Hello everyone,

I admit that my experience actually driving FCs is quite limited, so I don't know if this is the norm. I have a T2 and a GXL that I've driven, both 87s, and both made a whirring noise from the footwell whenever the clutch pedal was not touched. As soon as you press the pedal in to disengage the clutch, the noise sounded like something spinning was slowing down and the volume would drop off. It would make the noise in neutral and in gear (I think it varied with engine speed, but that might have been a bad bearing in the accessory drive). I've also heard the noise in a few other videos of FCs, but I've also driven an FB and an MX5 NA and I never noticed a noise like it in either (to my knowledge, they also have the same transmission as the GXL). Searching around has told me that

1) this is not a TOB since it'd be the reverse case (although I did think it was since I didn't replace it on the GXL),
2) it could be low fluid levels or shitty fluid, but I made sure to check the fluid levels on the GXL (it was way overfilled somehow) and the T2 got a fresh fill of Neo Synthetic 75W90
3) it could be the pilot bearing, but it's not the metallic scraping noise often described, for the T2 it looked great on disassembly, and the GXL I put a new bearing and seal into. Finally,
4) it could be an input shaft bearing in the transmission, but the T2's transmission should have been fine since it was rebuilt (locked out of 3rd, 4th, 5th, and reverse due to worn synchros). GXL's transmission, I have no idea, but it shifts great and doesn't seem to transmit any weird vibrations into the shifter

I remember driving my friend's RX8 and it having a similar noise, but the respective forum for it said it was normal since the AZ6 transmission is inherently loud. But my friend's 6-speed NB doesn't make that noise (would having a PPF or not make a difference?). It seemed louder after we did the clutch on that RX8, and we made sure to replace both the pilot bearing and seal on it though. Maybe we're just awful mechanics, but we made sure to properly install it and grease it, use a transmission jack, not try to crank the transmission on with the bellhousing bolts, etc. Some additional points to consider...

-The center bushing for the transmission mount along with the actual rubbers holding up the transmission in my GXL might be crapped. I think it was RotaryEvolution that mentioned that if it sagged, it could just be transmitting additional noise from the 2 metal sections contacting
-I was an idiot and installed solid engine and transmission mounts in the T2, which is inherently going to make everything loud
-The NA I drove had a loud exhaust and everything clanked, so maybe I couldn't hear anything
-The RX8 also had a loud exhaust, and I never stuck my head into the footwell before my friend pointed out the noise after the clutch install

This is a very old video of when the T2 ran, but it highlights the noise very well since I repeatedly pushed in and let off the clutch pedal several times while listening for it:


I will try to also get a video of it in the GXL, but I don't have many opportunities to get that car out of its lair.

What do you guys think?

 

Sounds like gearbox bearings are noisy, Is common they Just need replacing

 

TOB and pilot bearing work in concert. When clutch pedal is depressed that's the only time the TO and pilot bearings are being utilized.
Replacing transmission oil might help make it less noisy.
These transmissions do produce some gear noise. After all, they are now old technology since they are 30+ years old.
Most likely, your bearings are worn out. Most of bearings (I think there are 9 total) in the N/A FC transmission are sealed ball bearings. The input shaft bearing in the FC transmission seems to have a short lifespan.
Center bushing seems to be a common failure. Rubber bushings have a limited lifespan and should be replaced regardless if they look good.
Your video is not working. --> Ok, now it works. Sounds like a bearing(s) to me.
How many miles are on these cars?

 

Figures it would be internal to the transmission. The T2's cluster said 70k miles (questioned it after I had it apart and it had an NA gauge cluster). The GXL is at 100k but I dont remember if the engine donor's transmission was swapped in, which was at 120k miles. I have been considering dropping the transmission to replace a leaking front cover seal. At the very least, that means new fluid, new TOB, and an opportunity to inspect the pilot bearing. I would need to order in new mounts if I replaced that. How can I check if the ISB is crapped with the transmission out? Play at the input shaft? Am I looking at catastrophic failure in the next ____ miles if I dont replace the transmission straight away?

Also, how tricky could it be to replace the input shaft bearing myself? I get that the casing needs to be split and everything is pressed together. I have a hydraulic press and can figure something out for the gear puller.

 

>>> How can I check if the ISB is crapped with the transmission out? Play at the input shaft?
Yes, the shaft will wobble a bit. You can also try rotating the input shaft and check for bearing roughness.

>>> Am I looking at catastrophic failure in the next ____ miles if I dont replace the transmission straight away?
Not usually, at least that I'm aware of. Under normal use, these transmissions will typically run forever, but the noise and vibration will get worse. I put over 230k miles on my original NA transmission before it bit the dust. It wouldn't shift out of 3-4 gear so I just replaced it with a spare that I had laying around.

 

That's reassuring. I'm going to focus on getting the car smogged for now then, and poke at my spare transmission. Thanks for the help

 

If you like to mess with mechanical things, I'd say go ahead and tear it apart. I did, on a spare transmission, over 15 years ago, and got stuck at the part where all you have left is the center bearing housing with all the parts (gears, bearings, etc.) pressed on either side. At the time I was young, poor, too busy and not stubborn enough, and needed a LONG reach gear puller, so I gave up. Turns out you can make one if you don't want to buy one. Ended up having the bearings replaced at a tranny place for $500 at a later time (when not so poor lol).

 

these transmissions do tend to make noise, its kind of normal

 

The transmission in my 1990 NA FC makes that EXACT same noise from your video, and exactly as you described it. I assumed it was bearing noise, glad to see someone else has the some problem, lol. I ended up just buying another trans with "supposedly" low mileage, going to install it next spring when the cars out of storage and see how that goes.