Hard upshifts 16' S550 MT-82.

[DonPatr0L]

Hi All,

I just did a brake fluid flush a couple of weeks back with my motive power bleeder. Pushing 13psi. After I finished, I went for a drive and its having pretty rough upshifts.

Running from 1st - 2nd - 3rd- 4th, all gears have a rough upshift/kick. Feels similar to if you were to do a high rev match when the gear you are shifting to should be at a lower rpm.

I put vacuum on the reservoir (20psi) for 1 minute, then released, reapplied the cap, and pumped about 30 times. Repeated this 5 times. Went for a drive and its still happening. Slightly better, but not by much.

My assumption was, there's air in the clutch line, and its causing the clutch to stay engaged slightly at shifting, causing the grab but then releases. though not so sure. When I shift, Ive been giving it a second for the revs to drop but its still happening regardless.

Anyone have an idea?

 

[Mad Hatter]

Maybe its just me. But now I do my brake flushes with two people and pumping the pedal the old fashioned way. Was never happy with the results of my Motive bleeder. Since yours got a little better after a repeat session, I would bleed the system again, one brake at a time with the pedal.

 

[EF1]

I hope the MT82 curse hasn't gotten to you. How many mile on the car, what is the horsepower level, are you still on the stock clutch, and how many RPM's are you turning?

 

[DonPatr0L]

I hope the MT82 curse hasn't gotten to you. How many mile on the car, what is the horsepower level, are you still on the stock clutch, and how many RPM's are you turning?

23k miles, 440hp, 7000 rpm redline. Still in the stock clutch. Probably seen 30 hours of track time and maybe 500 autocross laps

 

[TMSBOSS]

I would go back to the clutch hydraulics and vacuum and pump until the last of the air is out of the lines and TOB. I had a similar issue with my Boss when I swapper slave and master cylinders. The pedal was “Almost Right”. Then it finally came around. Consider pumping the pedal with a vacuum applied. That worked for me.

 

[EF1]

23k miles, 440hp, 7000 rpm redline. Still in the stock clutch. Probably seen 30 hours of track time and maybe 500 autocross laps

Your hp and rpm redline are below that when most started having trouble. Also, I just noticed that you have a 2016. The 2011 and 2012 cars had clutch issues but I think they were pretty well sorted by the S550's. It does really sound like an engagement issue. If it was a bad synchro it wouldn't happen in all gears and it is unlikely they all went bad at the same time.

I have used a motive power bleeder for years on my 2011. It has worked great and never had any problems after flushing brake fluid. I would try a vacuum bleed like TMSBOSS said just to make sure you don't have an air bubble somewhere. You can take the adapter from your motive and attach a MityVac. If it doesn't help started looking at the slave cylinder. Unfortunately, clutch engagement issues can lead to synchronizer problems pretty quickly. The MT82 can be somewhat fragile at times.

Also, there have been some reports of DOT4 fluids such as Castrol SRF being hard on slave cylinders. Many of us have separated the clutch and brake circuits to allow the use of DOT 3 fluid in the clutch for this reason. Good luck on getting to the bottom of it.

 

[JDee]

I got 2 seasons out of the stock clutch and when it went it did so silently and took the trans with it. About 6 grand later I had it fixed......
If you're hard core tracking the car the stock clutch is just not up to the task and it will kill your trans. It's the heat....a trans cooler is a good addition to any seriously driven track day car. Not that hard to do.

 

[Mad Hatter]

Would absolutely agree that the stock clutch is something that should be changed if your going to track our car... Its not worth the potential problems it can bring.

 

[DonPatr0L]

UPDATE:

I keep driving it and to be honest I think there is something a miss. I've been playing around with it and essentially, when driving normally say, shift at 4.5-5K, if I dont shift fast, the RPMs drop below 3K and it will be upset. If I shift fast and its at 3K, smooth as can be....so I have no idea.... This was never a thing before. I'll be honest, my weak skills in wrenching is clutch/transmission and recognizing symptoms. Doesnt get better after warming up.

With regards to how much I've tracked the car so far, I think the car has probably seen 15-17 hours of HPDE days and call it 300 autoX laps. Any thoughts? Clutch going down the tube?