Got a Funky, Barely Audible Drivetrain Noise

[darkman]

Originally Posted by rand49er

This may indeed not be a "problem" other than the noise. The noise is horrible, though. But, like you say, it may just be a manifestation of the steepness of the overdrive ratio and the cut of the gear teeth and the less-forgiving nature of a lightweight FW.

If there are a number of 6th gear failures in Tremec trannys with drivers who drive like I do, then that is actually comforting, if you can believe it. Now, I have to decide if I want to spend the buck$ to put a new 6th gear in it, or just put up with the muffled sound. I intend to consult my mechanic.


That could explain why I hear so much more of the heavy click or clunk sounds from mine. Still, I do not hear that portion of the clunking attributable to the OEM dual-mass FW, and I definitely like that about the UUC FW.

The only adjustment I made in response to the noise is that I simply use 5th gear more often and only go to 6th above 40 mph. Since most of my neighbor roads are have speed limits of either 35 mph or 45 mph they have simply become 5th gear roads and 6th gear roads, respectively, and I never hear the noise any more.

Of course I don't have maggie - I'll bet with the dual mass flywheel and the maggie you probably only ever used 1st and 6th.

[rand49er]

Originally Posted by darkman

... Of course I don't have maggie - I'll bet with the dual mass flywheel and the maggie you probably only ever used 1st and 6th.

Ha! That's not true, though I did start a thread way back when asking whether guys with maggies ever even use 1st gear since it's basically useless and just always start out in 2nd gear.

Naw, truth of the matter is, she can be a very thirsty lady, she can, and she's been known to whine for more and more gasoline to drink than I'd prefer, so I tend to keep her quiet ... most of the time.

However this whole episode ends, I'll be changing my driving habits just like you.

[Black Sunshine]

This is the gist of my PM to R.

First, the actual cause of my tranny failure was the reverse gear bearing failing and locking up on the shaft at 80 mph on the highway.

No major warning other than a lil "hitch", "hesitation" that was noticeable enough for me to wonder about it as I slowed to get off at my exit. Then I heard what I would have sworn was a plastic zip tie wrapped around my drive shaft slapping the tranny tunnel (I swear (with fingers crossed behind my back) I've never played that prank on anyone). I stopped at the top of the exit ramp and even inspected the undercarriage hoping to find something stupid wrapped around an axle or the drive shaft. Found nothing. Managed to roll it into the local caddy dealer 2 miles from the exit. No reverse. The dealer let me leave it there til we got it picked up and taken over to the builder in IN from Akron.

The builder of my new unit @ RPM Transmissions actually complimented me on my driving. (How the hell would he know to do that?) He said he could tell from the condition of all the parts that I had never missed a shift or mistreated the car. That was cool.

This was what wasn't cool. When the builder showed me my old parts the 5th-6th gear assembly showed excessive tooth wear. There was barely a lip on the end of each gear tooth still left with the rest of the teeth worn WAAYYYY down. He asked me if I was running a blower. I said no and asked why. He said he sees the excessive 5th-6th gear wear on the blown cars because the owners were typically lugging around during daily driving in those gears. We decided it must be wear caused by me lugging it around town AND doing so much highway cruising (>100,000) at constant speeds. If the reverse gear hadn't done what it did, he said the 5/6 gear would have definitely left me on the side of the road within a few weeks.

He said one way to extend the life of that gear assembly (because I have no choice but to do the highway miles I do) was to just be more mindful of letting the car rev a little higher before I shift when driving around town, which I do quite a bit of, too. So, I now stay in 4th and 5th gears a hell of a lot more than I used to.

I've got some pics of the worn 5th/6th gear assembly, clutch plate (mounting holes elongated from slippage) and other parts from the original tranny on my laptop at work. I'll try to post them when I can find the time.

[Jbawden]

Everyone has their own driving style, but wow, 6th gear at 35 mph? I read your post a few weeks ago that suggested that you shifted into 6th at 35 and I tried to duplicate it on my own and at 35 4th gear seems more than appropriate for economy. 6th isn't on my radar until at least 50 mph, but again, this is my driving style and may not be how others roll.

[your maker]

what about the tranny just saying cause of the muffled sound you hear??

[darkman]

Originally Posted by your maker

what about the tranny just saying cause of the muffled sound you hear??

I don't understand your question. Can you clarify?

[rand49er]

Since this thread sort of went into the higer numbered pages, I've driven my car several times while REALLY listening to the tranny and sixth gear in particular. The sound I'm talking about here just does not seem like it's coming from the transmission now. I'm stumped.

Next time I meet up with some V guys around here, I'm gonna ask a couple of 'em to take a ride and listen and see what they think. Hopefully, this will occur on the 15th at the Woodward Dream Cruise.

You comin' lolly?

[darkman]

Since I last posted here I reconfirmed the noise I have been talking about, which may, or may not, be the noise others are experiencing. Comparing noises in an internet exchange is after all risky business.

The noise I have been talking about can be replicated in 3rd gear, 4th gear, 5th gear, or 6th gear. All I have to do is launch gently in 1st gear, switch to the "test" gear, and give it full throttle. Stated more directly I can induce the noise by trying to accelerate from 5 mph in 3rd, 4th, 5th, or 6th gear. The higher the gear, the more pronounced the noise. Thus, the test is much like that used to see if your gasoline has enough octane although the cause, which originates from having a lightweight flywheel, has nothing to do with pre-ignition/detonation.

[rand49er]

Michael, the noise you're referring to is loud ... I have that one, too. Horrifically loud abnoxious sound it is! The other one I'm having a hard time identifying is much more subtle and is so hard to describe. Let me get some guys around here to listen to it plus my mechanic (also Michael) who has a lot of experience in these sorts of things.

[VfReaK]

I'll just throw this out there in case it's been simply over looked.
have you checked the drive shaft heat shield to see if it's vibrating
at a certain rpm/load, and possibly hitting the drive shaft or exhaust?

[rand49er]

Originally Posted by VfReaK

I'll just throw this out there in case it's been simply over looked.
have you checked the drive shaft heat shield to see if it's vibrating
at a certain rpm/load, and possibly hitting the drive shaft or exhaust?

Funny you should say that. When I was under there last week, I looked at that shield. I tugged and I wiggled it ... tried my best to see if it was involved. I more or less concluded that it was unaltered from the way it was originally installed which really didn't exclude it from further scrutiny, just didn't ID it as the cause yet. When the car gets up on the lift again, I'm gonna look at it again. And let me say that this whole thing may still end up being some silly-ass thing just like that!

[Twitch]

Dunno, I think you guys are hurting your cars by "over babying" them.

[Jbawden]

Originally Posted by Twitch

Dunno, I think you guys are hurting your cars by "over babying" them.

Gotta agree. It's certainly an unusual driving style. I'm certain that GM never intended the car accelerated from 5 mph in 3rd-6th gears (or driving around in 6th gear at 35 mph). With all due respect, I think the issue that needs to be addressed here is how you operate your V. Take an auto V2 for a spin and note the shift points under light throttle and I think you'll see that you have long ago passed the point of diminishing returns on your babying style.

[The Tony Show]

Sorry I didn't read this thread earlier and weigh in- I'm 99% sure it's just the flywheel.

As you (correctly) postulated earlier, GM put the dual mass flywheel in these cars to eliminate a LOT of NVH issues- gear lever shake at idle, chatter on takeoff, and general gear/clutch noise are all reduced by the DM flywheel. Switching to a solid, lighter, single piece flywheel like the UUC (or the Z06, which I used) introduces all those lovely noises that used to be masked by the flywheel.

That being said, I would change your shifting habits as soon as possible, and start changing gears around 3,500 or 4,000 rpms in casual driving. Not only will you reduce the buildup of carbon in the intake and valves (which you are undoubtedly getting now by short shifting everywhere), but as Black Sunshine learned, low RPM lugging is no good for a trans (and at 2k, you're lugging it). Also stop using 6th gear at 35 immediately, as you WILL wreck the gearset. There's no appreciable difference in fuel economy by driving in that gear at those speeds, as you need to press the throttle harder to maintain speed. Use 5th only above 45, and 6th above 60.

Final word? I'd say that the reduced dampening of the flywheel is allowing you to hear the damage you're doing to the gears by keeping it below 2k in high gear. You probably haven't caused serious damage yet, but need to adjust your driving habits.

[atdeneve]

Wow, the nay-sayers on short shifting have seemingly grown from previous discussions. Curious as to whether it really does cause damage, since I am one of those that do like to use the higher gears when not romping on the engine. But, 5th only above 45; 6th only above 60? Sheesh.

I, like some others, am in 6th by 30-35. Mind you, I'm not WOT in 6th at those speeds; just maintaining speed. And, if I need to accelerate or put the throttle down an appreciable amount to maintain speed, I downshift. But, by and large, I use the highest gear possible...