Vibration while stopped in drive Options

[mimicit]

I have a 96 St AT. When I am in drive with the breaks applied, I get vibration in the steering wheel. It's not real bad, but I notice it.

I just replaced the drivers side CV and dumped some AT fluid out when I pulled it. I Checked the levels and it reads good for HOT, that was a little weird as I expected to have to add more.

I have been driving around this weekend testing the new CV, and the vibration is really noticeable now.

I put it in neutral and it goes away. Every other gear including reverse vibrates. Park does not.

I ran a search for this symptom before I posted, and this is my first post, so hi!

[NOVAKx17]

Check your Motor mounts, you Probably need inserts

[cheela]

yeah, i got the same vibration. I think most ST owners do. there's been discussion but i forget what they all said.

[95CST]

I have the same thing, its an automatic tranmission thing i think, I have had other cars that do the same thing. The only thing I can think is because it is still in drive and it wants to go but pushing the brake holds it there, just my 2 cents....

[blu94gt]

Welcome to a front wheel drive 4-banger with an automatic.

[stephen_lee]

yeah. all st i heard of with auto has done it. even the two i own

[4-eyed-freek]

same with my gt. it has always done it.

[cheela]

solution: manual swap. well that'll be mine anyways. LOL!

[4-eyed-freek]

i agree with cheela

[stephen_lee]

add a 330 ohm resistor inline with the ecus coolant temp sensor. its the 2 wire CTS on the water neck kinda pointing towards the throttle body.

this will raise idle to about 1000 in neutral, and 800-900 in gear. if you think thats a bit much try the next smallest resistor.

[zfjohnson07]

listen to novak, motor mounts i had an st and it vibrated but not very badly, but i know it was a motor mount.

[mimicit]

Awesome suggestions, really active community, you guys rock.

My thought is once the car is put in gear, there is a load placed on the engine from the transmission. Once that transfer of energy to drive the transmission happens, the motor has to work a bit harder and that is translated into vibration. I would suspect it could be resonance from the transmission at that specific idle level, so changing the idle might work. It would change the frequency of the coupling between the engine and the transmission. I also think engine mounts would work as well. More then likely a combination of the two.

I don't have a lot of experience with working on cars, and changing out the engine mounts seems tough. I would imagine I need a hoist to hold the engine up when I changed the mounts? I have a manual but it does not go into detail.

Could anyone give me a high level breakdown of what I will need to do this?

[4-eyed-freek]

i would make sure its the mounts before you go and spend money on something thats not the problem. my mounts only have 40k on them and the car vibrates at a stop, when i got the car the mounts only had about 20k on them. th vibrtated then and still does now.

[Spider77]

All this talk, and only one person touched on RPM's. OP, what are your RPM's reading at idle while in gear? I had a slight vibration issue, and I just made some slight adjustment to raise the idle a touch and the problems are barely noticeable. As of now, my out of gear (p/n) RPMs read round 950-1k, and while in gear it drops to 850-900.
As far as changing mounts, Ive never done them on a ST, so I cant say anything about that.

[stephen_lee]

really guys. do the idle thing. only takes ~30 min

[senick]

I have a 95 ST with AT, and it does the exact same thing. Two things effect this though: how fast I accelerate, and how much gas I have in the tank (you think it's crazy but I promise there's a definite correlation- a more full tank means less vibration). I have about 160k on the engine. I've yet to change the idle, but I've thought of doing it in the past, it's just the shaking doesn't really bother me at all if I drive modestly.
My suggestion, put some fuel system cleaner through it and a tank of premium, and that should make it more bearable. Change the idle if it's really something you can't stand, but I don't think it's a serious issue.