Dltreezan

iTrader: (3)

Ok guys I am picking up an s4 for a few hundred bucks today and I have driven it before. The tranny whines like hell and I will be putting a spare I have in it. The engine was recently rebuilt and since the rebuild it ran fine. After 100 miles or so it started getting this nasty vibration that was not related to the tranny or anything else. Once you rev past 1500 revs or so in neutral it starts to vibe pretty bad. He was told it was his flywheel and feels for sure like something on the back of the motor.

Any ideas?

Johnsgxl

does the vibes get worse or quicker with rpm?Is the flywheel stock or aftermarket.Car s4/s5 and what it the flywheel?

Dltreezan

iTrader: (3)

yes

texFCturboII

iTrader: (17)

Fixed

Johnsgxl

Ok thanks

Dltreezan

iTrader: (3)

stock s4 flywheel.

rnz520

iTrader: (10)

Is the engine an S5 engine with an S4 flywheel?

texFCturboII

iTrader: (17)

I don't think it matters if you have to match the flywheel or not between series.... I may be wrong. If it's a stock flywheel I highly doubt that it came unbalanced from the factory, and if the starter had chewed a bunch of teeth off of it, or enough to misbalance it somehow (that's a **** ton of teeth missing on one side only) you would definitely notice it when you were trying to start it... What condition are the motor mounts in? Tranny mount / crossmember? Truth be told you won't find out until you pull the tranny off and see the thing for yourself

rx-711

iTrader: (2)

im pretty sure it has to be the same series flywheel and counterweight as the motor

IanS

iTrader: (4)

This is very true - it DOES have to be correct fly for engine internals.

farberio

iTrader: (7)

+1, its for the same reason you have to match the correct series counterweight on a lightweight flywheel. Ask me how I know!

OP: I had a S5 flywheel on my S4 once, it had bad vibration from about 3.5k on up, getting worse with rpm until about 6k where it smoothed out.

arghx

iTrader: (3)

the flywheel can be out of balance. It happened to a friend of mine, he had an aftermarket flywheel that had been through some abuse. The car would vibrate pretty bad with the vehicle not even moving.

texFCturboII

iTrader: (17)

yup, im wrong again.... thanks for clearing that up fellas

Dltreezan

iTrader: (3)

Ok so that being said I need not put my s5 flywheel on this s4 then? What about when they resurface it. They do have to rebalance it right? And if I have another s4 flywheel how to know if it matches the rest internally?

farberio

iTrader: (7)

Do not put the S5 on the S4.

I am not sure if a factory flywheel can be rebalanced, the rear counterweight is built into the flywheel. An aftermarket flywheel could be rebalanced because you balance it to itself and bolt on the counterweight.

If you get a balanced flywheel resurfaced, it shouldn't need to be rebalanced.

If I were you I would just get another flywheel. If its an n/a it will be super cheap. If its a turbo it may be a bit more. Now's also a good time to go to a lightened flywheel!

rnz520

iTrader: (10)

I have an S4 flywheel I can sell you for cheap, PM me if interested

Dltreezan

iTrader: (3)

i have a spare s4 motor laying around. If I can get the damn nut off i will just take it from that. i dont think this is my vibaration issue though. Despite this however the guy had it resurface and the parts of the flywheel that stick up to meet the PP were ground down a little bit. I dont know why.

farberio

iTrader: (7)

It has to be ground down there. If not you are grinding the clutch area but not reducing where the P/P mount so it will be out of spec.

Dltreezan

iTrader: (3)

hmm. Well then I assume the flywheel is fine and wont mess with it anymore. Thanks guys.

Dltreezan

iTrader: (3)

here are some pics. not all points are equally shiny, but I dont think it matters.

nycgps

iTrader: (4)

There is no way to tell if your flywheel is balanced or not by pictures.

You need to measure it with instruments.

Why dont you just get another FW? make sure u use the right counterweight.

Dltreezan

iTrader: (3)

because the pain in the *** of removing it and the other I want to replace it with.

The guy said that the vibration started about 100 miles after the rebuild. He thought it was the flywheel, had it resurfaced and reinstalled and it still did it. I dont think it would be the flywheel to do all that by itself.

nycgps

iTrader: (4)

might have something to do with the engine internals.

Dltreezan

iTrader: (3)

that is a whole other issue to try to figure out.