Im getting close to being done with purchasing all my parts for my winter build. I almost forgot that the motor mounts are shot! The engine wiggled left and right a bit while idling.

Are solid engine mounts a bad idea?

I understand they will make the car vibrate. As long as my steering wheel isnt jumping, I can deal with that. I drove a fully gutted (besides dash) car with a 3" exhaust and no radio for a few years.

Will it put extra stress on the housings and could possibly crack them?

Thank guys.

 

I think you're asking the wrong question.
If the (presumably) original motor mounts were bad, the question should be, "Why not replace them with another set of stock mounts?".

In other words, why increase NVH to no good purpose?

 

What's NVH? And there should be no reason why engine mounts are blown after 67000miles on a stock car with an exhaust. I'm not going to put garbage back on.

A solid or poly mounts on a piston fwd engine help eliminate wheel hop. I figured there would be some sort of performance benefit to installing an aftermarket set on a roto too.

 

You can get the mazdaspeed mounts from the infini for $70 a mount. I have them and the engine barely moves, but yet I don't have much vibration either.

 

NVH= Noise, Vibration, Harshness.
67 K miles maybe but how many years?
The stock mounts are rubber, a material that degrades with time as well as usage.
A twenty year old part that hasn't crumbled into dust is hardly "garbage".

Your logic would require that an oil filter that doesn't last the life of the car be considered "garbage".

At any rate, performance modifications that work for a piston engine are not applicable to the rotary.
This is why the performance cam in your 13B didn't work out as expected.

 

No need to be an *******.

 

Solid mounts do transmit a bit more vibration, but far less then any piston engine. So it won't make the car unbearable.

That said, for a mildly modded car I'd just stick with the stock or stock competition mount. You won't be tearing the stock mounts up, so why bother increasing NVH, if even just a little?

 

Agreed.

However, I have solid mounts in one of my street machines and the jury is till out on whether or not the added stress on the mount arms themselves have any ill effects.

I also use them in my racer with no issue and will use them in my next build. Just don't solid mount the trans. the case on the trans does not like that so much.

IMO, NVH is a personal thing. I don't mind a little more as my raceport 13b solid mount is no where near as shaky as my 355 small block chevy muscle car with poly mounts and floaty boat suspension!!

 

+1, not a fan of solid mounts, there is little point. although the vibrations aren't as bad as a piston engine

my favorite mount is actually the stock vert mount. its not as stiff as the competition ones, but its stiffer than the stock coupe mount.

FB67-39-040 if i recall correctly.

 

the worst part about solid or even urethane mounts are the rattling interior plastics. The vibration isn't a big deal. You can get used to it easily. The rattling plastics are extremely irritating to me though.

 

My windshield defrost vents vibrated their way loose lol

I have himni solid mounts and from the vibrantion, you get used to it, the noise is bearable, not really loud to me, compared to a piston engine with solid mounts....holy hell.

I wouldnt recommend solid mounts though.

 

I ran solid mounts and wasn't bothered by them one but. Yes there is more vibration but not very much at all and it is nothing like a piston engine with solid mounts. I thought they stiffened things up and the kept the shifter from moving.

 

no need to go solid, they're so annoying i wouldn't want to drive a car with them for more than 30 minutes at a time. there's alternates to going with solid mounts anyways, which are my stainless straps for the stock mounts so that they do not overflex(think FD mount).

 

I use solids on my dd. Unless your drifting(think clutch kick), or putting down a massive amount of power they are unnecessary imo.

Besides for some rattling around 2700rpm, they are not bad at all for a street car. Only draw back is I've noticed the stock electronics(window switches, etc) don't like the additional vibration.

 

Sounds like it's a personal taste thing.

Get some if you want. If you don't like them, I bet they would be easy to sell.

 

I run poly engine mounts in my 91 and and there are almost no vibrations and wheel hop is greatly reduced. Swapping the trans mounts for poly added a fair bit of vibration under cruise conditions. In my 86 (track car) I run solid mounts and with the loud exhaust the car would be unbearable for street driving.

Everyone has different opinions of what is best, but for the majority of people who drive hard poly mounts are best. Solid mounts are best suited for drifting or racing.