Originally Posted by Chiburbian
(Post 1458931)
Just for educational purposes, what sorts of things could be wrong with the clutch that might cause this? I am just trying to think this out...
Lumping the flywheel in with the clutch, a bad pilot bearing or poor concentricity of the pilot bearing hole in the flywheel would do bad things with the clutch disengaged pretty quickly. |
I see in your video that your pilot bearing hole was too large, and that you used bearing retaining compound to hold it in. A badly machined pilot bearing hole is pretty suspicious given that you're having weird resistance when the clutch is disengaged. It also looks like you installed it below flush, though that is probably less of an issue. |
Originally Posted by afm
(Post 1458987)
I see in your video that your pilot bearing hole was too large, and that you used bearing retaining compound to hold it in.
A badly machined pilot bearing hole is pretty suspicious given that you're having weird resistance when the clutch is disengaged. It also looks like you installed it below flush, though that is probably less of an issue. |
I've never once, ever, on any car, for any reason, have had to use retaining compound on a pilot bearing, nor have i ever been told to do so.
And i've done a clutch or dozen in my time. |
I didn't know such a substance existed.
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Originally Posted by 1993z32
1) Will not go into any gear without unreasonable persuasion.
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Originally Posted by concealer404
(Post 1458990)
I've never once, ever, on any car, for any reason, have had to use retaining compound on a pilot bearing, nor have i ever been told to do so.
And i've done a clutch or dozen in my time.
Originally Posted by afm
(Post 1458994)
The tricky thing is that a single application of "unreasonable persuasion" can add a bent shift fork (and partial synchro engagement, and creep in neutral) to a different problem.
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Well. You have two broken 6 speeds, so you need another.
And you have a pilot bearing that didn't fit right, so what you do there is probably up to you. :) |
Good info that soothes my mind... Savington knows :likecat: - Hopefully removing that clutch will resolve your issues.
I think most of us know what its like to take your time fixing something and then breakage :vash: :vash2: |
I vote crappy or incorrectly installed clutch and or flywheel
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Originally Posted by 18psi
(Post 1459000)
I vote crappy or incorrectly installed clutch and or flywheel
Seconded |
Greg, do you have a Patreon account? You have a bunch of viewers at this point and I'm sure enough would pitch in to help you get this resolved. Hell, I've learned enough from your videos and enjoy them to the point where I'd pitch in $20 to help you get a new clutch/flywheel and trans. Get something reliable from Trackspeed or 949 this time. Those guys know their stuff and I'm very curious to see this get resolved.
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Originally Posted by 1993z32
(Post 1458995)
And after further research the BMW trans swap is $4300... and that doesn't include the differential or the transmission.
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Originally Posted by Ryan_G
(Post 1459027)
You don't have to do the diff. You can just do the transmission swap for under $3k all in.
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Originally Posted by 1993z32
(Post 1459028)
And have ratios even shorter than the Miata 6-speed. If I'm spending thousands more dollars, I'm doing it proper.
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Two main things stick out to me.
1. You mention that in neutral with clutch engaged, it will try to roll forward as though it is pushing against a synchro. This is obviously transmission. 2. When it did fail, the car still was locked when the clutch was pushed in. This could be anything from the flywheel to the hubs, but if you can clarify that the diff is good and that the engine was still running when you clutched it, we can narrow it down to the transmission. On top of that, you opened up the trans and it looked 100% fine, and the only thing was synchro dust. To me, though you have a widely used shifter, I figure maybe it's too tall from the pivot point to where it meets the little cup that actually changes the gears (don't know what it's called). And as a result, it relaxes in a position where it is trying to go into a gear. The only other thing is likely the clutch and trans not mating properly and the input shaft wreaking havoc on the internals. VERY strange. Edit: I read back through your symptoms. It absolutely has to be the shifter or linkage. The only thing that doesn't line up is the fact that it locked up, but I guess two or three gears could somehow both be engaged by accident and lock up the transmission (from the linkage being screwy) and then pop out and return to normal. Perhaps the power does just pull things apart or move them around and just mess up everything. Is there a way to access the gears and shafts but leave a part of the housing off? I bet even if you lock up the output shaft and use a torque wrench somehow to apply 300+ ft lbs of torque to the input shaft, you can listen or see if anything weird happens. Edit 2: I figure you could even cut a hole in one of the transmission to look, lol. |
Reading up (time zones...) makes me wonder. Would pressure applied to the input shaft (by to thick clutch assembly) have an effect?
I made the mistake once of not installing the pilot deep enough, which resulted in an engine not turning over, so a pressure hard enough to move the input shaft would probably have seen immediately. |
Honestly ive seen people put the clutch disc in backwards and it locks the clutch setup so that its engaging all the time. They get the movement while in neutral. Not saying you did that but it just makes me think the clutch setup is suspect.
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Hey Greg, I'm a fan.
More speculation here, maybe the overall engine vibrations at certain RPMs ranges are killing the transmission boxes? You are running two clutch discs with no springs at all, although the one is fibrous, I doubt that is enough to dampen all the harmonics from the power waves. So my take is that vibrations push the transmission internals to a state they shouldn't be, and bang. Mount a sacrificial 5-speed to drive around and diagnose if the clutch itself has manufacturing/tolerance errors. Until it dies, start collecting parts for a transmission swap! No no, not the BMW.. At your power level, a stronger transmission box is a must IMO. There are known partial failures of the 6-speed at 390hp at the flywheel. Although I believe you don't want to daily over 400whp power, it makes sense to have a better solution even at 300whp. I would like to suggest an RX-7 box. Turbo FC ribbed version for a notchy feeling or FD version for smoothness. I went with the FC version, but car isn't running yet so can't offer a first hand experience. The turbo FC is what mattman runs, with a twin plate clutch. Hopefully your torque won't be able to kill it :P Basically, I believe it's the most cost effective option for you. In Greece it is a pretty common swap for high power miatas:
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Originally Posted by NiklasFalk
(Post 1459032)
Reading up (time zones...) makes me wonder. Would pressure applied to the input shaft (by to thick clutch assembly) have an effect?
I made the mistake once of not installing the pilot deep enough, which resulted in an engine not turning over, so a pressure hard enough to move the input shaft would probably have seen immediately.
Originally Posted by omnislashx82
(Post 1459033)
Honestly ive seen people put the clutch disc in backwards and it locks the clutch setup so that its engaging all the time. They get the movement while in neutral. Not saying you did that but it just makes me think the clutch setup is suspect.
Update: Trans #2 is out. Inspected clutch/flywheel, everything looks fine, including the pilot bearing being in place and butter smooth. Trans itself is definitely jacked up. The only way I can see the clutch causing the problem is if the pilot bearing hole isn't perfectly centered which would cause vibration in the input shaft that I couldn't feel, and then somehow spawning unicorns inside the trans to rearrange the shift forks. I suppose at this point I'm going to try a different clutch and flywheel, and put my 5-speed back in, and none of the mysteries will be solved. Unless trans #1 miraculously seems fine after I put it back together, I suppose I'll try to run that. |
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