-URETHANE ENGINE/TRANSMISSION MOUNTS-

September 7, 2001.

While taking out my engine and transmission for the second time, I decided to "upgrade" my drivetrain mounts.  Because the stock mounts are made out of rubber, they become less resistant to flexing over time.  AE82s are at least fifteen years old, and even lower mileage cars at this age suffer from rubber softening.  However, by using urethane, the mounts will become quite a lot stiffer than a new car.  I will talk about derivability later.  Let's see how it is done:

1. PARTS

80 Shore A Durometer - 1 lb. resin/hardener  (p/n 8644K11 from McMaster-Carr)
As many engine mounts you want to apply this to
Duct tape (masking tape would work too)
Bucket
Sand

II.  PROCEDURE

3 of the 4 mounts have holes allowing urethane to seep from the side being poured upon to the underside (that has tape on it).  For the 1 mount that does not have this property, I simply drilled 3-4 holes to allow the urethane to flow to both sides.  Use a larger bit than instincts tell you to because the rubber likes to deform during drilling, and make the hole a lot smaller than you want it to be.  Be safe though, and always start off with a smaller bit.

Tape the underside of each mount and sink each mount into the sand.  The sand's purpose is to hold the tape to the mounts and not allow any urethane to seep through.  Now mix the urethane according to the instructions.  However, since the urethane is supposed to be mixed by weight, I found that following Hess' advice of having a mixture of 2:1 (by volume) much easier to mix.  Simply pour in the mixture and allow to sit.  Don't worry if you get urethane on the sids or on the sand, it is easy to remove (in most places).

After waiting at least a day (I waited 48 hours), remove the tape, and you will have 4 urethane mounts ready to go that cost you under $30 to make, while other people are buying these mounts upwards of $150!
 
 

Before Urethane

With Urethane Poured In

Bucket #1

Bucket #2

III.  COMMENTS

I really liked the stiffness found with using urethane.  It makes everything feel "tighter".  Throttle response is indeed better with stiff mounts.  The first couple miles will feel quite stiff, and a lot of engine vibrations will be transfered into the chassis, especially during idle.  However, after 400-500 miles of breaking in, everything becomes a lot smoother.  An analogy would be going from stock tires to lower profile tires.  They do transmit more vibrations, but the general feel of the car is greatly enhanced.

References:  Dr. Hess' homepage