solid rear engine mount?

[crobaa]

Hi guys, Is it possible to only replace the rear mount with a solid one. I'd just like to reduce engine vibration but not totally make the car rattle, is this an option? the engine is a b18c7 in eg hatch

[bennjamin]

ofcourse its possible. On your setup - the rear mount takes the brunt of pivoting from the engine and is the only one to break , so to speak.
Get a hasport/innovative rear , or get inserts for your existing rear mount. Or - grab yours or another and fill it with sikaflex or similar to stiffen it.



Pm me I have a ITR rear engine mount which you can fill or put inserts into easily.

[crobaa]

thanks mate ill look into a hasport one. How much vibration am I going to cop by changing that one mount?

[bennjamin]

fair bit ! it has the most influence on vibrations :)

[DLO01]

Like Ben said above.

By doing so at idle you would not cop too much vibration as the engine is just sitting on the oem right a left mounts, so they would absorb the vibration of the engine and not transfer it through to chassis where you can feel it.

With gentle load it would probably be the same, maybe a bit more vibration though as engine wants to torque.

On heavy load/acceleration, you'll probably feel more again, cause engine really wants to torque.

Take note though, because your putting a solid mount in the rear only, everything has an equal and opposite reaction, thus at heavy load although your solid rear mount will hold tight in place and your oem right an left mount will now deform to its max under load to take the torque and you may find they won't last as long as you'd usually expect.

[crobaa]

Wouldnt they last even longer? I would have thought as the rear mount does most of the shake prevention making it solid would stop the engine shaking- thus stop the side mounts moving around as much, thus increasing the life of them?

[Bludger]

read post #5 closely and have a good think about physics.

The energy has to go somewhere.

putting a solid rear mount in doesn't make the energy disappear.

[crobaa]

I thought the body would just shake more as the engine doesnt shake side to side just front to back?

[Bludger]

think of a kiddy playground see-saw.

The pivot in the middle is the engine and either side are the mounts.

Now if you were to get the largest person from the biggest loser to sit on one end.......... and the engine is still providing that twisting force.

think of it, essentially the see saw pivot are your timing side & tranny side mounts.

something has to give.

I have tried to give the best explanation i can without giving out too much time. if you don't understand then kindly go back to school.:)

[crobaa]

think of a kiddy playground see-saw.

The pivot in the middle is the engine and either side are the mounts.

Now if you were to get the largest person from the biggest loser to sit on one end.......... and the engine is still providing that twisting force.

think of it, essentially the see saw pivot are your timing side & tranny side mounts.

something has to give.

I have tried to give the best explanation i can without giving out too much time. if you don't understand then kindly go back to school.:)

First you said the pivot in the middle is the engine, then you said the pivot is the timing side and tranny mounts. Your explanation is crap and theres no need to be a hero mate. It still seems to me that the energy absorbed by the solid rear mount would just go to the body and make the body shake. Wouldn't the engine move less overall and put less strain on the other two mounts? Wouldnt the body take the brunt of the engine shudder? If the other 2 mounts were on the front of the engine your theory would make more sense. I still accept that it is entirely possible I am wrong, but being a dickhead is not a good way to convince me

[Bludger]

I didn't mean any hostility in my comments, didn't you see me smile?

I was merely asking you to kindly educate yourself to better understand. no one knows everything and old farts are still learning when they're 80 years old.

It's unfortunate I was of no help. maybe someone else can clarify this for you.

[Bludger]

ok, how about this.

you have 3 wires connected to a power source, the power source is a 12v car battery.

wire 1 has 10ohm resistance. (solid rear mount)
wire 2 has 6 ohm resistance. (good condition timing belt side mount)
wire 3 has 4ohm resistance. (bad condition tranny mount)

which wire will receive the most current? (which engine mount will bare the brunt of the torque & vibration?)

any form of energy, be it torque, heat, electricity, etc, etc. has to go somewhere. it doesn't just disappear. the most likely route of the energy will be the path with least resistance.

I hope this was of better help.

[Bludger]

what absorbs the bounce better? a stiff suspension damper or a soft comfy one?

the stiff one will send the energy right back into your spine where as the soft damper will absorb the energy.

In this case the stiff engine mount will send the energy back to the other softer engine mounts.

sigh, I'm tired.

[crobaa]

I understand that metaphor (especially as im a sparky), but I don't believe it translates over to engine mounts as the engine shakes alot back and forth and barely any side to side. The rear mount takes nearly all of the shaking even when all the mounts are stock and the side two are basically just holding it off the ground and to the chassis right?

[crobaa]

I get what your saying to a certain extent but I dont think its big enough a problem to worry about/ deter me from just changing the rear mount? Or possibly even just install an engine damper?

[Bludger]

believe or not, its physics, no one can break those laws.

[Bludger]

your engine won't fall out from underneath.

i was just proving a point and being a fraction anal.

[bennjamin]

Please dont just do a super stiff rear mount. I have a ep3 , and have anrear innovative with side standard mounts and its
Horribly sloppy in shifting and vibrations etc.

Imo get three stiff and remove your front lower torque mounts , or just get new oem mounts

[crobaa]

how about torque dampers for the engine? anybody have experience with these?

[Bludger]

waste of money.

i had one.

[DLO01]

Torque dampers are just band aid fixes to a degree. If you need new mounts, get new mounts.

Going back a few posts..... Think if it this way.

Picture it from the drivers side of car, looking at the car. Under acceleration (heavy load) you want to turn the wheels forward, through driveshafts to the wheels, lets say clockwise in this instance. But resistance is the grip on the road. So in turn your engine wants to torque the opposite direction because of this resistance, anticlockwise. Because you now have a solid rear mount and oem side mounts, the pivot point becomes the solid rear mount and therefore the anticlockwise rotation will make the engine rise to a degree and deform your side mounts in an upward direction.

[crobaa]

Thanks for that mate. So what's the best option for reducing engine movement but not creating discomfort to the extent of solid mounts?

[Bludger]

there is no holy grail.

sweet - sour

hot - cold

power - economy

you get the idea.

find your compromise

comfort<----------------------------------------somewhere here maybe------------------------------------------->performance

[DLO01]

Unfortunately it is a trade off. You could however instead of solid mount, go Mugen mounts, Spoon mounts, J's racing mounts. As above "somewhere here maybe". They are like oem mounts but harder rubber.

[crobaa]

That sounds like an option, I'll have to look into it thanks

[fuzionz]

Unfortunately it is a trade off. You could however instead of solid mount, go Mugen mounts, Spoon mounts, J's racing mounts. As above "somewhere here maybe". They are like oem mounts but harder rubber.

And also Hardrace makes Oem like eng mounts

[Bludger]

good point.

I would go hardrace.

[on-tec]

In other words his trying to say that if your rear engine mount is strong then the weaker joints (oem) will get a shake , that's the whole reason for it - reducing - the vibration . Picture a hard surface and two softer surfaces and place them in the form of your engine mounts and now picture someone rolling a steal ball into the harder surface or the strongest , it will take the shock but it will bouce of and hit the weaker mounts , and because the joints are weak it will then viabrate, not as much as having all oem mounts ( all soft surfaces ) but it will still copp some vibration . Your best bet would probably be to get all your mounts done ( hasport ) and or a torque damper . I hope this helped u understand :)

[TheSaint]

i put int a 12lbs flywheel on my D15b7/D16a6/D16z6 hybrid build - and it made the engine vibrate alot - so i started searching for similar things

the torque damper i already had did almost nothing and was the most expensive solution apart from hasport mounts etc

so i got the Energy Suspension Engine Mount Insert kit off ebay - and this was a nice in-between

they are stronger than a torque damper but not as harsh as a full race style mount kit

i recommend them if its for a daily/street car