Gearbox(?) Knocking

[Space Monkey]

Morning :-)

posted a topic in the Celica forum but didnt get any replies so hoping someone can help a little here.

lately ive been getting a knocking noise when rolling along at low speeds, usually in traffic. it knocks as i come on and off the clutch pedal but it doesnt really happen any other time. if i take it out of gear and coast there is no noise so ive eliminated it being stone or something loose.

i get a little knock sometimes when going from 1st to 2nd and 3rd and me and my mechanic think its the synchromesh cones in the gearbox that are the problem. however would this cause the knocking when rolling slowly when not pressing the accelerator?

we are going to try changing the gearbox oil for something a little thicker, but now im unsure this is even necessary if it might not even be the gearbox.

basically im stumped and any thoughts would be hugely appreciated.

btw i drive a 96 Celica GT, the 6th Gen type.

Thanks

[Space Monkey]

no help here either?

[Z33kdud3 E]

no help here either?

ru sure it's not a mount?

[KPARRIS-JONES]

Could be your release bearing on the way out. Just rattling away at low speeds because it isn't sitting evenly on the BB anymore due to wear and tear.... Just a thought, I'm not saying for definite.

[Z33kdud3 E]

Could be your release bearing on the way out. Just rattling away at low speeds because it isn't sitting evenly on the BB anymore due to wear and tear.... Just a thought, I'm not saying for definite.

wut kinda bearings?

[KPARRIS-JONES]

Could be your release bearing on the way out. Just rattling away at low speeds because it isn't sitting evenly on the BB anymore due to wear and tear.... Just a thought, I'm not saying for definite.

wut kinda bearings?

The Clutch Release Bearing. It could be making the noise as pressure is applied when he presses the pedal.

[Z33kdud3 E]

Could be your release bearing on the way out. Just rattling away at low speeds because it isn't sitting evenly on the BB anymore due to wear and tear.... Just a thought, I'm not saying for definite.

wut kinda bearings?

The Clutch Release Bearing. It could be making the noise as pressure is applied when he presses the pedal.

sry i did not see that part, correct me if i'm wrong but i think when release bearings are goin bad is that they usually makes a kinda like winding noise not knocking.

[Space Monkey]

if its a clutch release bearing how difficult is it to replace?

its def a knocking and not a whirring or a grinding. it does knock when im just rolling along though, without me touching the clutch, would it still knock?

[KPARRIS-JONES]

z33 I think that you are most likely right there, I think it would be more like a whirring, but I just thought it was a possibility.

Spacemonkey, to replace the release bearing you will need to remove the gearbox. I don't know how difficult it would be with a Celica, but it wasn't exactly a small job on my GTi anyway.

Here is the bearing;

I am NOT saying it is the bearing for sure, so don't go and get it replaced to find that isn't it.

As previously mentioned, it sounds more likely that it's the gearbox mount or something like that, letting the gearbox hit the engine bay. If it is the gearbox mount, then it won't be too hard to replace. You will be able to see any obvious signs of deterioration.

[Space Monkey]

cheers thats really helpful

ive got it in the garage on wed afternoon for a professional view ( at the car itself ), was hoping for a few possible areas to check.

i think its telling that it only makes the noise in gear, not when freewheeling. although im not sure myself what that tells.....

what could possibly only make a noise when the car is in gear?

i'll keep you in the loop

[KPARRIS-JONES]

No problem mate,

By the sounds of it, I doubt it's the clutch bearing now, so I am leaning more towards the idea of the strain from the engine on a component(s) of the gearbox.

Could it be anything to do with your CV joints?

Just a question, Do you have Coilovers?

[Space Monkey]

not that im aware of..... think ive just got normal springs

im thinkin towards CV joints, is there one on the gearbox/driveshaft connection?

theres no knocking when i turn so not thinking it would be the CV boots on either wheel, but then it might be?

it must be the driveshaft if its only noisy in gear, ah well its in tomorrow so hopefully it'll be nice and obvious

[KPARRIS-JONES]

o.k. well not having coilovers has ruled out one possibility. :)

I think its going to be either the gearbox mount or the drive shafts. There are not CV joints on both sides, only to the wheels, you will probably have something like this;

Could be worn out components... not too sure now. Hope all goes well.

[Space Monkey]

what is that exactly?

hoping it will be something the mechanic can see easily, as the noise only seems to occur when slowing from 70

[KPARRIS-JONES]

That's the end of the drive shaft that goes into the gearbox.

It goes into the slots behind the gearbox. :)

But I just can't really imagine exactly what it would be to be honest. I would look towards the wheel bearing but it wouldnt be at certain speeds.

[Space Monkey]

nothing mechanically wrong with the car.

mechanic checked everything and the noise just seems to have stopped.

guess its a mystery until it shows up again.

thanks for all the posts, if nothing else ive learned a lot

[KPARRIS-JONES]

I'm glad that it's gone now, sorry that I couldn't help all that much. Did what I could. Probably nothing.

Lets hope it never shows up again. :)

[Space Monkey]

not at all mate, you couldnt have done much more.

if it shows up again i know the places to look 1st instead of having to wait for a mechanic.

going to keep a closer eye on the CV boots and any wear on the gearbox.

thanks again