How Long Does The Clutch Last?

Clutch life depends a lot on driving style and technique, obviously, but here's when owners have reported replacing it:

[GW] 38,000 and I can feel the clutch beginning to go

[RW] Just replaced mine at 37,000

[GM] I have 50K miles on my original clutch. The car has been on the track several times, driven on trips and used for daily commutes.

[TP] The clutch in my 91 was replaced at 42,000 miles. I now have 70,000 miles and the clutch does not slip and feels as strong as new. One track event on the original. Street driving since.

[CM] My first NSX needed a new clutch at 20k, while my current 1995 has 53k miles on the original clutch with several track events.

[MSH] 100k and still the original clutch.

[CW] I've got 79,000 on my '91 and my clutch is strong. I dont race the car, but definitely don't baby the car either.

[BSD] Exactly 111,000 miles with very heavy track use.

[CW - 98/12/25] I've got 82k and still the orig. clutch on my '91....

[MSH - 98/12/26] I bought my '91 with 9,500 miles. It now has 95,500 miles and still on my original clutch!

 

Why Do Many NSX Clutches Wear Quickly?

[BM] I will admit it. When I bought the NSX, I didn't treat the clutch any differently than any of the Corvettes or Porsche I had previously.

I used it to brake on hills, slipped it, etc. That was until I read the secret to longevity is to not use it as a brake, et al. In fact, it was either Brian St.D, or Ken that said it is far better to pop the clutch than to ride it like conventional plates.

The first clutch in my car went 39K, the second about 55K, and now we will see with the Comptech version. Remembering that the dual plate unit is different than what most of us are used to should impact significantly on its life.

Had I not read it on the list, I would not have known it. I know all you old timers know this, but for the newbies, or the uninformed, I offer myself as the stupid example.

RTFM does not apply to this bad habit. Since you now own an NSX you can now put aside your evil clutch ways and be more refined! Good luck with the new one. As an aside, I would not put a stock clutch back in.  Patronize Comptech, RM, or whomever. You will be far more pleased with the performance of your car.

[BSD] The purpose of the clutch is to allow the engagement and disengagement of the engine from the trasmission. Be aware that the transmission is permanently attached to the rear wheels and the weight of the car.

When stopped, you use the clutch to engage the engine (running at some revs per minute) to the tranny (and car, which are stopped). Your choices are to: a) dump clutch and lurch forward - may require higher rpms to keep from stalling
b) let slutch slip a little as you take off

If you have the engine rpms as low as possible and give it only the amount of throttle necessary to launch, then you can get he car rolling with little wear on the clutch. Soon as the car is rolling, you can let the clutch out the rest of the way. This takes a little practice, but is something we should all do.

If you want a "performance" launch or a drag race start, the best technique is to rev up the engine to, say, 2500-3500 rpms and then dump the clutch. Dumping the clutch takes the power and momentum of the engine and applies it suddently to the tranny and the car lurches forward. Gradually letting out the clutch in this situation is bad for 2 big reasons. The first is that it wears the clutch a lot. High rpm engine versus low rpm (0 rpm) tranny is huge wear. This can even overheat and glaze the clutch disks making them useless. The second is that you are wasting the energy (power) in the high revving engine if you don't apply it (all of it) to the car to make you move. The best launches are by dumping the clutch which is just short of side stepping the pedal. Even in a drag race launch where the throttle is mashed as the clutch is let out, the clutch is strong enough to grip the tranny and force it to move to the point of breaking the tires loose (ala burnoff). This does not wear the clutch significantly.

Once rolling, we have a completely different situation. Since the car is rolling, so is the tranny. When you let out the clutch, after up shift or down shift, the engine/tranny spins up the engine to whatever speed it needs. The engine has much less inertia than the parked car does. This is not much work for the clutch to do so there is little wear.

In road racing, you do a ton of down shifts which do increase the rpms of the engine much more than an upshift. Many drivers us heel-toe downshift which is a method where you speed up the engine with the throttle before you let the clutch out. This minimizes clutch wear (2nd reason you do it) and avoids jerking torque to the rear wheels (main reason). I only do "some" heel-toe as I have not mastered the technique. Remember, once rolling, the mass of the car and its momentum are spinning up the moving parts of the engine, not the other way around. The clutch is designed to move 3000 lbs from a dead stop so it can easily spin up an engine a few thousand rpms.

All in all, clutches are designed to take the abuse of stop and go traffic where the clutch repeatedly is used to launch the car. If you do it smoothly with little clutch slippage, your clutch will last years. Mine is 6 years old. I have the service records for the car and clutch replacement is no where in there.

Your mileage will vary but driving technique is the big factor for clutch wear.

[HS] This may seem out of character for me, since I normally have no opinion to state, but in this case I've chosen to make an exception. I've held several used NSX clutches (including one of my own) in my hands over a period of time. NONE of these clutches was "worn out." Mine was replaced (warrantee, at 15,000 miles) for "shudder," which turned out to be a release bearing in need of lubrication -- it didn't really need replacing. Ya gotta pull the transaxle to get to it. So, while it's out, ya might as well look at the clutch too while you put some super-lube on that release bearing's friction points.

The deal is, that once the technician has the transaxle on the floor a NEW clutch is *going* to go in whether it's needed or not. ("Well, as long as we have it out...") The NSX clutch is robust. Assuming ALL NSXs are driven in a "sporting manner" all should still last 50-, 60- maybe 75,000 miles if the drivers knows how to use a clutch. If driven by a "LOL" we're talking about a 150,000 mile clutch here.

I live in San Francisco and was taught how to activate a clutch properly. Flatlanders tend to be blase about clutch use. They pay the price. Don't let a dealer tell you the NSX has a 30,000 mile clutch... look over there, his parts manager is smiling.

Caveat emptor.

[BSD] I had my clutch examined at 90k miles and the technician said it was 1/2 worn. My car gets driven every day and in all types of envirionments... street to aggressive track.

Using a clutch properly, whether street or track, wears it _very_ little.

One thing I have thought of that might be a factor is the vibration of the engine and the grabbiness of the clutch. On my car, as I disengage the clutch, the revs are between 1500 and 2000 rpms. The clutch starts to grab and it does so in a jerky way. The engine also has the normal NSX vibration about at that rpm. One might be tempted to use more rpms during launch. This can make the launch smoother, but at the cost of more clutch wear. I bet this is the cause of most clutches that wear out early.

Another solution is to let the car launch slowly... don't add more throttle, just let the clutch out as you begin to roll forward. Give it just enough gas to keep the revs at or above 1000 (after an initial 1500 to 2000 rpm start.) This brings my revs down to about 1000. It also lets me leave smoothly and with almot no clutch wear.

[A/H] The clutch on my first '91 lasted 30k miles and every person (35+) in my department had their turn (burnouts, launches, etc) at the car. The second clutch in the same car lasted 60k. There is no design problem with the clutch. But it is more like an Indy car (on/off) than the typical mustang clutch (lots of disengage space and lots of surface area).

Diagnosing A Bad Clutch

[AW] Another list member asked me, in so many words, how I tell if my clutch needs replacing. Since this is a rather challenging thing to describe via the written word, for the sake of comment and debate, here's what I wrote. Comments? Improved descriptions?

  1. When I disengage it it makes a creaking/groaning noise, and the pedal action is "sticky". I'm pretty sure this is dust buildup and/or lack of lubrication on the tranmission mainshaft shaft splines on which the clutch slides. The reason I think that is because a couple times when I've driven the car really hard the problem's gone away for a couple days. This suggests to me that the high centrifugal force developed when I run at high RPMS for a while throws the dust and stuff off the shaft.
  2. More importantly, the clutch never engages "with authority". In other words, if I accelerate at full throttle in 1st, shift, and simultaneously and suddenly release the clutch and re-floor the throttle going into 2nd, the clutch should basically "bang" into gear and the RPMs instantly drop to about 5,000 and start climbing; in other words, it should provide a sensation of slamming the car forward and perhaps chirping the rear tires. Instead, what my car does is engage over a period of, say, 1/2 second, where as it engages it drags the RPMs from 8,000 down to (say) 5,000 and then begins accelerating in 2nd gear. This is typical behavior of a worn clutch who's ability to transmit the engine's full torque is marginal. This latter behavior is what people probably talk about observing on the
    tachometer: the RPMs sort of hover just after the shift before dropping into the right range for full engagement in the next gear.
  3. One specific test I can do that demonstrates the above phenomenon is to accelerate up a slight hill in (say) second to about 4,000 RPM, and while holding a moderate amount of throttle, very quickly jab and release the clutch. With a good clutch the effect will again be that the revs will suddenly rise as I depress the clutch, but when I release it the clutch should snap into engagement and "bang" the car. Instead, the engages "slowly" i.e. over a period of a large fraction of a second.

In any event, don't assume you need a new clutch due to mileage. The only real reason to replace it is if it "slips" enough to bother you. IOW, it demonstrates the above indefinite behavior with respect to engaging fully and suddenly at full throttle."

Clutch "To The Floor"

[BP] The second day I had my NSX the clutch peddle went straight to the floor and I couldn't shift the damn thing. I checked the clutch fluid and it was low, so I put the car up on a friends rack and found a seal had broken on the slave cylinder. I went to Acura and they had the part in stock for about $100. It took me 10 minutes to install it and the problem was fixed!

 

Hard To Select Gears (esp. w/ aftermarket clutch)

[A/H] I found the problem when I put one of the aftermarket disks on the lathe and measured the runout. Then did the same thing to a stock disk. The stock disk had less than .5mm, (1/2 mm) runout and is consistent from disk to disk. I measured over 10 aftermarket disks and all had over .5mm, some as high as 1.5mm. The travel of the mid pressure plate isn't enough to overcome much more than about .75mm runout. Also: heat will make the disk grow and thus will not want to fully disengage making it harder to select a gear w/the trans is hot. Try turning off the car, if it goes in gear easy  then it is the clutch not fully disengaging. Also the splines on the main shaft will get full of the dust and will not let the disk slide away from the flywheel and will give the same hard into first problem.

[HS] It has been my experience (with all "stick" transmissions) that at rest it is always easier to select 1st gear if you first slide the lever into 2nd. In other words, sitting at rest in neutral, push in clutch pedal, slide gear lever back into 2nd gear, THEN slide it forward into 1st gear.

[AT] That's how it works for me and all the 5 speeds I've owned. I also find that if I really keep a relaxed grip on the shifter and basically just push it lightly toward first gear even while shifting from 2nd to 1st even while I'm moving in a real tight slow corner, the shift goes in real smooth and quickly. Take care.

 

Why Do I Get A "Shudder" From My Clutch?

[A/H] The easiest way to create the shudder is to increase engine RPM while the clutch is in its "engagement" stage, meaning that the clutch is still slipping but starting to bring the transmission mainshaft speed closer to the engine speed.

The easiest way to minimize the shudder is to blip the throttle just before engaging the clutch so that the clutch starts to engage as the engine speed is falling. This will get the car rolling as the engine speed is dropping. Fully engage the clutch at between 1100 and 1500, then apply throttle, or have the clutch almost fully engaged before applying throttle.

Don't ask me why it works, it just does.

If the transmission has been out (clutch replace, trans repair, etc) the engine mounts may have shifted and now are "shorting" to the frame, Re-center all the engine mounts and the shudder may be a little better.

[SA - 99/7/15] Shudder occurs when the clutch plate does not smoothly match the rotation of the flywheel, but instead vibrates a bit as the clutch plate and flywheel come together. I do not know why some clutches shudder and others don't. Even my Honda Accord has mild clutch shudder at low RPMs.

[LL] The NSX clutch is a dual-disc system. On a single disk setup, when the clutch is released, the pressure plate presses against the disk and actually MOVES it, I would guess around .015" (the disk slides on a splined shaft). If the disk starts hanging up on the shaft you get Shudder! The actual origin of the shudder is that when the disk hangs up, the disk BENDS and the grip surface becomes uneven around it's circumference, this cause even more pressure on the sliding surface, and starts an oscillation.

On our setup, we have TWO disks to slide AND a heavy intermediate pressure plate which must be moved BY the disks, which as before are moved by the pressure plate. The traditional system is not ideal to start with, but our system has multiplied the potential risk by three times. Obviously some NSX's have gone out of Honda's "risk" envelope.

[HS] After complaining about shudder my clutch was replaced (4,000 miles ago) and has been perfect.   They also lubricated the release bearing. Have your mechanic lubricate the mainshaft (where it's exposed in the bell housing). It will allow the clutch release bearing to slide smoothly on the mainshaft (or "pilot shaft"). This will stop your "shudder."

[LE] This requires taking things apart to the tune of several hundred dollars in labor.

[A/H] Harry is right, On page 13-40 in the 1991 service manual there is a part called the "release bearing guide". This guide sometimes gets dry and dirty with all the clutch dust, and it starts to grab the T/O bearing as it slides in and out to engage the clutch.

[LE] This requires taking things apart to the tune of several hundred dollars in labor.

[MS] There are several explanations concerning the clutch and synchro behavior found in the NSX. The clutch is a dual plate clutch, with two friction discs. My early NSX, number 601, had a hitch in its gaddyup. The conclusion was the apparent binding was actually the second of the two friction discs binding on the spline.

The first gear synchro in the NSX is unusual in that it has two cones, effectively two synchros, to help it engage. This makes it slightly more difficult to move the lever, but insures a matched speed on engagement.

Doing very high rpm shifts can often cause a grinding, inspite of you thinking you have declutched. The high rpm will cause the pressure plate and friction discs to bind on their splines, and not really disengage as you press the clutch in. Then, when you shift, the strain on the input shaft to the transmission is too great for the synchros to handle, and the gears grind.

[JPA] With 13k miles on my 93 I finally gave up on accepting the subtle, but definite shudder. I actually got to hate it. I switched to an RM clutch. *What* a difference. The shudder is gone. The shudder is now butter. When the original clutch came out, it looked brand new. There was absolutely no sign of abuse/wear

[GL] It's been a week after the new clutch has gone in. The shudder has diminished after the plates has worn in. It is still there, but not bad enough to get me all worked up. I'm concluding that some NSX's clutch will shudder to some extent.

I did return to the dealer and made sure that the release bearing guide was greased and then asked the tech to "recenter" the engine mounts. The tech basically loosened the bolts for the 4 engine mounts and rocked the engine by revving it with the car in gear and brakes on, then retightening the bolts. This "recentering" also did reduce shudder.

[BSD] My clutch has always done this. I have had the car since about 56k miles and now have 107k+.

I think that many NSX owners try to avoid the shudder by using higher rpm launches. This, in turn, wears the clutch at a high rate and they end up putting in another clutch each 30k miles.

I have just used slow, low rpm launches which reduces shudder and prolongs clutch life. It would be nice to have a smoother engaging clutch but for my money, I just live with it.

 

Clutch Replacement

Cost

[[email protected]] I recently purchased a 93 NSX (approx 39k) and after several weeks driving concluded that the clutch was slipping under heavy stress and I would change it.

The dealer recommends the two disks, throwout bearing, intermediate plate, flywheel, and pressure plate, be changed at a total parts cost in excess of $1300. However a careful reading of the manual reveals this is not necessary and gives the appropriate measurments for the last three. Mine were OK so I changed only the disks and bearing with an acceptable result and big savings.

[HS, GW] Reported clutch replacement prices: $2,000 in San Francisco, $2300 in SoCal. The flywheel is always included in clutch replacement.

$2,020 total in the Chicago area.

[TB] Here in Houston my Dealer charged me $1930.00 for a new clutch

[AVE] This is negotiable if you are willing to play the "good cop, bad cop" routine. I was quoted $2350 by a local Acura dealer. After a little friendly price debating, the agreed to price was $1900, including the throwout bearing. I suspect a few pizzas thrown their way helped out too. <g> Moral of the story - everything is negotiable.

[TSC - 99/11/14] Clutch parts were $1272, labor was $552 at Ann Arbor Acura.

 

Break-in

[A/H] New (stock) clutches do get better after about a weeks worth of gentle heating up, cooling down cycles.

[BMC] I had the same thing happen to mine 6 weeks ago. After about a week of driving normally, it bedded in just fine and now it's as smooth as the original one. Give it a little while, I think it's normal behavior for the new disks.

New Clutch Smell

[A/H] The OEM clutches do really smell for about the first 3-400 miles. The proper thing to do is to drive, heat up the clutch, then let it cool. Do this at least 4-5 times with out doing any really hard starts. Clutch material is similar to brake pad material and does need to gas when new. Stock clutchs smell like burned fish.

 

 

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