tranny removal?. clutch chatter..

[shmoo]

suhweet, i'll go wipe the rain from my car and start waxing

[J. Fast]

Take a stethiscope and hold it on the endcover, midcase, and bellhousing. Next, pull the plastic fender deflector on the passenger side and expose the trans input, intermediate, and shift fork positions on the trans. Have someone start the car on stands and have a listen to everything while you load and unload the trans with the clutch. If there is slack on one of the shafts or something is rattling it will resonate thru one of the cases or end cover and you will hear it thru the stethi. I use a Steelman Chassi Ear all the time to find wierd noises and what not. Give it a try, it works!

[shmoo]

Take a stethiscope and hold it on the endcover, midcase, and bellhousing. Next, pull the plastic fender deflector on the passenger side and expose the trans input, intermediate, and shift fork positions on the trans. Have someone start the car on stands and have a listen to everything while you load and unload the trans with the clutch. If there is slack on one of the shafts or something is rattling it will resonate thru one of the cases or end cover and you will hear it thru the stethi. I use a Steelman Chassi Ear all the time to find wierd noises and what not. Give it a try, it works!

that actually sounds like fun. i'll see if i can get my hands on a stethiscope . but what else could it be besides loose bolts? what is clutch chatter. if it is these slacking shafts, does that constitute a rebuild, or can i just open the transmission up and replace the shaft?

thank you

_isiah

[J. Fast]

I would say "clutch chatter" is a discrepancy between the flywheel, clutch disc (to include hub), and/or pressure plate. Chatter is isolated to just the pressure plate, clutch disc / hub, and the flywheel. When a clutch chatters it generally means one of the clutch interface components is not hitting square. In other words, the pressure plate, disc, or the flywheel is not hitting the adjacent contact area square which results in overheating and grabbing, slipping, or skipping. A few things can cause that.

The first could be heat or warpage. Say you like to slip your clutch or it's dragging and it gets hot, well, the flywheel and pressure plate surfaces will warp similar to standard brake rotors. When the metal faces become hot they warp. The warpage creates a non uniform clamping surface in which eventually leads to the clutch disc not grabbing evenly. In turn it "bounces" or "skips" which causes chatter.

The second cause of chatter can be a tell tale sign of the condition of the pressure plate. We rely on pressure plate springs to clamp the pressure plate evenly with the clutch disk and flywheel surfaces and demand they hold the clutch disc/hub to the flywheel. Over time it's possible for the spring’s performance to decline in the pressure plate. They may begin to lose their holding capability which leads to a non uniform clamping surface due to uneven load distribution on the clutch disc to flywheel interface. The unbalanced clamping load leads to the bouncing or slipping of the disc which results in chattering.

Next cause might be something caused by a lack of precision. Say your flywheel is not decked correctly and the surface, step height, or cut height is out of spec? Any of those conditions may cause a clutch to either slip and grab (which in turn will cause a clutch to heat up and warp), or wear the clutch disc unevenly which will throw it out of balance by heating it unevenly which will cause it to grab and skip, or "chatter".

Last thing that comes to mind is the condition and composition of the hub/disc. Depending on the style of clutch hub being used, disc composition, power requirement, and driver feel there's a broad range of selections of hub/discs. Some hub discs have a higher thermal capacity and stress/strain tolerance than others. Additionally they may include some sort of mechanical advantage device such as springs to help absorb some of the rotational energy. Well, over time the load, temperature cycling, stress and strain may take its toll on some of the functional designed holding capacity parts. They may become dislodged and become wedged between the pressure plate, disc, or flywheel. Since there's an obstruction in the contact areas which prevents them from interfacing evenly, the disc isn't clamped evenly and may yet again skip or chatter.

There are a few other things I might describe or others may describe but for the most part (off the top of my head) I would describe clutch chatter as the grabbing or slipping of the disc due to heat or improper balance in the clutch assembly. A bad TOB is not clutch chatter, a dragging clutch is not clutch chatter, a bad output shaft is not clutch chatter, transmission noise... not clutch chatter, and etc. Just my .02

Jeremy

[DrGonzo]

So I got the video for the trans noise. Ignore the video and just pay attention to the sounds.

http://youtu.be/PEbiT-Y36lw


Edit: I would embed the video here but it seems Alan did not install the YouTube Link Parser And I'm not going to spend all night trying to guess/search as to what the BB Code tags are!

[J. Fast]

Ohh damn, that would drive me nuts Greg! Goes away when you depress the clutch?

[DrGonzo]

Yep!!! Going to try a heavier weigh gear oil and see if that helps. Running straight Penzoil Syncromesh right now. Going to pick up some Amsoil.

[shmoo]

thanks a lot jeremy! very helpful!! can you describe the contact points? as in exactly where on each piece that contact is made. and which ones are prone to heat up faster than others. flywheel, disk, pressure plate, output shaft? i've got some questionable work done that i'm sure some of you know about.

i'm thinking i'll take my tranny off again.just to replace the throw out bearing, resurface my flywheel, i should replace my clutch disc.. does anyone know where i can get a suitable unsprung disc for my spec stage four six puck pressure plate? is there anyway to inspect a pressure plate? what about light weight flywheels? i've heard bad things.

i currently have a mix of cheap 75 90 and probably some 75 90 or near it castrol in the transfer case. and i've got royal purple and lucas in the transmission. what is the best weight and brand to have in both? i like to have something cheap in the transfer case because it leaks still.
if ya say redline, where is the most reasonable place to get it?

y gonzoe, i questioned synchromesh the moment i put it in. what's the deal with amsoil? where do you get it?

_isiah

[TwIzTeD_3kGt]

Ahh Spec clutch. Should have said that in the first post. I can tell you all about a Spec clutch chattering when engaged at idle. Their disc quality control is crap at best. The rivets that held mine together were improperly sized and off-center. My Spec 4+ blew itself apart, and I've found countless others who've had the same issue. I ignored it thinking it was just a throw-out bearing because it went away with the clutch pedal depressed, and the hub eventually separated from the disc. I ended up having the disc properly rebuilt by a local clutch manufacturer. My advice is to get that disc out of there asap.

As far as oils...Mobil-1 Full Synthetic 10W-30 in the trans, and Mobil-1 Full Synthetic 75W-90 in the x-fer, 5 years of running those, 5 years of perfect shifting (with massive amounts of abuse). Prior to the 10W-30 I ran 75w-90 and 2nd gear would grind sometimes.

[DrGonzo]

Yeah I'm thinking mine is due to the fluid I'm running. I still have a stock clutch so I doubt mine is actual clutch chatter!! Might pick up the fluid tonight and get it changed out.