LS transmission whine

**Del** · #1 (**permalink**) 04-16-2006, 12:03 AM

I have an interesting question for the tranny gurus. The 94LS (60k miles) has a slight but noticeable whine in the transmission, more noticeable in 4th and 5th gears upon acceleration. The workshop manual Mechanical Transmission Test/Check E says that if this whine is present and noticeable, check the spur gears and, if need be, change those spur gears. It doesn't say anything about the whine changing pitch as the transmission is shifted from gear to gear.

What spur gears are they talking about? Nowhere else do the writers of the manual describe or identify these particular "spur" gears.

Spur gears by definition are straight cut gears, not helical, and they whine, depending on the amount of meshing. Helical cut gears tend not to make gear whine noise, one of their attributes. The only straight cut gears in the transmission are the reverse gears.

The other characteristic is that this whine changes pitch (down) when shifting from, say, 4th to 5th, ie, to a lower engine rpm at constant vehicle speed. This seems to indicate that the mismatch (these whines are usually caused by gear mismatches, not bearing problems) is caused by something amiss in the main shaft stack, since the gears on that shaft change rpm when shifting, but the main shaft stackup (the gears being indexed to the shaft by keys) does not. By the same reasoning, the problem shouldn't be in the diff, as that also doesn't change rpm when shifting gears, and the noise is present when driving in a straight line, when the gears in the spider cage are not turning.

Is it possible that this particular whine, even while it seems to be described by the workshop manual as a (spur) gear problem, is in fact a main shaft bearing problem? The transmission does perform flawlessly, and unfortunately just had a new clutch installed last year. Should have had the transmission checked out at that time.

thanks for any ideas,

Del

**Alfisto Steve** · #2 (**permalink**) 04-16-2006, 07:24 AM

Could be driven shaft bearing which you can inspect in the car by pulling the 5th gear outer case cover off. You would have to jack upper tranny and remove tranny mount to pull cover.

**Del** · #3 (**permalink**) 04-16-2006, 12:12 PM

Steve,

That was kinda my thoughts as well, since I can't identify the spur gears the manual talks about. Richard King said that, with his automatic, he had this same sort of whine, and changing what he thought were spur gears eliminated the noise. I don't know where these spur gears might be in an automatic, let alone the manual transmission. So I'm left thinking it might be that big "rear" bearing between 4th and 5th gears on the main shaft.

Would be nice to know, though, just which gears the factory thinks are the relevant straight cut spur gears in this transmission. All I can find are helical cut gears. Maybe they think one or more of these helical cut gears are their straight cut spur gears. Spur gears being straight cut by normal definition.

**elite38868** · #4 (**permalink**) 02-12-2007, 10:39 PM

Del, was your problem resolved?

jontg428 · #5 (**permalink**) 02-13-2007, 08:47 PM

Mine has always had a slight whine, never has got any worse or any better. I have also heard this in a few 164's I have driven, but not all. Could be a sign of things to come maybe.

**elite38868** · #6 (**permalink**) 02-13-2007, 09:08 PM

Whew! I started hearing this whine in 2nd and 3rd pretty loudly, but then I checked my tranny fluid and it was really low! I filled it up and the noise went away. Good thing I caught this in time. Also, I noticed a hairline crack near the bottome drain plug which could be where the leak is. The leak is VERY slow, maybe 2 drops per day, but that adds up I guess. Also, the Redline D4 ATF works wonders.

WheldenL · #7 (**permalink**) 02-13-2007, 09:08 PM

My 93' L has a whine in 1st, 2nd, and a little in 3rd........I definitely don't have any answers.....but I hope you find the problem Del....and get back to us because it would be useful information for me.

WheldenL · #8 (**permalink**) 02-13-2007, 09:10 PM

thanks sean.....off to check the tranny fluid!

**Del** · #9 (**permalink**) 02-14-2007, 12:27 AM

Nope, I've not worked on the problem to this point. My dealer just says that "it might do that forever", figuring that it is due to a slight manufacturing mismatch. Irritates me, though, because we had the transmission out when I had a new clutch put in when I bought the car. At that time, I hadn't driven the car enough to notice the noise. Grrrr.

The noise is heard in 4th and 5th gears, not the lower gears. That puts the source on the main shaft stack, not the transmission shaft stack or differential assy. Noise in 1st, 2nd, and 3rd comes from the transmission stack, I think.

The best solution, if I had my druthers, would be to install a good but used 94/95 Q transmission, with the slightly different rear end ratio, but probably impossible to come by, and I'm not sure I would want to go to all that trouble and expense.

Like my dealer says, just drive the darn thing and enjoy, it will eventually let you know if something is truly wrong.

ChazzyD · #10 (**permalink**) 02-14-2007, 07:00 AM

Quote:

Originally Posted by WheldenL

My 93' L has a whine in 1st, 2nd, and a little in 3rd........I definitely don't have any answers.....but I hope you find the problem Del....and get back to us because it would be useful information for me.