[ds968]

No, not that kind of a vibrating tip , you pervs ;-) So flash forewarned me before I bought the automatic that for some unknown reason ALL 968 Tips have a significant vibration at idle, even with brand new motor mounts. Once you rev it even 100 rpm beyond idle, it's completely smooth. Sure enough, this tip is no different . And the motor mounts are practically new . When the car is cold it's quite pronounced, after it gets warm it still vibrates enough just to bug me but I suppose as they say ; it is what it is.. Does anyone know what it is exactly that causes vibration in tips at idle ? Not that I could do anything about it, but just curious ..

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[banditsc]

Raise the idle by 100? Not sure what effect that would have on putting it into gear though (ie: thud into gear).

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[ds968]

Thought about that, but also not sure of what cumulative effect even 100 rpm might have on the flex damper when shifting it into D or R.

By the way, I did not see that throttle body rpm adjustment screw ( which a lot of other older cars have ) on the 968 . How is ours adjusted - electronically ?

So, that aside..why does it vibrate a lot more than the six speeds ? Obviously it's transmission related but what specifically ?

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[flash]

the adjustment screw is underneath, right where you can't get to it with the throttle body actually on the car. REALLY dumb design.



the vibration is likely due to the lack of sufficient dampening at the flex dampener. it's solid rubber. that is going to transmit some vibration that the DMF won't. also, the tip engine mounts are different than the manual ones. not sure how though.

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[968Syncro]

Yeah my TIP has that vibration also, but it seems to be getting worse, not sure why, it might just be my imagination. I always guessed it might be related to the torque converter. Perhaps the Porsche design / spec has them tighter than at idle than most other cars. Sometimes I shift into neutral if I know it is going to be a long wait at a red light. I had the motor mounts checked last summer, they were fine. I think the motor mounts are a different height for the TIP.

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[ds968]

Never paid attention if the rpm drops below idle level when you shift into reverse from park , but it vibrates even stronger in R than it does in P ..if I back out very slowly that is, which I do MOST of the time.. :-)

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[gbarrier]

Be sure that your flex plate is good.

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[ds968]

The flex plate is just over a year old and less than 12k miles on it, but again, my point is that I was told by a couple of people who own tips that ALL of them vibrate that way, so it just seems strange to me no matter how " normal " this may be .. I can't imagine they came off the factory floor with that characteristic.

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[flash]

lol - i think you've been driving the mercedes too long

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[ds968]

Nah, comparing apples to apples ; the six speed ( and I have at least ten year old motor mounts in that one ) is still smooth as butter at idle, whereas one would think the tip was previously owned by Michael J Fox :-) it shakes like a food blender. You drove it after all , and told me not to be concerned how pronounced the vibration is, because that's just how tips are .. nonetheless, I am curious as to what causes that, it's pretty annoying and not sure something to which one can quickly get used..

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[flash]

lol - what i meant is that you are too used to the smoothness of the mercedes. the 968 is by no means as smooth as that car (including yours), and a tip version is even worse. i just went through the same kind of thing when i drove the blue 968 the other day. not nearly as smooth as the SL550.



anyway, like i said, i think it has entirely to do with the flex dampener design. the DMF has a linear absorbing trait that the rubber disk does not. the rubber absorbs some vibration, but really has more of a deflecting nature, and consequently has the resultant rebound. if they made it softer though, it would rip under load.



i'm not sure why they didn't just run the DMF in there. seems to me that it would have been the logical choice

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[968Syncro]

[quote name='ds968' timestamp='1388168772' post='153897']

... the tip ....it shakes like a food blender. .... how pronounced the vibration is, ......

[/quote]

Dan, this more emphatic wording got me thinking. Although I wrote before that my Tip vibrates, it is not very very pronounced. However once it did vibrate a lot. Just prior to the purchase, the previous owner had about a year of 4-6 expensive repairs (likely one reason he was selling); one recent one was new motor mounts. When I drove the car I could tell something was not right, it vibrated. I was not buying, and told the seller to bring it back to the shop and get it checked out, which he did. Turns out they had installed the wrong motor mounts (the manual trans motor mounts). Once they put in the proper motor mounts for tiptronic I drove it again and that vibration was gone. My current tip is really just a very mild vibration and typically only noticeable when thinking about it. So a suggestion, next time you bring it in have the shop check, and then double check, that the proper motor mounts are in place.



By the way, the PET shows the part numbers of the 2 different mounts in illustration 109-00.

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[flash]

i checked the part numbers on the bill for the mounts. they are the right ones. that doesn't mean that somebody didn't install the wrong ones though. i'd have to check the part itself.

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[ds968]

Well, I must admit that "shaking" might have been an overstatement, lol.

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[flash]

it felt pretty normal to me. the next time it's down here, i'll have you sit in the white car.



i always thought that if i blew the flex damper, that i would work out a DMF substitution. it might cost me a few hp, but i think it would calm down the vibration

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[Rap]

I didn't feel your white one shake at the Ortega run. Of course I was also concentrating on keeping up with you as you increased your speed! Lol

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[PorscheG96]

Dan, I volunteer to drive the piece of junk this weekend, hehe. Flash, I didn't know there's an idle adjustment on 968 tb - awesome - I wanna try raising mine 1-200 rpm. It was a tip and still vibrates a lot due to low idle around 600 rpm. When I did the head everything was replaced with new and isv was clear.

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[flash]

yup - it's a slotted screw on the bottom of the armature. really hard to get to, stuck with loctite (you'll need to reapply that), and very touchy.



i flipped the screw upside down so i could get at it.

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[ds968]

I only drove flash's white one around the block but did not have it in neutral long enough to notice / pay attention to vibrations. And again, just as is the case with my car , the moment you even touch the gas and the rpm goes up by a mere 100 there is no vibration whatsoever.

Trevor, if you want to drive that "piece of junk" THiS weekend , since I'm in still in London you might have to hack the security code at the house, then find the car key ( or alternatively hot wire it ) and go wild !

At least, you'll know what a fast car feels like, but then you'll get all upset and by Monday you'll have those snails you're driving on craigslist, lol. But next weekend might be good, maybe you can figure out how to set that throttle screw on your car first and then help me with mine if I can't manage to figure our how to reset it without screwing things up even more :-)

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[ds968]

So last evening while driving very slowly ( less than 5 mph ) in bumper to bumper traffic for a good 20 minutes or more, the vibration seemed to be even stronger than when the car is cold. Warm engine and transmission makes the vibration even more pronounced ?

Really getting on my nerves, especially since I know it's not a worn flex plate or worn motor mounts..so essentially, there is no fixing this. Aarrrgh. I'll see if we can get to that slotted throttle screw and move the rpm up by 100-200, and keeping fingers crossed that won't cause undue stress to the plate when I keep the brakes on in D, or shifting from P to R or N to D, etc, etc..

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