yet_another_fc

Hi all!

Figured I would ask this here before blindly replacing parts. I recently bought a N/A '87 which had been sitting for a few years due to a "clutch issue". The previous owner had it for a few months and was working on getting it running again, with new fuel pump, filter, replaced secondary injectors, fuel relay, etc. but didn't succeed. I have since done oil/coolant/spark plugs/marvel treatment, and added some gas with premix & it fired right up! The clutch pedal was completely screwed up and bent, both the pushrod & main bolt though (I'm guessing the hydraulics failed, causing the car to be parked in the first place and then the PO stomped on the pedal when the master froze from sitting? Either way, I replaced the assembly and put in new hydraulics and the clutch seems to work just fine.

Unfortunately, the transmission makes a lovely whining noise. I drove it up and down the neighborhood briefly, and then checked the trans fluid. It was low and I added roughly 1 qt before it began spilling back out of the fill port. I drove it roughly 90mi to test the coolant system and everything else (which thankfully didn't have any issues) and the noise quieted down a bit, but it's still whining pretty bad. Here is a list of potential issues I have been able to think of so far-
-Pilot bearing
-Input shaft bearing
-Throw out bearing
-Any/all bearings/gears inside the trans
-Excessive vibration/noise from bad transmission mounts?

I've attached a video below for reference (ignore it popping out of gear in the second video, used to the shorter throw in my miata ) but the noise is quite loud. It is present in N and all gears, only going away when the clutch is FULLY depressed (i.e. trans is disengaged). You can hear the noise slowly stop which I believe is the trans slowly spinning to a stop. 4th gear is a little quieter than others, which I read might point to the input shaft bearing? Also, there is a slight smell of burning transmission fluid when driving and the shifter itself gets burning hot to the touch. I have rebuilt the shifter but not replaced the worn outer boots, so maybe the heat is just from that? I have also noticed that the mount/bolt on the transmission is slightly down from the crossmember, so the mount definitely isn't in great shape.

I'm looking for any possible input/solutions to what the issue might exactly be. I've got a few paths I can take, but would rather try and diagnose before replacing parts (and pulling the trans as I plan on using a buddy's lift ) Any input is appreciated, thanks!
Possible solutions-
-Just send it until the trans blows up and focus on other maintenance
-Drain and fill with completely fresh fluid only
-Test transmission mount?
-Standard clutch job (pilot, throwout, new clutch, machine flywheel, change fluid)
-or all of the above while throwing another trans in there (probably will need to happen, but pricey!)

Idle
IMG_3272.mov
Driving
IMG_3273.mov

diabolical1

iTrader: (3)

welcome to the board.

the good news is i'm not an expert, so i can totally be wrong. however, i do have some tranny experiences. i did lose one tranny many years and it made similar noises before and after it tapped out. also, keep in mind, i'm hearing this in a video, not in person.

the bad news is i think the tranny is hosed. between the noise, your mentioning it pops out of gear, and the fact that you're feeling such heat coming up through the shifter, it doesn't sound like anything external. throw-out bearing can make a couple noises, but yours sound different to me. in my experience, the pilot bearing makes a different noise as well. i suppose draining and refilling wouldn't hurt (plus you'll get to inspect the fluid in it now), but i wouldn't advise that you place much faith in an oil change from what i heard. one thing that is certainly free is pulling it out and inspecting the case for cracks and/or leaks (including the input shaft) - see if its getting on the clutch (the burning smell you mentioned).

probably should start looking for another one. rebuilding in not an easy task, but it can be done, so i suppose that's an option as well, but if you can't do it yourself, then i suspect it might cost the same or even more than just getting a used one.

Monika

iTrader: (1)

Rock auto sells bearing and syncro kits. Take the pan off and inspect the gear to see if its worth rebuilding. It will cost you more to rebuild but at least its not a mystery trans anymore.

DR_Knight

iTrader: (23)

Don’t think n/a trans have an inspection plate like the t2 trans does.

Might as well drain the trans fluid and inspect for metal.

Either way it sounds like the transmission is coming out. Replace the usual parts while trans is out and price out a used trans in the meantime.

yet_another_fc

Thank you all for the input! I think the trans is most likely gone as well but wanted to check. It only popped out of gear once in that video because I didn't put it all the way into 1st and I haven't had it pop out otherwise, so it's not completely gone yet. I've since driven it another 30mi or so, and noted the following-
-Noise is quieter in 4th and occasionally non existent once warmed up in 4th
-Noise gets quieter when pulling up on the shifter (see video)
IMG_3492.mov

Both of these lead me to believe it's the transmission itself as mentioned above. The mounts are making the noise much louder, but aren't the source.
I'm going to drain & fill the trans again completely and check to see what the fluid looks like, and order some replacement transmission mounts. Either way I'll need to replace them, so might as well see if it'll help the issue haha.

So far I've found two S5 trans local for ~$500, neither are confirmed good but do come with the crossmember (which I believe I'll need since trans needs to match crossmember). Can probably get them for cheaper than that too with a little negotiation I'm also considering the miata gearset swap into the FC case, since I imagine the case itself isn't bad. I can get the machine work for the input shaft done, though I'm not sure about the rest of a job as it seems pretty involved, and it might be cheaper/easier to just drop in a used trans. Thoughts between the two? I've been searching across the various threads for both options so far. I don't believe I could rebuild the trans, but swapping the gearsets seems possible.

diabolical1

iTrader: (3)

funny you should mention this because last night when i responded to you, as i started talking about possibly rebuilding it, i thought about mentioning the Miata gearset, not so much because of the performance qualities, but moreso because i suspect they might be easier to find (possibly cheaper - i honestly, don't know) - that may also apply to new parts as well, again, i don't know. bottomline is you could kinda get a two-fer out of going that route. however, like i said, the rebuild process is not easy (not just the skillset required, but also the tools), so it's not something you can just do on a whim. there will be costs involved.