5 speed vibration

[DERS]

Hello everyone,

I recently put an impreza 5 speed in my 92 svx, and I've got a weird vibration now. It 's not due to the driveline at all because it does it while it's idling, and the vibration progresses according to the engine RPM. I think it might be due to the clutch unbalancing the motor, since the clutch pack is a lot heavier than the original flex plate. Has anyone else experienced this? Any ideas/ input would be greatly appreciated.

Thanks

Daniel

[mbtoloczko]

I think there is not problem with the weight of the flywheel/clutch assembly. There are several people who are running standard WRX flywheels which are as heavy or heavier than your Legacy flywheel. Might be that your flywheel and/or clutch is out of balance.

[huck369]

The manual flywheel/cluth asembly is LIGHTER than a flex plate and Torque converter filled with tranny fluid.....
It's not the weight.

It could be a bad flywheel, or a baddly balanced clutch/pressure plate.

[DERS]

That is most likely the problem then. I read a post about a vibration being caused by the angle of the motor being slightly wrong after doing a 5 speed swap. Has anyone else run into that problem?

[mbtoloczko]

Yeah, I posted that. A significant change in the tiltback of the motor would only cause driveline vibration through bad u-joint angles. No effect like what you are seeing with your car.

[DERS]

Thats what I thought, but I thought I'd throw it out there and see what the experts thought :) . Thanks

[Earthworm]

It's not something simple like your exhaust banging against the tranny crossmember?

[DERS]

Definately not. It really feels like something out of balance with the motor.

[mbtoloczko]

If the flywheel and/or clutch are out of balance, you should feel it very strongly when you rev up the motor. I guess you're going to have to drop the tranny?

[DERS]

Yeah, But I'm pretty used to doing Subaru trannies by now. I've got an impreza clutch in it now, but I was thinking about putting a legacy clutch back into it if it's a bigger clutch. Does anyone know if it is bigger, and if the sline is the same for the input shaft?

[huck369]

The Impreza and Legacy use the same size clutch, and same tranny, and flywheel, unless it's a WRX

[Subafreak]

YES! I was having the same problem. Do you have the STI mount in the car? I noticed the problem most after I instaled the STI mount. It had a vibration that would get really noticable around 3,500 to 4,000 RPMs just reving the engine. I even took out the tranny to check the flywheel and clutch plate tourqe to make sure that wasn't it. The problem seemed to get better after after I realized I was over filling the oil system put it was still there a bit. I was using the 92-94 turbo Legacy tranny and flywheel setup. I'm not sure if it has gone away with 6 speed swap yet or not.

[DERS]

No, I've got a stock '96 impreza tranny mount set up. The problem got better after you realized you were over filling it with motor oil? When you retorqued your clutch and flywheel, did you have them checked to see if they were balanced?

[Subafreak]

Well I didn't feel it befor I put the STI tranny mount in. I only thought the oil thing made a difference. The clutch and flywheel had no reson to be out of balance.:confused:

[huck369]

All engines have certain harmonics that will be apparent at different RPM levels, the flat 6 is about as close to perfect as they come…but still will produce vibrations, the factory liquid filled mounts really do a good job of hiding them, but with the STi mounts, or even the factory Impreza tranny mount, there are more vibrations transmitted through them since they are denser material,… So are you sure it’s not just normal engine vibrations?

[mbtoloczko]

My car with the STi Group N motor and tranny mounts also has a very very mild vibration that picks up at 3500 rpm but goes away by 4000 rpm. I always assumed that my motor wasn't in perfect tune, but maybe its a characteristic of the EG33.

[DERS]

The vibration in my is very abnormal. At a constant 3500 RPM it vibrates bad enough to make driving it pretty uncomfortable. With the auto in it before, it was extremely smooth, so I know it's not just the harmonics of the engine.

[mbtoloczko]

Your problem sounds like its not a simple harmonics characteristic. Didn't you say that you can even feel it at idle and that it gets progressively stronger through out the entire rpm range?

[DERS]

Yeah, I can feel it at idle, and it never really goes away at any RPM. I'm really thinking that you guys are right about a bad pressure plate or out of balance flywheel.

[DERS]

Well, After a new clutch and flywheel, the problem is still there. I did notice that my motor mounts are cracked. I'm starting to think that that is allowing the motor to sit closer to the sub frame, which is causing me to feel vibration inside the car. Anybody know a good source for motor mounts? They were stupid expensive from Subaru.

[Subafreak]

Originally posted by huck369
All engines have certain harmonics that will be apparent at different RPM levels, the flat 6 is about as close to perfect as they come…but still will produce vibrations, the factory liquid filled mounts really do a good job of hiding them, but with the STi mounts, or even the factory Impreza tranny mount, there are more vibrations transmitted through them since they are denser material,… So are you sure it’s not just normal engine vibrations?


Thats pretty much the conclusion I came to. I figure they put those squishy mounts in there for a reason, and that resone is that most people don't want to feel the car running.:D

Like I said I never realy felt mine untill after I put in the STI mount.

Also even when using the stock tranny mount in an SVX 5 speed conversion, the tranny is still not as isolated as in a stock 5 speed car. All of the conversion X-members I've seen are not triple rubber mounted like the stock Subaru 5 speed mounts.

[Subafreak]

Originally posted by DERS
Well, After a new clutch and flywheel, the problem is still there. I did notice that my motor mounts are cracked. I'm starting to think that that is allowing the motor to sit closer to the sub frame, which is causing me to feel vibration inside the car. Anybody know a good source for motor mounts? They were stupid expensive from Subaru.

Yeah, I'm thinking you may have a more serious problem. My vibrations are like the ones mentioned by other members. Yours seem to be excessive.:(

[DERS]

Well, I'll try replacing the bad motor mounts and go from there. Thanks for your help!