I just did the clutch on my n/a s4 and noticed how bad my motor and tranny mounts were and decided to pick up some "upgraded" motor and tranny mounts. 95A poly which after i installed were fantastic. My motor is rock solid in the bay and my transmission doesn't move an inch.

After a drive i changed my mind. These are way too stiff, my entire interior rattles and it seems that the noises from my tranny have been amplified from the stiffer mounts. It makes my fc unbearable to drive on the daily.

Onto my actual question.

Whats the difference between coupe mounts, vert mounts, and comp mounts? all from mazdatrix. A durometer would be nice to know.

Its a weekend car that is currently n/a but i plan on going t2 in the near future. I know vert mounts are stiffer than coupe but would the comp mounts be better? I want my drivetrain to feel nice and solid but not have it feel like my car is going to fall apart. Thanks!

 

I believe the "comp" mounts are @ 20% stiffer than stock (but have no immediate supporting evidence).

I'm somewhat dismayed by discussions about bushings and brake lines because they always ignore the obvious...OEM replacements.
(In this discussion price is not a paramount factor)

How many folks have replaced their 20 year old rubber brake hoses w/ braided steel and then crow about how much better the brakes are "compared to stock".
Yeah right, compared to old worn out stock...I'd bet money that most people could not tell the difference between new rubber hoses and braided steel hoses.

The same would hold true for chassis bushings.
Unfortunately, this is where price does become a factor because aftermarket poly/delrin/alloy bushes are much cheaper than stock but there are significant downsides (as you already discovered) attached to the thrift.

It's all part of the false equivalency "hard=racecar=good".

 

I used the mazda comp mounts and they work great.

every so slight increase in vibration, but virtually eliminates clutch clatter.

 

i couldn't agree more. even with the race car hard isn't good, we did solid mounts on the race car, and all kinds of weird stuff started falling off of it, like a gas RC car or something. plus the driver didn't like the solid mounts, it scrambled his brains. so we lost the solid mounts, because they didn't provide any benefit, while having big downsides.

with the FC motor mount we have three OE choices.

the coupe which is the softest.
the vert is 10% stiffer, and my favorite.
the comp mounts are 40% stiffer.

 

You have to let Poly mounts break in, it takes around 500 miles or so. Also from what I understand the comp mounts are also 95A durometer, but being rubber they don't have to be broken in.

 

Agreed. I installed the mazda competition mounts in my x girlfriends t2. Engine did not shake anymore. I didn't notice any vibration in the car while driving.

 

comp mounts

how often do you plan to change motor mounts? i hate those semi solid delrin mounts, unless you drive a racecar..

 

It looks like the comp mounts are 75 durometer. So I was a little off.

 

Consequences, consequences.

Every bit of compliance removed from the drivetrain/suspension mounts results in more energy transferred to the chassis structure. If you're a race car builder, you compensate with seam welding, roll cages, foam injection, etc. and then repair whatever breaks later.
Hardly a viable option for the average owner.

I'd bet that if we had two identical cars, one with all new OEM rubber bushings and one with say, a full Energy Suspension kit, a majority of us would prefer the stock setup in a blind test.

 

The problem with most mount options for FC's is that they are a flawed design to begin with all of the puck style with a single through bolt are basically solid mounted on the tension side of the torque because of the single bolt which makes the poly not even work. The compression side will do its job but the reason for all the noise and awfulness is the tension side the bolt essentially becomes a solid mount.

Aside from the Competition mounts are there any aftermarket mounts that dont suffer from this obvious flaw?

 

This is a reality/truth that most FC owners REALLY need to learn. I was only able to learn it after going through and replacing most of my mounts with stock OEM replacement as opposed to derlin and such.



Man Law.



I honestly never would have guessed the vert mounts were different. Now i wanna get a pair and see how they feel.....

 

bad comparison, unless you're talking new, which i have never driven a brand new second gen RX7 with less than roughly 20k miles but years of use.

the stock suspension feels extremely mushy to me, when i upgraded the suspension bushings to polyurethane they gave it a much more solid feel when take a fast corner versus the stock suspension which felt overly soft as if it was about to wash out. in a straight line though, i would agree, stock gives the best feel as you don't notice cracks in the road so much.

comparison being grip is a little hard to compare to vibration, there's little to gain from solid drivetrain mounts. i never understood everyone's infatuation with solid engine, transmission or differential mounts, even in a drag car. if there's no give you are likely to break something.

what would the benefit of sitting on a wood seat be? this is how i view solid drivetrain mounts.

 

I must have had some seriously worn out engine mounts before replacing them. The car had 180k on the odometer and I was (yes... I'll admit it) a bit naive, so I ordered solid engine mounts. I put them on and actually did not get much more vibration than stock. No, they weren't ripped or oil soaked or anything. I only have a small shudder on takeoff around 2500 rpm. I'll be replacing them with the competition mounts though. I too have been concerned about breaking things with the solid mounts.

In a related story, I once filled the holes of my "roll stop" mounts on my old tiburon. I used 3m windo-weld (I saw it on the internet, so it must be a great and worthwhile investment, right?) Anyways, that was a huge mistake. Solidifying engine mounts on a fwd piston engine is a terrible idea. It was so bad that I thought the steering wheel was going to fall off in my hands. Compare that to the Rx7 with the solid aluminum mounts that I can comfortably drive on a daily basis...

 

Reading through this read has made me feel a bit dumb for choose poly mounts, as these have a single bolt going through it basically making them solid mounts.

The only problem i'm left with is whether i want to go with vert mounts or comp mounts...

 

You mean the old, worn out stock suspension?

 

yes, but it is a sports car and suspension give isn't necessarily a good thing. i'm sure a car with brand new OEM bushings would feel much better but for performance i wouldn't put suspension bushings and drivetrain mounts in the same category.

same goes with tires, a nice tall tires has more cushion but will tend to roll over more than a wider shorter tire, which has less give. traction sacrificing for softer ride qualities.

 

Go to rx7.com buy the Mazda comp mounts. No vibration in my streetport 228 hp n/a. They are almost double the stiffness of stock. done and done

I guess you could also get them from Racing Beat or Mazdatrix.

Although I tried going to Mazdatrix to see what they had and my securety system said Don't go there.

 

I read that the stock engine mounts for the Vert are stiffer than stock Coup mounts.

True??

 

If you read the thread you would see that it is true