bad clutch?

[Sri Ram]

Downshifting from fourth to third, I've heard a bad sound a few times lately. It sounds like a bad bearing, almost a screech, coming from the clutch area. This only happens--if it happens--downshifting into third, and not very often (for example, I drove over 400 miles last weekend and never heard the sound). Any ideas?

 

[TKingsbury]

Sounds like a trans problem to me. If it were the clutch, it would do it anytime the clutch was pushed.

Travis. .

 

[Paychk]

Throwout bearing is nearing the end of it's throwing life.

 

[NIsaacs]

When, exactly, during the sequence of the shift, do you hear the screeching sound? As you are shifting, as in pushing on the synchros? As you are letting out the clutch after the completed shift. When you are down shifting, is there a big rpm difference in the two gears? Kinda sounds like a bad counter shaft bearing, maybe even a main shaft bearing. If it was the throw out brg. , it should make noise every time you depress the clutch.





"NICK"

 

[Sri Ram]

I was thinking it might be the throwout getting ready to throw in the towel. But here we have 1 'yea' and 2 'nays'



Nick: the noise occurs as I puch the shifter into third from fourth, happens before it's all the way in. I had considered that maybe I'm downshifting too early, and need to let the rpms come down a bit before pushing into third. Where are the bearings you mentioned located?

 

[NIsaacs]

Sri Ram, the bearings are inside the transmission. Since the noise starts as you are making the shift, it might be third gear syncro, but more likely it is the pocket bearing. It is located in the rear of the input shaft. This is where the output shaft meshes with the input. When you are in 4th gear (direct), the two shafts are turning the same speed. As you shift into third, the input shaft speeds up and makes the pocket bearing change speed also.





"NICK"

 

[Sri Ram]

When you are in 4th gear (direct), the two shafts are turning the same speed. As you shift into third, the input shaft speeds up and makes the pocket bearing change speed also.

ok, that makes sense…Why then doesn't it screech every time I downshift into third? Is it a question of engine rpms? And, more importantly, is it time to drop the trans and have a look-see, or should I just change the oil?

 

[NIsaacs]

I am not sure why the sound is intermittent, maybe it has something to do with the rpm of your shift and the amount of side torque that is taking place on the bearing.



Changing the oil will not cure the problem, however it might show you how bad the oil looks and can give you an idea on condition of the transmission. You might pull the pto cover and use a flash light and pry bar on all the shafts, looking for side to side or up & down movement.





"NICK'

 

[DieselBuzz]

My 2 cents

If the syncro is shot then it would almost be like you were trying the shift without the clutch, more banging and grinding. If the throwout bearing is going then it is more of a squeal or screech when the clutch is engaged. If you hear the noise try pumping the clutch to see how that effects it. You might even be able to recreate the noise by having the truck parked, engaging the clutch and have it drop through the RPM range (if it's not too high) that you were shifting through. Ok, if you couldn't tell by now I think it's the throwout bearing. Mine went and I replaced the clutch too, even with plenty of life left in my original Sachs. Good luck with yours and keep us posted.

Art

 

[Sri Ram]

Thanks for the replies…I would've thought it was the getrag, but there is no resistance to shifting, and the noise is not transmitted to my hand via vibrations through the shifter. Am I correct to assume that bad syncros or bad bearings would vibrate the shifter, too?

 

[TKingsbury]

If it makes the noise when you are moving the shifter, and not when you are pushing the clutch, I'd say the trans is the culprit.

Travis. .

 

[Sri Ram]

Heard it again last night…only happens when I get lazy with the downshifting, and only third gear. I'm gonna change the oil and see what comes out of the trans. Regardless, I'm gonna taker her in and have the trans pulled down and inspected. And, while I'm at it I suppose I ought to replace the clutch. I'm going to start a new thread for suggestions. Thanks again for the comments, guys.

 

[Sri Ram]

got it?

O. k. , I think I've got it figured out, nut I need a second (or third) opinion. My getrag doesn't like to shift into 1st, 2nd, or 3rd much above idle. That has something to do with the syncros, right? Is this normal? When I downshift into 3rd (from 4th), if the rpms are too high, the shift happens anyway and I get the screeching sound (or is it grinding?). To accomplish the downshift without letting the engine come down to, say, 1000rpm, I have to practically stand on the clutch pedal. What, then, then is wrong? Bad syncros? bad clutch? bad bearings? low fluid in the clutch slave cylinder? (Last time I checked several months ago, fluid level was fine. ) Again, any help appreciated.

 

[RHancock]

pull it down and take a look ... . isn't that hard and may save you more money doing it now than later... parts are fairly cheep and easy to get for Getrags now ... just make sure to set the end play right when you reassemble... and there are enought people here that are members of the GPS Getrag Preservation Society... to help

 

[Sri Ram]

pull it down and take a look ... . isn't that hard and may save you more money doing it now than later... parts are fairly cheep and easy to get for Getrags now ... just make sure to set the end play right when you reassemble... and there are enough people here that are members of the GPS Getrag Preservation Society... to help

Thanks, RHancock, I'll be pulling it next week or so. I'm making a checklist from all the knowledgeable posts here. Thanks to everyone!