3 speed manual transmission noise

[dave123]

I have just bought a 1977 jeep with a 3 speed. I hear a rattling noise, but only under the following circumstances: The clutch is depressed while the vehicle is in gear and coasting. Any other time, there is no funny noise. No noise while accelerating, decelerating, or in neutral, or with the clutch out. No noise when the vehicle is not moving.
Any advice would be most appreciated.

Thanx,
Dave

 

[mud4feet]

I'm thinking something to do with the throw-out bearing, but...........should still hear some sort of noise even if it's not moving......Perhaps u-joints?!?! They'd probably make some noise when not under stress......but there should be some "clunking" as you upshift and downshift.......??????:???:

Just my thoughts...........my $.02.............someone will chime in (trust me!!) and help you out. Just something to think about........................


Maybe a little more detailed description about the "rattling" noise...........could be as simple as a couple of loose bolts somewhere.


Wish I could be more help,
mud

 

[elkman]

Sounds like maybe the bearings in the mainshaft are going bad, or the pilot bushing is worn out, which probably means that the mainshaft bearings are going bad too. Either way it sounds like a transmission pull is in order to check for bad parts.

 

[dave123]

Thanx for your input.

I hope you are wrong, Elkman, I was really hoping it was clutch related. If the mainshaft bearings were going bad, should I not hear noise anytime the transmission is turning? If it were the pilot bushing, would I not hear noise when pushing in the clutch? I get no noise in neutral with the clutch in or out. Right now, I just slide it into neutral when I'm stopping and don't hear any noise at all. Also, no noise in gear, accelerating, or decelerating. Any idea how long it will hold together? I really can't describe the noise any better, it's just a rattle coming from about where the shifter is, not real loud.
thanx

 

[elkman]

The reason I think it is the mainshaft bearings is that you can only hear it with the clutch pushed in and coasting, when the clutch is tight it holds the shaft/disc from moving laterally and does not allow them to rattle, but when you press in the clutch the disc is released and allowed to move laterally in between the pressure plate and flywheel, thus allowing the bearings which are being spun by the jeep coasting turning to rattle. I could be way off on this diagnosis, but it seems like a good place to start.

That being a three speed it should be a T-150, drain the fluid and look for shavings/glitter, then take the cover off of the top and inspect all of the gears for unusual wear or play, if you have never been into a transmission before find someone to help you inspect it. You should be able to press in the clutch and see if you have major play, however if the pilot bearing is good you will not get much if any.

 

[dave123]

did some more teasting. also getting the noise under same conditions in reverse. i'm thinking you are right, elkman. i have never removed a transmission from a jeep before. I have done regular cars with no problem. is it much tougher since the rear is hooked up to the transfer case? thanx
dave

 

[redrooster]

Sounds like the throwout bearing to me. The transmission is not that hard to pull, especially if you have done a car before. You will have to drop the driveshafts, then remove the transfer case. You can pull the transmission with the transfer case attached, but it's much harder that way.

 

[ndnatty]

I have a '79 cj with the t150 in it that did the same thing a while back, turned out to be the throwout bearing, but that doesn't rule out the mainshaft bearings. Good luck!

 

[dave123]

drained the trans fluid. looks like glitter. Not good

how much you think i could get a T150 used in good shape for?

anybody got one?
thanx

 

[dave123]

I was under the jeep today (only had it a month),
it looks like a new T150, not even dirty. i drained it and
got quite a bit of very small shavings in what looked to be
pretty new 90weight. The yoke where the transfer case hooks
up to the rear drive shaft has some play, and there is evidence
of fluid leaking around the shift linkage for the transfer case.
Wondering if the shavings migrated to the transmission from the
transfer case? I was thinking the transmission was bad, but now
i wonder if it isn't the transfer case (dana 20)?
any opinions?

 

[redrooster]

They are seperate and don't share fluid.
How much can you get a T150 for??? probably free if you look around. No one wants them.
If you are going to spend any money, go with a used T176 4 speed mated to a Dana 300. You can probably get both for under $500.