TC's Garage - Mazdaspeed Engine Mounts
Well... Brown Santa arrived today with part 4 (in 4 packages, of course) of my latest replenishment order. Boring stuff that I didn't really need came first (spark plugs, oil filters, blue banner for the garage). Spiffy engine mounts that I didn't really think I needed but really really wanted came last.
So... what better way to spend a Wednesday evening that inventing new ways to swear at my car? I propped her up on the stands, took off the front wheels, strut-tower bar, air filter (and *#$&* cool box), the heat shield for the header (why 300 bolts?) and had a beer.
Then I set to work undoing Yoshi's torque job on the engine mount bolts. Driver's side went well and passed right up between the wheel well and header. Passenger side was like those little rope puzzles you see in tourist towns, but I eventually got it turned the right way, passed it toward the front and dropped it out through the pan (only had to undo the rear 4 bolts).
Being a stickler for instructions, I then headed over to the Doghouse to use the vice to unbolt the rubber bit from the bracket. Gary made fun of me and we unbolted it sans vice. That's when we noticed the lovely cracks in the old rubber - at 33,500 miles... Hmmmm, I thought.
I headed home with the new mounts ready to install. Fortunately my wife was home. She's good at inventing new swear words, you see.
Two hours later I finally got the driver's side mount in the correct hole and attached to the engine at the same time. The passenger side happily dropped into place whether I wanted it to or not. With all the important bolts torqued to 50 ft/lbs, I gave it a quick test-start - just in case I had pinched something between the engine and firewall. Sadly, it started right up, so going to bed at 10:30 wasn't an option. Had to finish it up.
So, I set about re-attaching the pan, heat shield, intake, *#&$* cool box and strut-tower brace (seriously... don't forget to remove this, as it can't possibly be good to jack up the front of the car by placing your jack under the oil pan and shoving the engine into the STB).
A quick check of the garage floor revealed no leftover parts, so I took off for the requisite test drive. I've seen about 400 requests for NVH commentary on the pointy board... Never seen the answer. Well... here's mine. Take it as you wish.
Noise: +0
No additional noise. At least not after I removed all the loose hard objects from the glove compartment, and tightened the bolts on my radio (in the trunk) an extra notch. Put anything loose and hard against anything hard in the car anywhere, and it will rattle like a diamondback when the car is at or near idle. Objectionable? Not really. I mean... who wants to sit around idling? Noise at any engine speed >1500 RPM is unchanged.
Vibration: +2
Yup. It vibrates. At idle, it is just registering on the scale as objectionable in my taste. If your sensitive to such things, it may be a problem, but I don't mind constant low-level vibrations. If I were the front tires, however, I'd be pissed. The front wheels vibrate quite noticeable at idle, as I discoverd while torquing the lug nuts (see... you KNEW I forgot something).
At engine speeds between 1500 and 3000, I couldn't notice any more vibration than before. Above 3000, there is a tingle in the steering wheel that wasn't there before, but I don't find it particularly objectionable - especially since I no longer have the 65 mph shimmy (I'm guessing that's what the crack in my stock mounts was for...)
Harshness: -1
Phooey. It's a Miata. It ain't harsh unless your top blows off in the middle of a blizzard and you're driving on corded Hoosiers. The car is ergonomically more pleasant than it was before. There's no sensation of unwinding when smacking the clutch at 7100 RPM in the middle of a corner. Stomping on the throttle in 2nd gear produces 1 hiccup instead of a chain reaction of 4 or more. Rev matching is easier, but that's probably because my butt is feeling vibrations that it couldn't before. But, it's still not complaining about them.
Performance benefits?
Well... since my stock mounts were toast, yes. The car is much smoother in response when I ham foot the throttle. I managed to finally and forever remove the lovely yellow size markings from my street tires in a burnout without a trace of wheel hop. And 3rd gear full throttle over my favorite set of railroad tracks produced to wheel spin, although most of that was corrected when I installed the stiffer FM springs.
Bang for the buck?
Lots. Mazdaspeed mounts are between $35-$45 from Mazdaspeed if you're a registered racer. Stock mounts are $10-20 higher. If you're not stuck in a stock autocross class, you should probably consider the competiton mounts.
Can I do it myself?
You should probably do it at a tech day if you've never seen it done. I've watched other folks do it, and still had trouble, so don't rely on me for help. :-)
Tools required?
On my '02, a 24 inch 1/2 inch extension would have been nice, but 3 eight-inchers did the trick (don't try this at home, kids).
10mm socket for the belly pan and header heat shield
14mm socket for the STB and all engine mount bolts
One of those nifty ratcheting box wrenches in 14mm would be nice on '99+ cars for removing the rear-lower engine bracket bolt - probably similar on earlier cars.
A vice, or someone to stand on the bracket while you torque new rubber mounts into place.
A torque wrench for re-tightening all the engine mount bolts.
An assistant. Particularly one willing to climb under the car to chase bolts you drop-kick trying to thread them in.
