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clutch slave and third gear

15 September 2000
Hillsburito, OR
Anyone have this experience:

When sitching into third I get a slight gear grind every now and then. If I push the clutch all the way to the floor and shift much slower it engages better, somtimes. I noticed my clutch slave has minor amounts of brake fluid leaking around it. Does this sound like and impending clutch slave failure?

Hopfully I still have my honing kit in the cob webs somewhere. Has anyone fixed their slave, slapped in new piston seals, etc?

Any info would be much appreciated.

Could be I am a crappy shifter but the problem just started cropping up. So I think I need to shift out the crappy part.
If you are seeing fluid leak then yes you are probably on the road to failure, especially given your grinding problem.

I have not rebuilt one so I'm afraid I don't have much advice to offer on that. Sorry!
Scott, I have a similar issue with my NSX... i have a 91 NSX that has 88K miles on it now.. and when shifting quickly (not hard, just fast) from 2nd to 3rd at or near 8k RPM it grinds as it's going into gear.

Now I hope to God it's not the synchonizers going bad, but I think that is what it is. I looked under the hood and found 3 different resevoirs that contain brake fluid. The one that's closest to the front of the car had a small amount of fluid around the cap, but none was dripping down the sides or anything...it was just a little moist.. I wiped it up to see if it will come back, but the fluid levels in all were fine and to the maximum allowed limit.

90K miles is rapidly approaching and so is the scheduled maintenance... so while i have it in the shop i'm going to have the synchros replaced... and try to have all the other engine work that I can while the engine and tranny are dropped.

What year is your X? how many miles?

Hope there may be a cheaper fix, but i dont think there will be...

good luck! -Electro

I have a 91 with 82k. You have me beat
I would insert a pic if I could figure out how to do it...

What would lead you to believe it is the synchros? Have you heard of similar situations from other NSX ownwers? I may be in denial but I really try to avoid cracking the tranny. A possible experiment may be to double clutch the switch and bring the tranny up to speed. Old school style. If that eliminates the grind then it would probably be the synchros. I will have to give that a try.

I would be curious how your slave cylinder looks just for hoots. If you look under the front part of the tranny up and to the right you will see the slave cylinder with hydralic clutch line attached. Typically when the seals start to go it leaks around the area where it mounts to the tranny.

I had a Porsche with a slave failure. It had the same type symtoms, which I convieniently ignored. Then one day the clutch dropped to the floor and I was hosed.

Acura does not sell a rebuild kit, but a new slave is only $115.

I am going to do a little prayer now. God please don't let it be my synchros! I be not thy bearer of the bread to remmedy a synchro.

Synchro would make logical sense though.

The three fluid resevoirs are as follows:
The big one up front is the ABS soilenoid. The big one in the back is the brake. The small one is the clutch witch is direcly above the master cylinder. My ABS had a little fluid as well.

Let me know how the synchro's go. When are you taking it in for repair?

How much did it cost to fix? I would expect the syncros to be more robust. This sounds like a design failure. I wonder if they beefed up the synchros on later years?

A variable you may wish to eliminate as you diagnose your problem is the freeplay adjustment of the dual shift cables. Over time, the cables stretch. If you have the 91 service manual, you will find the adjustment on page 13-5. The tolerance is tight -- 0.04 inch! There is some difficulty with finding an accurate reference point for one end of the measurements. In making the measurements, one can easily be off by the tolerance depending on how accurate one determines the centers of the bushings that connects the cables with their corresponding shift levers.

A 360 degree turn of the "adjuster" on the "select cable" solved a balky downshift problem (5th to 4th) in a 91.

Hope this helps. At least it costs no money to check.
I tried double clutching and it switches in 4th to 3rd fine. Without double clutch it grinds. Below about 400RPM it doesn't grind. I am starting to think this is the synchro's. I am going to give the cable adjustment a look next.
Scott, I think the syncros were about $500 or so, but I really can't be sure. I told my mechanic what my symptoms were so he knew what to look for when we did the short gears. He showed me the parts and they were'nt ugly yet, but they had considerable wear.
And yes, I too was double clutching whenever possible, but it's hard to double clutch when you're trying to keep the revs up on that 1st-2nd redline shift!

Did you have to double clutch all gears? I just have to double clutch 3rd gear, down shift from 4th or up shift from 2nd at high rpm. It still takes too much time for double clutch. On my normal downshift I just have to pop the throttle.
Scott, I didn't HAVE to double clutch. But since I was grinding most gears at redline shifts, I chose to pamper the gearbox and double clutch whenever possible. Now that I have the shorties and new syncros, I don't have any problems. It sounds to me like you may need a rebuild.
Sorry, but what is double clutching? I'm not familiar with the term altho i may be doing that to prevent the grinding already.

I took my NSX today for a trip up to see my family in the mountains... broke my all time top speed record of 142mph on a straight away road in the middle of no where! that was funn....

Scott - I discovered that the grinding isnt isolated to 2nd to 3rd shifts... it also happened when i shifted from 3rd to 4th.

So 90K miles is coming up soon.. and while i have my ride in the shop for the scheduled maintenance, i'm going to see if the clutch needs adjusting or if the synchros need to be changed out.. hopefully that's all that is wrong.

CHOPSJAZZ - how much did you pay to have your synchros replaced? you said $500 for the labor *and* parts? I would be suprised if it were that cheap... nothing's cheap on the X.

Where can I get a service manual? I would guess the dealership? thanks

So, how fast did you go?
Double clutching is a style of shifting where you press the clutch once to shift out of gear into nuetral, and press the clutch again to put the car into gear. I helps to get everything rotating at the same speed before engaging gears. Newer gearboxes and better syncros, however, have made double clutching all but obsolete. But some race drivers still do it, and many recommend it. You can brush up on a lot of terminology and techniques in Skip Barber's book "Driving Faster". I review sections of that book for about a week before every track event.

The old school style of shifting gears before they had sychro's was to double clutch. When you switch gears you go to N let the clutch out pop the throttle and then switch. This brings the gears up to speed so you do not get a grind. The synchro's perform the same function for you but you just shift gears and do not have to screw around with the double shift.

142mph! pretty rightious in the need for speed category. I spooled my bad boy up to 155mph a couple weeks ago but did not have enough straight section to go any faster. I noticed it did get lighter above 120mph! The accelleration from 120 to 150 is slow though so you need some space. From what I understand the car is drag limited in 5th gear so the lower RP might be your friend.

I had a to do a bit of driving today but worked on lower speed corners out in the boon dogs(sp??) Did manage to get 120mph. But I really desired a long straight.

Ever since I bought my NSX I don't fly as much as I used too. The funny thing is the NSX is faster than most piston powered aircraft I fly!
It's not looking good. Looks like I need new sychro's. So how much bread did you have to through down for the synchro situation? Including labor and parts..

I should probably consider the clutch and rack and pinion if I have the synchro's done.


Check out the dealer for the manual. I think it is Helm a third party that makes the manual? If you can't find out the info from your dealer let me know I will send contact info. Some greedy bastard was trying to sell a manual on EBAY for $90-100. You can order a new one for less than that! The manual is the best wriiten manual I have ever seen. It is a must have. The price of admission.
ChopsJazz, so how much was it to replace the synchros? Labor and all??

It's either my synchros are going out or the clutch needs adjustment...which i hope to God it's the latter of the 2.....
As I mentioned before, I had the syncros done when I had the shorties and R&P installed. The tab for the whole job was about $4,100. If you're already in the gearbox take care of everything else that may need attention.
BTW, the name of the Skip Barber book is "Going Faster" not 'Driveng Faster' as I stated in a reply above.