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Old 08-24-2011, 04:39 AM   #1
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Default 6 speed woes

Ok first post so please be gentle.

Just bought my 05 Mazdaspeed Miata. Factory except for some aftermarket 18's that the previous owner had installed.

The car grinds going into third unless i shift very slowly. I am not power shifting the car and i am letting off the gas between shifts. if it is below 5k it is generally fine depending upon speed of shift. 5th gear does it to in some circumstances but no where near as bad as 3rd.

I plan to check pedal adjustment as it seems my engagement point is fairly close to the floor. i have read this is a fairly common issue and the dealer is using that as a reason not to fix it. I have a warranty on the car and plan to have it checked out, but i am the type that i would rather fix it.

So clutch adjustment? Is there anything else I can check?
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Old 08-24-2011, 04:41 AM   #2
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Might want to do a fluid swap, I use AMSOIL MTG, you can do a search on here for what other people suggest. Some fluids have been reported to fix grinding problems.
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Old 08-24-2011, 04:42 AM   #3
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That's it. You can try switching fluids - Redline MT-90 isn't my first choice for trans fluid (I use MTG as well), but it is a GL-4 and it can help a crappy synchro perform a little better.
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Old 08-24-2011, 07:17 AM   #4
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Motorcraft MTX-75 IB5 has also been reported to help with sync.

And nice choice for a username, when people click your thread, they at least know what is coming.
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Old 08-24-2011, 12:48 PM   #5
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alright i will do the clutch pedal adjustment today and i will do the fluid change tomorrow or friday. Is there a factory service manual pdf available on the mazdaspeed cars? also. regardless of price what fluid has been the best at helping correct grinds? I need to get this fixed either by me or the dealer so i can start modding it!
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Old 08-24-2011, 01:08 PM   #6
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Quote:
Originally Posted by NeedDirection View Post
alright i will do the clutch pedal adjustment today and i will do the fluid change tomorrow or friday. Is there a factory service manual pdf available on the mazdaspeed cars? also. regardless of price what fluid has been the best at helping correct grinds? I need to get this fixed either by me or the dealer so i can start modding it!
Re-read the responses. They said which were good fluids to try.
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Old 08-24-2011, 02:12 PM   #7
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i seen the responses. sorry i should of asked a bit more clearly. Is there a particular product that has been used to fix the grind issue with a higher success rate then others? Also any fsm's? i have read of a bolt to not touch while changing fluid and would like to know a lil bit of what to expect before i go under looking for the drain. also what about the turrent oil? never heard of this.

Ok i adjusted the pedal to where the engagement point is about half. i will report back to see if that fixes it. unsure of what free play you were all talking about though...
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Old 08-24-2011, 02:20 PM   #8
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Amsoil MTX is what most people run in the 6 speed. It may or may not fix the grinding issue.

When you are under the car the drain and fill plugs are on the drivers side. The turret on the 6 speed just drains into the rest of the transmission. Feel free to fill the trans from the turret.
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Old 08-24-2011, 06:35 PM   #9
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Quote:
Originally Posted by NeedDirection View Post
i seen the responses.
Really? Post 3:

Quote:
Originally Posted by Savington
Redline MT-90 isn't my first choice for trans fluid (I use MTG as well), but it is a GL-4 and it can help a crappy synchro perform a little better.
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Old 08-24-2011, 09:59 PM   #10
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FWIW some 6 speeds just grind and there's not much you can do. I've read of a few people here dealing with this problem. I know running MTG helped hustlers grinding go away, but my 5th gear grinds every single ******* time. I'm also on MTG, and I've tracked this tranny 5-6 times. Still grinds.

I gave up trying to fix it, and I have a spare 6 speed sitting in the garage anyway.

tl;dr do what you can and if it still grinds just drive it.
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Old 08-24-2011, 11:38 PM   #11
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I've used BG Synchroshift for this with great success. The DSM guys call it a rebuild in a bottle. It is exceptionally good.
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Old 08-25-2011, 08:24 AM   #12
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Well, there are different "grinding" issuses. The common one is the 1-2 shift when cold...or any other grinding when the trans is cold. If if keeps grinding after you've been driving, that is NOT a common problem and is a sign of a problem. Adjusting the clutch pedal in all honesty won't help you. The part that could be causing an issue would be the slave cylinder on the transmission. If it's leaking, it could cause difficult shifting (including reverse and 1st BUT some 6spds are hard to get into reverse so don't take that as a for-sure sign). Check the clutch fluid level and color...if it's anything but a transparant light brown, you've likely got a bad slave cylinder.

If the slave is fine, the fluid is fine and it's grinding after extended driving, it's really a wear problem caused by the previous owners shitty shifting technique or abuse. I'd recommend changing the fluid to the Motorcraft or AMSoil and checking the slave cylinder. If neither of those fix it, you'll be stuck with it until you either rebuild the transmission or replace it with another unit (used 6spd transmissions typically sell for $500-900).
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Old 08-25-2011, 08:26 AM   #13
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..also the pilot bearing could be an issue.
If it doesn't work properly, there's still contact between the gearbox and the flywheel.

It will be accompanied by some wicked sounds from time to time though..
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Old 08-25-2011, 10:25 AM   #14
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Quote:
Originally Posted by MartinezA92 View Post
FWIW some 6 speeds just grind and there's not much you can do. I've read of a few people here dealing with this problem. I know running MTG helped hustlers grinding go away, but my 5th gear grinds every single ******* time. I'm also on MTG, and I've tracked this tranny 5-6 times. Still grinds.

I gave up trying to fix it, and I have a spare 6 speed sitting in the garage anyway.

tl;dr do what you can and if it still grinds just drive it.
My 6-speed had a 3rd gear and 5th gear upshift grind for about 1-year after changing fluids until it magically went away.
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Old 08-25-2011, 01:26 PM   #15
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I've got the same problems with my 6spd. Grinding most every where but particularly bad going into 5th. I tried redline but that didn't improve the problem. New shiftboots and a heavier shiftknob has masked it some what.

Going to try a new slave cyl, new clutch system fluids and motorcraft here in a bit to see if that has any effect. If that doesn't work then I guess it's time to tear it down and take a look at hte clutch/throwout. If that looks like **** its' time for a rebuild.

On the subject does any one know of any shops that rebuild 6 speeds... preferably in socal.
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Old 08-25-2011, 02:19 PM   #16
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Really? Post 3:
yes i did read your post i am assuming that when you say you run myg that it is the redline oil your refrencing. but you also say your not crazy about the choice. hence why i asked if there was anything anyone has had better results with.

Did the clutch pedal adjustment. no improvement there. noticed today that the throwout bearing is making noises. can hear it at idle in neutral but as soon as you push the clutch pedal down it goes away. so currently the car grinds on relatively quick high rpm shifts into third and lightly in 5th.

gonna try the bg stuff since they are a local company to me and see from there. may try the redline fluid too. but since i have a warranty i may just take it in and have them deal with it...
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Old 08-25-2011, 03:16 PM   #17
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I run MTG because my tranny doesn't grind, ever. I used to get the occasional 2nd and 3rd gear crunch in my 5-speed, and Redline MT-90 helped it significantly.

I would try Redline MT-90.
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Old 08-26-2011, 08:10 AM   #18
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facepalm
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Old 08-26-2011, 12:58 PM   #19
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Originally Posted by Savington View Post
I run MTG because my tranny doesn't grind, ever. I used to get the occasional 2nd and 3rd gear crunch in my 5-speed, and Redline MT-90 helped it significantly.

I would try Redline MT-90.
Sav... Do you know of any rebuild shops in our (your) area that do a decent job?

Also the MT-90 didn't do much for my crunch box. I'm thinking that a rebuild is otw.
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Old 08-27-2011, 01:14 AM   #20
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Originally Posted by Doppelgänger View Post
Well, there are different "grinding" issuses. The common one is the 1-2 shift when cold...or any other grinding when the trans is cold. If if keeps grinding after you've been driving, that is NOT a common problem and is a sign of a problem. Adjusting the clutch pedal in all honesty won't help you. The part that could be causing an issue would be the slave cylinder on the transmission. If it's leaking, it could cause difficult shifting (including reverse and 1st BUT some 6spds are hard to get into reverse so don't take that as a for-sure sign). Check the clutch fluid level and color...if it's anything but a transparant light brown, you've likely got a bad slave cylinder.
THIS^

I just recently had this similar issue especially when trying to down shift [engine brake] i tried adjusting pedal and new fluids neither really helped.

you had mentioned low pedal engagement which is the same issue i had as well... i checked the slave cylinder and it was moving about 5mm when i depressed the clutch all the way and the fluid was black and leaking

after replacing the slave everything worked perfectly and i had great pedal engagement

hope this is helpful
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