[Euro] Clutch and engine harmonics

**yfin** · 29-09-2005 08:04 PM

This is a long winded way of asking a simple question but here we go....

Recently when I depress my clutch at higher revs (particularly when the clutch is pressed slowly) I can feel the engine working through the clutch pedal - it is like a very slight grainy or humming feeling. At other times the clutch feels totally like butter. This feeling doesn't happen all the time.

An example - run 3rd gear up to 100kph - the engine is under 5000rpm. Press the clutch to release the gear- i can feel through my foot a very faint buzzy feeling from the top of the pedal to the bottom - especially if I depress the clutch slowly.

No sound in the pedal - just a slight tingly feeling through my foot.

If the car came from the factory like this I wouldn't think twice as it is so slight it is barely noticeable. The reason I notice it is because it feels different to how my car used to be. The clutch grips perfectly, doesn't slip and it changes gears fine.

I took this to a Honda dealer this week. They spent a lot of time inspecting the car. They said there was no issue whatsoever. I insisted they take it for long drives, etc.

I took the car back this morning - and said I know how to replicate the issue. I asked to speak to the head mechanic who apparently drove the car for up to 1 hour previously. I took him for a drive on the freeway. Eventually he could see what I was talking about. His said it is only engine harmonics through the pedal at certain RPM. He said to leave it as nothing detrimental is happening. He confirmed the clutch is fine and the master cylinder is fine. Changing fluids will make no difference in his opinion.

My Euro only started doing this - previously the clutch felt like butter all the time. Car is at 35,000kms. I asked the mechanic to confirm it wasn't master cyclinder - he said it can't be as there is no noise in the clutch and it doesn't happen when the car is stationery.

Does anyone have any ideas about this or experienced it on the Euro? I am happy to let it go as it is not annoying me too much at the moment. Is this engine harmonics through the clutch normal?

**Chris_F** · 29-09-2005 08:42 PM

hey yfin... i think i know exactly what your talkin about... i've experienced the grainy feeling at higher rpm too. Engine harmonics seems like a fairly bad explination if it started doing it suddenly like you said... you'd think that it'd be doing it from day 1 unless the harmonics of the engine can change sudenly which i very much doubt.

I've always thought something was a bit weak with the euro clutch/master cylinder and wouldnt be suprised if the sound is because of something dodgey going on with either one. I remember before i got my master cylidner replaced for the second time it felt as though the clutch wasnt properly engaging and disengaging - i noticed a grainy feeling like you described when this was happening and my clutch has never really performed the same since (i swear it slips in the high rpm).

**yfin** · 29-09-2005 08:47 PM

Originally Posted by Chris_F

I've always thought something was a bit weak with the euro clutch/master cylinder and wouldnt be suprised if the sound is because of something dodgey going on with either one. I remember before i got my master cylidner replaced for the second time it felt as though the clutch wasnt properly engaging and disengaging - i noticed a grainy feeling like you described when this was happening and my clutch has never really performed the same since (i swear it slips in the high rpm).

Hi Chris - the thing is there is no sound - just a slight buzzy feeling in my foot. The Honda mechanic is sure it is engine harmonics as when he got it to buzz - he blipped the throttle - and the feeling stopped.

**Chris_F** · 29-09-2005 11:35 PM

oh ok - interesting... i have no idea what it could be then.

**wynode** · 29-09-2005 11:47 PM

I get that feeling sometimes in my civic but mainly while the engine is cold.

Given its happening while you are using the clutch, it could be the master/slave cylinder IMO. Or could even be the pressure plate itself (as the release bearing pushes against it). Could it be the diaphram spring itself that is warped ?

**yfin** · 29-09-2005 11:51 PM

Originally Posted by wynode

I get that feeling sometimes in my civic but mainly while the engine is cold.

Given its happening while you are using the clutch, it could be the master/slave cylinder IMO. Or could even be the pressure plate itself (as the release bearing pushes against it). Could it be the diaphram spring itself that is warped ?

Yeah - it is only when depressing the clutch pedal - not releasing it (ie taking up drive) and only at certain RPM. Would you let this go or should I take it to another dealer for a 2nd opinion?

**wynode** · 30-09-2005 12:13 AM

I don't think it is a major issue and you might find that it will go way after awhile.

As long as you have some evidence that you brought this issue up with the dealer and they said it is not a problem, then you should be fine (incase something does go wrong).

The clutch seems to be disengaging and engaging fine (from what you've said) so I wouldn't worry about it too much

**shane** · 04-10-2005 12:45 PM

yrfin, what I believe you're experiencing is indeed engine vibrations vibrating the clutch pedal. I also experienced the same symptom on my Subaru Liberty 2.5i, which I cured.

Various manufacturers, including Honda, have developed mechanisms to cure this. Firstly, a decrease in the hydraulic clutch fluid pressure will reduce the vibrations. This is acheived by increasing the diameter of the clutch master and slave cylinder pitsons (these will be a matched pair). Secondly, the clutch master cylinder should have a device called a hydraulic damper incorporated.

On the Subaru Liberty 2.5i, the flywheel is a dual mass unit which acts to damp driveline vibrations. But I still experienced vibration in the clutch pedal above 3000rpm. I was told by dealerships that this was normal - and it was for these cars. I did some further research and discovered that the GT models did indeed use a clutch master cylinder with a hydraulic damper whereas the non-turbo models used one without. I bought the GT clutch master and slave cylinders (both because of the lowered pressure) and I haven't noticed any vibration whatsoever since. In fact, the clutch pedal is lovely and I can't believe no one else I have mentioned this to has bothered with what I've done!

Some of this might apply to you. When I testdrove the Euro I didn't notice any of the vibration you described though. Maybe over time I would have.

Perhaps you can find out if your clutch master cylinder incorporates a hydraulic damper and if not, if the clutch cylinders used in other Honda models which do have a hydrualic damper incorporated could be used in your car?

Good luck.
Shane.

EDIT - I forgot to mention that on the 2.5i, the vibration was worse immediately after an engine computer reset. The vibration would then lessen over time as the engine adapted to the fuel used but I found it intolerable (obviously) after even 1000km on BP Ultimate. Perhaps before going to too much bother, think about using Mobil or BP 98 RON fuel for say 4 full tanks to see if the vibration goes away?

**yfin** · 04-10-2005 01:27 PM

Shane - great first post on Ozhonda

Don't be shy now - post up some more.

Do you have any idea why this sort of thing would develop after almost 2 years? In your Subaru was it happening from when the car was new?

I don't think I will try and source a different hydraulic system -it really isn't that much of an issue. What would concern me is if this could lead to some failure - ie cause clutch failure if I don't get it fixed. From the sounds of your experience this is more an annoyance rather than something that can cause a failure.

You make an interesting comment about fuel - I always use BP Ultimate so will try something else for a few weeks.