Shifting/grinding woes..tranny rebuild time?

[annointed]

Well, I just recieved my NSX on Wed, and I must say, the previous owner assured me that the car shifts smoothly, but upon recieving it, I have found the car very challenging to drive without grinding. Now, I learned on a stick, and have driven them for 11 years. I log 800-1000 miles/week in my various manual tranny cars for my job. 14 of the 15 cars that I've owned have been stick, and yet I can say that I've never had a more difficult manual transmission than this NSX, which I expected to have a silky smooth tranny, since it was an $81k car originally (it does have 122k miles). Yet, downshifting is a nightmare, as I have to double clutch and/or rev match just to keep from grinding in the first two gears, and patiently wait for synchros to do their job in the upper 3 gears. Failure to submit to the will of the synchros generally results in immediate and embarrasing grinding. Getting into first or reverse from a standing stop takes some finesse, as well, often requiring triple clutching

I own 7 cars, but I have driven this NSX exclusively since recieving it on Wed, and in those 200 miles, I've gradually grown accustomed to how it wants to be driven, and started to think it wasn't so bad. Then, tonight, I got into my '98 Subaru Legacy Outback, which has 145k miles, and has what I previously considered a worn tranny...to my dismay, I was so pleased with how easy it was to shift, and how easily and effortlessly the gears engaged, that to say the least, I grew annoyed again at how rediculously difficult the NSX is to shift and avoid grindage on, not to mention its rediculous notchiness. In fact, even my '94 Saturn beater has a shifter that is many times smoother and easier to use.

Anyway, this is surely my fault, as I had the car inspected prior to paying for it, but I don't think it was test driven as part of the inspection, unfortunately. Yesterday, the previous owner also told me that he never owned another stick shift, so he had no other frame of reference when he told me the car shifts smoothly

So now, I'm stuck with an NSX that is a pleasure in every way except shifting.

Basically, I assume the car, with 122k miles, has extremely worn synchros, and that I'm probably going to end up upgrading the gearset and replacing synchros, etc at the same time. However, I was wondering if the NSX clutch can be adjusted, and that if its possble that the clutch is not fully disengaging between shifts, perhaps? I know this car got a new clutch 5k miles ago, but I'm not sure what exactly what was put into it. I'm beginning to think it wasn't a stock clutch, as the clutch is very heavy, even more so than any of my other sports cars that I've owned that had upgraded/heavier pressure plates/clutches. But that's another story. I probably should have done more DD before buying this car, but I fell in love with it, and was hooked.

Anyway, I really do love this car, and since I'm new to this NSX world, and I just wanted to confirm that my NSX is not normal for having such a finniky transmission. Am I looking at a rebuild? I'm guessing jdm short gears would be a good option. Is it common to replace synchros and what not at the same time? Thanks,

Mark

 

[nsxtasy]

It is not normal for the NSX transmission to grind or crunch. The only peculiarities of the NSX transmission/clutch are that the engagement point tends to involve a higher pedal than other cars, and when starting out in first, it engages easier if you blip the throttle and let the clutch out as the revs are falling. Other than that, it should shift as smoothly as a Civic (and that is high praise indeed).

If your transmission is grinding, then you are correct in your assessment - the cause is almost certainly worn teeth on the hub selectors and synchros, which are more likely than the teeth on the gears themselves (although that is also possible), and the best solution is to open up the transmission and replace those parts. (If your car is in the snap ring range and was not repaired, then you should replace the snap ring and tranny case at the same time.)

Some owners have found that GM Synchromesh transmission fluid may reduce or eliminate those symptoms by making the tranny easier to shift, but it doesn't really address the root cause. Still, if you're looking for an inexpensive expedient to reduce the symptoms, you might try that first.

 

[Zennsx]

Do a search for GM synchromesh transmission fluid.

 

[annointed]

Do a search for GM synchromesh transmission fluid.

Hmmm...nothing comes up when I search NSXPrime using the google search feature built into the website. I tried some varieties of the search terms, as well, to no avail.

But boy would it be nice if a simple fluid change solved or minimized this problem. I'll have to pursue this possibility...

 

[D'Ecosse]

Hmmm...nothing comes up when I search NSXPrime using the google search feature built into the website....

Sounds like your are not using this search (the one on the Red toolbar with UserCP; FAQ; MembersList; Calender; NewPosts; Search; QuickLinks; LogOut)
but this one (which is the google search)
The first one I referenced is the one you need.

 

[Larry Bastanza]

Check the fluid in your clutch reservoir. If it is low AT ALL, you need to replace your clutch master/slave cylinder. This is a classic symptom of incomplete clutch disengagement, and a common cause is the master leaking. I am 8 for 9 NSX's as of late. Just had a 1992 arrive here today, bad clutch master.

How does the pedal feel?

If this is not the issue, try shifting with the engine off. IF all is smooth , you may need to look further into your clutch.

HTH,
LarryB

 

[UnhuZ]

If this is not the issue, try shifting with the engine off. IF all is smooth , you may need to look further into your clutch.

HTH,
LarryB

Hi... i think my clutch is ending....it is smooth if i'm not revving my car....

if i drive hard...when i change from a redline 2nd to 3rd it grinds....or redline 3rd to 4th.....it only grinds in this situation....in any other gear change it is smooth....

when the engine is off, it's hard to engage gears...

is this all due to clutch alone....or it can also be some syncros dead?

 

[Larry Bastanza]

You did not answer my question. What is the level of the clutch master reservoir?

LarryB

 

[nsxtasy]

Hi... i think my clutch is ending....it is smooth if i'm not revving my car....

if i drive hard...when i change from a redline 2nd to 3rd it grinds....or redline 3rd to 4th.....it only grinds in this situation....in any other gear change it is smooth....

when the engine is off, it's hard to engage gears...

is this all due to clutch alone....or it can also be some syncros dead?

The classic sign of a clutch needing replacement is slipping, not grinding. When you engage the clutch, if the engine revs freely so that it seems disconnected from the road speed of the car, it is slipping. If your car is not doing that - and it sounds like yours is not - then the clutch probably does not need replacing.

As stated previously, you can try checking the level of fluid in the reservoir, and you can try changing to GM Sychromesh transmission fluid. But if the transmission still grinds (particularly when upshifting from second to third), then it probably has worn teeth on the third gear hub selector and possibly synchro, and will need to have these parts replaced to prevent the grinding.

If you have to open up the transmission to replace hub selector(s) and synchro(s), you can check the thickness of the thickness material on the clutch at the same time, to see if it needs replacing.

(Note: Larry B is much more of an expert on these things than I am, so he's welcome to correct anything I said here.)

You did not answer my question. What is the level of the clutch master reservoir?

Different poster...

 

[UnhuZ]

The classic sign of a clutch needing replacement is slipping, not grinding. When you engage the clutch, if the engine revs freely so that it seems disconnected from the road speed of the car, it is slipping. If your car is not doing that - and it sounds like yours is not - then the clutch probably does not need replacing.

Exactly, there is no signs of slipping ... never did...

As stated previously, you can try checking the level of fluid in the reservoir, and you can try changing to GM Sychromesh transmission fluid.

As i daily drive the car, and very frequently drive it hard...i bleed the clutch circuit very often.....about every 5000kms (about 1,5 moths)...
i check every fluid level every day before i use the car the first time in that day...engine oil, engine coolant, brake fluid and clutch fluid.... and besides a little engine oil consumption (about 1L every 5000kms), every other level was always unchanged.
The clutch fluid i use is the Honda one....it comes in a 20L black barrel with Honda label in it.

But if the transmission still grinds (particularly when upshifting from second to third), then it probably has worn teeth on the third gear hub selector and possibly synchro, and will need to have these parts replaced to prevent the grinding.

just to clarify what "grind" is....is that sound that appens when you'r clutch foot is faster/slower than your hand in a gear change, right?? that "ggrrrrrrrchh" sound?? :tongue: :tongue:

If you have to open up the transmission to replace hub selector(s) and synchro(s), you can check the thickness of the thickness material on the clutch at the same time, to see if it needs replacing.

If is something wrong inside the trans. i'll try to do all at once... but right now, i don't have the cash that i need for the clutch kit i want (exedy twin carbon), ence, i'm driving slower to save the trans and do not damage other parts.
The grind only appens when i redline the 2 or 3 gear and do a very fast upshift....if i upshift slower at the redline it doesn't make a sound.... and if i make a ultrasonic upshift at 6000rpms, it doesn't make a sound....

so, only ultrasonic redline upshifts from 2nd to 3rd (all) and 3rd to 4th (sometimes) produces the sound....every other situation, despite the shift speed and the rpm are always smooth.

 

[nsxtasy]

Exactly, there is no signs of slipping ... never did...

Then you don't need a new clutch.

just to clarify what "grind" is....is that sound that appens when you'r clutch foot is faster/slower than your hand in a gear change, right?? that "ggrrrrrrrchh" sound??

That's the sound.

The grind only appens when i redline the 2 or 3 gear and do a very fast upshift....if i upshift slower at the redline it doesn't make a sound.... and if i make a ultrasonic upshift at 6000rpms, it doesn't make a sound....

so, only ultrasonic redline upshifts from 2nd to 3rd (all) and 3rd to 4th (sometimes) produces the sound....every other situation, despite the shift speed and the rpm are always smooth.

That's the way mine was, when the teeth on the hub selector and synchro were worn.

 

[UnhuZ]

Then you don't need a new clutch.

It surprises me that this is the original clutch..... 9 years and 150000kms of life to date...

That's the way mine was, when the teeth on the hub selector and synchro were worn.

And can you tell me what parts i'll need and the type of cost should i expect to this trans. issue?

 

[annointed]

Check the fluid in your clutch reservoir. If it is low AT ALL, you need to replace your clutch master/slave cylinder. This is a classic symptom of incomplete clutch disengagement, and a common cause is the master leaking. I am 8 for 9 NSX's as of late. Just had a 1992 arrive here today, bad clutch master.

How does the pedal feel?

If this is not the issue, try shifting with the engine off. IF all is smooth , you may need to look further into your clutch.

HTH,
LarryB

Larry, incidentally, I was on the verge of emailing you 2 or 3 weeks ago to find out the cost of installing a Comptech SC kit, but despite the group buy sale price, I just couldn't justify buying the supercharger for the car before I'd even recieved delivery of the car, and driven it in its current form, lol. Anyway, you're probably my closest NSX expert shop, so I anticipate a future date to bring the car to you to work some upgrade magic

Anyway, thank you for this bit of insight. I suspected I may need a new clutch master cyl, due to this other problem: http://www.nsxprime.com/forums/showthread.php?t=67615

I do believe the clutch fluid was on the low side when I checked on Wed upon recieving the car. I was planning to do a whole car inspection on my morning off on Monday, so I did not remove the cap, or even inspect the clutch master cyl closely yet. I just remember looking at the fluid level and thinking it looked low.

So it appears that my sticky clutch pedal and grindage may be related. Solving these two problems would result in me being almost 100% :biggrin: with this car.

Thanks!

Mark

 

[Larry Bastanza]

I am not so sure it is still not the clutch. A clutch friction disk worn out would be "slipping". But NSX clutches are notorious for having the tangs that support the disk springs actually break off, then the tang gets lodged in there, which would keep the clutch from disengaging completely, which would cause grinding.

But....the shifter should feel OK if the engine is off and the clutch pedal is depressed. To work from the most inexpensive thing first, I would agree try the GM stuff and observe the results. If it smooths out, your trasmission syncro's are definately worn. It may last quite some time with that fluid though.

Good luck,
Regards,
LarryB

 

[Ski_Banker]

Larry/Others, any thoughts on this exact same grinding problem on a brand spankin new NSX? It has done it in the 1st-2nd upshift since mile 16. Haven't had time to drop off for warranty work, but it would be nice if I could offer a solution to the local dealership (not where I bought it unfortunately, so I hope they won't hassle me over warranty coverage if something expensive is wrong). My issue is the 1st 2nd upshift grinding, at any RPM unless I double clutch or really finesse the shift. Gets better when the car is REALLY warm, but even then I have to be careful. I've read all about the Synchromesh solution, but I don't want to do that just to mask an underlying problem in a new car. Has anyone else heard of similar tranny issues in new Xs? Thanks for the help.

 

[annointed]

I am not so sure it is still not the clutch. A clutch friction disk worn out would be "slipping". But NSX clutches are notorious for having the tangs that support the disk springs actually break off, then the tang gets lodged in there, which would keep the clutch from disengaging completely, which would cause grinding.

But....the shifter should feel OK if the engine is off and the clutch pedal is depressed. To work from the most inexpensive thing first, I would agree try the GM stuff and observe the results. If it smooths out, your trasmission syncro's are definately worn. It may last quite some time with that fluid though.

Good luck,
Regards,
LarryB

This clutch in my car is only 5k miles old, and, it is the heaviest clutch I've ever felt, and I've owned several sports cars with upgraded pressure plates before this. I suspect the previous owner had some kind of upgraded clutch, rather than a stock clutch installed. So I doubt I'm looking at a worn clutch, although the other fellow hi-jacking...err, I mean posting in my thread might be lol...no worries. I think I know what's wrong w/my car now

Thanks,

Mark

 

[nsxtasy]

It surprises me that this is the original clutch..... 9 years and 150000kms of life to date...

Larry says it may still be the clutch. Larry is the expert.

And can you tell me what parts i'll need and the type of cost should i expect to this trans. issue?

The hub selectors and synchros cost a few hundred U.S. dollars. The exact amount will vary, depending on how many of them need replacing, which you won't know until you open it up.

The bigger cost is labor, 8-12 hours to open up the transmission.

 

[UnhuZ]

Larry says it may still be the clutch.

I read what he wrote about the possibility of a broken spring in the clutch disc....it happened once in my Integra engine....a broken clutch disc spring on a clutch with surface to do about 30000kms.....but thats life....

 

[Larry Bastanza]

Just to clarify, as far as broken tangs are concerned I assumed this is an OEM clutch. If you have a hign pedal effort it is not an OEM for sure.

Ski_Banker, be persistent with the dealer to actually fix it, do not let them blow it off as "normal", it is not.

HTH,
LarryB

 

[NSX/MR2]

The GM transmission fluid: Where do they sell them? American dealership right?

 

[Zennsx]

The GM transmission fluid: Where do they sell them? American dealership right?

Gm dealership, Do a search here on Prime for details.

 

[Ski_Banker]

Ski_Banker, be persistent with the dealer to actually fix it, do not let them blow it off as "normal", it is not.

HTH,
LarryB

Thanks, good to hear I guess. Something defective with the synchros you think?

I'll let you know what happens.

Andrew