6-5 Downshift Grind/Difficult Reverse
Thread Starter
Cruising
Joined: Dec 2023
Posts: 13
Likes: 2
6-5 Downshift Grind/Difficult Reverse
Hey yall, so I’ve recently developed a 6-5 downshift grind, but what’s weird is if I’m going 65/lower rpm it’ll downshift 6-5 just fine but anything above 70ish mph it will grind. Could that be the lockout solenoid? Also, I put in a softer solenoid spring, would that also cause issues? The Trans is definitely worn, near 160k hard miles, but it never has any pop outs or issues going into gear ever. Only this 6-5 new downshift issue. Also reverse is insanely difficult to get into, and once it’s in it does not pop out, but it requires so much force, I think that’s just due to high mileage trans. I also just installed a new mgw shifter replacing my old model that used the stock lower box hoping the lower box was super worn, but that wasn’t it 
before anyone else asks, it has fresh amsoil torque drive in it, and I’m gonna change clutch fluid again too see if it does anything (motul rbf600) anyway, if someone can confirm a lockout solenoid could cause a downshift grind, before I go crazy and waste another $100 when in reality it’ll need a trans rebuild eventually
before anyone else asks, it has fresh amsoil torque drive in it, and I’m gonna change clutch fluid again too see if it does anything (motul rbf600) anyway, if someone can confirm a lockout solenoid could cause a downshift grind, before I go crazy and waste another $100 when in reality it’ll need a trans rebuild eventually
Safety Car
Joined: Jan 2012
Posts: 3,947
Likes: 519
From: Da U.P.
Reverse sucks in these, but it sucks more in the 6060. I got my car with 99k and reverse had already been replaced. A year after I got it, I too fixed reverse. It's the first thing you see when you open up the trans.
Melting Slicks
Joined: Nov 2014
Posts: 3,399
Likes: 1,338
From: Havre de Grace Maryland
No thoughts on the downshift issue but the reverse gear easy is always an issue with my C5 base since purchase 10 years ago. My workaround in the M6 is first put in neutral, wiggle the shift many times and then put in reverse gear. Seams to work for me.
Thread Starter
Cruising
Joined: Dec 2023
Posts: 13
Likes: 2
bummer, the downside thing is tripping me out. So I can downshift around 65mph in 6th but around 70 it’ll start to fight back and grind. It’s also having more trouble finding reverse, it’ll be in the slot but not engaged. Now I beat the **** out of it so what do I expect. But it never grinds or pops out while in gear or when upshifting ever, oh well guess I’ll just live with it
Le Mans Master
Joined: Jul 2010
Posts: 5,923
Likes: 705
bummer, the downside thing is tripping me out. So I can downshift around 65mph in 6th but around 70 it’ll start to fight back and grind. It’s also having more trouble finding reverse, it’ll be in the slot but not engaged. Now I beat the **** out of it so what do I expect. But it never grinds or pops out while in gear or when upshifting ever, oh well guess I’ll just live with it
Thread Starter
Cruising
Joined: Dec 2023
Posts: 13
Likes: 2
it’s a fully built car. Tick master, new oem slave, and ls7 clutch correctly broken in for 500+ miles before aggressive driving. But the trans is original with 157k. Clutch stuff done maybe around 131-3k I forgot. But it still drives great going in first and all the rest. Gets into 2, 3, and 4 at 7k rpm no problemo. I just think from aggressive driving while racing it’s hurt the trans, maybe bent the crappy aluminum shift forks. Guess I’ve accepted that’s the result of my driving haha, maybe in a few years I’ll rebuild it if it doesn’t get any worse.
Pro
Joined: Apr 2018
Posts: 563
Likes: 201
From: Montgomery City, MO
Sorry I haven't been watching the forum in a while. I had the exact same problem (downshifts to 5th at > 65mph). I didn't see anything obvious when I went through it, but you're likely going to want to replace 5th and the slider because the engagement teeth are going to be pretty chewed up.
I replaced all frictions and rings as well as 5th gear and the syncro slider and downshifts to 5th are smooth at any speed now. But I will add that I'm not sure running synthetic fluid in these is a good idea, and I suspect that's probably what was in mine (from a previous owner). Not because it's reported to damage the paper blockers, but because it's designed for automatic transmissions with hydraulic clutches. Here's why I filled with regular Dex 3 - TDP does not recommend any type of synthetic in the T-56 or the 6060. See here.
I replaced all frictions and rings as well as 5th gear and the syncro slider and downshifts to 5th are smooth at any speed now. But I will add that I'm not sure running synthetic fluid in these is a good idea, and I suspect that's probably what was in mine (from a previous owner). Not because it's reported to damage the paper blockers, but because it's designed for automatic transmissions with hydraulic clutches. Here's why I filled with regular Dex 3 - TDP does not recommend any type of synthetic in the T-56 or the 6060. See here.
Thread Starter
Cruising
Joined: Dec 2023
Posts: 13
Likes: 2
Sorry I haven't been watching the forum in a while. I had the exact same problem (downshifts to 5th at > 65mph). I didn't see anything obvious when I went through it, but you're likely going to want to replace 5th and the slider because the engagement teeth are going to be pretty chewed up.
I replaced all frictions and rings as well as 5th gear and the syncro slider and downshifts to 5th are smooth at any speed now. But I will add that I'm not sure running synthetic fluid in these is a good idea, and I suspect that's probably what was in mine (from a previous owner). Not because it's reported to damage the paper blockers, but because it's designed for automatic transmissions with hydraulic clutches. Here's why I filled with regular Dex 3 - TDP does not recommend any type of synthetic in the T-56 or the 6060. See here.
I replaced all frictions and rings as well as 5th gear and the syncro slider and downshifts to 5th are smooth at any speed now. But I will add that I'm not sure running synthetic fluid in these is a good idea, and I suspect that's probably what was in mine (from a previous owner). Not because it's reported to damage the paper blockers, but because it's designed for automatic transmissions with hydraulic clutches. Here's why I filled with regular Dex 3 - TDP does not recommend any type of synthetic in the T-56 or the 6060. See here.
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Pro
Joined: Apr 2018
Posts: 563
Likes: 201
From: Montgomery City, MO
That may be true, but it's made with synthetic base stocks, which have significantly higher lubricity. Also, the Dex 3 specification was developed for autos with hydraulic clutches. The frictions and cones in the synchros were designed for dino ATF, which is why TDP recommends it over anything made with synthetic stocks.
I'm sure there are others that have this issue but may never notice it due to not downshifting quickly to 5th. I tend to use 5th when in traffic on the interstate instead of the brakes. After a while, any time there was "spirited" cornering on the horizon I started trying to skip directly to 4th, until I accidentally hit 2nd once. Near death experience.
I'm sure there are others that have this issue but may never notice it due to not downshifting quickly to 5th. I tend to use 5th when in traffic on the interstate instead of the brakes. After a while, any time there was "spirited" cornering on the horizon I started trying to skip directly to 4th, until I accidentally hit 2nd once. Near death experience.