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Old 01-30-2016, 07:46 AM   #1
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Just completed 3.6 swap into 986 and have vibration.

FINALLY! After chasing down some oil leaks (no crush washer on replaced top right chain tensioner, oil pressure sender...my bad.) I finally drove car. Hugely disappointed in a driveline vibration especially around 3K. Engine sounds normal, no visable shakes, audible rattles, or rolls, but an inherent vibration exists through out range with distinct harshness at above stated RPM. Can feel through steering wheel (pump? ), floor, and seats. Upgraded to 993 TT motor mounts and did the 1/2" drop to accommodate increased height of 3.6 motor with new OE trans mount. Don't remember seeing any direct contact of motor to non "buffered" areas of monocoque or bulkhead. Would 1/2" drop effect axle /cv relationship? How would a CV or axle manifest if starting to go bad? (Were good before.) New clutch, pp, throw out. Resurfaced flywheel. 3.2 was silky, and this is coarse. I did do the oil pump mod to facilitate oil going through IM shaft to enable oiling of IMS bearing as it had the LN IMS bearing already in motor prior.
Thoughts?
On another note, I had Softronic do 986 ECU upgrade to factor variocam plus and add performance tune. While no cel's, also had distinct lean situation. Horrible drivability on launch and lack of power (relative) throughout Rev range. Scanned and discovered irregular voltage issues tied to mapping. Stuck at .0875 mv with no compensation for load/rpms. Not bashing, just wondering if anyone had done this conversion and had ECU issues. I am confident they will make it right but was surprised.
Thanks everyone!


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Old 01-30-2016, 07:52 AM   #2
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can't help you, but would do two things to narrow it down ...

- get the vibration with clutch in? ie, is it engine or driveline?
- i presume a new exhaust system - any contact there? check for contact between your driveshafts and the midpipes.
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Old 01-30-2016, 08:10 AM   #3
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can't help you, but would do two things to narrow it down ...

- get the vibration with clutch in? ie, is it engine or driveline?
- i presume a new exhaust system - any contact there? check for contact between your driveshafts and the midpipes.
Vibration still there with clutch in. Didn't check exhaust because for now am running OE set up due to emissions. No noises either. I did do the Pedro PES mod, but no contact.

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Old 01-30-2016, 11:18 AM   #4
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Are the 993TT mounts solid or hydraulic ? Did you have the engine &/or flywheel balanced? What year 986?
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Old 01-30-2016, 11:21 AM   #5
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In my experience that much vibration is probably from a big item eg. clutch plate, clutch or even flywheel look at them first. I would scratch out the drive train since the vibration continues even with the clutch pressed down

hope this helps
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Old 01-30-2016, 12:24 PM   #6
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What about the engine accessories: PS, AC, Alternator, or even a loose idler pulley? Run it with the front engine cover off at 3k. Watch the belt and observe all those spinning parts.
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Old 01-30-2016, 12:31 PM   #7
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What motor mount did you install. When I replaced my engine and changed to a semi solid motor mount I picked up a horrible vibration and it was the motor mount. Second I also added GT3 split control arms. I was a little too aggressive with my camber and got a bad vibration every time the car got loaded. I only added 5 MM spacers but it pulled the joints out too far, I imagine pushing them in would do the same.
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Old 01-30-2016, 02:35 PM   #8
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mounts

You mentioned adding a new motor mount up front. I had to shim the front motor mount as well as both rear mounts. If you did not sim the front that might be your problem.
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Old 01-30-2016, 07:40 PM   #9
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If I understand correctly, I want to clarify that the engine is backwards in a Boxster vs a 993 so the 993 motor or engine mounts are the same as Boxster transmission mounts. And yes, they are interchangeable between the 993 engine and the Boxster transmission.

You said that you used the 993 TT engine mounts - are these the stock 993 C2 hydraulic (fluid) units, the semi-fluid units from the C4, or the non-fluid/solid RS units?

I am going to guess that you used the semi-fluid or non-fluid mounts and if so, that is likely the source of the vibration. Swap back to the stock 993 C2 fluid mounts to see if this fixes the problem.
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Old 01-30-2016, 09:36 PM   #10
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Hugely disappointed in a driveline vibration especially around 3K. k
Congrats on your swap!

RE vibration, based on the description of your issue I'll have to stand with BYprodriver on the balance. Having vibration which is more noticeable at certain RPM range is a pretty clear indication of something out of balance.

Get the flywheel dynamically balanced and that should solve it. That assuming the crank is stock to its engine (i.e already factory balanced). RE engine mounts; even if those are made out of soft gelly I'm afraid it won't solve a 400kg engine which is wacked out of balance :/ Might actually make the problem more noticeable.... just at a different RPM range.

ps: I am not a Porsche engine engineer nor a specialist. Just had this issue myself only very recently with similar/heavy rotational parts. Dynamic balancing sorted it.
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Old 01-31-2016, 09:03 AM   #11
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Are the 993TT mounts solid or hydraulic ? Did you have the engine &/or flywheel balanced? What year 986?
996 dual-mass flywheel is different from 986 & none of them are precision balanced so that is probably the main source of the vibration, non-stock engine mounts amplifies it further.
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Old 01-31-2016, 10:37 AM   #12
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Are the 993TT mounts solid or hydraulic ? Did you have the engine &/or flywheel balanced? What year 986?
Ironically, the mounts I replaced ended up being exactly what came out. This 03 had a previous 3.2 exchange (this being 3rd engine now...) so motor had been out by PO. I was surprised and bummed since I bought the replacement mounts thinking it was an upgrade. They were used but perfect.
Clutch and PP were Sachs units. Flywheel was resurfaced but not dynamically balanced as a unit because I wasn't going with anything lightened or changed from OE.
While we shimmed (lowered ) engine and rear trans mounts I don't know that we did same for front engine mount which might cause some of this, since as I mentioned, I can actually feel vibration in the steering wheel...tied to pump being in contact with something towards front of engine...
Pedro mentioned that the Vertex oil pump galley (allowing some oil to go to IMS through hollow shaft) mod tended to cause a noise, but nothing about vibration.

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Old 01-31-2016, 01:35 PM   #13
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From what you said its unclear if you can replicate the vibration when the car is stand-still. You did mention that the vibration occurred when "you finally drove" the car and noticeable at 3k. Like I said earlier I am not a expert but you may want to consult one to rule out drive line and suspension. To my knowledge those can equally cause pretty nasty vibrations.

If you can replicate this vibration when parked, at 3K, then like BYprodriver said... a slightly out of balance flywheel sounds reasonably accurate here

Luck2u there
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Old 02-01-2016, 07:38 AM   #14
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996 dual-mass flywheel is different from 986 & none of them are precision balanced so that is probably the main source of the vibration, non-stock engine mounts amplifies it further.
So prodriver, you are saying I should have gone with the 996 flywheel , vs using the existing FW which was already in car? I had the 986 FW resurfaced as it was in excellent condition.

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Old 02-01-2016, 07:41 AM   #15
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If I understand correctly, I want to clarify that the engine is backwards in a Boxster vs a 993 so the 993 motor or engine mounts are the same as Boxster transmission mounts. And yes, they are interchangeable between the 993 engine and the Boxster transmission.

You said that you used the 993 TT engine mounts - are these the stock 993 C2 hydraulic (fluid) units, the semi-fluid units from the C4, or the non-fluid/solid RS units?

I am going to guess that you used the semi-fluid or non-fluid mounts and if so, that is likely the source of the vibration. Swap back to the stock 993 C2 fluid mounts to see if this fixes the problem.
The mounts ended up being identical to what I removed from the car. Had already purchased the 993 mounts but PO had evidently gone with these as well when replacing precious 3.2.

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Old 02-01-2016, 01:19 PM   #16
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The shims lowering the engine will not cause a vibration, at least they don't on my car. Mine are closer to 3/4"
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Old 02-01-2016, 05:37 PM   #17
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I used a 996 fly wheel and had no vibration problems. Did you have your unit re-balanced before install? Re-serface will change balance. Not sure you can use 986 FW in a 996 motor...may be your problem along with balance.

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Old 02-03-2016, 07:00 AM   #18
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FYI, you can put the motor at stock height if you use a 987 Cayman S engine cover. Your rear shelf may not fit anymore but the engine will be in it's correct location. This is what I did with my 3.4
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Old 02-08-2016, 01:58 AM   #19
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Thanks JAAY I will try that.
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Old 02-08-2016, 07:29 AM   #20
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FYI, you can put the motor at stock height if you use a 987 Cayman S engine cover. Your rear shelf may not fit anymore but the engine will be in it's correct location. This is what I did with my 3.4
Jaay any issues with it interfering with the soft top going down
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