I understand poly is used to lessen the flex that rubber has. That being said, I fully understand why you would want to do that regarding suspension. Why would you put in poly motor mounts though? Wouldn't this just cause excessive vibration? What about tranny mounts?

 

im guessing better transfer of power. torque is lost when the tranny or engine shift up and down or side to side as they're transfering the power to the drivetrain and wheels. less movement from poly mounts = more torque to the wheels.

that's my guess but i could be wrong.

 

the stock motor mounts are crap rubber that tends to squash and weaken thus resulting in the motor turning or moving. with poly mounts it stiffens the motor up and keeps it from moving. if you are really concerned about it you can step up to solid motor mounts but then you would have to upgrade the tranny mount or that will be toast very quick, possibly resulting in more serious problems.

 

i ran the poly mounts and they suck!! The camaro motor mount is a captured design, my 18 year old ones were not even broken but i changed them just for the hell of it with poly when my motor went in. they transferred more vibration and raised the motor up about 1/2 inch. i removed them and put stock replacements it. i don't see any reason why you would use them on a street car. maybe if you were running slicks or a drag only car but i didn't like anthing about them.

 

Maybe if you were going to have a really snappy motor on the street you might want them. I bought solid mounts I plan on using for my new 383.

 

i was running them on a 383. The stock mounts are clamshell type mounts that totally enclose the rubber bushing. even if the rubber breaks ( i really don't see that happening) the motor is still safely retained. I really didn't notice any difference in motor movement going back to rubber. I prefer my rubber mounts

 

actually the rubber wont necesarily break. most likely it will kinda of squash out. the rubber will become soft. the clamshells dont really hold the rubber in aall that much. on the ones i removed from my camaro they were really gone. the actual mount itself was movingand the rubber was way to easy to twist. so i changed them for my somewhat beefy 383.

 

I'm using poly in a street-driven 85 IROC. I felt no difference nor did I experience any difficulties. I swapped from rubber because both sides were pretty much shot--so much so that the pass side would allow noticeable motor lift.

JamesC

 

I'm using the Moroso solid steel mounts on my daily driven 92.
Vibration is a little more noticeable, but not uncomfortable.
I've run steel mounts on every Camaro I've owned (6).
Plus,They last forever.
-Rich-

 

Personally, I would avoid a solid mount for anything but serious racing. Much has been written about how solid mounts will distort a block with repeated hard runs, especially in the main bore and cylinder area. They are not recommended for street use.

 

I agree with JamesC I have the poly ones on my daily driver and I haven't had any problems what so ever. I don't notice any more vibrations than stock. One thing I do like is it raises the motor about 1/2 to 1 inch and it makes the oil pan that much harder to hit something on the road.

 

why i would use poly mounts:

1. they keep the engine from moving as much when i floor it. therefore, i can have the motor (and aircleaner/intake) closer to the hood without it hitting.

2. the stock ones squish over time. that is why, like someone mentioned above, polys make the engine sit a lil higher. this would be GREAT for me since i can have my longtubes a lil higher off the ground (i will "tweak" the headers/floor if needed)


basicly, they are a cross between stock mounts, and soild race mounts...


some people experiance too much vibration because of them.... and hate them....most of thoes people seem to also have a motor that vibrates more then others...

some dont mind running soild mounts on the street....

 

I have had poly mounts for three years now. With my original 350 I had considerable vibration, particularly around 2000 rpm cruising. My current 383 (internally balanced) is smooth. The poly mounts coupled with the revised exhaust port design cause serious clearance problems with my Hooker longtube headers. Also the plenum on the Stealth Ram hits the hood, where other report enough clearance with stock mounts. Drive line angle was off due to the higher engine/trans mounting & lower pinion of the 9 inch rear. These are all the cons I ran into with a fairly modded car. The pros would be longer lasting & much less deflection. This is why I have stuck with them.

 

I would just like to say... I blame this thread for my weak passenger side OEM motor mount

Turns out I'm ripping it and the driverside headers at pushing against the K member. I got under the car today to look at an exhaust leak and went "That doesn't look right."

Now I gotta decide if I wanna put another OEM one back in (I got a spare on in my room somewhere) or just wait till I get the new motor and use my solids.

 

i have poly mounts, and the prevention of movement notwithstanding they are FAR stronger than a rubber mount.....if you are making any kind of good power its something you ought to have.

i dont have any vibration problems of any kind, and the mounts SHOULD NOT move your motor up or in any direction as they are captured inside the clamshells that house the rubber mounts, unless of course you put the poly inserts in upside down,

they DO have a top and a bottom, and should be installed inside the clamshell correctly

i have a poly trans mount too, one of the more important reasons for poly mounts is keeping the drive line aligned properly under hard accleration, the motor and tranny can twist and throw off your u-joint angles to a certain degree which can eat some power and cause other vibration

and the motor mounts on the camaro are nearly indentical to almost all other GM motor mounts from that era, at least for v8's....the design is the same

 

poly lasts decades....rubber not quite so....many of you probably noticed it raising the engine because the old mounts were getting squished and the new mount is in perfect condition?

 

My poly mounts were installed correctly. The motor was higher with the poly than with the original 19 year old mounts ( understandable) and when i went to the performer RPM i had in mind that that extra height might be a problem, so i switched back to parts store rubber mounts, that saved about another 1/2 inch. I'm not saying that poly is bad, in my case i saw no advantage. Yes poly will last longer, especially once oil enters the picture. My point was that from the stand point of the motor comming loose with poly vs rubber that there was no real difference since your worst case scenerio was that the clamshells hold it in place and you get another 15 dollar mount. Also just as a side note I welded the nuts for my mounts to the chassis when i had my springs out.

 

ya that does make sense

 

For those running poly mounts, anyone got a part number? ... there seem to be so many, it can get confusing. Any brands u feel like throwing out there? Thanks, Efrain.

 

Prothane and Energy Suspension make good poly mounts. Spohn sells Prothane; Jegs sells ES. Summit sells both.

 

from a mechanical engineering standpoint, it's kinda like this. it takes energy (in our case, mechanical energy, or torque) to twist the engine in the mounts. You know, how you see your engine twist when you hit the gas with the hood up. if you hold the engine still, that energy gets transfered to the rear axle, thus more rear wheel torque. Best case senario, you would use solid mounts. That's why that's what race cars run, they aren't worried about the cons, just the pros of solid mounts. The poly mounts are a good comprimise, as is a solid mount on one side and a rubber one on the passenger side, acting like a torque strap like you see on a lot of race cars that don't use solid mounts. The strap allows vibration to be absorbed while idling, but doesn't allow extreme engine movement while under acceleration.

 

btw, i run one poly ones

 

well guys, I decided to go for it and bought both poly engine and tranny mounts from prothane. Any tips for changing the motor mounts since I know it won't be easy. I'll be doing this tomorrow on my day off.

 

the tranny mount is easy as pie......
and i agree on buying that one as ive broken two ruber tranny mounts in 2 sumers of driveing...and everyone says its real hard to break one of thoes poly ones. Im ganna stick with rubber engine mounts its not worth the effort and price for me to change my good rubber ones.

 

hope you have a helper and a spring compressor for removing the front coil springs. I did mine on a lift with my fathers help. It is a PITA, even with a lift. While I had the coil out I had ordered del-a-lum bushings for the a-arm and painted the a-arm with POR-15 and installed the new bushings. I should have welded the nuts as mentioned above. Still have to do the pass side yet. I am saving that for a week off around thanksgiving. Good luck.

 

I was able to change them without tearing the a arms out, and I know there are others out there who have. it takes some thought and patience and a spare set of hands.

I run the solid mounts, as seen here. they sure make a huge difference....

 

i am running the same ones. i had to take out the a arms to get mine in though. for whatever reason i just had no i dea with changing them with the a arms in.

 

.

 

Moroso, two parts. 62510 and 62610. one is the frame piece, other is for the engine.

 

Did you weld them the rest of the way? My set only has the top semicircle weld'd up... I'm thinking about having it Mig'd the rest of the way around.

 

.

 

if it's just street driven i wouldnt get solid mounts then.

 

racing.

of course theres always some "hardcore" guy with a stripped interior, AC delete, monster cam, running solid mounts on the street.. (and usually a 14 sec quarter )


for performance street, go Poly.... or stock rubber replacement. if you really get worried about engine movment when you get on it, add a strap to the motor.... that should let you have the vibration resistance on the street, and still hold the motor under load.

 

chris what are you planning on welding. there is only need for two welds and that is where they already are. they is no other place on the mounts that have a seem besides the engine mount holes.

 

I'm talking about welding the pin in each bracket the rest of the way around... if you look closely you will only see a short weld on each side on the top. I don't think my welds even went all the way around the pin. I was saying I was thinking about having them migg'd up the rest of the way.

 

I hadn't noticed that before, but it seems like a good idea...

 

mine are welded all the way around.

 

Mine weren't. Guess that's what I get for spending a good 10 bucks less on them.

 

yeah i checked mine, they are fully welded too

 

i bought E/S poly engine mounts. i put them in the clamshell. the stock 5" long 7/16" wide bolt slops around in them. i called e/s, they tol dme to you 9/16". they don't fit all the way through, neither do 1/2" bolts. not sure what to do here. it seems that the inside of the poly mounts are beveled, as the larger bolts do go in part way, then stop.

 

hhholly Cra@@@p bat man..talk about Bringing back the Dead!!!

 

lol. i did a search first, before i asked