Noizemaker

I've noticed this since I got my car, and it's happening increasingly often now.

Car is: 2001
Mileage is: 86,000
Drivetrain mods are: None.
Trans fluid/diff fluid changed: 5k miles ago.
Trans fluid is: Honda MTL
Diff fluid is: Royal Purple 75/90 IIRC


Repro:
Start car, back out of driveway. (no "thunk")
Shift into neutral
release clutch.
depress clutch.
Shift into 1st (or any other forward gear)
Release of clutch not nessesary, problem repros before clutch released.

Result:
Car goes into gear with slight hesitance followed immediately by a "thunk" from the drivetrain somewhere, and a shudder from the rear of the car that feels like bushings moving. Issue reproduces when vehicle warm or cold.

This issue does not repro every time you shift into gear. It does always occur the first time you shift into gear though from a stop. If you notice the thunk and then immediately go back to neutral, release/depress clutch and return to gear, no thunk is heard. If you immediately go back to neutral and return to gear w/o release/depressing clutch, no thunk is heard.

If you remove car from gear, release clutch and wait 10 or so seconds to re-depress clutch and move back into gear, this reproduces 100 percent of the time.

There's no throwout bearing noise, the clutch doesn't slip that I can feel or smell. There are no fluid leaks from the vehicle master/slave cylinders.

Anyone know what it could be? Worn clutch? Dying slave cylinder? Dying master cylinder? The fact that repeatability takes a few seconds leads me to believe a fluid pressure issue, but I hesitate to jump to a conclusion.

grippgoat

With the car stopped and the transmission in neutral, with your foot off the clutch pedal, the engine is spinning the input end of the transmission, while the output end is not spinning, because the rear wheels are not spinning. When you put the car in gear, the input end has to stop spinning to mesh with the output end. If this happens quickly, I'd expect a thunk. As to WHY it's happening quickly, I can only guess wearing synchros (or synchros not liking the fluid), or you're pressing on the lever too hard and forcing the issue.

-Mike

Billman250

IF I am following you correctly, the disc is dragging against the flywheel. Causing a thunk, from incomplete dis-engagement.

This can be caused by:
-Dirty clutch fluid, poor clutch rod adjustment
-rusted friction disc splines

KstreetDC

I am having this same problem, but have an additional one as well: Sometimes my car will not shift into 1st, without first shifting into 2nd. This will happen perhaps 1 in 100 shifts and under the following conditions:

1. When I first start the car in the morning. I start the car and release the clutch while in neutral. After I am ready to start driving, I depress the clutch and try to shift into 1st, but it will not do so unless I shift into 2nd and then move the shifter into first.

2. I have been driving and have to stop at a stoplight. When the light turns green, I have to move the shifter into 2nd before it will go into 1st.

Any thoughts?

minh

you know, i was driving today and was wondering the same thing, it started doing that thunk noise recently after i accidentally grind 2nd and 3rd gear a couple times before

are our S known to grind 2nd under heavy acceleration and fast shifting? the 3rd gear grind was totally my fault though so no excuse there

s2krey

i have the same problem. But i do need to change my tranny, bleed the clutch fluid, and change my diff. its been a while since it was last change so hopfully my "clunk" and other issues i have is fix...