Do-It-Yourself Liquid Urethane Motor Mount Replacement Inserts

A complete guide to modifying stock motor mounts to make your own motor mount inserts

Do It Yourself Liquid Urethane Motor Mount Replacement Before
Do It Yourself Liquid Urethane Motor Mount Replacement Final

If you’ve already done your research, you know for sure you want the DIY motor mount, skip down to the actual creation of the motor mount insert. But if you need a little convincing, keep reading.

A breakdown of the article:

But first…

Before you dive into creating your own motor mount insert, its a good idea to understand the few basic principles of motor mount inserts and why you would even want to use them. There’s pros and cons, like everything, in making your motor mounts more solid. So before you do, here’s a few pros/cons:

The Pros

  • Increase Horsepower Potential
  • Reduce Wheel Hop
  • More Responsive Motor

The Cons

  • Increase Cabin Vibration
  • Increase Cabin Noise

So taking those pros and cons a bit deeper, the first and foremost reason to firm up your motor mounts is to hold the engine firmly in place. Often the more pliable stock motor mounts allow the engine to move excessively – resulting in wheel hop and loss of power. The more extreme version of this is when an owner has to increase the vehicle’s horsepower more than the stock motor mounts were designed to handle. This can cause tearing of the stock motor mounts as well as damage to the engine and engine bay should the engine be allowed too much movement.

Easily the most frustrating result of solid motor mounts is increased vibration felt by passengers in the vehicle. Stock motor mounts are designed with a fair amount of flex, designed to absorb natural motor vibration and reduce vibration noise. In most cases, this increase in noise and vibration is not terribly significant, however, it is increased by the firmness of the urethane used to fill the mount and the number of mounts that are filled.

Do It Yourself Liquid Urethane Motor Mount Replacement Cabin Noise

Cabin Noise, Really?

The trade off for increased performance is cabin noise and vibration. The harder, more firm your motor mounts are the more efficiently they will transfer horsepower to the wheels. Likewise, the softer the motor mounts are the less vibration and noise will be transferred to the rest of the vehicle. There are a number of ways to make the trade off between vibration/noise increase and performance.

Firming up the Correct Motor Mounts

Most Front Wheel Drive vehicles have several motor mounts, typically 4 or 5. Some of the motor mounts are designed significantly different from the others. TORQUE mounts are the motor mounts designed to reduce the amount of engine movement when power is applied. Main Mounts are the mounts designed to support and hold the weight of the engine.

Torque mounts are the most effective mounts at providing a great rigidity to the engine assembly without transmitting as much natural vibration to the driver. Torque mounts are typically located at the front end or rear of the engine. Main mounts are typically located higher on the engine assembly as the engine weight usually hangs from these.

While it is typically possible to firm up all the mounts on a vehicle – the torque mounts will provide the best trade off between performance and vibration.

Using a Softer or Harder Universal Motor Mount Insert Formula

There are several firmness or “durometer” levels offered:

  • 60A – For the Daily Driver – This is the softest formula offered that will still make a noticeable difference in vehicle performance. This softer formula is best for tuners that still want to increase performance without trading off as much personal comfort.
  • 80A – Even trade off between performance and vibration – When it comes to motor mount inserts, this formula is the most popular for its ability to significantly increase vehicle performance while still allowing some small amount of flex in the mounts to keep vibration and noise to reasonable levels.
  • 80A HIGH PERFORMANCE – The next best step – A newer version of the most popular choice balances high performance with ride quality, while boasting a higher tear rate and standing up to heat even better.
  • 94A – Race Quality – Not for the daily driver. This formula is the hardest of the 4 available. Providing the best reduction in motor movement – this version will also allow a rather significant amount of engine vibration to be transmitted into the vehicle. Best you can get without going with an aluminum mount.

Do it Yourself Liquid Urethane Motor Mount Replacement Choices

With four choices in hardness, there is a formula for any level of performance

Materials Required for this Project:

All items listed are absolutely required in order to complete this project safely and easily. In total they shouldn’t cost you more than $10 from your local Home-Depot or Wal-Mart (aside from the actual urethane). Save yourself future frustration and buy these before starting the project!

  • Liquid Urethane – available in the 60A, 80A, 80A High Performance, and 94A
  • Contact Cement – Helps the duct tape seal against greasy surfaces
  • Duct Tape – Seals one side of the mount
  • De-greaser – Cleans the mount of grease and oil
  • SAND – in a box – vital to the project – DO NOT skip this step
  • Level – makes sure the mount if level for a level pour

Do It Yourself Liquid Urethane Motor Mount Replacement Materials

Instructions –
DIY Motor Mount Inserts

Prepping The Mounts

Step One – CLEAN!

For the urethane to bond correctly and to ease the overall process – the mounts must be thoroughly cleaned of grease and dirt. A little cheap degreaser can go a long way over simple soap. Take the time to use real degreaser – it’s usually just a spray on – spray off process anyway.

Do It Yourself Liquid Urethane Motor Mount Replacement Clean

Cleaning the mounts with a degreaser will allow the urethane to properly bond to the rubber

Step Two – Sealing One Side

The motor mount inserts are made by pouring a liquid urethane into the voids of the mounts and allowing it to dry. In order to do this you’ll need to completely seal off one side of the mounts. When you first pour the urethane into the mounts it will have a very liquid consistency. Even the smallest hole in your sealing jobs will allow the urethane to seep out.

Do It Yourself Liquid Urethane Motor Mount Replacement Cement

Contact cement will give you an improved seal job to ensure your urethane stays in the mount

The best way to do this is with some contact cement and duct tape. While duct tape alone will usually work – the contact cement will ensure a good seal – especially if there’s any greasy residue on the mounts (the tape will not adhere properly). Start by painting the outside edge and inside circumference of the side of the mount you’re going to seal off – with contact cement. Anywhere you need to be sure there’s a good seal – use this liberally – you’ll be able to pull/scrape it off later.

Do It Yourself Liquid Urethane Motor Mount Replacement Contact Cement

Once you’ve set a good layer of contact cement, seal off the mount with the duct tape. Use several strips of tape at different angles from the center of the mount. Continue adding tape around the center of the mount until you’ve sealed it off completely. Some users wont have the center piece sticking out of one side and won’t have to work around it – either way just keep adding tape until it’s properly sealed off.

Do It Yourself Liquid Urethane Motor Mount Replacement Tape Start

Duct tape is cheap – so use as much as necessary until you feel good about the job – then add a little more.

Do It Yourself Liquid Urethane Motor Mount Replacement Tape

The better the tape job, the better the mount will turn out

Setting Up the Mounts

It’s important that the mounts are completely level before you pour the urethane into them. If they’re laying at an angle the mount will not turn out right.

Prepare a small box of sand for the mounts. Setting the mounts into the sand will serve two purpose:

  1. Allow a perfectly level placement – even if there are protrusions from the mounts that would otherwise make it sit screwy
  2. Help seal off any small holes in your sealing job. If the hole is small, a little urethane will leak out into the sand and the sand will help it congeal faster – effectively sealing the hole in the mount

Do It Yourself Liquid Urethane Motor Mount Replacement Sand

DO NOT attempt to do this without the sand box. While it is possible to do so – using the sand box will help ensure you do the job right the first time. Once you mix the urethane, you’ll only have 15-20 minutes of working time before the urethane is to firm to pour. You won’t have enough time to decide you SHOULD have used the sand box.

Do It Yourself Liquid Urethane Motor Mount Replacement Level

Don’t skip the sand and the level, once you mix the urethane you won’t have time to realize you shouldn’t have skipped this step

Mixing the Urethane

DO NOT DO THIS UNTIL YOU’RE 100% Ready to Pour!

The correct mixing ratio is absolutely VITAL to the urethane setting correctly. That’s why each set comes in a pre-measured container. Do not attempt to use only PART of a kit – doing so may cause the urethane to not set correctly

Each kit should include:

  • Urethane – in the hardness level you ordered. Comes in small paint can style container
  • Activator – a very liquid substance in a small bottle
  • Stirring Stick

Do It Yourself Liquid Urethane Motor Mount Replacement Contents

Before doing ANYTHING with these substances read through all the warnings and adhere to them! Most importantly – mix and use these outside in a well ventilated area.

Do It Yourself Liquid Urethane Motor Mount Replacement Open
Remove the lid from the larger paint can containing the urethane and set it aside. Take the bottle of activator and shake it well before adding it to the urethane.

Do It Yourself Liquid Urethane Motor Mount Replacement Mix

Thoroughly mix the activator and urethane with the provided mixing stick.

Do It Yourself Liquid Urethane Motor Mount Replacement Stir
Be sure to scrape the sides of the can and even scrape off the stirring stick to ensure you’ve mixed all of the urethane in with the activator.

Once you’ve mixed the urethane and activator you’re ready to pour it into the mount! Once the urethane is mixed you only have about 15-20 minutes where it’s pour-able!

Pouring the Urethane

Slowly pour the mixed urethane into the open side of the mounts. Allow for the urethane to fill all the voids in the mount. It may take a minute for it to settle completely flat – so take your time. If it seems to be leaking out a LITTLE – don’t panic – the sand will help clot up the hole and slow the leak.

Fill the mounts to the top – it’s even OK if some spills over the outside edge.

Once the mounts are full wait about 10 minutes. In 10 minutes the urethane should still be very liquid and you can top off the mounts with the remaining urethane in the can. This is particularly important if you have a small leak in the sealed side of the mount. Don’t wait longer than 20 minutes to check up on the mounts as by that time the urethane will start to become less workable.

Do It Yourself Liquid Urethane Motor Mount Replacement Pour
Do It Yourself Liquid Urethane Motor Mount Replacement Last Pour

A Job Not So Well Done

It is very important that you use sand. If you do a poor job of setting up the mount in your sand, your results can be disastrous. If there is any type of hole in your seal job, the urethane can seep out. The sand can stop that, so be sure to pack the sand under the mount in order to clog any leak. If not, you get this:

Do It Yourself Liquid Urethane Motor Mount Replacement Bad Sand

If the urethane seeps out like this, you’re final product will be less than desired. Check out the mount we did with a poor sand job:

Do It Yourself Liquid Urethane Motor Mount Replacement Bad

Make sure you pack in the sand and keep the mount level, otherwise you’ll get this..

The Finished Product

By the next day you should be able to take the mounts out of the sand box and remove the tape from the opposite side. Sometimes if you had a small leak you’ll find small clumps of sand attached to the other side – these pry/peel off easily and will not affect your new mounts.

Do It Yourself Liquid Urethane Motor Mount Replacement After1

The tape should pull off easily and if you want to clean them up further you can scrape off the left over contact cement – however if you really don’t care too much you could even leave the tape on – it won’t hurt anything.

Do It Yourself Liquid Urethane Motor Mount Replacement After2
Do It Yourself Liquid Urethane Motor Mount Replacement After3

Finished “Do It Yourself” Motor Mounts

Do It Yourself Liquid Urethane Motor Mount Replacement final1

Additional Notes For Users

Some users have asked if this will work for their mounts if the center portion has completely torn away from the rest of the mount. The answer: YES! The only additional consideration is the correct centering/alignment of the mounting point that goes through the mount. While the sandbox will make it significantly easier to do this – special care will be needed to ensure centering and alignment.


In using these instructions and urethane kits you accept complete responsibility for the outcome of your project. Only you can ensure this is done correctly and we will not be held responsible if your mounts do not turn out like you wanted.

A significant amount of information has been provided here – however some projects may be unique and will need special attention or a different mode of creation. While we’re happy to help with any questions – we cannot guarantee the outcome of your particular project.

You may not copy, post or reproduce this “How To” information or pictures without written consent from Diverse Suspension Technologies.

Do-It-Yourself Mount Mount Inserts


    1. Profile photo of Josh DanielsJosh Daniels

      Hey Alex,

      We looked around and couldn’t find a satisfactory answer to your question, but we here at DST do not know the word “defeat”, so what did we do? We cracked open a can of urethane, mixed it up, and poured it into a measuring cup.

      When everything settled, it came out to 400mL which is roughly 13.52fl oz or 1 2/3 cups. We hope this helps!

    1. Profile photo of Josh DanielsJosh Daniels

      Thanks Jimmy,

      The process isn’t too hard and it’s awesome to be able to tell your buddies, “I made my own motor mounts”.

      Has anyone had success with pouring their own urethane motor mounts? Please post pictures or tell us how it turned out!

    1. Profile photo of Josh DanielsJosh Daniels

      We love Moog too Jimmy!

      Moog is the official suspension of NASCAR and every cup champion for the last 50 years has used Moog ball joints and in those 50 years they have never had one fail.

      Moog has a great history and they are always innovating, like with the new integral dust boot¬†on some of their ball joints that holds it’s seal longer than the traditional design and has less of a chance of being torn because of its low profile.

      Moog is just a great brand that we’re happy to provide to people who need reliable replacements.

      Happy trails.

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