Hey guys just got finished with my AT to MT swap and I was driving around and there seems to be a lot of grinding noises coming from the transmission no matter the gear it is in, even neutral, and the only way to make it stop is to put the clutch in. What could cause this? I was thinking low transmission fluid but let me know what you guys think.

Ps. It is an 83 transmission so I dont know if that is a common problem with those trannys

Thanks

 

Since you swapped from auto-to-manual, did you install a pilot bearing in the end of the e-shaft?

 

Pilot bearing in the end of the e-shaft would be my first thought as well

 

How loud is it? With a socially acceptable exhaust system, trans whirr is a remarkable percentage of cab sound at idle, especially if any of the shift boots are torn or missing.

Even my freshly rebuilt trans makes its presence known.

OTOH, the trans is also pretty loud in Miatas, although they have much better soundproofing so you mainly hear it with the window down and next to a building.

Ignore the pilot bearing, it only turns when the clutch is not engaged (meaning pedal depressed). With the clutch engaged, when you are hearing the noise, there is no relative motion between the E-shaft and trans input shaft.

 

Alright to answer these questions,
1) The pilot bearing is on the end of the Eshaft, I swapped both the engine and transmission from a manual car so that would not be an issue. @KansasCityREPU @rotorhead_izzy
2) It is a pretty ear scraping noise. I would say it is equivalent to scratching a chalkboard... I wouldnt say it is super loud except for first and second gear. I only have the main weather boot on as I haven't bought the interior piece yet, and there is a rip in it so that could be why it is so loud. @peejay

I tried to refill it with fluid today making sure it was not low and when i opened the drain plug it just dumped out what looked like a quart of fluid, (could have been I was on uneven ground but I changed that when I refilled it) so I dont think it is a low fluid thing.

 

I agree that a new pilot bearing is always a good idea and a logical, easy place to look for trouble, but depressing the clutch disengages the transmission from the engine. The transmission stops turning while the engine continues to run and turn. I would think that if the noise only goes away with the clutch depressed, the noise would most likely be in the transmission itself.

The pilot bearing is pressed into the e-shaft and continues to rotate around the pilot diameter on the end of transmission input shaft when the clutch is depressed. If the pilot bearing was bad wouldn't you be more prone to having the noise once the clutch is depressed? With the clutch engaged (foot off the pedal) the input shaft is turning along with the e-shaft.

There's no real great load on the pilot bearing, it just supports the far end of the input shaft, keeping it aligned with the e-shaft. How sure are you of the transmission and its condition?

 

maybe I missed it, but did you seperate the engine and tranny and/or drive it before the swap to know if it had the noise before?

has the tranny ever been opened up and inspected seperate from the engine?

 

To answer @Bonzai I am not sure about the health of my transmission. It came out of a lower mileage car but that was out of the car long before I even bought my car. And @ATC529R I have torn the engine and tranny apart to check the flywheel, clutch, and pressure plate but I did not look at the gears.

ALSO, probably not pointing to a healthy transmission but sometimes (its only happened in my gravel driveway and never on asphalt) when I put it in reverse the shifter is shot out of reverse to neutral and you can hear a grinding sound super loud.

 

Not the best of quality videos but i think the first half shows very well the sound.