hey guys FINALLY GOT THE EVO ON THE ROAD so im excited,

currently working out all the kinks because we all know cars dont like to sit

however ive got this harmonic noise in 5th gear on the highway, its very audible any wear from 3k rpms and down and is basically gone from 3.5k rpms and up

I do have a act lightweight flywheel and disc set up if that would matter, i know on my m3 my lightweight flywheel makes a nice old harmonic through my car untill 2700 rpms under heavy load

my alignment is fine, just had it checked
my tires are balanced just did that as well
car drives straight as an arrow ( perks of running a tire shop )

I think im leaning towards the lightweight flywheel being the culprit but id like to see if any of you who have the act flywheel have the same problem

i dont think the harmonic changes if the air is on havent really tried that as of yet though,

thanks for the responses ahead of time
Kyle

 

I have the ACT "street light" flywheel on my car, and I can't say I'm aware of any weird vibrations on the highway. Since you say it's 5th gear related and at a certain rpm, it could have something to do with the driveshaft or axles (speed dependent). Check the bearings that hold the driveshaft up and make sure they aren't shot. I can't remember if Evo's have those rubber vibration dampers on the front and rear axle shafts or not (my civic does). I can check on mine tomorrow if you need me to.

Can you tell where the noise is coming from to narrow it down?

 

Note the speed it makes the noise at and try that speed in another gear.

On a side note aftermarket clutches and flywheels still need balancing unless otherwise specified. The only clutch setup I've ever purchased that didn't need rebalancing was a Clutchmasters stage 4 that came with the flywheel and was specified as being assembly balanced ahead of time. I won't do a clutch job without it, imagine being out of balance at 8k.

 

Quite a few of the '03's do this, mine included. My issue started after I replaced the OEM tire. I'm now on star specs and it does it only a little.

Some say it is fifth gear wearing and a gear and shaft replacement will fix it. Since I've driven about 75K with this vibration I'd suggest the gear is taking it's sweet time in wearing out. So, dunno.

 

Interesting on balancing the clutch assembly never heard of that but learn something
new every day right, as for noting a speed it does it at and then shifting to a lower gear like 4th, the harmonic goes away -- if im going 60 in fifth gear its got the hum, i down shift and get in 4th gear at the exact same speed, its gone no noise/harmonic/vibration

 

honestly the entire car has this noise coming from it, cant isolate it however when im coming up to a traffic light and engine brake, or simply am decelerating i hear
gear noise/ almost a shuttering coming from the tranny -- sounds like the flywheel
chattering around a little

as for the driveshaft bearings they re all in good shape i did take a look at that

car drives like a dream at any speed in any gear untill im in 5th -- when i am in fifth its got to be 3500 rpms or up so i dont hear it

 

Try putting pressure on the clutch when it's making the noise. Perhaps the TOB is going.

 

id say its tires for me to however its not a speed balancing issue no physical vibrations at all in the car at any speed, if at 70 mph and im in 4th gear smooth as glass -- besides the motor really spinning at higher rpms the cars in great shape-- i shift to 5th and hum so tires would be speed related not gear related

sounds like its the tranny and ill just keep an eye on her

thanks for all the input guys

 

I mention the tires because I have a pet theory concerning what happened. Mitsu had this special tire manufactured especially for the Evo. This tire has sidewalls of iron. So, anyway, I figure the engineers drove their Evo 8 mules around on these tires and all was well. Also, the Evo was an enthusiast's car so build the drivetrain loose so it won't bind with racetrack heat.

Since the tread on these special tires consisted of bubblegum they soon wear out and customers replace them with tires they can afford - tires with soft sidewalls. The powerful Evo engine now shoots its power strokes down through the drivetrain and the tires flex and like rubber bands shoot this pulse back through the loose built drivetrain. When the customer complaints arrive, Mitsu closes the drivetrain tolerances and the problem disappears on later cars.

I may be wrong but until someone comes up with a better story.........

Search and you will find many similar complaints.

 

I work in the tire industry for a living and I seen and heard some crazy stuff, your theory is a valid one and i can appreciate it

happen to know what tire came on our 03 s stock? id be intregued to know if there still around and what performance rating they were --

 

Your response is a pleasant surprise. My flame suit was getting itchy.

The car came with Yokohama A046 in size P235/45R17 93W. The tread wear # was 160. I'd say they were an extreme summer, street/competition tire.

Tire Rack was running a clearance on them this summer at half price (regular price was about $1200 per set) and this was production from a couple of years ago. Looking on Tire Rack now I don't see them. So, it appears they are gone.

When the 03 Evo hit the showrooms reviewers described the handling as telepathic. Think about being over two lanes and you were there. I've had some expensive tires on my car since (currently running star specs) but nothing has come close to the OEM tire.