Exactly. Poly mounts with 2 dogbones would be overkill I think. You could solid mount the 3.4dohc, its such a smooth engine you would hardly notice it.

[This message has been edited by crzyone (edited 07-26-2005).]

well the stock mounting points for the 2.8 and the 3.4tdc couldn't be more different. It is like they are mirror imaged exactly. That puts the stock 3.4 dogbone pretty much directly above the (single) trans mount in a stock Z34 setup. I guess that is where they didn't want flex so that is the reason for that location. Makes sense.

The stock 2.8 has the dogbone pretty much in line wiht IT"S single mount near the front (what I call the pogo-stick mount) as that is where THAT engine can move the most so they put the dogbone in a plane (?) with that flimsy front mount. That makes sense to me too, just that I can't help but shake my head at that spindly little front mount.......

The 3.4 tdc has two substantial mounts just behind the front of the engine and then one pretty substantial one under the trans.
The 2.8 does the reverse. I suppose it sort of works out the same as far as TOTAL weight and TOTAL support go but the amount of weight on that wobbly 2.8 front mount can't help but make me shake my head......

That is one reason I decided to replicate the 3.4 mounting points all around AND use the dodge truck engine mounts as well. Still not sure what I will do about the dogbone but I think I will have it somewhere above the single trans mount now if I can find a place to connect to the engine! - which IS a problem.....

And that is what is so great about people sharing their info on this forum too! Even the bad stuff and maybe most importantly the bad stuff. So thanks guys for the info!
gp

quote Originally posted by crzyone: Exactly. Poly mounts with 2 dogbones would be overkill I think. You could solid mount the 3.4dohc, its such a smooth engine you would hardly notice it.

I disagree. Not only do I not think that'd be overkill (that is what I want to do), but the last statement is untrue. In a Z34, with all stock engine mounts, and a poly dogbone, it vibrated. It shook the car at idle. And this was with stock mounts. Solid mounting any motor will make living with it hell on earth, DOHC included.

Furthermore, a test seeing how much you can move it by hand is nothing. I could not move my Z34's engine (Above, new stock mounts and a poly dogbone). I couldn't move it at all, not even a quarter inch. Even with a 3ft prybar, I could barely nudge it. Then on the dyno I was amazed to see it moving the front end of the motor up 1" and back an inch, basically rotating on the back passenger mount. And compared to my red Z34, this was very minor, but still pretty odd.

------------------

quote Originally posted by AaronZ34: I disagree. Not only do I not think that'd be overkill (that is what I want to do), but the last statement is untrue. In a Z34, with all stock engine mounts, and a poly dogbone, it vibrated. It shook the car at idle. And this was with stock mounts. Solid mounting any motor will make living with it hell on earth, DOHC included. Furthermore, a test seeing how much you can move it by hand is nothing. I could not move my Z34's engine (Above, new stock mounts and a poly dogbone). I couldn't move it at all, not even a quarter inch. Even with a 3ft prybar, I could barely nudge it. Then on the dyno I was amazed to see it moving the front end of the motor up 1" and back an inch, basically rotating on the back passenger mount. And compared to my red Z34, this was very minor, but still pretty odd.

now replace those shite rubber stock mounts with poly and i bet it won't move -- right now i have poly trans mounts and poly engine mount, plus a poly front strut by the AC compressor - the intake is only about 1/2" from the sheetmetal U bracket on the trunk that the dogbone normally mounts to - and has not touched it after driving - with no dogbone (granted i haven't driven it that hard just yet, but it doesn't move at all) it also idels pretty smooth with the poly mounts all around

I do plan to add one dog bone but it will be rubber on one end

Yah poly mounts would make it great, but common sense would tell me you'll feel it for sure, but compared to the 2.8 it may still be smoother. Its movement would definately be kept to a minimum though! I think that is the best plan, full poly mounts with dual poly dogbones. Solid serves little purpose IMHO, and will just vibrate to death, and rubber is just too loose.

Darth used those very thin and thus very inflexible Dodge mounts and I doubt that he would have if there was a problem with excess vibration..........
I am putting two of them in mine and they won't allow much movement. (Once I get it running...... )

I am sure they are the same as using poly.

Using those dodge truck mounts is pretty much solid mounting the motor, not much vibration resistance there I still believe solid mounting the motor would be just fine. My N* is being solid mounted, and its a very well balanced motor.

Try Rodney's poly mounts, I think You'll Like them. They do transmit some more vibration, but its just enough to let you know something is back there. But not bad where you cannot see out the rearview. The 3.4 DOHC, is pretty smooth, Its no Inline six. or a counterbalanced 3800, but its better then a Quad 4 HO for vibration. Those mounts have tightened up my engine to more then acceptable levels, where I can chirp second without fear of breaking something. Ive had them for about 7 months, and they are great. I also opted to get the thicker heavier transmission brackets since I twisted and broke the last ones right off the transmission, taking parts of the transmission with it. I'm hoping to continue to use these mounts when the 3.4 DOHC makes its way across the contry and eventually into the back of my car.

rodneys mounts utilize an Energy-Suspension universal mount - it has in internal interlock so they can not pull apart (unlike the rubber dodge truck mounts)

I used rodneys front mount, used a matching energy suspension mount(24$) for the front mount, two poly end links for the front torque strut, and a 1/2" thick dodge truck mount for the rear transmission mount.. since it takes the least abuse and is generally under compression 98% of the time

No matter what material you decide to use for mounts, make sure you have two tranny mounts and two engine mounts, PLUS the dogbone. Its easy enough to use the mount bracket under the A/C compressor to make another mount. That will help limit front to back motion and take some stress off the dogbone and front engine mount. I drove my car with the decklid off to see how the engine moved during WOT acceleration. It would go back towards the trunk about 1/2" or at most an inch.

quote Originally posted by AaronZ34: I disagree. Not only do I not think that'd be overkill (that is what I want to do), but the last statement is untrue. In a Z34, with all stock engine mounts, and a poly dogbone, it vibrated. It shook the car at idle. And this was with stock mounts. Solid mounting any motor will make living with it hell on earth, DOHC included.

The only sign that my motor was running was the exhaust sound. I had rubber engine mounts and a poly dogbone. It did not vibrate. In fact, I could hardly feel any vibration from just putting my hand on the motor while its running. My duke was a monster compared to the 3.4 DOHC!
Many have solid mounted their V8s and I've never heard that it's "hell on earth" to live with.

Just a bump so that I can find this again.