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Lets talk motor mounts - solid or standard

M

Mudzer

1/2 ton status
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Missouri
I went to a swap meet this past weekend and purchased a set of solid motor mounts. I am thinking about installing these on the S-TON frame and using bushings on the T-Case to take up some of the frame flex. I had considered running solid all the way though, but dont want to bust my Trans case as a result of frame flex.

Give me your thoughts if you've done this or considered this.
 
Its my understanding that if you flex the t case but not the engine you end up breaking the transmission bell housing or the t case adapter. I dont have any first hand experience with this though. I have used poly engine and t case mounts without any problems though /forums/images/graemlins/thumb.gif
 
Dont use em if you have any frame flex. Poly or rubber ones work better. You must run solid trans mounts if you run solid motor mounts or there will be breakage.
 
You could switch to a single point case mount. That would give you a 3 point mount so there would be no way for frame flex to affect it.
 
How would you go about that? /forums/images/graemlins/ears.gif
 
My Doubler has a foot on the bottom with 2 bolt holes within 4" of each other.

I have a mid plate out of a drag car I had. What are your thoughts on using one of these as well?

What Im getting at - I have the factory replacement motor mounts and have a crossmember thats bushed on the ends, plus I run the doubler foot bolts real loose. I was afraid of busting the case so this way has sufficed for a year without problems. Now, I want to go just the opposite direction and solid mount the motor and cases because I don't like how the shifters jumped around in different situations.
 
Blazer Guy:
Basically, it would be a plate bolted to the stock holes with tabs hanging down pierced parallel to the frame rails. That would set down over a cross member and a bolt would pass through, mounted in double shear. Then the case could rock with the twist of the front motor mounts with no stress on the case from frame twisting causing the case cross member to move into a different plane. Basically, 3 points define a plane. 4 is one too many and means that if any one point moves off the plane, something has to twist. Think about a 3 leg stool, never rocks. But a 4 leg will rock if not on a flat surface. Dramatic over simplification, but that is the basics...

However, there have been recent discussions about the effect of Newtonian Action/Reaction due to torque multiplications. This setup would do nothing to deal with that force... Assuming that the effect is as stated in the previous thread (I'm still trying to resolve it with my observed results) then a significant, tortionally rigid brace would need to tie the case to the engine block.

Neil:
I wouldn't use a mid mount. I think that for the forces seen by a 4WD that any solution (that I can see) involving a mid plate would cause more problems for the trans case longevity.

As for shifters jumping, forcing the engine to follow front frame twist, and the trans/case being forced to follow that, you will likely get even more movement with a 3 point or any setup with a rigid motor mount. Not sure what the best solution for cable flop would be other than maybe a cable shifter setup.
 
OT
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I went to a swap meet this past weekend

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Find anything else cool? I didn't go cause I'm broke and don't really need anything.
 
dont solid mounts result in a lot of vibration though!? im not sure what all the pros and cons are to it but i rode in a guys G-20 that he converted to 4x4 in our club, and he had solid mounts on his engine and that thing vibrated like nuts! i dont think i could stand it..
 
I'm looking into putting in the ORD/AutoFab semi solid mounts.. They uses poly bushings for the engine mounting bolt... I have also installed poly tranny bushings.. During a run in March when I flexed my truck my fan blades (which are 1/2" from the shroud at stan still) were hitting my shroud. I believe this will help the flex /forums/images/graemlins/dunno.gif or not?
 
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Dont use em if you have any frame flex. Poly or rubber ones work better. You must run solid trans mounts if you run solid motor mounts or there will be breakage.

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I believe the exact opposite is true. If you run solid motor mounts I think you're supposed to run a rubber or poly trans mount so that there can be some flex somewhere.

I have never seen a manufacturer recommend solid everywhere. I've seen it done with sucess in a car, but I believe that to be the wrong idea.
 
I am using the ORD/Autofab syle motor mounts and hanging my doubler from the top. I used Steves Poly. pucks that he sends for mounting the doubler with the feet on the bottom except mine now hangs from them. I am not running a transmission mount at all and so far have been succesful.

I am a beliver that your mounting stiffness between the engine and trans need to be near equall wtih the motor mounts always being slightly stiffer.
The motor is what creates the most torque and sends it thru the rest of the drivetrain. The transmission and transfercase do create torque loads but they are not as significant as the motors. Control the motor torque, hold the transmision and transfercase up with like stiffness mounts and let the drivetrain work together.
One thing to always make sure of is the tightness all bolts holding the drivetrain to each other. Beck broke the back off of his transmission due to loose adapter bolts and a large torque input from the front end. Front tires in the air resulting in twisted splines on his front driveshaft, grenaded CV joint, to somehow broken transmission.

This is just my .02. I think that if you hold the transmission or transfercase from the torque reaction more than the motor the amount of torque that the motor can apply will break adapters or transmissions.
 
I have got the Energy Suspension poly inserts and the Daystar tranny mount...Worksgreat even when I REALLY load it up it doesn't move around too much

Chris
 
A lot of race applications use solid everywhere. After looking back through my catalog running a poly trans mount with a solid motor mount is prefered. I couldnt imagine trying to run solid mounts in a wheelin rig unless it had a FULL cage with very little frame movement.

As far as a fan making contact with the shroud....Its probably more of a body movement issue then anything else.
 
I heard an interesting tidbit from walker evans last week. I think his quote was "I've solid mounted the drivetrain in everything I've ever driven". Obviously if your frame flexes around this is a problem but if you're frame flexes much, that's a problem to solve in itself. A vehicle fabricated to this level should have a stiff frame.
Keep in mind that the transfer case unit (in this case a 203\205) will try to twist itself relative to the trans when you're using low gears in the T-cases. I think if you had a pivot type mount under the cases, you would twist the trans housing right off. I vote for using all the same mount, if you want to try solid, solid mount the whole thing. Just make sure you cage it front to rear. Personally, I've had good results from using the same bushing assemblies to mount the motor and t-cases and keeping them approximately the same mounting width but with the rear mount slightly narrower. I think if this setup was a problem I'd have torn it up by now.
 
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Obviously if your frame flexes around this is a problem but if you're frame flexes much, that's a problem to solve in itself. A vehicle fabricated to this level should have a stiff frame.

I vote for using all the same mount, if you want to try solid, solid mount the whole thing. Just make sure you cage it front to rear.

I think if this setup was a problem I'd have torn it up by now.

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Wow, typically you're the last person I'd disagree with, but I think you're WAY off with this post.

1. Frame flex is not a problem. Frames are designed to flex. If it doesn't flex, it's going to crack. I personally would rather have flex myself. For your rig you can choose cracking if you so desire. To say that a rig fabricated to any point should have a, "Stiff frame" is an opinion and a poor one if you ask me. I guess we'll agree to disagree here.

2. Since frames are designed to flex, solid mounting the whole thing is the wrong answer if you ask me. From an engineering standpoint you're asking cast iron and aluminum to flex and spring back, and that is unacceptable in my opinion.

3. Just because you haven't broken it yet doesn't necessarily make it a good setup, and to try to use that to justify such a setup really just isn't a statement I'd be making at all. Next thing you know, you'll go out next weekend and break everything and all of a sudden you'll be the poster boy for softer mounts.

This is not a flame, simply a disagreement on engineering ideas. Typically you'd be the last person I'd disagree with on such issues, but I believe your points made to be far from reality in this case.
 
Sweeeeet. I find out now that all of the buggys out there will crack out because the are to stiff. /forums/images/graemlins/thinking.gif I am so hosed!

I think where you are getting confused here is that if you are going to stop frame flex you have to stop all of it. If you make the center of the vehicle stiff and the ends limp you will get cracking.

If the whole thing is stiff: Stephens blazer, all buggys, desert race trucks, mount things up solid. These things are made stiff for a reason.

Frame flex is a problem for the offroad community. It can lead to popped rivets, alignment problems for anything drivetrain related, broken drivetrain parts ect.
 
[posthijack]
Branndon, you going out to Las Cruces in May?

[/posthijack]
 
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