Clutch vibration

[bruckner]

My 1991 had its first clutch change last year at 92K miles. Although it didn't slip, a slight vibration at the bite point in first gear was diagnosed as a worn flywheel, and frequent resistance in getting the shift lever out of gear was a sign of clutch trouble to come. The time was right to go ahead with a replacement. I ordered the full Honda genuine kit including flywheel, discs and pressure plates, TO bearing and guide, fork, and had it installed.

Now, the gearbox shifts beautifully, but the vibration got worse. When taking off in first gear, I can't work the clutch to avoid annoying shakes felt throughout the car, even the steering wheel visibly shakes momentarily. However, there are no pulsations through the pedal (as reported in some similar instances).

I did my research and found that motor and trans mounts could be the culprit. I went ahead and ordered the full set of 4 mounts. They're now installed but no luck, the clutch bite point rattles the car.

To me it feels like the clutch grabs too abruptly, the friction material allows for too little slippage, no matter how quickly or slowly the pedal is released, with little or more revs.

The technician who did the work is not a seasoned NSX guy, none exist in my area, but he did great work on my Porsche cars of the same era and followed the shop manual closely. The fact that gears engage and disengage nicely leads me to believe the initialization was done correctly, but I could be wrong.

Any ideas?

 

[Bram]

Sound like the Tech did not perform the clutch synchronization procedure.

Bram

 

[bruckner]

Sure is possible, but quoting LarryB:

Did you initialize the clutch? If not, start there, if it is not initialized it will not disengage, and not go into gear.....

No such problem here, goes in/out of gear normally.

 

[drew]

Pilot or input shaft bearing?

You can do quite a bit of black box diagnosing if you know how a transmission works.

 

[Honcho]

Another possibility is over-greasing the splines and guide. LarryB taught me that too much grease can cause clutch shudder because it gums up the free movement of the clutch discs on the splines. If your mechanic is not familiar with NSXs, he may have used too much grease on the clutch assembly. Also, Honda Urea grease must be used here. You want a very thin/light coat on the throwout guide:



Also a very thin layer on the splines. The technique here is to spread some grease on the splines and then use a clutch disc to slide forward and back on the splines, wiping up the excess. This leaves exactly enough grease on the splines. You can barely see the grease below, which is what you want.



Applying more grease than shown above definitely can cause clutch shudder on the NSX.

 

[silver2002]

There is such a thing as clutch "chatter" - I've had it with a new clutch -- usually with a non-oem clutch breaking in - I had it for a while then maybe my clutch seated and mated better with flywheel.. Never heard of chatter with an oem clutch. Interested in other's thoughts.
Here's what I'd try as an experiment - apply emergency brake, lightly let out clutch in first, not to stall or wear it but to heat it up a little bit, then see how it works.

 

[bruckner]

Thanks everyone.

The Honda urea grease was used, I'll enquire with the mechanic about how much was used. If he remembers.

With regards to the input shaft bearing, it was replaced along with other angular bearings (5 in total) in the transmission. Are we on to something here?

I found out that the initialization of clutch guides can be performed without dropping the gearbox. We may start there.

 

[bruckner]

Update: I had the car put up on the lift to inspect through the clutch case cover. Using a boroscope camera fitted between the flywheel and the case, I confirmed that all 3 guide pins are where they should be in terms of clearance as shown in the manual, and that the wave washer disc is on the spring side as specified. So far, nothing unusual, but there's only so much to see through there.

With the car hoisted up, I engaged the parking brake and simulated the conditions of the shudder, the technician under the car confirmed that the rear mount was visibly shaking up/down. We ran out of time so next time we will perform the procedure to re-center the bolts, this may well be my problem.

To be continued.

 

[ralph cerbone]

My 97 had the same chatter on take off , I loosened the trans mount and opposite engine mount , tightened all good . this is a common problem with transverse engine applications . I am not saying this is your problem with out seeing your car but its worth a try .

 

[Old Guy]

My 97 had the same chatter on take off , I loosened the trans mount and opposite engine mount , tightened all good . this is a common problem with transverse engine applications . I am not saying this is your problem with out seeing your car but its worth a try .

That is interesting. My 2000 has always had a slight shudder on 1st gear take off. I just lived with it because it has not changed at all in 12 years and I figured 'that is just the way it is'. When you loosened the mounts, did you loosen the engine side, chassis side or both sides of the mount and 'opposite mount' means the right side mount? Because this seems like a relatively simple thing to do I might give it a try.

 

[bruckner]

That is interesting. My 2000 has always had a slight shudder on 1st gear take off. I just lived with it because it has not changed at all in 12 years and I figured 'that is just the way it is'. When you loosened the mounts, did you loosen the engine side, chassis side or both sides of the mount and 'opposite mount' means the right side mount? Because this seems like a relatively simple thing to do I might give it a try.

I knew that incorrect motor mount torque sequence could result in excessive and uncontrolled drivetrain movement. In fairness, the WSM isn't clear about the proper sequence, but it states that noise and vibration can result. However I was under the impression that only the 3.0 twin disc clutch produced the sort of vibration that upset the mounts, as opposed to the dual mass flywheel single clutch setup. I was wrong about this.

Ralph, please confirm it is the center bolts that need loosened, after applying adequate support under the motor of course, and the engine raised or lowered to center the rear mount bolt, then torque to spec. I'm hoping I can reach a satisfactory result working only the easily accessible side and rear mounts, the front one is awkward to reach without removing cross member.

 

[Honcho]

I knew that incorrect motor mount torque sequence could result in excessive and uncontrolled transaxle movement. In fairness, the WSM isn't clear about the proper sequence, but it states that noise and vibration can result. However I was under the impression that only the 3.0 twin disc clutch produced the sort of vibration that upset the mounts, as opposed to the dual mass flywheel single clutch setup. I was wrong about this.

Ralph, please confirm it is the center bolts that need loosened, after applying adequate support under the motor of course, and the transaxle raised or lowered to center the rear mount bolt, then torque to spec. I'm hoping I can reach a satisfactory result working only the easily accessible side and rear mounts, the front one is awkward to reach without removing cross member.

The torque sequence is on page 5-13 of the 1997-2005 service manual. It assumes you are installing the subframe, but if it is already installed, do the following:

1. Loosen transmission mount, right mount and rear mount center bolts. You do not have to remove the bolts- just take all torque off the nut.
2. Tighten the right side mount center bolt to 69 lb/ft
3. Tighten the transmission mount center bolt to 69 lb/ft
4. Tighten the rear mount center bolt to 56 lb/ft

This sequence makes a difference in shudder and vibration. My NSX is rock solid still after doing this. If you are installing the subframe, start with the front mount and then follow the steps. With the engine already in the car, you can leave the front mount tight since it is first in the sequence.

Also, do not support the engine in any way- it will hang on the center bolts just fine. You want the full weight on the mounts as you sinch them up.

 

[bruckner]

Thanks Honcho. My only concern about not supporting the engine is the right side mount which has, contrary to the other 3 mounts, a vertical center bolt. Also I had previously understood that once center bolts are loose the engine had to be manoeuvred up/down so that the rear mount bolt is centered, but I recognize that the (1991) manual doesn't specify this.

 

[ralph cerbone]

That is interesting. My 2000 has always had a slight shudder on 1st gear take off. I just lived with it because it has not changed at all in 12 years and I figured 'that is just the way it is'. When you loosened the mounts, did you loosen the engine side, chassis side or both sides of the mount and 'opposite mount' means the right side mount? Because this seems like a relatively simple thing to do I might give it a try.

correct ,right side means mount above T/B cover ,

 

[Honcho]

Thanks Honcho. My only concern about not supporting the engine is the right side mount which has, contrary to the other 3 mounts, a vertical center bolt. Also I had previously understood that once center bolts are loose the engine had to be manoeuvred up/down so that the rear mount bolt is centered, but I recognize that the (1991) manual doesn't specify this.

That's only if you remove the bolt completely. The holes won't line up unless the engine is tilted and moved into position. Here, you're just loosening the bolt, not removing it, so you don't need to position the engine.

 

[Nsxdwon]

Any update on this? I also experience chatter/shudder when taking off on 1st only. I'm planning on replacing my clutch soon and can ask the shop to take a look at other things while they're in there.

 

[Honcho]

Any update on this? I also experience chatter/shudder when taking off on 1st only. I'm planning on replacing my clutch soon and can ask the shop to take a look at other things while they're in there.

Make sure they use the Honda Urea grease and that they don't goop it on the mainshaft splines. This causes shudder because it prevents the free movement of the discs.

Also, see: https://www.nsxprime.com/threads/clutch-chatter.107345/#post-1021838

 

[Nsxdwon]

Make sure they use the Honda Urea grease and that they don't goop it on the mainshaft splines. This causes shudder because it prevents the free movement of the discs.

Also, see: https://www.nsxprime.com/threads/clutch-chatter.107345/#post-1021838

Thank you! Are these the correct parts I would need to order?

1. Clutch set - 22000PR7305
2. Bearings - 22810PR8003 & 21102PR8010

 

[Honcho]

Thank you! Are these the correct parts I would need to order?

1. Clutch set - 22000PR7305
2. Bearings - 22810PR8003 & 21102PR8010

A "complete" NSX clutch job, like they would do at the NSX Refresh Center or T3TEC is the following:

1. Clutch set - 22000PR7305
2. Throwout Bearing - 22810PR8003
3. Throwout bearing guide - 21102PR8010
4. Clutch fork and spring - 2820PR8000 & 22835PR8000
5. Clutch hose - 46970SL0A02
6. Flywheel bolts (8) - 90011PR7000

Also, they will typically replace the clutch master and slave cylinders at the same time.

For a U.S. Acura clutch job, they just use #1 and #2 in the above list.

 

[Nsxdwon]

A "complete" NSX clutch job, like they would do at the NSX Refresh Center or T3TEC is the following:

1. Clutch set - 22000PR7305
2. Throwout Bearing - 22810PR8003
3. Throwout bearing guide - 21102PR8010
4. Clutch fork and spring - 2820PR8000 & 22835PR8000
5. Clutch hose - 46970SL0A02
6. Flywheel bolts (8) - 90011PR7000

Also, they will typically replace the clutch master and slave cylinders at the same time.

For a U.S. Acura clutch job, they just use #1 and #2 in the above list.

Thanks Honcho!

For the clutch fork, did you mean 22820-PR8-000? I may order all of these since the cost isn’t too terrible.

Also for the hose, is this the one that some folks replace with a stainless reinforced option from SOS? Any thoughts on this upgrade?

 

[Honcho]

Thanks Honcho!

For the clutch fork, did you mean 22820-PR8-000? I may order all of these since the cost isn’t too terrible.

Also for the hose, is this the one that some folks replace with a stainless reinforced option from SOS? Any thoughts on this upgrade?

Yes that's the right number- I just mis-typed.

I don't like any of the aftermarket clutch lines- they tend to leak. The OEM hose lasts 20+ years with no issues.

 

[bruckner]

As an update, I performed the procedure with center mount bolts as explained above. The result is that shudder remains but mounts do a better job of reducing the transmission of the vibration to the chassis. For me this is not satisfactory.

As a side note, I noticed that engaging first gear from neutral with the clutch pedal only half way through its travel results in reduced shudder. This is strange to me. I wonder if this further points toward the "too much/little grease theory" as the disks and TOB travel less distance on the guide and splines than they do if the clutch is fully depressed.

 

[bullithollywood]

Is your problem shuddering thats shaking thru the seat of your pants on clattering at engagement? A little dual disc clutch clatter is normal.

 

[bruckner]

Yep the vibration is felt through the car. I have sort of developed a technique to minimize the shudder on takeoff: rev to 1500rpm and swiftly release clutch as revs drop a bit before full engagement. Feathering the clutch while manoeuvering the car in parking lots or driving in trafic will inevitably result in unpleasant jerks in the drivetrain. I am slowly getting used to the idea that I'll have to get the clutch re-done next summer.

 

[docjohn]

I have made it a habit to look at the trunk spoiler of other cars at club events, and most vibrate noticeably on take off..