Quote:
Originally Posted by radroach
@zippee
I experienced poor shifting as parts started wearing out on my car. Things became noticeably worn out and are pretty easy to identify. Throwing new parts at it provided immediate results.
The clutch throw-out bearing is one of the first things I'd change out, if it hasn't already. I'm on my third throw-out bearing at 130,000 miles. I was getting grinds going into gear, shh-shh and tapping or vibration noises - all from this bearing. Here's a sound clip of my engine from over a year ago exhibiting noticeable tapping sounds before I took my car into the dealership for the engine / spring recall and had a new clutch throw-out bearing put in: https://voca.ro/1iC9k45HPQoS
The other part I think wears too much is the transmission mount. It is too soft, and after lots of miles and hard driving it gets sloppy, and the transmission / drivetrain bangs around and makes 1st-2nd gear shifts HELL. Either get a new transmission mount, or get a Whiteline "positive shift kit" which will reduce this movement. Huge improvement in shift-feel.
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So, I recently replaced my stock manual transmission oil at about 68K miles in my 2014 BRZ (I know its way overdue
) with Motul Gear 300 75W90 oil. However, I'm now in about the first 100 miles after the oil change and I'm regularly experiencing hard shifts from 1st to 2nd, but also from 2nd to 3rd and even 3rd to 4th. The issue is more pronounced when changing gears at higher RPMs. That is, if I'm changing up through those gears at higher RPMs, I experience something like a half-second to a one-second delay before I can actually get into gear and let out the clutch. Howevere, I'm not necessarily experiencing any grinding, it just routinely takes that additional amount of time for the gear (the synchros?) to fully engage. It doesn't seem to get too much better as the transmission warms up, but I also haven't gone on an extended drive to test that out yet.
I'm considering a number of potential issues.
From searching the forum and the internet, it seems like GL-5 oil is generally not good for BRZ/FR-S transmissions because of the material composition of the synchros, but the Motul 300 LS from CounterSpace Garage says it is GL-4/GL-5 compatible. So I'm assuming that means its rated up to GL-5, but is also will work with transmissions that need GL-4, and that it presumably doesn't harm the transmission synchros. So I'm trying to first understand if maybe my new transmission oil is the issue or if these are separate issues that just happen to have started manifesting themselves. With that said, I can't imagine that CSG would have knowingly sold transmission oil they indicate is compatible with the BRZ that is not actually compatible or could harm the transmission, so I will assume this is more my lack of understand than that.
Along the lines of potentially separate issues, I've wondered if perhaps my clutch is not fully disengaging when the pedal is fully depressed. I have some evidence that this
may be the cluprit as the issue seems to be a little less worse when I'm really mashing down the clutch pedal and might suggest a clutch adjustment or perhaps needing to replace the throwout bearing? But if that is the issue, my question is whether and why there would be a connection between that and a transmission oil change? I've also learned more about the benefits of installing a bushing for the rear transmission mount (e.g., whiteline, cusco), which seems to help stiffen up the transmission and can help greatly in getting back easy gear shifts, but again, I don't understand why needing to install something like that would become an issue all of the sudden after changing my transmission oil.
Any ideas on troubleshooting this further before I start dropping cash? Perhaps I'm thinking about the problem wrong?