Fixing the intermittent grind

Jpierro79

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I know you there are going to be a lot of critics about what I’m going to recommend. But after 21 years as a professional automotive technician and some time of fabrication and 7 years of tuning and modifying I would never suggest something unsafe. EVER!!!
Changing the viscosity of a manual transmission has drastic affects in synchro operation. Go too thick it won’t shift when it’s cold go to thin it grinds and wears out prematurely.
It was obvious Honda went too thin for their synchro design. I’ve come up with a solution that keeps feel closer to stock but smoother.
There are 3 mixtures that work
1. 1.5 qts amsoil Honda certified .5 qt Lucas transmission
Firmer shift no lockout. Slightly more pressure to engage gear. Higher film strength than stock.
2. 1.5 qts torco racing mtf gl-5. .5 qts of Lucas transmission.
Firmest shift but better film strength. Higher wear protection. Than method 1
3. 1.5 qts torco racing mtf gl-5 .5qts lucas trans 2ounces of Liqui Moly cera tec
This has closest to stock feeling due the decreased friction of cera tec. Highest protection due to cera tec creates ceramic barrier on high pressure contact areas. Absorbs into metal leaving long lasting protection.
Most engines now have some type of coating on cam shafts or other engine parts often being ceramic. Yes that’s more effective than additives but there’s no doubt this has helped a lot.
It will NOT affect the limited slip differential like typical clutch style as it is a Torsten style and works under gear meshing not clutches.

If your worried about warranty then just use 2 qts of amsoil. It’s better than the Honda fluid and certified but really isn’t much of an improvement at all by itself.
I personally do not use additives often at all. With engine oil is sooner change oil more often than out additives in. But this issue with transmission on hot days and random 1-2 grinds was driving me nuts. This transmission was already replaced.
I had already done acuity bushing and shifter selector upgrade to little avail.
If you don’t agree with this please just don’t comment. I’m not going to listen to people who have less than 1/10th the actual experience I have. This is for people who want the best help as there is no real solution until an upgraded synchro design is made. Unless you want to buy a 10k racing transmission.
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JoYu

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Cool, I hope it works! Let us know how it holds up after a few months as fresh fluid seems to make a big difference itself.
 

Z06Chris

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How did you get them to replace the trans? I've had 10+ grinds over 5k miles. They're getting worse and longer but 2 dealerships won't do anything because they "cannot replicate" during their 2 mile drive.
I've got a lot of the grinds on video. Normal driving conditions and I've been driving manual 15 years but they still won't do anything even after seeing the videos.

https://www.youtube.com/playlist?list=PLSeIdI-fNuWrtZEokpz3HfoYxZz3l07aC
 

HiSpdTouring

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It's extremely disappointing knowing that even changing the tranny still won't fix the issue. I am about to do the warranty process with my dealer and they are willing to help me. They adjusted my CMC and just that alone has helped a lot. Shifting the 1 to 2 gears and going into reverse is now butter smooth. I can actually drive the car now which is awesome, however, I still get grinding from 3rd to 2nd when in a higher RPM range usually always tends to happen when driving spiritly. It's even happened twice shifting from 2nd to 3rd in higher RPMs. I had a fa5 si awhile back and beat this shit out it and never had this and have been driving manual for over 16 years. I wonder if changing the tranny oil to Amsoil Syncromesh will fix it completely since the CMC is adjusted already.
 


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Jpierro79

Jpierro79

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Cool, I hope it works! Let us know how it holds up after a few months as fresh fluid seems to make a big difference itself.
It’s been over a month already. I’ve driven the car locally in my wonderful 95 degree Myrtle beach weather. It holds up to spirited driving as well. I’ll post again in a few months but I’m sure based upon feel colder weather won’t make it worse.
 
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Jpierro79

Jpierro79

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It's extremely disappointing knowing that even changing the tranny still won't fix the issue. I am about to do the warranty process with my dealer and they are willing to help me. They adjusted my CMC and just that alone has helped a lot. Shifting the 1 to 2 gears and going into reverse is now butter smooth. I can actually drive the car now which is awesome, however, I still get grinding from 3rd to 2nd when in a higher RPM range usually always tends to happen when driving spiritly. It's even happened twice shifting from 2nd to 3rd in higher RPMs. I had a fa5 si awhile back and beat this shit out it and never had this and have been driving manual for over 16 years. I wonder if changing the tranny oil to Amsoil Syncromesh will fix it completely since the CMC is adjusted already.
The acuity select lever bracket with the bushing in the transmission being replaced will helps but there is no adjustment that’s going to fix the fact hondas fluid is too thin. What’s happening is the synchros are allowing the engagement too soon due to the thin fluid. Thicker fluid requires more shift effort. What happens also is as you pass the synchros at high rpm shifts the gear literally start spinning again between the time the synchros let you shift and gear contact. Hence the grind. The thicker fluid changes the pressure for synchro engagement while the cera tec allows less friction so running heavier fluid won’t cause excessive wear elsewhere. If we required a friction modifier from the factory or had a clutched lsd this would never work. Fortunately we do not have these issues.
Honestly though Honda has never been great at transmissions. S2000 were expensive as hell and they have problems. For some reason this is the one thing Honda always falls short.
 

RS-EVO

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Could you please tell me what is the name or part number for the Lucas transmission fluid you are referring to? I see a lot of additives but not really a fluid. If you could provide links to exactly what you used that would be awesome. I'm ready for a solution that works and would love to try this out!.
 

bbp

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The acuity select lever bracket with the bushing in the transmission being replaced will helps but there is no adjustment that’s going to fix the fact hondas fluid is too thin. What’s happening is the synchros are allowing the engagement too soon due to the thin fluid. Thicker fluid requires more shift effort. What happens also is as you pass the synchros at high rpm shifts the gear literally start spinning again between the time the synchros let you shift and gear contact. Hence the grind. The thicker fluid changes the pressure for synchro engagement while the cera tec allows less friction so running heavier fluid won’t cause excessive wear elsewhere. If we required a friction modifier from the factory or had a clutched lsd this would never work. Fortunately we do not have these issues.
Honestly though Honda has never been great at transmissions. S2000 were expensive as hell and they have problems. For some reason this is the one thing Honda always falls short.
What problems are you referring to regarding S2000?
Honda transmissions are one of the best ones compared to any other brand.
Honda MTF is great, been using it for over a decade.
 

Lust

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Trans fluid is just a part of the equation. I’m on Amsoil fluid now and though it did feel better after 1,000 miles, it’s not 100% better all the time.

The biggest impact for me was adjusting the clutch pedal. From factory, the clutch had way too much slop and not enough pedal stroke which resulted in the clutch not being fully disengaged.

After installing a modified CMC and doing the pedal adjustment, my shifts for the most part have been pretty effortless without any grinds or notchy shifts
 


FanboyFK8

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Trans fluid is just a part of the equation. I’m on Amsoil fluid now and though it did feel better after 1,000 miles, it’s not 100% better all the time.

The biggest impact for me was adjusting the clutch pedal. From factory, the clutch had way too much slop and not enough pedal stroke which resulted in the clutch not being fully disengaged.

After installing a modified CMC and doing the pedal adjustment, my shifts for the most part have been pretty effortless without any grinds or notchy shifts
What’s CMC? Please post a video of pedal adjustments if you can. That would really helpful
 

Lust

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What’s CMC? Please post a video of pedal adjustments if you can. That would really helpful
I made a video recently since people kept asking



Here’s a video by a popular transmission builder in regards to the clutch drag issue

 

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Trans fluid is just a part of the equation. I’m on Amsoil fluid now and though it did feel better after 1,000 miles, it’s not 100% better all the time.

The biggest impact for me was adjusting the clutch pedal. From factory, the clutch had way too much slop and not enough pedal stroke which resulted in the clutch not being fully disengaged.

After installing a modified CMC and doing the pedal adjustment, my shifts for the most part have been pretty effortless without any grinds or notchy shifts
Do you have the Slave clutch cylinder moded also?

I think the only way for get rid of those grinding gears is if you do all, CMC mod Slave clutch cylinder mod , cable bushing and amsoil. ( the shifter helps too) I got mostly , just I need the CMC mod.

(I'm still having grinding issues , 2 gear mostly )
 

Lust

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Do you have the Slave clutch cylinder moded also?

I think the only way for get rid of those grinding gears is if you do all, CMC mod Slave clutch cylinder mod , cable bushing and amsoil. ( the shifter helps too) I got mostly , just I need the CMC mod.

(I'm still having grinding issues , 2 gear mostly )
No other additional mods. When consulting with another transmission builder, he said that the slave cylinder won’t help. Deleting the delay valve will only help with the clutch engagement speed and not the disengagement. This will increase the driveline shock and not help with the grinding.

Modified CMC and pedal adjustment is the most significant out of everything IMO. Deleting the dampener here will help disengage the clutch quicker. The feed hole bore is also increased to get even more fluid through the system as fast as possible.
 

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No other additional mods. When consulting with another transmission builder, he said that the slave cylinder won’t help. Deleting the delay valve will only help with the clutch engagement speed and not the disengagement. This will increase the driveline shock and not help with the grinding.

Modified CMC and pedal adjustment is the most significant out of everything IMO. Deleting the dampener here will help disengage the clutch quicker. The feed hole bore is also increased to get even more fluid through the system as fast as possible.
where did you get the modded CMC? Link would be good too.
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