Solid mounts. Motor, tranny and diff mounts OH MY

[SATAN]

I have heard that if you run solid mounts anywhere you should start at the engine. Meaning you can do the engine and nothing else or the engine and tranny and not the diff or all three.

I have also heard that you should NEVER do the diff with out the tranny and engine. Like wise with the tranny. Never do the tranny with out doing the engine.

Now, who can explain why this is? OR who can tell me why this is wrong?

[Benedict]

the motor and trans are bolted together solid. Solid mount one and not the other and you may crack/break a solid mount since your other mounts have some range of motion.

Same goes for the diff and x-member since the diff is bolted solid to the x-member.

[homestar]

so if i have poly xmember bushings does the same hold true for not having rubber diff bushings? as in i should probably invest in poly diff bushings or should i not worry about it since poly has at least a little compliance?

[SATAN]

homestar wrote: so if i have poly xmember bushings does the same hold true for not having rubber diff bushings? as in i should probably invest in poly diff bushings or should i not worry about it since poly has at least a little compliance?

Yes, dont worry about it if you have poly mounts. They still allow play. Just far less than rubber.

[rc10ps85]

the motor is what creates all the moving bolt it soild you get the most effect. lock one of the others soild and the motor is still moving.

Pete

[craZed]

SATAN wrote: I have heard that if you run solid mounts anywhere you should start at the engine. Meaning you can do the engine and nothing else or the engine and tranny and not the diff or all three.

I have also heard that you should NEVER do the diff with out the tranny and engine. Like wise with the tranny. Never do the tranny with out doing the engine.

Now, who can explain why this is? OR who can tell me why this is wrong?

That's the first I have heard of it, but it seems to make sence in my mind.
Think of it as wave reflection/absorbtion.
Meaning that if you shoot the loose vibrations towards the solid diff mount, then they will bounce back towards the engine.

[cheezmonta]

Any of the racers I've spoken to about this said solid suspension and poly engine and trans.
Reason being that you want to eliminate any flex from the suspension that isn't directly related to the suspension. However because of the vibration and flex from the engine and trans you want some give.

[G-E]

just to sum up, any mount points attaching a rigid piece should be similar

so the engine and tranny should be uniformly supported, likewise the diff and rear crossmember, as a set....

you don't need to keep both ends of the car the same because the driveshaft does move, it can articulate a little in every direction

[mark86t]

Well I ran OEM motor mounts with aluminum tranny/diff. mounts & subframe bushings. No problems. Then I upgraded to Jason's poly engine mounts. People told me I would have vibrations in the car from all the solid mounts. I also have a roll bar. CAG8OR rode in my Z when he was in town. He said my car rides less harsh than his (he was quite surprised actually) & we have the same 18" wheels/tire aspect ratio, springs & struts. Some time I will have to take a picture of how little room I have between my plenum & strut tower brace (I installed Jason's plenum spacer). They should surely hit when I rev the engine but they don't. Not a mark on the plenum. I like the all solid mounts & have not noticed any harshness. If any of you come to MSA you can ride in my Z to judge for yourself. I highly recommend all solid mounts whether they be poly or aluminum.

[SATAN]

mark86t wrote: I highly recommend all solid mounts whether they be poly or aluminum.

Yeah, but I wouldnt consider a poly mount anywhere near a solid mount.

[mark86t]

I wish I had kept the Z32TT solid aluminum eng. mounts I had for my Z.(can't find those for sale anywhere now) But people scared me into thinking that something would break due to running soild tranny/ diff. mounts & solid subframe bushings with the solid eng. mounts. Oh well, I love Jason's poly eng. mounts. Though I definitely like the solid subframe bushings over the urethane ones. No wheel hop on hard launches.

[SATAN]

mark86t wrote: I wish I had kept the Z32TT solid aluminum eng. mounts I had for my Z.(can't find those for sale anywhere now) But people scared me into thinking that something would break due to running soild tranny/ diff. mounts & solid subframe bushings with the solid eng. mounts. Oh well, I love Jason's poly eng. mounts. Though I definitely like the solid subframe bushings over the urethane ones. No wheel hop on hard launches.

So then with your solid subframe bushings do you have a solid diff mount also like was suggested earlier in the thread or do you have a poly mount or a stock mount?

[mark86t]

SATAN wrote:
So then with your solid subframe bushings do you have a solid diff mount also like was suggested earlier in the thread or do you have a poly mount or a stock mount?

Jason's poly engine mounts
solid aluminum tranny mount
solid aluminum diff. mount
solid aluminum subframe bushings