87 924 Vibration

Nan00k · 03:33 PM

Hey Guys, I have this vibration @ idle that vibrates the whole car, not so bad at about 1050 RPM, when put into drive (yes it is an automatic) and the rpm drops to about 900 RPM it really gets worse. I just replaced belts making sure that balance shaft rollers were on there marks. I also replaced the motor mounts upgrading to turbo mounts, all with no improvement. Anyone have any suggestions?

John_AZ · 03-01-2009, 02:26 PM

Since you have changed the MM to turbo and positively checked the BB to make sure you have not put the rollers upside down...

First the least expensive maybes: Take out the injectors, clean, reseal or send to www.witchhunter.com.
Second. The IVC may be dirty or the hoses cracked. Clean the idle control valve and check for cracks in the hose at the bends.

Last-expensive--bad auto trans flex plate.

GL
John_AZ

924Sman · 03-02-2009, 05:58 AM

You can check the injectors for spray volume without sending them off. There are write ups on the process. Save 60-70 bucks then if you have a questionable injector, yes send them off to witchhhunter.

Not to be the bad person here but my bet the flex plate is shot. If it is the stock plate, most likely that is the issue. Read up on the flex plate and common issues that it causes and relate it to what you experience.

Dal

commdiver · commdiver's Garage

99% of the time the automatic 924S and 944 owners have the same problem, it is the vibration dampner its a rubber disc basically with a metal insert on the inside for the driveshaft to slip into and on the outside it has the starter ring gear bolted to it to start your car. It basically takes the place of a clutch flywheel setup in a manual transaxle car! The rubber fails and finally cracks and then breaks but it will just shed chunks of rubber for a while and you can still drive the car, however it could be bad news for your engines bearings and rotating assembly because the vibration will get worse!

Dawg44 · 03-03-2009, 06:57 AM

Trust me....my 87 944 NA is in the shop now, having the flex plate replaced, it will cost more than the car is probably worth, but oh well, its only money, right?

This is my second one....it lasted about 75,000 miles....

Here's something to worry about. These new dampers were probably made what 15 or so years ago...do they dry rot???????, like tires, or is it only from exposure to the sun?

924Sman · 03-03-2009, 08:56 AM

Highly doubtful the new dampers were manufactured 15 years ago. No one buys a product to shelve for 15 years in hope it sells. Not to mention it cost money in taxation, this is one reason why companies do inventory because they have to disclose what products they have in store and are taxed as future income, hence many companies only stock what they can turn over in a short period of time to avoid excessive taxation.

Sunlight cannot get to a damper under the car or covered by the bell housing. And if someone has one sitting out in the sun they need to buy a garage to keep it in!

But yes sunlight, lubricants, heat and age will deteriorate rubber in due time.

Dal

Dawg44 · 03-03-2009, 05:08 PM

I asked this in a separate post, but is there a factory procedure for replacing the damper plate other than just bolting it up and driving away?

I have read the 928 needs to be "detensioned" by turning the engine over, then sliding the clamp up until the plate relaxes...

Is this also true for the 944? Just trying to get a handle on why the new (75,000 miles) damper failed.

Obviously the "dry rot" notion was just head scratching.