Clutch feels "weird" when pushing the car..

[Chromatic]

Just to keep everyone up to speed I have a 2008 350Z with 27k Miles (all verified).

 

Prev. owner didn't so much as put in a new bulb on his own, he handed me a stack of papers where every oil change, brake job, etc was done not only at a shop, but at Nissan! ouch! But, buying the car that wasn't a "minus"

 

So this car was not driven hard.. I checked for all those signs before buying it.. and only "worked on" by Nissan cert. mechanics at Nissan.

 

It has 27k miles (had 26k when I bought).

 

Now the car drives phenomenal..

 

However I've been driving it "normally" .. shifting at reasonable rpm's.. etc.

 

I've pushed it a few times but not much.

 

Tonight I decided to give a couple 3 or 4 .. rolling starts from 30-40mph till (shh.. 120'ish mph) .. So that equated to down shifting into 2nd.. and pushing it and winding out 2nd,.. and pushing 3rd a good bit.. and in this car you wind out 4th gear you are WAY beyond the low 100's..

 

Here's my question of sorts.. Clutch is low mileage (relatively).. hasn't been ragged.. be me or anyone else.. And it does NOT slip. I've tested it many times to ensure (even after I did this) -- (Easy check is to throw it in about 2 gears too high for your speed (say you are going 40mph.. throw it in 5th or 6th and floor it.. If the clutch is beginning to slip,.. you'll see it very clearly (and feel it) on the RPM gauge as it ever so slightly slips up the rpm gauge (when it's toast, you can put it in 5th gear at a dead stop and it will rev like you had it in neutral for example).

 

But.. When I pushed it.. after it gets into the mid/upper rpm range.. say 5k+ The *clutch* pedal feels completely different (it's sort of a feel you get after driving manuals all your life).. I'd say spongy but that's a little different feel.. but I'll use that description for now. When the car comes back down to under 4-5k RPM the clutch pedal feels like it should.

 

What's going on here?

 

Answers I sort of expect are.. "The slave cylinder in these cars are poor.. maybe it's that". Well, if that is , indeed, the case.. Is this how a bad slave cylinder feels? Just funny in the pedal but holds the power on the flywheel fine, and feels normal under 5k rpm?

 

I guess I'm just wondering if I need to be saving for an aftermarket clutch and slave cylinder (I've heard you should go ahead and replace this cars slave cylinder regardless of if it's gone out on you with any clutch change).

 

I'm in "modification" mode with money.. but if this is some indication of the clutch/and or slave going out .. My priorities need to shift to saving for new aftermarket clutch + slave cylinder (aftermarket) Plus the big cost the installation.

 

Sorry I can't describe a 'feel" better .. maybe you have some insight -- and maybe it's nothing?

 

Thanks

Edited February 9, 2014 by Chromatic

[rothers2901]

I wouldn't say it was anything to do with the clutch, (28k) is hardly run in. It is more likely to be a fluid or slave cylinder issue. That said. I cant see what effect the engine RMP or load would put on the salve cylinder. I'd change the oil and bleed the system before doing anything else.

 

symptoms, A per the Nissan service manual.

 

Clutch Pedal Spongy

 

Clutch line (Air in it)

Master cylinder Piston cup (Damaged)

Operating cylinder Piston Cup (Damaged)

[WhackyWill]

Had the same problem, new slave cylinder, braided line and Motul fluid from Zmanalex / Clark

 

solved the problem. PM Zmanalex / Clark .

[Ewen@Clark Motorsport]

Thanks Will

 

As Rothers2091 says its might be worth changing the clutch fluid first to see if that improves things before going for a new slave cylinder. Is there any mention of a clutch fluid change in the paperwork?

[Chromatic]

Decided the clutch fluid looked bad.. and I suspect it hasn't been touched ever. This is what it looked like:

 

 

And here's what I got from bleeding it!

 

 

Here it is now.. looks a little better.

 

 

Haven't gone out and "pushed" the car again yet to see if it makes any difference, but I think that was needed regardless.. it was nasty!

 

I just used Some good name brand Dot 3 fluid,.. Thought about switching it out for high temp Dot 4, but that stuff is more prone absorbing water, etc.. I'm not on the race track,.. so

Edited February 9, 2014 by Chromatic

[Chromatic]

Thanks for all the suggestions.. I actually did the fluid before reading them.. but it's a pretty obvious one I guess. The slave cylinder should be ok.. I know all the 350's have issues with them potentially.. but they did change the later models (mines an '08) to a CSC, sort of a step up from the old technology the earlier 350's had. However, I do not think that solved the "weak" Slave cylinder issue that had been plagueing people under warranty.

 

If I do end up changing the Slave Cylinder.. Is that something fairly easy? No dropping the tranny or anything right? I know it's right there by the bell housing IIRC.. as the bleed valve was that I used.

[Chromatic]

Is there any mention of a clutch fluid change in the paperwork?

 

No, none. And from the looks of the old fluid.. It looks like the fluid Nissan put in it in 2008.

[WhackyWill]

Thanks for all the suggestions.. I actually did the fluid before reading them.. but it's a pretty obvious one I guess. The slave cylinder should be ok.. I know all the 350's have issues with them potentially.. but they did change the later models (mines an '08) to a CSC, sort of a step up from the old technology the earlier 350's had. However, I do not think that solved the "weak" Slave cylinder issue that had been plagueing people under warranty.

 

If I do end up changing the Slave Cylinder.. Is that something fairly easy? No dropping the tranny or anything right? I know it's right there by the bell housing IIRC.. as the bleed valve was that I used.

 

Changing to a braided line will also help..

[Chromatic]

Thanks for all the suggestions.. I actually did the fluid before reading them.. but it's a pretty obvious one I guess. The slave cylinder should be ok.. I know all the 350's have issues with them potentially.. but they did change the later models (mines an '08) to a CSC, sort of a step up from the old technology the earlier 350's had. However, I do not think that solved the "weak" Slave cylinder issue that had been plagueing people under warranty.

 

If I do end up changing the Slave Cylinder.. Is that something fairly easy? No dropping the tranny or anything right? I know it's right there by the bell housing IIRC.. as the bleed valve was that I used.

 

Changing to a braided line will also help..

 

Ya,.. If I do the Slave cylinder (obviously won't if this miraculously makes a huge difference).. then I'll run braided lines,.. Just like brakes they should help with heat and generally just be more resiliant. Any way to really know if the Slave cylinder has gone bad?

[Chromatic]

Been hunting/researching the Net for "how to change Slave cylinder in 350z" for hours now.. And I now know why I can't find it! lol..

 

One unfortunate thing maintenance wise for the 2007 and 2008 "redesigns" is Nissan used a Concentric Slave Cylinder (I may have that first word wrong) -- but the bad part is up until then the 350's had the Slave cylinder in an accessible spot.

 

On the 2007 and 2008 350's the Slave cylinder is IN the Bell housing.. so to change it you have to drop the Tranny!

 

That's not a DIY project I feel comfortable with, and is something that if your gonna drop a tranny you better go ahead and put in a new clutch, flywheel, etc.. Similarly now.. if you are replacing a clutch in an 07/08 you better go ahead and replace that Slave cylinder.

 

The money is in the Labor time costs.. not the parts there.

 

Hrmm..

 

Some other people have said that Running the braided line where you can.. and Changing the Dot 3 out for Dot 4 (and some say Dot 5.1)? -- (but not DOT 5 cause it's silicone based) Solved their pedal issues (most of these people didn't have just a funny feeling, they had clutch pedal not raising back up.. or only coming half way up.. etc. Mine goes down and up just fine. (haha.. that's what she said right )

 

So given this.. Is the Line to the Slave cylinder easily accessible to run a Braided line if the Slave is actually inside the Bell housing? Makes me wonder because I'm curious how I would hook it to the actual Slave cylinder you know?

 

Any help/pics/ input would help. Thanks

[Chromatic]

Ok the bleed didn't "fix it".

 

I'm wondering if this is normal? It's just when I'm in high RPMS and push the clutch pedal when the engine is spinning at high RPMS the pedal feels like I FEEL the engine through it (that's a better description).. But makes no sense really..

 

I mean could it just be those RPM's create INSTANT heat that cause the pedal to do this.. and when the RPM's go back under 4k it's perfect immediately?

 

Or could it be the engine/flywheel/driveshaft etc spinning so fast gets transferred through that pedal and I'm over sensitive to it? I dunno..

 

I guess you guys can tell me your experiences.. When you rev a gear up to say 6500'ish then push the clutch in to shift.. Does the pedal feel EXACTLY the way it would if you were in 5th gear at 2100rpm shifting to 6th? If you aren't sure.. try it out for me, see if there is any "normalness" to this?

 

I picked up some Dot 4 fluid as I did some research and it's fine to put in there. I'm going to put that in to see if the higher temp rating will help.. won't hurt.

[Ben.B.HR]

On 10/02/2014 at 00:07, Chromatic said:

Ok the bleed didn't "fix it".

 

I'm wondering if this is normal? It's just when I'm in high RPMS and push the clutch pedal when the engine is spinning at high RPMS the pedal feels like I FEEL the engine through it (that's a better description).. But makes no sense really..

 

I mean could it just be those RPM's create INSTANT heat that cause the pedal to do this.. and when the RPM's go back under 4k it's perfect immediately?

 

Or could it be the engine/flywheel/driveshaft etc spinning so fast gets transferred through that pedal and I'm over sensitive to it? I dunno..

 

I guess you guys can tell me your experiences.. When you rev a gear up to say 6500'ish then push the clutch in to shift.. Does the pedal feel EXACTLY the way it would if you were in 5th gear at 2100rpm shifting to 6th? If you aren't sure.. try it out for me, see if there is any "normalness" to this?

 

I picked up some Dot 4 fluid as I did some research and it's fine to put in there. I'm going to put that in to see if the higher temp rating will help.. won't hurt.

Did you ever find the cause, as I think I'm having the same issue? 

[Tricky-Ricky]

If only people would update these threads, it would make searching worthwhile! But anyway I would also suggest checking the clutch release bearing, could be dry or failing, these can give very odd effects at high rpm/load.