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View Full Version : clunk noise from trans when shifting at low RPM


nep
02-11-2008, 02:56 PM
i recently did a auto/manual conversion on my 96 240sx. everything was replaced during the swap, including master/slave, T.O. bearing, clutch fork, etc. my problem is this:

when shifting gears from 1-2 and from 2-3 at low RPM i get a clunking noise that appears to be coming from the transmission area. if i i take it much above 3k rpm the noise goes away and the shifts are pretty seamless. i have done quite a bit of searching and have come away with a few suggestions:

1. drivetrain slack
2. rear end bushings. sub-frame, diff, etc.

i was bored so i let a local mechanic drive it around the block, and his diagnosis was bad transmission gears or some shit, and offered to rebuild it for $1500. that price is ridiculous as fuck, and im hoping my problem has nothing to do with the actual transmission anyway. maybe i need a new driveshaft? any thoughts?

180sx Fan
02-11-2008, 03:03 PM
could be the stock drive shaft they are two piece and sometimes when they get old and used the rubber bushing thing that holds them together can wear out and when mine did it made a sort of cluncking sound you can check it out to make shure it is not that.

nep
02-11-2008, 04:25 PM
could be the stock drive shaft they are two piece and sometimes when they get old and used the rubber bushing thing that holds them together can wear out and when mine did it made a sort of cluncking sound you can check it out to make shure it is not that.

you refering to the part circled in red?

http://img211.imageshack.us/img211/3526/cbqq8.jpg

it did look weathered when i put it on, guess i could trade out the old one from my auto driveshaft. thanks. any other suggestions?

Deftec
02-11-2008, 08:10 PM
Carrier bearing it sounds like. Reach under there and shake it and see if you get any movement in it.

180sx Fan
02-11-2008, 08:29 PM
nep: yes i am refering to the pice you circleded in red the little cage thing that holds it might also just be lose so you might wanna check that too.

sleepy_s13
02-11-2008, 08:40 PM
lol @ $1500 to rebuild a tranny. You put a pilot bearing in right?

evidens83
02-12-2008, 12:18 AM
BUMP! This auto-manual conversion s14 is the cleanest of North County San Diego!! Dang Nep I told you, forget about that clunk and think about some boost ya digg?!! lol

importdude
02-12-2008, 02:44 AM
i have the same problem, but i hear grinds or so if shifting low rpm

nep
02-12-2008, 12:57 PM
BUMP! This auto-manual conversion s14 is the cleanest of North County San Diego!! Dang Nep I told you, forget about that clunk and think about some boost ya digg?!! lol

I'm obsessive-compulsive man, no rest for me until it shifts smoother than a pair of silk panties. and no boost until those student loans come in lol.

sleepy: yea I used a pilot bushing.

I found some local driveshafts, ill pick one up and see where that takes me

Dream240
02-12-2008, 01:07 PM
I'm obsessive-compulsive man, no rest for me until it shifts smoother than a pair of silk panties. and no boost until those student loans come in lol.

Nice to see that education fundage going for something useful..... LOL

As far as the clunking, definitely check the driveshaft carrier bearing. Also check the diff bushings, and driveaxles for excessive freeplay.

My drivetrain has a slight "clunk" when I first put it in gear while the clutch is still disengaged. I'm guessing it's the syncros just moving in the tranny. Some noises are not necessarily bad. Just typical wear and tear. And a KA drivetrain has ALOT of vibrations in stock form while working properly. That's just how they built them.

That mechanic is full of shit. He's just trying to make some cash. 1500 for a rebuild is ridiculous. Shit new intenals only cost about 300 bucks. All you need is a press and some gear pullers and you can do it yourself.

Or you can just source out another tranny for about 200 bucks. Done.