Reducing Engine Vibration

[spooled240]

Whats up guys. I have a KA-T with Nismo motor mounts, Nismo trans mount which were purchased new and installed approximately 10 years/maybe 50k mi ago. I remember the engine vibration was increased, but I cant remember by how much. The motor doesnt move much at all which is nice, but the byproduct is my rattle box on wheels is even more of a rattle box.

Maybe I'm getting old, but whenever I drive the car now the engine vibrations really annoy me..even though the chicks love riding in my car for some reason. The damn spoiler acts like a tuning fork emitting noise from the vibration. It seemed to have gotten a bit worse after the Tomei cams as it idles a bit rougher now.

Its not really bad, but I'm thinking of throwing on some OEM spec motor mounts off rock auto to dampen some of those vibrations a bit. I also have some weird resonance around 2200 rpms. Cranks damper issue?

Any thoughts? I figured I'll sacrifice the engine moving an inch for some peace inside the cabin. Anyone put the rock auto motor mounts to 3-400 crank hp?

[jedi03]

mine was same way in sr swapped FC. i was using the drift freaq mounts but for some reason that rpm range just hums a certain way...put it back to stock and should stop doin that lol. I think its just a getting old thing too, i now have a nice STI with AC heat, etc. done a few mods to make it more reliable but keep the noise down at the same time...

[zer0c123]

I guess that's the downside of solid motor mounts. I got the nismos too and definitely noticed the extra vibration and cabin noise. I got used to it overtime, but now I got another car. I swap cars every week and always notice the difference driving the 240 now.

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[tacotacotaco]

freshen up the mounts. Make sure your idle and timing and all that idle air stuff is in proper working order no vacuum leaks. and make sure all exhaust bushings are in proper order and place especially the one at the trans mount.

[spooled240]

Thanks for the responses, guys. Taco, ill take you for a spin next at a meet next time

It definitely doesnt idle as smooth as it used to with the stock cams which I think is part of the problem. May need to bump the idle up a bit and clean/replace the IACV. The mounts on rock auto are like 60 bucks for all 3 so I may give that a shot for the hell of it.

Im also curious if a new crank damper with help eliminate the resonance at 2200 rpms.

[jedi03]

i have heard the fluidyne helps...its a bit pricey to just try out and see lol

[spooled240]

I think you mean Fluidampr? I didn't see one for the KA on their website, but I know ATI makes a good one. I'm pretty sure the crank damper on my car is the original one so replacing it wouldn't be a bad idea even if it doesn't fix the resonance issue. But for now, I'm gonna try something else..something much cheaper and simpler of a fix.


Been doing some searching and I remember that there was a damper on the factory exhaust system near the rear differential. I'm not a sound engineer, but I'm reading that this is supposed to help with eliminating vibration by changing the natural harmonics of the exhaust.



So I bought one of these exhaust dampers from Dodge and I'm gonna clamp it on the exhaust at different locations to see if it helps with this resonance I'm getting at 2200rpms.

[240KA]

haha thats pretty cool. sub'd for updates.

[Coupes_FTW]

subscribed




characterslimitations.

[jedi03]

ty for correction...mind is everywhere lol, but that is interesting...is it fluid filled or just a rubber counterweight?

[spooled240]

Originally Posted by jedi03

ty for correction...mind is everywhere lol, but that is interesting...is it fluid filled or just a rubber counterweight?

It's just a rubber-coated metal counterweight.

[burnsauto]

so any updates? I'm curious to see how this works?

[spooled240]

Originally Posted by burnsauto

so any updates? I'm curious to see how this works?

No updates yet. The damper came in, but my tags are currently expired so I havent been driving or messing with the car lately.

I will update this thread when I get around to it. Stay tuned.

[solo_ryder]

I too have thought about this at some length.. I have similar issues in my s14.. I think some of it has to do with the engine mount design.. I read somewhere of a guy who used older bmw 5 series engine mounts successfully on a SR.. I purchased some on rock auto some time ago and in a few weeks I will be putting them in. They are only 10mm taller then OEM mounts. They are cylindrical in nature and have offset studs so that any vibration will be absorbed by the rubber, similar to driftfreqs design (I think) but rubber instead of urethane.

[spooled240]

Originally Posted by solo_ryder

I too have thought about this at some length.. I have similar issues in my s14.. I think some of it has to do with the engine mount design.. I read somewhere of a guy who used older bmw 5 series engine mounts successfully on a SR.. I purchased some on rock auto some time ago and in a few weeks I will be putting them in. They are only 10mm taller then OEM mounts. They are cylindrical in nature and have offset studs so that any vibration will be absorbed by the rubber, similar to driftfreqs design (I think) but rubber instead of urethane.

Nice, keep us updated!

[spooled240]

Does anyone know if the Nismo motor mounts are hydraulic? (filled with oil)


I believe the factory motor mounts are hydraulic which provide much more vibration dampening and less NVH..


A 3" clamp for the exhaust damper was ordered yesterday. I will throw it on as soon as it comes in.

[singlecamslam]

What’s wrong with running oem motor mounts?

[burnsauto]

Nothing really. a lot of people like to fix problems that aren't there, and upgrade to Nismo, because….Nismo. Honestly just new OEM mounts would be a large improvement over 30 year old mounts that most of us are running...it's what I plan on doing. I don't need to drive around another s13 rattle trap.

[slideways2004]

Get an inline 6 and you won't have any vibrations.

lol

[spooled240]

Originally Posted by singlecamslam

What’s wrong with running oem motor mounts?

Originally Posted by burnsauto

Nothing really. a lot of people like to fix problems that aren't there, and upgrade to Nismo, because….Nismo. Honestly just new OEM mounts would be a large improvement over 30 year old mounts that most of us are running...it's what I plan on doing. I don't need to drive around another s13 rattle trap.

The Nismo's do work in eliminating engine movement, though. This was my car with the original motor mounts and about 270whp/280tq. (12 years old at the time w/ approx. 130-140k miles?) The engine doesn't move much at all anymore. They are ok if you are a hardcore, but I am not lol.


https://www.youtube.com/watch?v=leztC_UPIXQ


I am curious how new OEM motor mounts would have performed.

Originally Posted by slideways2004

Get an inline 6 and you won't have any vibrations.

lol

I have an IS300 for that

[burnsauto]

yeah they help eliminate movement, improve torque transfer, yada yada...but I don't see the huge benefits of that theory in anything other than a track car. Call me crazy (or worse..). As long as nothing is being broken from the movement, I'd rather have that then my car buzzing at a stoplight while I try to convince my wife that this is a cool car.

[spooled240]

I clamped the exhaust damper in the factory location, but it seems to have done nothing to reduce or shift the resonance at 2200 rpms. I'm gonna move it around in a few place to see if there's any difference.


If this doesn't resolve the issue I may temporarily add a much more weight to the exhaust for testing. I may have a few dumbbells laying around that I can clamp on to this thing lol

[jr_ss]

Originally Posted by spooled240

Does anyone know if the Nismo motor mounts are hydraulic? (filled with oil)


I believe the factory motor mounts are hydraulic which provide much more vibration dampening and less NVH..


A 3" clamp for the exhaust damper was ordered yesterday. I will throw it on as soon as it comes in.

No, they are rubber mounts. The durometer is softer than the Nismo mounts though.

[spooled240]

Originally Posted by jr_ss

No, they are rubber mounts. The durometer is softer than the Nismo mounts though.

Interesting. On rockauto they offer hydraulic motor mounts for the KA. They must be pretty smooth..

[240sxTuck]

Little late to the party, but why not run polyurethane mounts? My car came with poly motor mounts, and a solid trans mount. Vibration was a little too much for my liking so i swapped out the trans mount for poly, and immediately noticed a reduction in vibration. And it's still stiffer than OE rubber.

[spooled240]

Originally Posted by 240sxTuck

Little late to the party, but why not run polyurethane mounts? My car came with poly motor mounts, and a solid trans mount. Vibration was a little too much for my liking so i swapped out the trans mount for poly, and immediately noticed a reduction in vibration. And it's still stiffer than OE rubber.

That doesnt sound right. Everything I've read mentions a solid trans mount being the most attributing factor of NVH..

[240sxTuck]

Originally Posted by spooled240

That doesnt sound right. Everything I've read mentions a solid trans mount being the most attributing factor of NVH..

That's what i'm saying. I swapped the solid mount out for a polyurethane, and reduced my NVH