Solid Tranny Mount

90mustangGT · Aug 8, 2005

I ordered one today along with solid mounts but did a search and some people are saying that you'll crack the tranny due to chassis flex. No one had seemed to have any personal experience, just what they had "heard". Anyone with first hand experience?

ram360 · Aug 8, 2005

No first hand experience w/ solid mounts all around but I do know some people go w/ solid mounts for the motor and go w/ something like an energy suspension mount for the trans.

Mustang5L5 · Aug 8, 2005

If you are gonne run solid mounts, you need to run all 3 mounts. If you run a solid trans mount with rubber engine mounts you will def crack something.

90mustangGT · Aug 8, 2005

Mustang5L5, that makes the most sence.

How I figure is that when you add a solid mount, that of course does not have any give, when a shock goes throught the drivetrain, it won't be as easily absorbed into the mount, the energy has to go somewhere. On the other side, having a tranny that stays perfectly in line prevents the movement of driveline components preventing other stresses.\

I ordered all three mounts from Maximum Motorsports, both motor and the tranny, they called on the tranny mount being a reason for breaking anything. "Internet Legends"

90mustangGT · Aug 12, 2005

Different day... different crowd....

I got the Maximum Motorsports Solid Mounts today, all three. Definatly nice peices. I guess I'll just have to find out. Will post pics tomorow if people request.

306stroker · Aug 13, 2005

go with the solid motor mounts and a poly trand mount the best way, i have all the solids now and im changing over to a poly trans mount tomarrow from energy susp. i was told to do this through from a local speed shop it will give me less vibration which is really bad now and i mean BAD

ratrapp2 · Aug 13, 2005

on my old 68 nova sb car i ran all solid mounts.after i race season i cracked the th-350 case on my car.the internals were fine.i didn't realize the case was cracked until i removed the tranny and the case where it bolts to the bellhousing fell off in two pieces.i later converted to a urethane tranny mount and no more tranny case problems.

85_SS_302_Coupe · Aug 13, 2005

The problem with solid trany mounts is that if you run them with solid motor mounts, SOMETHING is going to flex SOMEWHERE, and it's most commonly right around where the trany mounts are bolted up, and it's most commonly in the form of cracking/busting them off. Maximum Motorsports might sell them, but they probably sell them more for their open track/autox crowd than for drag racing, since there arent any hard launches and the trany will see much less abuse.

I can't say i've used solids myself, but just from reading and from people i've known who run them, DO NOT run both, and just out of a hunch i wouldnt run just a solid trany mount either, as it would seem to me that the engine would flex even more in the engine mounts. I'd run solid motor mounts and an Energy Suspension urathane trany mount.

89MustangGX · Aug 13, 2005

I bought all three MM mounts myself, and went back and forth over this and eventually decided to use a rubber mount.

My arguments were 1) any flex would be taken up by the x-member bushings if it does have to flex, and 2) why would the tranny flex more than the engine -- seemsl ike they flex the ame and no breakage.

In the end, enough people beat me into submission and I am not running all solids.

90mustangGT · Aug 13, 2005

I have the poly mounts as well, I might run the poly tranny mount, but I am definatly going with the solid engine mounts. I'll probally run one then swap to the other and then make the decision from there. Anyways, they are some nice looking pieces. Here's a pic:

85_SS_302_Coupe · Aug 13, 2005

89MustangGX said:
I bought all three MM mounts myself, and went back and forth over this and eventually decided to use a rubber mount.

My arguments were 1) any flex would be taken up by the x-member bushings if it does have to flex, and 2) why would the tranny flex more than the engine -- seemsl ike they flex the ame and no breakage.

In the end, enough people beat me into submission and I am not running all solids.

It flexes pretty much everywhere, because the frame itself and the body of the car flexes, so if the motor is bolted solid in one section of the frame, and the trany is bolted solid to another section of unibody, and the two flex in opposite directions well enough, something is going to break, and i don't think the xmember bushings are anywhere near sufficient enough to absorb the average 300ft/lbs of torque that the typical 302 is puting out, let alone a warmed over/bolt on 302 that's making big numbers. The urithane bushings arent as stiff as rubber, but they absorb more without being squishy, and they last longer than rubber.

89MustangGX · Aug 13, 2005

85_SS_302_Coupe said:
It flexes pretty much everywhere, because the frame itself and the body of the car flexes, so if the motor is bolted solid in one section of the frame, and the trany is bolted solid to another section of unibody, and the two flex in opposite directions well enough, something is going to break, and i don't think the xmember bushings are anywhere near sufficient enough to absorb the average 300ft/lbs of torque that the typical 302 is puting out, let alone a warmed over/bolt on 302 that's making big numbers. The urithane bushings arent as stiff as rubber, but they absorb more without being squishy, and they last longer than rubber.

Not that I'm still debating, but I've heard this before as well.

My thoughts about this were that if you go with this theory, then it sounds like saying the unibody flexes more than the engine and transmission under load -- so put rubber mounts in and it could be completely out of control -- all over the place between the flexing unibody and loose mounts.

Now throw subframe connectors into the mix -- does that change things? How about a roll bar? Roll cage?

Like I said - I gave up and decided any potential benefit wasn't worth the risk of a tranny, so I am not running the solid tranny mount. I don't know the whole story, but I have mixed feelings on the subject.

90mustangGT · Aug 13, 2005

I have MM full length subframes, and I will probally run a cage soon. I shoudn't have flex through the tunnel, more on the outside if any.

The tranny case is another component that can break, with or without solid or rubber mounts. I think it is kind of like the solid/sperical rear controll arm bushings and/or lift bar LCA's controversy, where there being no give in the bushings resulting in extra stress in the torque boxes.

89MustangGX · Aug 13, 2005

90mustangGT said:
I think it is kind of like the solid/sperical rear controll arm bushings and/or lift bar LCA's controversy, where there being no give in the bushings resulting in extra stress in the torque boxes.

...just to throw a little more fuel on the fire, how about this: spherical bushings simply transmit everthing through them, past the boxes that are solid, and into the frame somewhere. Rubber bushings that allow the control arms to move around in the torque boxes hit the boxes harder, since they are the first solid thing after the rubber bushings and they are actually getting hit now by any movement.

I can see this one going either way as well...

I don't have any real answers -- only what's been relayed to me and my thoughts on things. There are plenty of peopel who make these things work no matter which way they go. I think the only right thing to do is do your own research, talk to people, and decie how much (if any) you are willing to risk by going to a more race-oriented setup.

90mustangGT · Aug 13, 2005

89MustangGX said:
...just to throw a little more fuel on the fire, how about this: spherical bushings simply transmit everthing through them, past the boxes that are solid, and into the frame somewhere. Rubber bushings that allow the control arms to move around in the torque boxes hit the boxes harder, since they are the first solid thing after the rubber bushings and they are actually getting hit now by any movement.

I can see this one going either way as well...

I don't have any real answers -- only what's been relayed to me and my thoughts on things. There are plenty of peopel who make these things work no matter which way they go. I think the only right thing to do is do your own research, talk to people, and decie how much (if any) you are willing to risk by going to a more race-oriented setup.

That's fuel for the fire no doubt. Good point. A rubber mount vs. a solid mount could work the same, only backwards. The car launches, chaissis is alowed to flex feely and then the mount is at it's limit it either rips or puts the same if not more stess on the tranny. Or another tranny buster (usually the tail shaft), where the flex causes a mis-alignment, causing stess on the tranny as well as the driveshaft. Maby this wouldn't be enogh to cause brakage, but I am no expert.

85_SS_302_Coupe · Aug 13, 2005

90mustangGX,

I definately see what you're saying. Maybe it's more that the sudden "impact" of all that torque at once is enough to shock the drivetrain hard enough that the frame/unibody actually DOESNT flex, and without the rubber mounts to absorb the shock, that's where the breakage would occur? I have no personal experience with breaks, but my logic just seems that it would eventually break the weakest link, and that HAS to be the trany mount, since the trany itself has a solid mount to the engine block, and solid motor mounts arent going to break before the trany mount "ears" do. I'm not so much trying to debate anything, this is just interesting to see different points of view. Like you said it's really down to the user to decide anyways.

Solid Tranny Mount

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