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Just put in GM Friction Modified.

NSX2398 said:
I just followed the earlier instructions re: jacking car and removing driver side rear wheel and although there's not a lot of room, it wasn't difficult.
Yeah, very easy job. I guess I was due for a change so no harm done.
 
Sorry for bringing this back out, yes I did the search and I have experienced the grinding at third gear for awhile. It doesn't have any problem at downshift, regardless with heel and toe or not, street driving doesn't have any problem either, I just shift a little slower, it's not like I frequently goes to that 6000rpm and up in everyday driving... This 3rd gear grinding problem happened after my last track session, and however, I had the grinding on shifting from 2nd/3rd to 5th on track from day 1.

Does that mean that my hub selector is worn but the synchro is still fine??

The more important question, SOS offered a rebuilt and blueprinted transmission at around $1500. Seems like if I wait and totally trashing the tranny I have right now until I totally lost 3 gear, then I just get that SOS tranny... In this case, I'm buying more time (my savings) as I saved some money for the bench repairs and instead getting a new tranny... Am I on the right track? or I'll get something else damaged if I kept driving?? BTW, my clutch and everything else is fine...

Please help... and comment on my decision, thanks.
 
DO NOT pay to replace/rebuild your transmission until you give the FM sycromesh fluid a try first...it will work wonders. I used to 2 QT's of the Friction Modified and 1 QT of the regular Schromesh fluid. Experienced the 3rd gear grinding being completely eliminated after a few minutes of driving the car (basically as soon as the tranny warmed up for the first time). Grinding has still never return ever since I first started my thread on this topic....that was half a year ago and over 3500 miles* :)
 
NSXDreamer2 said:
Does that mean that my hub selector is worn but the synchro is still fine??
It probably means that the hub selector is worn. You won't know whether the synchro is okay or not until you open up the transmission. A knowledgeable, experienced mechanic, who opens up a lot of transmissions, can tell by looking at the gears (and synchros and hub selectors) which ones are worn and should be replaced. The parts themselves are relatively inexpensive; the major expense is the labor to open up the tranny, typically 8 to 12 hours (Larry B can confirm these numbers).

NSXDreamer2 said:
SOS offered a rebuilt and blueprinted transmission at around $1500.
You might want to discuss this with your mechanic and see what he thinks. You'll be comparing rebuilding your own transmission and paying for parts and labor, against the cost of buying and installing a rebuilt transmission. I'm not sure which will cost you less overall, or which will be more reliable.

NSXTASY_MD said:
DO NOT pay to replace/rebuild your transmission until you give the FM sycromesh fluid a try first...
If you want to give the fluid a try, go for it. I didn't do that, and instead had my hub selector and synchro replaced, because I wanted to fix the cause of the problem, rather than just making the symptom go away.
 
So I just changed my fluid and decided to try the synchromesh 2/1 combo. Since I bought my car, I have been experiencing grinding at high RPM from 2-3. I have to say after using Synchromesh, I am very pleased with the feel of shifting now. It is *SUBSTANTAILLY* smoother - it goes into all gears really easily now. The grinding I experienced is still present but to a lesser degree - noticibly reduced but still existant. I know my I'll have to fully repair these internal parts to fix the problem, but until I get my clutch done - synchromesh will be in my tranny.
 
I put GM FM in my Honda 5 spd last year in late July after reading this post....the capacity is only 1.9qt(vs. 3 in NSX).

8 months later, I must say....it was worth every penny! The tranny shifts more smoothly than I ever imagined possible and grinding is down approximately 100%
 
sorry to bring this from death. I changed the fluid, did notice that when the car is cold in the morning, the shifter is a little less notchy, the grinding was there as nsxtasy suggested.... 1000 miles later, to be precised, I just came back from my first track day of the year... The gear grinding issue is totally gone.
I still noticed the third gear grinding when I got on the track, however it felt like it's doing less and less, so I had spent more time stepping the clutch and glide into the third gear... After second session of the day, the gear is a little notcy to shift to third, but there's no more grinding, at the end of the day, I just shift like normal to 3rd, even shift into 5th from 3rd gear, I don't need to depress the clutch pedal in extended time, Amazing...

I waited 3 days to post this, because I was checking it out on the street... (after the transmission totally cool down serveral time and just normal street driving.) I wind up the rpm and do serious of quick 2-3 shifting... no more grinding.

PS. I don't remember exactly what I put into the tranny, I believed I messed up and only put 1 friction modifier in it. That could explain the "slow" result. When I have a chance going back to my parent's house, I'll check on it and keep you guys posted.
 
Well clip my ears and call me streamlined, I decided I'd try this stuff before a track event last week and it works!

I did 2qts GM Synchromesh Friction Modified (12377916) $13.56ea, 3/4qt Synchromesh (12345349) $11.88 and 2oz EXP4 Oil Additive.

I've been living with a high RPM 2nd and 3rd gear shift grind for a while and dropping this fluid in all but removed it. This is good technology!
 
Ed, did you have the results simular as mine? or you "cure" it instantly??

I found out that I used only 1 qt. of Friction modifier and 2 qt. of GM Syn... Yeah, I messed up, but it works now... I'm more than happy that I saved $1000......
 
Its a two hour drive to the track, so it had plenty of time to 'work in', and over that two hours the little grinds got less and less. At the track it happened just a couple times going into 3rd, on the way home I think I only had one little grind, and nothing since.

Saved a $1000? Probably more I'd say.
 
I used 3 qt's of the FM and it didn't seem to do much. I still grind going into second, and still feels notchy, but I'll drain out 1 qt and add the syncromesh stuff and see if that helps.
 
ive been looking for a place to order online and so far ive only come up with here:

http://www.sdpc2000.com/
$10.35 for the friction modified, $9.03 for the synchromesh
$6.75 for shipping so it sort of evens out.

however, you have to search by the item numbers, it just lists them as
"FLUID" and "FLUID TR.". I've tried calling the 800 number to absolutely
verify they are what we want but no answer at any of the numbers listed
on their website. I haven't ordered yet.............


I just reached them and they confirmed... $37.48 total with shipping (it was a bit more than the advertised $6.75).
 
Last edited:
Just did mine with the "recipe." The fluid that came out was gold and clean. Didn't notice any diff. Cheap DIY, did not know when the fluid was changed last, (had car almost a year) figured it was time anyway, couldn't hurt.

BTW, REMOVE WATCH WHEN DOING.............DOH!

homer.jpg
 
CokerRat said:
Its been almost a year now for many of you, any problems to report? Has anyone been running this for >5 years?

Thanks

im not even certain this stuff has been around for 5 years. i think this is a fairly new discovery for the NSX crowd here, so I can't imagine anyone having run this for much more than a year.
 
Russ said:
I'd have a tough time putting anything from General Motors in my NSX. :eek:

That's pretty much how I felt putting it into my honda, which is why i wanted to try Redline first. I've been running with GM Synchromesh for 1.5-2 years now and all I can say is i wish I had known about it sooner. I'll run this in all my hondas/acuras.
 
I can't remember how long ago I put it in my car. Probably a year or so though. No problems here. Didn't notice a change either. Guess I was expecting more from it.
May put it in my Integra and see if it makes a difference there.
 
CokerRat said:
Its been almost a year now for many of you, any problems to report? Has anyone been running this for >5 years? Thanks
Had mine in for about 10 months .. probably about 8K miles. I posted then that I didn't notice much difference although I didn't really have any obvious synchro problems other than 1-2 notchiness. I still haven't noticed any difference and 1-2 is still notchy. Not that anyone but me cares, but for what it's worth, it seemed to work as well as the Honda stuff at -35 temps.
 
NSXDreamer2 said:
sorry to bring this from death. I changed the fluid, did notice that when the car is cold in the morning, the shifter is a little less notchy, the grinding was there as nsxtasy suggested.... 1000 miles later, to be precised, I just came back from my first track day of the year... The gear grinding issue is totally gone.
I still noticed the third gear grinding when I got on the track, however it felt like it's doing less and less, so I had spent more time stepping the clutch and glide into the third gear... After second session of the day, the gear is a little notcy to shift to third, but there's no more grinding, at the end of the day, I just shift like normal to 3rd, even shift into 5th from 3rd gear, I don't need to depress the clutch pedal in extended time, Amazing...

I waited 3 days to post this, because I was checking it out on the street... (after the transmission totally cool down serveral time and just normal street driving.) I wind up the rpm and do serious of quick 2-3 shifting... no more grinding.

PS. I don't remember exactly what I put into the tranny, I believed I messed up and only put 1 friction modifier in it. That could explain the "slow" result. When I have a chance going back to my parent's house, I'll check on it and keep you guys posted.

Immediately after filling my gearbox with the GM synchromesh I took my NSX for a test drive and the grinding was still there ,a couple of days later it was completely gone. Nice to know GM is still good for something :smile:
 
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