ROG100

Dave,
Brilliant point - I will try and see if they will fit the later cars.
Roger

SharkSkin

danglerb

Engine shocks reduce movement, solid MM have less movement than hydrolic. What gives the glassy feel is allowing some movement, adding shocks would just further reduce the movement of the engine relative to the chassis transmitting more vibration.

SharkSkin

Engine shocks provide some resistance to initial movement, true, but more importantly they damp resonant frequencies -- they were originally fitted to cars with solid motor mounts for this purpose. Resisting movement is a beneficial side effect; the primary purpose as with the hydraulic feature of the later mounts is to act as a damper.

Vilhuer

Threads are there up to '87 S4 at least and even '95 GTS uses same casting.

Can't remember off hand if later style rear subframes have mounting points for '78 MY gearbox shocks. These were deleted when battery box was changed to be part of the body and one of two gearbox mounts got bigger. They might be useful in later cars also. Not sure about PSD boxes but I think at least all earlier transmissions have mounting points for shock mounts in casing. Also without threads.

Anyone know what parts transmission shocks need to mount into rear subframe. PET only shows locking nut but I suspect something else is also needs. Maybe couple of washers and some rubber in between.

heinrich

Gentlemen, my solid mounts are just as smooth as stock, and have lasted 7 years. There is no perceptible difference.

ROG100

H,
Don't spoil the fun - I was looking forward to putting Koni adjustable shocks on my engine.
Now should I go for external or internal adjustment???
Now that is a really good question.

heinrich

LMFAO Rog ....

SharkSkin

H, the later solid mounts may isolate better than the early ones. I could tell the difference between having one engine shock vs having two on my car.

heinrich

Dave I think that's exactly it, you're right!!

83 onward:

78-82:

danglerb

Could be the old engines didn't run as smooth and needed the shocks etc.

My guess is that the extra shocks were a type of "insurance" that Porsche found unnecessary.

In modern cars I think an engine shock is most often used to manage torque, not vibration, thats the way they are mounted for most FWD cars.

Jim bailey - 928 International

Solid rubber ***** bounce , ballons full of liquid do not...the later liquid filled mounts are designed to BOTH support the engine and absorb vibration. Clearly solid rubber mounts are vastly superior to collapsed liquid mounts. Solid rubber mounts use the engine shocks to absorb vibration and more than one rennlister with the old style has commented that the car feels better with new engine shocks. The aftermarket solid rubber mounts are probably "good enough" after all millions of Ford owners use them after all , I have never heard of any of them fitting Porsche liquid mounts !

SharkSkin

A shock will not manage sustained torque -- it is only effective during a change in position along the axis of the shock's travel. This is the same as in the case of a shock used for suspension. Leaving the effects of differently-pressurized gas shocks aside for a moment, a shock that is twice as stiff as stock will not reduce the ultimate degree of body roll in a long corner; it will serve to slow the transition of the body from level to the full amount of roll but it is only the springs and swaybars that determine the ultimate extent of body roll.

Similarly, with a FWD car having a shock on the engine mount, the shock will not have any effect on how far the engine moves with sustained torque applied; it will only slow the movement to that position. The deflection of a FWD engine like you describe will be exactly the same with or without the shock, once the torque has been applied for a second or so.

Shocks resist transient movement, they have no effect on the ultimate deflection when the force is applied for sufficient duration.

heinrich

Just for my own clarification: There are solid and liquid-filled mounts for ALL years, right?

danglerb

Some balloons full of liquid bounce very nicely, but its not the liquid, its the compliance of the walls. Hydrolic shocks aren't balloons, and they aren't "full" of liquid, they slosh, which means they have some air that can squish.

What sort of forces do the mounts have to deal with on a 928?

Is it it just engine vibration, or is it also torque related?



**** edit, I typed hydrolic shocks, but meant hydrolic MM above.