Is my trans about to take a dump? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 02-07-2009, 02:45 AM   #1
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Default Is my trans about to take a dump?

Its a 5 speed from a 1994, and its loud! I just rebuilt my engine, and got it back in the car roughly 3 weeks ago, and the first 15 miles or so was with little or no trans fluid. I noticed a nice gear whine when I was test driving it and breaking it in, about 5 miles from home, and I drove it back and filled it. Since then its been quite noisy. It had a bit of noise before, but not like this. Im aware that light weight flywheels add some noise, but not like this. The majority of the noise is at idle, under 1200rpm. It sounds like tons of slack in the gears, a clacking noise/rattle. I originaly thought this noise to be t/o bearing, but realised after playing with the pedal, it was the trans. It also has increased whine, which is probably the reduced weight from the flywheel. At ~30% throttle and higher in all gears, I get a higher frequency rattle, which I also am pretty sure is the trans.

Anyway, do you think this is going to cause a failure in the near future? Or should it just be a noise issue. Im not sure with the state its in if I would feel safe boosting it and daily driving it. Cant really afford to be stranded on the side of town I work on (in one of the top 10 most dangerous cities from the last few years). Im trying to decide if I should just chance it if it may be alright, or if I should delay my turbo plans even further to save up for a 6 speed and rear gear.

Outside of Allison automatic transmissions I have built (I can pull apart and assemble a 1000 series with my eyes closed) Im not much of a transmission man, which is why I ask. Figured some of you that have had them fail might have some insight.
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Old 02-07-2009, 02:52 AM   #2
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you drove it without fluid????!!! my brother did that on a civic once. almost same story. we replaced tranny weeks after. dont mean to sound like a buzz kill but good luck
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Old 02-07-2009, 02:55 AM   #3
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I'm not an expert but usually crackling is caused by input shaft bearing or flywheel/pressure plate bolts loose. My guess is input shaft. Either way borrowed time and best to replace now if possible. It will leave you stranded soon.

Edit* Can't spell after being up 22hrs.

Last edited by ChuckyZ; 02-07-2009 at 12:20 PM.
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Old 02-07-2009, 02:58 AM   #4
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Haha, yeah, I kind of figured maybe that was the case. It was only 5-10 miles though, maybe not even that. Oh well. I wonder if heat is as big of an issue as friction when it comes to cases like this. I dont think I ever really got over about 50mph, and drove home in 5th at maybe 40mph, keeping the throttle about right to maintain speed. I guess noise is noise no matter how I drove it. I guess I will just keep driving it till it either becomes really obvious its about to blow up, or till I can decide if its worth it to go ahead with a 6 speed. I'll never be boosted at this ******* rate!

Further info, when the trans was out, I was noticing how much slack there was when turning the input shaft. In both the fact that the input shaft had some movement, and the fact that I could turn the input shaft one way, then reverse direction, and feel what felt like the internals spinning maybe another 5 degrees before catching. Maybe it was already sloppy before, and the low/no fluid thing just really pushed it over the edge. How tight should an input shaft feel on a new or rebuilt trans? I know the gears have to have some play in them.

But now all of this is really making me just want to find another 5 speed, or maybe have this one rebuilt (if that could be done for under $800 or so, though from what Ive seen, rebuilds arent cheap. I wouldnt trust myself to do it, having nearly no hands on experiance with manual trans). Im only going to be aiming for 200whp or so, which shouldnt be a huge issue for a stock 5 speed.
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Old 02-07-2009, 03:10 AM   #5
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Quote:
Originally Posted by NA6C-Guy View Post
Haha, yeah, I kind of figured maybe that was the case. It was only 5-10 miles though, maybe not even that. Oh well. I wonder if heat is as big of an issue as friction when it comes to cases like this. I dont think I ever really got over about 50mph, and drove home in 5th at maybe 40mph, keeping the throttle about right to maintain speed. I guess noise is noise no matter how I drove it. I guess I will just keep driving it till it either becomes really obvious its about to blow up, or till I can decide if its worth it to go ahead with a 6 speed. I'll never be boosted at this ******* rate!

Further info, when the trans was out, I was noticing how much slack there was when turning the input shaft. In both the fact that the input shaft had some movement, and the fact that I could turn the input shaft one way, then reverse direction, and feel what felt like the internals spinning maybe another 5 degrees before catching. Maybe it was already sloppy before, and the low/no fluid thing just really pushed it over the edge. How tight should an input shaft feel on a new or rebuilt trans? I know the gears have to have some play in them.

But now all of this is really making me just want to find another 5 speed, or maybe have this one rebuilt (if that could be done for under $800 or so, though from what Ive seen, rebuilds arent cheap. I wouldnt trust myself to do it, having nearly no hands on experiance with manual trans). Im only going to be aiming for 200whp or so, which shouldnt be a huge issue for a stock 5 speed.
If I can get the money together in the next week i'm going to purchase a 6-spd so i'll have a 5-spd for sale cheap i'll let you know.

When you checked the input shaft was there any side to side motion or up and down motion. Thats where the bearing noise would come from. A weak point on datsun's trannys. So thats where my experience comes from.
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Old 02-07-2009, 03:12 AM   #6
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I dont really recall there being much movement that way, mostly just slack when spinning it.
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Old 02-07-2009, 03:22 AM   #7
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lets hope for best case scenario
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Old 02-07-2009, 03:46 AM   #8
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Well, the best case scenario is that I find the money for a 6 speed and 3.636 gears, and find someone willing to do the work for me for free.

Would the trans being 1/4 quart low cause any noise? I know its supposed to be filled till it runs out of the filler hole, but when I added the fluid I only had about a quart and a half, so its still a bit low. I didnt think at the time it could cause any issues. This weekend I will flush and refill with some better stuff. Im using Pennzoil, what I thought was the synchromesh, but its the non GM stuff thats not synchromesh. I was using Redline, but the Pennzoil is all I had at the time. Its also been sitting outside for probably 2 years, though one quart was brand new still sealed, and the other was capped, so I dont think anything was wrong with it. Again, oh well, its only money
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Old 02-07-2009, 10:52 AM   #9
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wtf? You're putting "gear oil" in the manual trans, right?

You are fine if it drove it at 1/4qt low, but not much lower. Redline MT-90 is ****. I'm putting either Schaeffer or Motul in mine because they use real, high-end esters that others don't.
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Old 02-07-2009, 12:10 PM   #10
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Quote:
Originally Posted by NA6C-Guy View Post
Well, the best case scenario is that I find the money for a 6 speed and 3.636 gears, and find someone willing to do the work for me for free.

Would the trans being 1/4 quart low cause any noise? I know its supposed to be filled till it runs out of the filler hole, but when I added the fluid I only had about a quart and a half, so its still a bit low. I didnt think at the time it could cause any issues. This weekend I will flush and refill with some better stuff. Im using Pennzoil, what I thought was the synchromesh, but its the non GM stuff thats not synchromesh. I was using Redline, but the Pennzoil is all I had at the time. Its also been sitting outside for probably 2 years, though one quart was brand new still sealed, and the other was capped, so I dont think anything was wrong with it. Again, oh well, its only money
So when you took off, was the oil empty or just a quarter quart? And if you just put penzoil in it instead of 90 weight. You can dumpall that oil and put 90 weight gear oil and the noise will probably stop.

The first time I put a tranny in, the idiot at Autozone sold me the wronge oil. I told him I wanted Synthetic. He gave me regular synthetic. I drove the car 100miles on a trip. It kept getting louder and louder. My dad looked at the oil cans and said THIS IS THE WRONGE STUFF!!!!!!!!!!!!!

BOY! forget that hottrodding crap. GET 90 WEIGHT! The tranny instantly quietened with the right oil.
A quater quart is nothing. Make sure you have 90 weight GEAR OIL. Not 10-40 motor oil.

Good Luck!
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Old 02-10-2009, 06:29 AM   #11
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Ok.

First 10 miles or so, no fluid, maybe 1/2 quart or so remained. I sort of did that bad thing I often do, assume, and assumed it had enough in it for a test drive just down the valley and back. Guess not.

Got it home, added ~1.5 quarts of Pennzoil Synchromesh "gear oil" though it did seem a bit thin... So that had to have put it at at LEAST what I had just put in it, but I assumed more was there. Drove it another 500 miles with noise.

Satuday I drained all of it (somehow only just a hair over a quart, I guess the last little bit in each quart bottle cant be sucked up by my hand pump) and refilled it with the best thing I could find at the local parts store, Royal Purple. Im STILL probably a hair low, since I think the 5 speed trans holds something like 2.2 quarts, and I only put in 2 minus a bit at the bottom. SO say its 1/4 quart low again. Either way, the last 50 miles is much quieter. The gear crunking and rattle sound is all but gone. I feel I can do fine with this trans on boost, just depends on what the trans itself says to that...

I will go buy another bottle this weekend and top it off. I just hate the methods of checking the level. Only way I can do it is either all 4 corners up, or front up, remove plug, then lower the car and look for it to drip. Really easiest to over fill, and lower the car flat and let the extra run onto the ground. Its only $15 a quart, whats money to me, I live in a tree house in the peak of a 200' money tree.

And yes, I know the difference between engine oil 10-40, and what I think is 75-90 with the RP stuff. Thats also why the asshats at the parts store get ignored. I dont want them butting in and trying to give me the wrong **** and act like they actually know what the hell they are talking about. Used to not be the case, but the best auto parts dealer Ive even know died and his store went to **** afterwards. I could ask for a hose about so long, and with a 45 degree curve at the end, and he could brush his beard one time and walk off and come back in 30 seconds with one in hand. Thatll be $3.87, just gimme 3.50 and we are good.

Dont get that kind of service anymore...
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Old 02-10-2009, 07:32 AM   #12
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I check mine by jacking up the car on stands and filling until I can feel the oil with the tip of my finger in the filler hole.
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Old 02-10-2009, 02:51 PM   #13
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Yea, if I want service, I have to go to the Napa on Belt line. Two guys in there are good. The rest are not so bright. And don't get me started on the local Oreiliys.
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Old 02-10-2009, 04:16 PM   #14
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I had a transmission with serious whine, it lasted about 3 years under 6psi, and 6 months under 12-15psi before it made the really crunchy noises.

How long yours will last is really a crap shoot. I'd be looking for cheap replacement 5 speed. Try calling the local spec miata shops.
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