3100-3200 rpm rumble

[callmethewander]

i get like a rumble or a rattle at about 3100 rpm in my '88S, under acceleration, any ideas, also where can i get those plastic arms that hold the glovebox door from falling all the way down, like mine does now? i don't see them at pelican

[Techno Duck]

Balance shafts out of phase?

[jwade944]

Paragon Products sells metal arms for the glovebox. Very nice and easy to install.

[nynor]

944online has them as well. if you search my posts, i have installed them.

[John_AZ]

I have read that the rumble may be the onset of clutch trouble and/or vibration. I had a rattle for years until I replaced my thermostat and found it did not have the wraparound rubber gasket.

John_AZ

1988 924S
1987 924S

[John_AZ]

I found the web site:[url]http://www.connactivity.com/~kgross/FAQ/944faq09.html

This may not apply to you. I am not familiar with 944S clutch disk. Is it original rubber? Good luck

John_AZ

[ERAU944]

i'm going to say it's a toss-up between these two:

the (rubber center, if so equipped) clutch took a dive

the balance shafts are out of alignment

if your car ran fine before, check your clutch. my clutch went and i drove it for probably close to 1k miles before i realized that that vibration was not due to the b/s's, but due to different BS altogether.

[Ferrara_racing]

Don't forget to check the fluid filled motor mounts, they dry up in storage and go bad, when one does you get shaking as a result.

[callmethewander]

hmm,thank-you all, the car idles smooth w/ no vibration i had bad mounts in my '87 and it vibrated a lot so i don't think thats it, i'll check 'em when i get under there tho. i changed my transaxle fluid today whatta PITA the old stuff didn't look bad but i still get that rattling at idle with the clutch engaged whenshe's warm, i wonder if that related to the rumble under acceleration, i sorta don't think so.balance shaft seems possible, i hope it's not the clutch, i'm just approaching 80,000 on the odo.

[ERAU944]

the rattling (both my cars have it, the 951 not as bad as the 944) i believe is caused by the throw-out bearing. it stopped for a couple weeks in the 944 after i changed the clutch (and pressure plate and bearings), then it started up again. if the clutch is rubber centered, mileage really isn't a consideration - rubber deteriorates no matter what. just crawl under the car and have a look-see at the clutch inspection hole. if you find little chunks of rubber(and your clutch is rubber centered) then you know what you're going to have to do (and you can replace that rattling bearing as well). just a side note, when my clutch went, i noticed that i had a LOT and i do mean a heck of a lot of drivetrain lash. i thought that my ring and pinion were on the way out, but then i noticed the vibration, and put 2 and 2 together.

ok, ramble over, have a good look at that clutch...

[StoneGrey]

I had the same rpm vibration when my S2's rubber clutch went. Almost replaced the CV joints....

[callmethewander]

wow, they still used the rubber clutches in the late models? thx.

[rberry951]

Originally posted by callmethewander
wow, they still used the rubber clutches in the late models? thx.

None of the turbos have rubber puck clutch disks. I checked into this when my first clutch went, in first car, only replaced it once. But have new car, and it needs one on the onset. Takes about 1/2 on the pedal to disengage it.

EDIT: I just looked and saw that you're speaking about your 88S, if not a turbo S the above isn't fully qualified because I have never owned an S and have no idea if it has a puck or not. But the troubleshooting below still applies either way.

Anyway, you want to do some tests. Sitting still, run it in neutral with clutch all the way in, vary rpm including your vibration range. When you find the spot in the rpm that it does it sitting still let the clutch out. What your testing here is

1) If it does it at all it is engine or clutch. If not, drivetrain troubleshooting.

2) If it stops with clutch depressed, it's not the engine or engine mounts. If it does still vibrate while disengaged, balance shaft could be loose and/or motor mounts are shot, or the clutch, including thorwout bearing, fork, etc. But, motormounts also come into play in the drivetrain troubleshooting part even if it does not do it sitting still.

3) If it does not do it at all sitting still you're looking at motor mounts, torque tube bearings, CVs, tranny mount, and basically anything that moves south of the bell housing.

My process was vibration, slipping, new clutch. New clutch killed engine mounts, vibration came back. New engine mounts got rid of vibration. But then I spun out at Watkins Glen, flatspotted all four tires, warped all rotors, and busted one ball joint that failed later at an inopportune moment. I'm not going to get into what happened after that...

Thing is, it may also be as simple as a tire out of balance, or an out of round tire. Just have them balanced first and watch them do it, look for true roundness and a true rim, as in no wobble. If they're balanced true and your vibration is still there, see above.

Regards,
Russell

[blk924s]

My drivetrain also vibrates around 3000-3100 rpm, I've got a spring-hub clutch, and I'm sure my balance shafts are on time, so I'm going to replace my motor mounts. My passenger side mount has been updated, but is collapsed, and the drivers is factory and far below the limit. Hopefully that fixes it.

[callmethewander]

ok, thx a lot. it's not a turbo S, just the 16 valve. i'll follow those diagnostic procedures.

[robm-951]

The 3kish vibration is mostly associated with balance shaft problems. Often the lower balance shaft pulley is installed in the wrong keyslot. The pulleys have 2 keyslots, one for the upper pulley and the other for the lower. Putting the lower pulley on in the wronk keyslot puts the lower balance shaft out of phase even if the pulley notches all line up correctly.

[callmethewander]

hmmm, thx