Poly Transmission Mount Question

[Jack B]

I bought the poly transmission mounts from someone on the forum about a year ago. I just tried to put them on. These are the mounts that have the preload plate on the top side. These have a GM kit number. They would not work on my car (97 GTS). They raise the back of the transmission approximately 1/2". The transmission cannot be raised this 1/2" because the top hits the console at about 1/4" above the stock height.

I know our cars are all a bit different, but, has anyone experienced this issue and if so what was the work-around.

 

[Purdue_Boiler_Viper]

I got Dave's mount. I had the same problem with the spacer, but not quite as bad. I was hearing strange transmission noises, so I took out the spacer. The stackup was the same as stock without the spacer. The noises disappeared, and the feel is very good. Just finished a track day and all was real good.

 

[chimazo]

I used the Energy Suspension piece mentioned on the forum and initially I had the same problem with the shifter hitting. All you need to do is drop the x-member about 1/2". There is room to adjust it. Install the x-member bolts when putting it back in, then pull down on the x-member, then tighten the bolts.

You should use the "spacer" - it is for preload and will fit. I used it on my '98.

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[TexasPettey]

I had a similar issue, but not with the stock shifter. When I installed my short throw shifter, the arm was a bit too tall. It would rub against the fiberglass tunnel in 5th/6th/Reverse pretty hard. I cut out that portion of the tunnel. It has worked fine on the road course.

 

[Purdue_Boiler_Viper]

Maybe someone can explain why we would all need the spacer? If we think of the mount as a spring, the spacer acts to load the spring. But, apparently all Vipers stackup a little differently, so the amount of preload will depend upon your car's stackup. If your car (mine is an 01) is tight, I think you overload the "spring" and raise the transmission if you use the spacer. If your car is loose, the preload spacer would be needed.

I would think that we should measure the old stackup and use / don't use the spacer to recreate the OEM spacing. Why mess around adjusting the cross member when you can just leave out the spacer?

Anyone else have thoughts?

 

[dave6666]

Anyone else have thoughts?

The preload is an internal condition of the urethane mount. It has nothing to do with which car, or how your car was built compared to others.

By squeezing the mount using the preload plate, you are compressing the urethane elastomer and changing its spring rate. Preloading it. Without the preload the spring rate will be softer.

It likely does not affect the structural durability of the mount to leave the preload plate out.

 

[ViperTony]

The preload is an internal condition of the urethane mount. It has nothing to do with which car, or how your car was built compared to others.

By squeezing the mount using the preload plate, you are compressing the urethane elastomer and changing its spring rate. Preloading it. Without the preload the spring rate will be softer.

It likely does not affect the structural durability of the mount to leave the preload plate out.

That's how it was explained to me and I tried it with and without the pre-load plate. I decided to keep the pre-load plate since the instructions state the plate is required. I don't have any issues with the shifter being too high or hitting things and there's no noise whatsoever. I'm using the SVS short throw shifter. In fact, the shifter does rattle even the slightest bit. Amazing improvement. I haven't missed any 3rd gear shifts since installing the mounts.

 

[Purdue_Boiler_Viper]

The preload is an internal condition of the urethane mount. It has nothing to do with which car, or how your car was built compared to others.

By squeezing the mount using the preload plate, you are compressing the urethane elastomer and changing its spring rate. Preloading it. Without the preload the spring rate will be softer.

It likely does not affect the structural durability of the mount to leave the preload plate out.

Agree with the last part about what preloading is, how the spacer accomplishes that, etc. But, don't agree with the first part, i.e. that is has nothing to do with which car...

All the spacer is is a piece of metal of a given thickness. Assuming that we are trying to achieve a given spring rate, and that spring rate is accomplished by a given compression of the mount, then shouldn't we all be trying to achieve the same compression? If the stackup of one car is 1/8th inch different than the next car, the compression will be different and hence the preload will be different.

All of this assumes that we are indeed compressing the mount with the spacer. Excuse my ignorance, but doesn't the transmission just sit on the mount? If that is the case, then the only force compressing the mount is the weight of the transmission caused by gravity. The spacer would not change that compression or the spring rate. In that case, the spacer is only a spacer, and would be used only if your stackup was low and you wanted to raise the transmission.

Help me out guys! This has been bugging me since my install.

 

[dave6666]

Agree with the last part about what preloading is, how the spacer accomplishes that, etc. But, don't agree with the first part, i.e. that is has nothing to do with which car...

All the spacer is is a piece of metal of a given thickness. Assuming that we are trying to achieve a given spring rate, and that spring rate is accomplished by a given compression of the mount, then shouldn't we all be trying to achieve the same compression? If the stackup of one car is 1/8th inch different than the next car, the compression will be different and hence the preload will be different.

All of this assumes that we are indeed compressing the mount with the spacer. Excuse my ignorance, but doesn't the transmission just sit on the mount? If that is the case, then the only force compressing the mount is the weight of the transmission caused by gravity. The spacer would not change that compression or the spring rate. In that case, the spacer is only a spacer, and would be used only if your stackup was low and you wanted to raise the transmission.

Help me out guys! This has been bugging me since my install.

The plate is not a spacer. It is a metal plate, who's thickness is determined by the thickness needed to preload the elastomer mount, without deforming or bending the plate.

By pressing that metal plate against the red urethane, you are as I stated altering the spring rate of that part. Making it more rigid if you will. Whomever designed that mount intended it to be that way.

You can continue to believe that this mount is unique from vehicle to vehicle, and that the plate is to adapt the mount to the variation of different vehicles. However, what is fixed in design and dimension is the mount. The vehicles are unique. When you leave out the preload plate you alter the design of the mount to fit your unique vehicle. Which you are more than welcome to do. It's your car.

It amazes me that someone will put in an aftermarket shifter that is of noticeably higher mount height, and then blame the tranny mount for their fitment issues in the tranny tunnel.

I used the preload plate in my '01 GTS.

Finally, if the mounting point of the transmission tail to the mount is essentially as flat as the plate is, then leaving the plate out has no effect whatsoever. The tranny then preloads the red urethane.

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[0209 CLK]

I know this is a newbie question but is there a difference between the red and black poly urethane mount or is it just 2 different companies with different color?

 

[ViperTony]

Agree with the last part about what preloading is, how the spacer accomplishes that, etc. But, don't agree with the first part, i.e. that is has nothing to do with which car...

All the spacer is is a piece of metal of a given thickness. Assuming that we are trying to achieve a given spring rate, and that spring rate is accomplished by a given compression of the mount, then shouldn't we all be trying to achieve the same compression? If the stackup of one car is 1/8th inch different than the next car, the compression will be different and hence the preload will be different.

All of this assumes that we are indeed compressing the mount with the spacer. Excuse my ignorance, but doesn't the transmission just sit on the mount? If that is the case, then the only force compressing the mount is the weight of the transmission caused by gravity. The spacer would not change that compression or the spring rate. In that case, the spacer is only a spacer, and would be used only if your stackup was low and you wanted to raise the transmission.

Help me out guys! This has been bugging me since my install.

it's not a spacer and the energy suspension instructions reference it as a pre-load plate. If you notice the stock OEM transmission mount sits flat against the transmission mount location. The poly mount won't sit flush against the transmission without the pre-load plate. There would be no pre-load without the plate or at least not as much pre-load as the pre-load plate provides. At the end of the day, the energy suspension instructions states that the pre-load plate must be used. You could call Energy Suspension and see what kind tech advice they give you. Here's the reference to the instructions: http://www.energysuspension.com/pdf_instruc/17112.PDF

 

[ViperTony]

I know this is a newbie question but is there a difference between the red and black poly urethane mount or is it just 2 different companies with different color?

The Energy Suspension site has a Tech Q&A post on this. It states that both the Black and Red mounts are made from the same HyperFlex Polyurethane but the black has a graphite impregnated into it for lubrication. Not sure what that means but maybe Dave can chime in.

 

[Dave's Big Brakes]

The Energy Suspension site has a Tech Q&A post on this. It states that both the Black and Red mounts are made from the same HyperFlex Polyurethane but the black has a graphite impregnated into it for lubrication. Not sure what that means but maybe Dave can chime in.

Hey Tony,

They use the black as control arm & sway bar bushings, that's why the lube.

Big Brake Dave

 

[Jack B]

The plate is not a spacer. It is a metal plate, who's thickness is determined by the thickness needed to preload the elastomer mount, without deforming or bending the plate.

By pressing that metal plate against the red urethane, you are as I stated altering the spring rate of that part. Making it more rigid if you will. Whomever designed that mount intended it to be that way.

You can continue to believe that this mount is unique from vehicle to vehicle, and that the plate is to adapt the mount to the variation of different vehicles. However, what is fixed in design and dimension is the mount. The vehicles are unique. When you leave out the preload plate you alter the design of the mount to fit your unique vehicle. Which you are more than welcome to do. It's your car.

It amazes me that someone will put in an aftermarket shifter that is of noticeably higher mount height, and then blame the tranny mount for their fitment issues in the tranny tunnel.

I used the preload plate in my '01 GTS.

Finally, if the mounting point of the transmission tail to the mount is essentially as flat as the plate is, then leaving the plate out has no effect whatsoever. The tranny then preloads the red urethane.

You must be registered for see images

Mine is hitting on the top of the trans where it has nothing to do with the shifter. I don't think the SVS is any "taller", if anything the cap bolt on the vertical arm brings the head of the bolt further to the right and it hits the console in the ashtray area - that is a separate issue and has nothing to do with the mount.

 

[Jack B]

I used the Energy Suspension piece mentioned on the forum and initially I had the same problem with the shifter hitting. All you need to do is drop the x-member about 1/2". There is room to adjust it. Install the x-member bolts when putting it back in, then pull down on the x-member, then tighten the bolts.

You should use the "spacer" - it is for preload and will fit. I used it on my '98.

You must be registered for see images

did you cut the bracket and reweld it?

 

[chimazo]

No cutting involved, just a lot of cursing initially. I installed the poly mount at the same time I installed the B&M shifter. I first assembled the crossmember all the way "up," but once I tried shifting the car (while still in the air, fortunately for me), I had trouble putting it into third. I had two choices - either try and get up into the trans **** and grind away, or see if there was any adjustability within the assembly. If you put the crossmember in with the bolts (untightened), you can pull it down, so to speak, then tighten everything up and have adequate clearance for the shifter to work without rubbing. No rattles, either.
Hope this made sense!

 

[ViperTony]

No cutting involved, just a lot of cursing initially. I installed the poly mount at the same time I installed the B&M shifter. I first assembled the crossmember all the way "up," but once I tried shifting the car (while still in the air, fortunately for me), I had trouble putting it into third. I had two choices - either try and get up into the trans **** and grind away, or see if there was any adjustability within the assembly. If you put the crossmember in with the bolts (untightened), you can pull it down, so to speak, then tighten everything up and have adequate clearance for the shifter to work without rubbing. No rattles, either.
Hope this made sense!

It does make sense. I do recall that the stock xmember could be moved up/down a bit which may be enough to clear he height issue. I have Dave's billet transmission xmember installed and the bolt holes don't have any 'play' but gave me no issue with clearance.