Thread: Filled my motor mounts with polyurethane. Awesome.

So I'm pretty poor right now, and I've decided to take the cheapest possible route to modding my car. And on top of that, I think filling the stock mounts is a lot easier than pressing in replacements.

Instead of buying the prothane mounts or the ES inserts, I just walked right in to home depot and found some construction adhesive that looked like it would work well.

And I must say, after waiting two solid days for everything to dry completely, it was well worth it. Car drives very differently...feels very solid and connected. I only filled the front and rear engine mounts, and then the tranny mount. Vibration was only increased a little bit. I don't mind it at all. Shifting feels better. Even the handling of the car feels a tad tighter possibly.

Total money spent: $8

Total actual time spent removing/filling/re-installing: 2-3 hours

Here's what I used:
StickWithPL - Sealants, Adhesives Products Page

I have always used the 3M windo weld. You can get it at autozone but it is a bit more expensive. I loved my 3M mounts. Compared to the full-poly I have now, they were far more streetable and had a lot less vibration. I have to have the idle at 1000rpm to keep my fillings in my teeth from falling out.

3M>polyurethane, but they don't hold as well. the full poly's are very stiff and will handle a ton of power.

I was pleasantly surprised at how little I notice any extra vibrations. Really, it's very minimal. Hopefully it might even get a little better once they break in.

Nice work. I love my prothanes though and to me the vibration is not really that bad to me. This is a good alternative though.

Sick idea. I think I will do this next time. Way cheaper, and a lot easier. If you don't have a place to do it pressing out mounts can be lame.

so all you did was fill in the gaps in the existing mount rubber?

damn sounds awsome, i love projects like this

Yes, you must fill in the gaps completely. Wear gloves so you can make sure there are no air pockets. I did mine like Coleman did.

1. Remove mounts (or remove weight off mounts)

2. Clean out the mounts completely to ensure there is no dirt or debris. Dirt/oil will not allow the urethane to adhere to the rest of the mount.

3. Tape one side of the mount with blue painter's tape. This will allow you to fill the mount from one side until it is full, and will keep the urethane from drooping out.

4. Fill the mount with the adhesive and a caulking gun making sure to leave no air pockets.

5. Let the mounts cure until completely dry before reinstalling.


When it is all done, the difference is huge. SCC's Dave Coleman did this on the Rally Spec V because the mounts were too sloppy.

I'm also doing this but only to the tranny and dogbone, I'm skipping the passenger side trying to avoid extra vibrations.

I have a Prothane for the rear subframe (not pressed in yet) since this is the most damaged one

If I could only take out prothanes and do this instead I would do it in a heart beat

You're a quick one Nate. Didn't expect you to do it so soon. I take months to do mods to my car... =]