What's causing my "THUNK!"
 

Posted this up in the transmission thread, but really need a sampling form you guys/gals to see if you're running into this issue.

First, this started the ~6000-7000 mile mark, but was more intermittent than it is now. Basically, after driving for a while, whenver I place the car into neutral and then try to shift into first, I get a big "thunk" noise.

I can avoid the "thunk" by "carefully" trying to thread the shifter into first, but unless I'm very deliberate, I get this God-awful sound.

What could this be and does anyone else have the same issue?

My dealer is in denial mode and will not even try to diagnose.

Thanks!

I can reproduce something like this on my car:
1) Car stopped, transmission in neutral, clutch out, engine at idle
2) Clutch in, shift to first as soon as the pedal hits full travel
3) Thunk. (and a little lurch too)

If I wait a second between clutch in and shifting to 1st, there's no jerk. I think what's happening in my case is that the input shaft and layshaft are spinning at idle with the clutch engaged, then if I don't give them time to spin down when the clutch disengages, I'm essentially braking them to a stop with the 1st gear synchro. The thunk is the rest of the drivetrain lurching a little when it takes up the slack.

So, is it possible that your clutch isn't fully disengaging? Slipping enough that you can still get the car into first, but it's loading the synchro more than it should be? Just a wild guess here.

Better guess than I could have made! Your 1) 2) 3) description fits my situation to a tee. Interestingly, this situation is much more pronounced after the car has been running a while versus when I just start it and go.

Appreciate the help!

hrmm...BMW's do that too. but mine doesn't. try takin' it to another Mazda dealership.

I also have this strange "thunk" and a little lurch, but never happens when the tranny is cold.
It is not too loud or lurches forcefully but noticeable. If I am really careful engaging first there is no jerk.

Sometimes I shift to second, just to test it, and it happens when engaging second too.

thats strange cause mine is hard to get into first gear and when it does it kinda jerks it in, kind of a clunking feeling... only does it when i start up and go, it will go away after a few minutes of driving

I would like to know more about this also. By searching using "1st gear clunk"
I came up with some good finds but nothing that totaly confirms wether or not every M/T 8 does this. It seems to be accepted as normal but it just doesn't seem right. I should mention that the build date of my 8 is august 03, so I'm nervous to start with. I would feel better if I could hear from some of the higher mileage owners that the clunk is normal even at 25,000 miles. If I depress the clutch and wait for 1-2 seconds, no clunk, but thats not always possible.
This is not about the ABS check that goes on shortly after moving.

Andy

Thunk
 

I think and I thunk!!

Nah seriously - mine does it too. Going from N to 1st and sometimes N to Rvs. I`m not too worried about it but I think it may be something to do with clutch drag...even when the pedal is fully depressed, potentially there is still a little clutch drag...which probably varies between our cars..but causes the gearbox to rear axle lash to be taken up...hence your thunk noise.

If i`m right about this clutch drag, then it is a problem of a sort. I'm sure that Mazda will be in head-in-the-sand-mode until enough people complain to their dealers...then a tech bulletin will be issued saying something like "if a customer complains about their thunking car, then tell the customer it is a characteristic of the vehicle, that they should be pleased about the uniqueness of it....then do everything possible to get rid of the :( complaining customer off your dealership lot as soon as you can"

Can you see it or am i twice burned already?

Tom

I just had my 8 in for servive about this exact issue. They said "According to the Mazda tech line this is normal and acceptable behavior". Sounds like BS to me. If so ALL 8's would make this noise.

I think mine has a very minor bit of this problem. Has anyone who has this issue checked to see if their car is in the TSB range for the 1-2 shift fork?

--Massive

I took the car in for this exact issue and got what everyone said here
"All Rx8 we tested had similar issues, it is normal"

um yeah... :rolleyes:

It isn't a major major issue, but it is kinda annoying and sure isn't comforting...

My car seems to have the same symptoms as you guys. It seems to have had it pretty much from day one. Personally, I think that it just seems to be one of the car's strange quirks.

another guy hear who has the same problem. Taking the car in on monday, i'll make them aware of the problem. At least if the tranny blows up one day they'll have this on record.

I've got 900 miles on my '05 and it's done it since I drove it off of the lot.

Mine sometimes has a little bump. I find it helps to move the lever briefly into 2nd gear before going to 1st. It's a habit I got into a long time ago with other cars, so it comes naturally now. Plus, you get that neat bolt-action rifle sound from the gearbox. Click-Click-Clack. Sometimes I do the full-parade version - Wiggle the stick in Neutral (left-right-left) then -1st-2nd-1st. Thud-Thud-Thud-Clack-click-CLACK. Ready.... Aim..... Accelerate.

syncronisers synchronising

A guess,: It does not clunk when cold since the oil is cold and thicker. The gears do not spin as freely and slow down as soon as you step on the clutch. Midn does it if I do not wait a few seconds after stepping on the cluthc. It helps if I shift into third and then first. I think it is normal since I have had it with other cars.

I've had this happen in just about every manual trans I've owned - and I dont abuse trannies - quite the contrary.