its almost like something is slipping while I accellerate.

Could my two bad upper motor mounts have something to do with it? (I'm waiting for the parts to come in)

I'm trying to read as much as I can find on how the tranny works now, so that I can at least have a generalized idea of what the possibilities are.
Sorry...I still think it is a hub bearing noise. They don't have the kind of play you would expect due to the disc brakes and FWD. Oh...BTW when they go bad they normally only grind on latteral forces such as left or right turn. Left turn...rt front, Right turn...left front noise.

When the 4L60E starts to go...it will freewheel (slip) while turning a corner but not make much noise at all, but is audible. They tend not to slip from a straight shot like from a stop sign. When they finally go south it will likely be on a downshift. You have the 4L80E transmission which may or may not exhibit the same characteristics.

Bad motor mounts normally cause other type problems like uneven idle.
 

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Discussion Starter #5
If they don't have the kind of play that I would expect, then what kind of play should I expect? When I check them I lift the wheel off the ground, place my hands on the 12 and 6'o'clock positions, and push and pull alternatly to see if the wheel can move at all. Is this the proper procedure? if not, What is? Thank you, for trying to help.
 

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A bad bearing will usually growl long before any play is evident, and the growl will come and go as you do a series of "S" turns like a Nascar driver warming his tires.

Have you considered a CV joint?
 

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I would also like to know how to test for a bad wheel bearing. At the dealer for other issues they stated the right bearing is bad. I had the left replaced a few months ago and would not like to have the same issue as you 91texas. But my warranty company wanted me to go elsewhere for a 2nd opinion. Goodyear says the bearing is fine.

MacK
 

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Discussion Starter #8
I have concidered CV joints but I haven't inspected them lately. I'm gonna go inspect my front end to see if I can find anything unusual. I will probably be back online in about an hour.

Wait I just remembered something. Whenever I reverse (wheel cranked to the left) into a parking space I hear a loud POP. Like the bolt for the knucle is loose or something. Sounds like its coming from the back drivers side wheel. I doubt that a knuckle bolt is loose but maybe these two noises are connected in some way... I'm thinking too much.. :bighead:


MacKiNBack, I'm pretty sure that my way is the usual way that you check the bearings. I worked at two different independant garages and both of them used that same procedure. My back passenger side bearing was bad a while ago, didn't make any noise, but I diagnosed it with that procedure. It had play so I changed it.
 

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Ill have to check it out sometime. I wonder how hard the hub is to change with a, lets say virgin mechanic so to speak doing it? There are plenty of things I refuse to have the dealer do due to price (like my upper front strut bearing), and such.

MacK
 

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Krashed,
That POP sounds like a CV joint from what I remember.

Mac,
A hub and bearing assembly is not terribly hard to do depending on your level of virginity.
 

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Discussion Starter #11
Ok I went out and checked for anything I could find. The only thing I found was that the passenger side CV shaft has about 1/8" of rotational play. Could this be my problem?


You guys are great. I love this forum. :thumbsup:
 

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You typically won't hear any grinding noises from a transmission for very long... if you see/hear something inside a tranny, it's going to break soon. Probably what you're hearing is something either failing inside one of the halfshafts or rubbing against one of the halfshafts while turning...

The axles will have a little bit of rotational play when you have a wheel in the air, no problem with that.
 

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I agree with Ranger...

The "pop" is a good indication for worn CV joint. A good inspection is in order. I really don't think your problem is transmission realated.
 

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Discussion Starter #14
I didn't have the wheels in the air, it was on a ramp, and I was on a creeper under it. I lifted the wheels off the gound only to inspect the bearings for play and the tie rods. Also the drivers side had no rotational play. The play is probably from the halfshaft though.
 

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Krashed989 said:
I didn't have the wheels in the air, it was on a ramp, and I was on a creeper under it. I lifted the wheels off the gound only to inspect the bearings for play and the tie rods. Also the drivers side had no rotational play. The play is probably from the halfshaft though.
You're on the right track.........
 

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Discussion Starter #16
Hmm, this thing is really puzzling me out of my mind.. It did it today on a RIGHT turn, twice. It's definatly coming from the passenger side of the car (the same side that has the worn CV joint, also the same side with the transmission's differential). But I'm haveing a hard time explaining to myself how the CV joint would create such a sound... Its like gear bindage or something, like the one of the differential gears has a bad bearing or something, gah. I guess I'l change the CV shaft and go on from there, but its a very strange sound. I've never heard a car make this sound before...
 

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My 1990 SDV was making the same sound. Almost a grinding noice on left turns with acceleration. I have been through hell to figure out what it was. Turns out that I was missing a tranny mount up front. On left turns the engine was leaning and either the tranny was rubbing up against something or two pulleys were touching. Either way the new tranny mount fixed the problem.

GOOD LUCK
 

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Discussion Starter #18
Well since I first started this thread, I found that if I press the gas hard enough (which isn't very hard at all) it will do this regardless of the direction of the wheels. It's like the traction control is overreactive or something. I don't think it's the CV joint, although I haven't changed the old ones out yet. I don't have the time to change anything out for a little while, so it's just going to have to hold up for now. I am still bewildered by this noise. I can't see how the CV joint could produce a sound like this and not produce a surginess around corners... Its a grinding noise that always stops at about 25mph... I hate not knowing... I'll figure it out when I get some time, but that might not happen till christmas.
 
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