: Rear grinding getting worse - please share your knowledge



Ziplicon Tuesday
12-14-05, 03:16 PM
I posted about this before and one person suggested it's the ABS doing a self check at start up - but it seems to be getting worse.....When I back up after the car has been sitting for hours, I get a grinding noise - just for a second or two after I back up about 10 feet. Especially if I'm turning at the same time. You can actually feel it in the car like backing up over a few stones or snow chunks. Then I shift into first and as I start to go, it happens again - only for a moment.

Do any of you guys who obviously know your shit have any thoughts on this? Could it be the ABS? I don't want to go to the dealer multiple times only to be told they couldn't duplicate it, or it's freakin normal or some other B.S. explaination.

Thanks in advance - it's too damn cold here (12F) to slide under the car and try to figure this out.

04CTSVFLA
12-14-05, 04:01 PM
I don't want to go to the dealer multiple times only to be told they couldn't duplicate it, or it's freakin normal or some other B.S. explaination.

I ****ing hate when they say that!! its the most annoying thing to hear come out of someones mouth, when you spent 50k on a car that clunks and creaks down the road like it is it's job.

for a solution for your grinding, i have no idea. im not an expert. maybe you should get your synchos and definitely your tranny looked at.

lawfive
12-14-05, 04:11 PM
No idea what's causing your problem, although the sound you're describing is a lot like what my 2004 Grand Prix GTP used to do when I would apply breaks while going over bumpy roads, even when going slowly. The Pontiac dealer said that it was normal for that vehicle's ABS to actuate under those circumstances.

I've never had it happen on the V, so your situation isn't normal in my experience.

Suggestion: leave the V at the lot overnight, then go there in the morning and show 'em while it's still cold.

keeksv
12-14-05, 04:13 PM
If it's coming from the rear of the car, it may be the limited slip diff grinding. At one point people on here were recommending going into a parking lot and doing some lock-to-lock turns or circles to help spread the diff fluid around inside. If I were you I would check the fluid level or better yet just change it altogether and see if the noise persists. May want to have the dealer change the fluid for you, but make sure the additive is put in. That way if it's something more serious with the rear, they are already involved.

ew

ylwjacket
12-14-05, 04:27 PM
Since it has gotten cold (yes, it's cold here in Central Florida in the morning), mine does the same thing. It's coming from the front, though. Once the engine warms up, it goes away. My kids even ask me what that souond and vibration is. It feels like the ABS on steroids pumping the front. It's more pronounced when turning, but there going straight as well. I've checked the power steering belt, and it looks OK, and the CAI is not rubbing on it. I figure if I take it to the dealer, the engine will be warm by then, and they would have to wait until first thing the next morning to experience it.

Ziplicon Tuesday
12-14-05, 04:28 PM
As always thanks for the input....I may not be alone in this...I just found a service bulletin dated 10-28-05 that discusses a differential "shudder or binding on low speed turns" such as in a parking lot. (good call ew) Oddly, they say it may happen at operating temperatures - mine is when its cold (I HATE the freakin' cold). Anyway, the fix is to replace the axle fluid, drain it, then replace it again with an additive. Looks like I'll be heading to the dealer (HATE that too).

If anyone happens to have other thoughts, please share'em - I could be wrong with the service bulletin.

keeksv
12-14-05, 04:35 PM
Glad to know that the countless hours I have spent on this site can help someone...:D

leap229
12-14-05, 05:17 PM
I have the same thing going on with my V. When cold and backing in a turn there is a grinding/bumping sound. It almost sounds to me like when a four wheel system is engaged on a dry surface in a turn and the drive line binds. It goes away when warm, and I really can't hear that it does it going forward. Here in Chicago it is pretty cold, and it will do it after only an hour of sitting outside.

The dealer had it for two days and reported first that they couldn't duplicate it and then that they thought it was the traction control/ABS cycling. I asked why it would be cycling like that, and particularly why it would make so much noise. They simply said it was normal, but it doesn't seem normal to me.

As for replacing the diff fluid, I asked for, and paid the dealer to do it. The sound was still there.

If anyone learns more about this, please let me know. It is an annoying sound, and I would hate to think I am doing long term damage.

cts-v ls6
12-14-05, 08:12 PM
I solved this problem on my V, but I can't take credit for the solution. Phil at DTE told me what to do, I tried it and it worked. My 2004 V was making the grinding noise every morning when backing out of the garage, hot or cold weather, and especially when I cut the wheels. You want to use Redline differential lube, not GM. Also, add the GM posi lube EVEN THOUGH the Redline product has the posi lube additive. I did, and bingo, no more problems at all.

Jack

Ziplicon Tuesday
12-14-05, 08:36 PM
Jack,
That sounds a lot like the service bulletin - they flush it and then replace the fluid plus some additive. Hopefully it's attached - does this sound like the same issue to you guys?

odysseus
12-14-05, 08:40 PM
I noticed my regular CTS (open diff) doing this recently when it's below freezing. Mine definitely is coming from the front wheel area and sounds like I'm running over snow or ice (popping, crunching kinda sound). It only happened when I was reversing with the wheels fully turned. It went away as soon as I shifted to first and went on my merry way. It did it three times this week (after several hours of cold soak). I'm assuming it's something with the ABS when it's very cold.

ahahnu
12-14-05, 09:45 PM
I was coming on here to start a thread about the same thing. Its really damn annoying. It does sound like your (front) wheels are skipping when backing up with the wheels turned.

leap229
12-16-05, 07:13 AM
Thanks for the note re the TSB, but it only does it when it's cold. The noise I get really doesn't sound like something from the rear. When warm, no problems at all. It could be the ABS when cold just being cranky. At first I thought it was the sticking break pads thing:

"Brake Lining Bind After Setting


The Brembo brake components have a tendency to a light bind, often noted as resistance, then a light clunk when attempting to move the vehicle forward or rearward after a cold soak. This is usually noticed after parking, when the brakes have been wet, as in driving in the rain or just after a car wash. This is normal and does not effect the operation or performance of the brakes. "

But the clunk is not what I would call "light" and there is more than one and as long as I stay in reverse in a turn (yes I did do backwards circles in a parking lot last night) it keeps on clunking until it warms up a bit.

Ziplicon Tuesday
12-16-05, 02:31 PM
Yesterday it was 14F - had the grinding noise and sucky 1 to 2 shifting. Today, it's 45F (freaky weather) and no grind this morning plus the shifting was better. So mine is only when it's cold too. But I can't make it happen continually (I did the backward circle thing too).

So I guess as long as I don't drive this thing in the rain, or cold, or snow, and I keep lubricating the wheel hop abortions, and assuming I can ignore the "normal" clunking - I'll be fine. WTF is Cadillac thinking?

V-Sting
12-17-05, 05:57 AM
OK, so while on the subject of superior gear lube, is there a better fluid for the tranny, like the Redline for the diff?

jenzkam
12-18-05, 02:35 AM
As always thanks for the input....I may not be alone in this...I just found a service bulletin dated 10-28-05 that discusses a differential "shudder or binding on low speed turns" such as in a parking lot. (good call ew) Oddly, they say it may happen at operating temperatures - mine is when its cold (I HATE the freakin' cold). Anyway, the fix is to replace the axle fluid, drain it, then replace it again with an additive. Looks like I'll be heading to the dealer (HATE that too).

If anyone happens to have other thoughts, please share'em - I could be wrong with the service bulletin.

Mine started to do the same thing your explaining. I get the I'm backing up over something noise, then when I make a turn (U-turn or just turning sharply) I hear this loud rubbing noise which sounds like it's coming from the front end. Well my V went into the shop for this in August and was told it was my busings and my rear differential needed to be flushed out with new fluid. WELL it's worked for 4 months and the same sounds are back. Finally, another dealer is ordering a new rear differential, sadly it's my 2nd one in a year! :banghead:
Good luck with your situation.

Jen

Ziplicon Tuesday
12-19-05, 08:20 PM
Jen,
On the site at 2:35am? That must be my time (EST).
Anyway, I take it this happened to you in the warm weather since CA (not to mention August) - Mine is only in the cold and from the rear. It almost feels like a dry gear binding. I'm taking it to the dealer on the 26th....but my hopes are not too high.