Homemade Urethane motor mounts

This page shamelessly ripped off from a Nissan SE-R site

The first portion stolen from http://www.geocities.com/CapeCanaveral/Hangar/6160/se-r/mounts.html








This page will tell you how to build heavy duty motor mounts for your Nissan SE-R (or nearly any other front wheel drive car).

Why would you want to do that?

Better throttle response (no "floppy engine" from ON to OFF throttle).
Less strain on the transmission mounts (caused by fatigued stock mounts banging into the stops under hard acceleration)
Save money by doing it yourself!

Why NOT do this?

More vibration / noise under 1500 RPM
Lazy / no free time / too much money in your wallet :)
Date: Wed, 15 Jul 1998 08:36:42 PDT
From: "Bill the arcstarter" 

Subject: Make your own urethane motor mounts - cheap!

Hi guys.
 I'm the guy who made his own solid urethane motor mounts (since I'm too
cheap to pay JWT for theirs).  I've seen a few inquiries about this on
the list.  So - if anyone wants to duplicate my efforts - here's what I

The big trick is finding the urethane resin.  I know of two suppliers.
Grainger's Industrial supply carries a line of "Flexane" (by Devcon)
castable urethanes, although they tend to be rather expensive

The better way is to go through McMaster-Carr at:

McMaster-Carr is a great source for all sorts of odd hardware.  Plus -
they'll sell/ship over the phone to anyone with a credit card!

They carry a generic "flexane equivalent" in two hardnesses:
80 Shore A Durometer - 1lb resin/hardener - p/n 8644K11 ~$19
94 Shore A Durometer - 1lb resin/hardener - p/n 8644K18 ~$19

I've only used the 80 Shore hardness compound.  One pound is more than
enough to fill all three mounts plus the torque strap!

So far I've 'treated' my front torque strap and the driver's side trans
to frame mount.  This weekend I'll do the rear mount.

Remove the offending mount from the car, being careful to support the
engine with something SOLID!  Note that over time most hydraulic jacks
will seep a bit, and will possibly lower the engine too much, damaging
the remaining mounts.  I use an old scissors jack for things like this.

Use duct-tape to seal off one side of the mount.  Place the mount on the
bench with the open areas facing up.  Mix an appropriate amout of resin
according to the instructions.  Wait for it to start to thicken (about
10 minutes) and pour it into the gaps in the mount.
Wait 12-24 hrs and reinstall.  The resin has a working time of ~15
minutes, is basically set up after 3 hrs, and achieves full strength
after 2 days.

Any questions - please ask!  Using this technique you can do the whole
car for about $18 plus time.

I'm not sure if this stuff could be used for making sway bar or control
arm bushings.  Anyone game to try?  You'd have to make some sort of mold
plus a jig to keep the steel bushing pivot tubes (where the bolt goes)
properly aligned within the arm, etc...  You'd also want to use the 94
durometer compound.

Some people use these urethane resins to re-create door moldings and
various other rubber parts for classic/antique cars...

- -Bill
'92 Classic

Frequently Asked Questions

Q) Is it expensive?

No, only about $20.

Q) Do I remove the rubber from the stock mounts before pouring in the resin?

No. Just pour the resin into the holes in the stock mounts.

Q) How do I mix it?

The instructions say to mix the 80 durometer componds by weight. However, I don't have a scale so I mixed by volume. I used two parts resin and one part hardener with good results.

Q) Are there any other resins etc which would work?

I'm told that Eastwood sells a rubber resin used for making reproduciton car parts:
The Eastwood stuff is a rubber casting material...the application they show is
casting replacment parts like pedals...probably about the same stiffness...
More than that - I cannot say.

- Stolen from http://www.abraxis.com/jays/hd_mounts.htm

February 99 - Well after lots more testing, I want to make some changes in my original recommendations. 1st, I would go with the Devcon Flexane brand urethane from Grainger I used the 94 shore material, and it works perfectly. My 2nd note is that you should mix this stuff *very* carefully. It has to be within 1% error to maintain it's consistency and strength. The formula for Devcon that isn't included anywhere on the box is 69/31, that's 69 parts mix to 31 parts hardener, and that's by weight. The 3rd thing is that you have to let these cure for a week at room temperature. Thanks to another one of Bill's ideas, I used a toaster oven to cure the mounts quicker. If you keep them at 200 degrees, they can be ready to install in a day.

From Roger S. Prior

Order them from from McMaster-Carr, http://www.mcmaster-carr.com McMaster-Carr is a great source for all sorts of odd hardware.  Plus -they'll sell/ship over the phone to anyone with a credit card! They carry a generic "Flexane equivalent" in two hardness's: 

80 Shore A Durometer - 1lb resin/hardener - p/n 8644K11 ~$19
94 Shore A Durometer - 1lb resin/hardener - p/n 8644K18 ~$19

I ordered the 80 shore and it works excellent.. there is a bit of give, but they are VERY solid.. I doubt I will have any problems with them at all. my order came the day after I ordered it off the web, the bill came the day after that..  I think I paid a total of like $22 total.  then I made them myself.

WARNING: When you get it you will think they sent you a bad can.. The rubber mixture only comes less than 1/2 full (by design) you will read about this
later on. I decided to start with my exhaust hangers as they are similar to the motor mounts, and if I screw them up, I can buy some more cheap.  So I wrapped
them up real good, and mixed the mixture as best I could by volume. I held one mount in one hand and then poured it in to the mount with my other. After it was filled, I realized my first problem. The mount didn't have a flat side. So it was filled with this liquid that needed to cure and I couldn't set it down. So I propped it up with a cardboard box small enough to balance it and poured in the other. Same problem and then the first fell off the cardboard spilling onto the work surface and it was a nightmare.

Then I came out the next day and saw it was still soupy. Not hardened at all. Basically, I screwed them up..So, I set everything aside and said screw it for a week. I then re-read the instructions, and it says very clearly "measure and mix BY WEIGHT  (for your convenience, the bottles have been sent to you pre-measured, if you need a large quantity, pour the entire contents of the hardener into the base"

So, I taped and propped up the rest of my moter mounts so that they were level and would hold the liquid... (do this while they are dry before you even start mixing) Then poured the rest of the hardener into the can of base. I mixed it up REAL good, then went mount to mount filling them all up. Then I forgot about them thinking it would take 2 days to dry. (this was at about 11pm) when I woke up the next morning (5:30) I went out to look at the mounts. They looked like liquid still.  I said to myself obscenities, then I touched one to see how syrupy they were. It was as hard as a rock. The surface was just so smooth it looked like liquid. I let it cure till I got off work, then I touched/tested them. They were perfect. Solid with the slightest amount of give to allow some vibration dampening  So, I shaped them later with a grinder, and I still have to re-fill the exhaust hangers, and one of the mounts where I didn't tape well enough, but this product was fantastic.. I was VERY impressed with the results.. I suggest it to anybody who hates that rubber band feel during hard acceleration

My Tips for this project:

1. Mix well
2. Tape well
3. Make sure mounts are solidly placed on their side so that it will hold the liquid..
4. Mix the entire hardener with the entire base do them all at once as not to waste it.
5. Use a drop cloth
6. Have a stick handy to mix well
7. Don't get this stuff in the center bolt hole.. you will have to drill it out.

 From  Austin Tracy

Basically, I picked up some "Prothane" from Graingers I think.  When it arrived the next day, I taped one side of my motor mount up with duct tape, make sure to tape it up well, or the mixture will pour through the mount.  I then mixed the two parts of the prothaine together (mix the whole can, otherwise you may not get the correct mixture) , then pour it into the motor mount surrounds.  gave it a day to harden, then pulled off the tape.  I suggest letting it harden for at least two FULL days before you use them, as the prothane may be hard to the touch on the first day, but it gets EVEN harder the second.

Austin Tracy