subduedracer

I have a simular issue. My steering wheel doesn't vibrate, but the car makes a rattle noise at idle whrn the a/c is on. I don't hear it from inside. When I pull up to a inclosed place where noise can eco, I can really hear it. I'm taking mine in tomorrow to see if I can get this fixed. It sounds like this could be the same problem.

TeamRX8

iTrader: (25)

mine is 12/04, I don't have any idle vibration issue, I would tend to believe these parts would go into production vehicles before TSB service

RX8_Buckeye

Hmm, very interesting, a durability issue with the mounts. The fact that Mazda released a new part with a heat shield indicates that engineering screwed this one up. Sounds to me like Mazda needs to add some requirements their mount design specifications.

I don't think my car has a failed mount. Every car vibrates to some extent while the engine is running. If the vibration feels severe, you should have the mount checked out. If it doesn't feel severe, please accept the fact that it is normal and save Mazda the warranty cost.

adrian-1

Great!!
This can't be good for Greddy turbo owners. Bought my car in Jan '04 and I mine has 3 dots on it. I haven't had a noticeable vibration at idle, yet. As you can see from one of my install pics, that turbo is adding alot more heat to that area and could present problems over time.
Anyone have a price on the new design ones, just in case.

snap-on

About 100 bucks..

I wonder if someone can make a heatshield better than the factory one?

It shouldn't be too tough to fabricate.

brillo

I dropped my car off today for the new part as I was heading out on vacation, so we'll see how it works when I get back in from D.C. on Sunday.

fray

iTrader: (1)

My 8 has 17711 miles on it.. so I'm pretty close to the 18k threshold listed in the original post.

I bought the car used w/ about 16200 miles on it. I've noticed that sitting at a stop light or whatever (especially w/ the A/C and/or defroster on) the 6 speed MT stick vibrates something aweful. The idle according to the tac is rock solid at just under 1k. Ever once and a while it feels like the whole car shudders.. but it's mostly in the stick.

Are these the symptoms of the broken motor mount? (It's raining outside, or I'd attempt to pull the splash guard back and take a picture..)

RX8_Buckeye

Absolutely not. The shifter mechanism is directly attached to the transmission, so it's always going to vibrate quite a bit. The occasional vehicle shudder at idle is also normal. This is caused by sudden drops in engine speed that cause high amplitude vibration of the engine on its mounts, some of which is transmitted to the body. The tachometer in the instrument cluster measures only average engine speed. In actuality, the instantaneous idle speed of the engine fluctuates around +/- 30 rpm of average speed. The sudden "dips" in speed are not picked up by the tach in the instrument cluster.

fray

iTrader: (1)

Ok, then I'm confused from reading the description of the problem.. what are the symptoms of a "rough idle" then?

Gomez

For what it's worth fray, my car has done 15000 miles and my shifter NEVER moves more than 1/8" at idle. A 1/16" in movement is average.

I have a different PCM calibration to you though.

Gomez.

StealthFox

do you like get a ruler out and hold it next to your shifter, film its movement, upload it to your computer, then slow it down to see how much its moving?!?

Gomez

I don't need to. It moves SFA...and SFA is about 1/16".

StealthFox

i feel really dumb...whats SFA?

Gomez

Sweet F*** All.

StealthFox

oh, right, i knew that >.>

RX8_Buckeye

Displacement is only one measure of vibration, and not the best. Displacement can be small while dynamic velocity and acceleration are high, depending on the frequency components of the vibration. When you touch the shifter lightly you're always going to feel vibration. It is not a sympton of rough idle.

A sympton of rough idle is excessive shake or vibration felt in the seat, floorpan, and entire vehicle body. However, as I mentioned before, even a car with perfectly fine engine mounts may occassionally have periods of rough idle, due to sudden drops in engine speed which create engine movement that can't be fully isolated by the mounts.

fray

iTrader: (1)

Just an FYI, I inspected the motor mounts on my 8 (17k miles, 05/03 build date). There are three yellow dots on it.. but as far as I can tell no cracks.

I have pictures of the mount if anyone cares.

So speaking of the cracks where are they present? At the weld of the two support posts and the metal ring?

ddub

Has anyone made solid aluminum/other type of mounts for these cars yet? For everything, motor and drivetrain?

I put solid aluminum motor/tranny mounts on my 2nd gen rx7, and solid steel front differential mount with solid delrin rear differential mounts and am much happier with them. Some people don't find the motor/tranny mounts to be streetable since you can get vibration at higher speeds and in 5th gear, but you'll most likely never break them. When I went to replace my mounts I had both tranny mounts cracked and one motor mount broken completely in half. For me it's just for piece of mind and I was curious if this had been done for the rx8 yet.

RX8_Buckeye

Hehe, would definitely not recommend solid metal engine mounts for a daily driver, unless you don't mind drastic increases in vibration and interior noise levels. Some people really don't care, others would be horrified at the results.

StealthFox

yeah true buckeye, for a weekend car it would be much safer, but it would probably drive you nuts as a daily driver

RX8_Buckeye

The primary reason someone would go to a solid engine mount is to handle the increased loads from an engine with major horsepower/torque upgrades, or if someone takes the car to a track a lot. The stiffer the engine mount, the less the dynamics of the car are negatively affected by the engine bouncing, rolling, and pitching on its mounts. The added safety/reliability is really an afterthought.

2ROTORZ

>>>>I have had this issue myself. Been to 3 different mazda dealers, 3 times each and have not had any resolution found. Theyy have only tried fuel injector cleaner and reflashing my PCM to "P" (which we all know has nothing to do with rough idle). The thing is, I seem to have noticed it as soon as my engine flooded in January.

>>>>>Only at a stop. I get a consistant vibration, that goes in and out about 8 seconds apart. Constant vibration is experienced when opening a window or the sunroof though. None while moving and RPMs are constant, no fluctuation.

>>>>>So this is normal then?

Go48

If you are saying that whenever you put an electrical load on the system at idle the car idle drops and you get increased vibration, then you may want to replace the battery with a more capable one like the Mazda recommended replacement, the Interstate MTP-35. The OEM battery is not up to the task.

2ROTORZ

They already did, a month ago. The vibration increase is not severe, just noticable. Would that still be an issue?

khoney

My mount was just replaced, and my vibration went from obnoxious to moderately irritating