Polyurethane vs Rubber motor mount height

[Bolt]

Here is the comparison of the stock motor mount and the polyurethane motor mount. As you can see the thickness of the polyurethane is less than the rubber motor mount. I also show how much the motor drops at the exhaust location. The exhaust drops about ¾ of and inch. This is not something to be concerned for the driver side but the passenger (right) side may need addressed. As the motor torques the right side will slam down into the frame. This will only happen if you are not using the stock exhaust hangers in this area. There has been posts where some people have fabed up shims to compensate for the polyurethane motor mount thickness. This is a good idea if you wish to keep the motor at the stock height. In my case I have a genII GTS running a Paxton SC set up and the motor sits to high which allows some bracketry and hoses to rub. Lowering the motor with these mounts give me the propper clearances I will need for this SC setup. One other note I wish to mention is that when using the stock rubber mounts you get a left and right side. When purchasing the polyurethane mounts you get only the right side. The right side can be used on both sides. You will have to modify the heat shield on the left side for the clearance of the mechanical lock on the polyurethane mount. There is no issues with the Polyurethane transmision mount. It is the same thickness as stock.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

b

 

[ViperTony]

Wow, that was quick! You'll find that the engine doesn't flex anymore with these mounts so you should be OK but it wouldn't hurt to shim it up a little. Had I thought of it, I would've sent along a couple pieces of steel plates for shims...Also, check your shifter. Make sure you can shift into all gears. A few people reported that after installing all the transmission mount they were unable to hit certain gears. Not a common occurrence but I've heard its happened to a few people. Get it on the road and report back the difference. Enjoy. - Tony

 

[dave6666]

Great pics dude. 3/4" drop seems a little high though, as I've seen pics of the 2 mounts side by side and they only look like 1/4" diff in thickness. It does however look that way on the pass side where the exhaust exits the frame - 3/4" drop.

 

[Bolt]

Thank you for the pointer on the shifter. I'll check it out.

I'm not going to shim these mounts up. I'm going to pull off the exhaust and notch the exhaust in the frame area a tad bit more. I really need the clearances around the SC.

Thank you Tony for the mounts. As you can see I needed them immediately

 

[Bolt]

Great pics dude. 3/4" drop seems a little high though, as I've seen pics of the 2 mounts side by side and they only look like 1/4" diff in thickness. It does however look that way on the pass side where the exhaust exits the frame - 3/4" drop.

Keep in mind there may only be 1/4 inch difference like it shows in the picture but when this 1/4 is on an angle and on both sides you get more than 1/4 drop. It's basic geometry. I'm not sure exactly how much it will drop. Maybe someone in here would like to do the math.

 

[dave6666]

Keep in mind there may only be 1/4 inch difference like it shows in the picture but when this 1/4 is on an angle and on both sides you get more than 1/4 drop. It's basic geometry. I'm not sure exactly how much it will drop. Maybe someone in here would like to do the math.

Hate to spoil your basic geometry skills, but dropping 1/4 inch on a 45 deg angle drops vertically 0.177"

You must be registered for see images

 

[Bolt]

I stand corrected. Thank you!

 

[EllowViper]

The Woodhouse mounts do not drop the engine into the frame like described with the Poly mounts. Costs upwards of $300.00, but has an OEM fitment. Good info on the poly mounts. I almost bought them.

 

[Bolt]

I got this to work. I shimmed the passenger side by 1/4 inch. This gave me the clearance I needed at the frame and exhaust. I did not shim the drivers side. This allowed clearance I needed around the brackets for the Paxton Super Charger. Yes the engine is tilted but nobody will be able to tell. It is so little that you can not see this by eye.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

b

 

[GR8_ASP]

Dave6666 I think you better check your math skills. If the shim is 1/4 inch thick and the mount is at an angle the drop is more than .25 not less.

 

[SNKEBIT]

Dave6666 I think you better check your math skills. If the shim is 1/4 inch thick and the mount is at an angle the drop is more than .25 not less.

I agree. Done many shim and unshim jobs, 1/4 inch shorter is alot of drop at an angle.

 

[dave6666]

Dave6666 I think you better check your math skills. If the shim is 1/4 inch thick and the mount is at an angle the drop is more than .25 not less.

I did not use math. I used AutoCAD. And sorry, but the farther you rotate from horizontal, the less drop there is.

What would the difference be with both of them rotated 90 degrees?

ZERO difference.

They are pointing at each other then, and thickness is irrelevant.

I have a mathematically and geometrically correct drawing posted.

Post one of your formula.

 

[GR8_ASP]

Sorry I am just a lowly engineer. If the mount is vertical it would be exactly .25 inch. And rotation from there increase the distance. At 90 degrees it is infinite as the mount would never contact. The drop would be 1/sin 45 if at a 45. That is .25/.707=.35

For your autocad program remember there are 2 mounts and the engine centerline should not move to the side.

 

[ViperTony]

I did not use math. I used AutoCAD. And sorry, but the farther you rotate from horizontal, the less drop there is.

What would the difference be with both of them rotated 90 degrees?

ZERO difference.

They are pointing at each other then, and thickness is irrelevant.

I have a mathematically and geometrically correct drawing posted.

Post one of your formula.

Your illustration makes an assumption that the engine was level to begin with. Apparently its not level if it's already pitching to one side before the new mounts were installed. Bolt probably already had 1/2" pitch toward the passenger side based on his dimple in the exhaust pipe. And Bolt may be measure the difference from within that dimple rather than the part of the pipe closest to the frame. That may skew his number a bit. Just a thought.

 

[viper spray]

Mine all bolted up just fine........

 

[Catwood]

Man I hate projects that make more projects. I bought mine mounts from woodhouse, bolted them in and everything is the correct height.

 

[Bolt]

Before this topic runs array. I'm very happy with my mounts and I'm especialy happy that they are thinner than stock. This gave me room to tweek my setup. I was also told to check my shifter. Guess in some cases with drop the shifter is an issue. I have not checked that yet.

I like projects! And like to read about others!

 

[Jim Wilson]

I did not use math. I used AutoCAD. And sorry, but the farther you rotate from horizontal, the less drop there is.

What would the difference be with both of them rotated 90 degrees?

ZERO difference.

They are pointing at each other then, and thickness is irrelevant.

I have a mathematically and geometrically correct drawing posted.

Post one of your formula.

Dave, you need to go back and read your basic geometry text book. The difference in vertical height is the hypotenuse of the triangle therefore it is the greatest length(i.e. longer than the two components of said triangle).

As GR8 ASP stated, the centerline does not move; therefore, your ACAD illistration is irrelevant.

 

[Disturbed]

I'll need to check mine as I heard the exhaust moving after the poly motor/trans mount install.

 

[Bolt]

I'll need to check mine as I heard the exhaust moving after the poly motor/trans mount install.

Cool!! Let us know if you find anything. I don get as much vibration as I hear others reporting. I wonder if their vibrations are from the binding of the exhaust and not allowing the polymounts the flexing they are designed for. Hence having a solid motor to the frame. Polymount should go back and correct the thickness.

 

[ViperTony]

There's a 4 or 5 part series on motor mounts in the illustrated section. A generous VCA member did some interesting write ups on the matter and I heard there's even pic of the 3 mounts next to each (OEM, Poly and Woodhouse) so you can guage the difference in thickness.