I've filled my rear motor mount!

[nerd racing]

window weld doesn't always fully harden. I have attempted using it before and I was never satisfied with the results like a pour-able urethane.

 

[Andy Hollis]

Ok, for those of you that haven't followed my thread in the Autocross section, I have decided to fill my stock motor mount with urethane. The benefit to this will hopefully be less sloppy shifts and reduced engine movement.

This started when I discovered my newly installed (and liked) AWR urethane motor mount is illegal for the SCCA autocross class that I am running in (ST).

My awesome (but Illegal in ST class) AWR motor mount compared to stock

I responded in your original thread in the Autocross section, but I wanted to get the info here, as well.

The AWR mount is perfectly legal for STF autocross. I've done the measurements and posted a note with pics and the calcs here.

Please update the original post in the thread so as not to further this misconception. Thanks!

 

[Richard_rsp]

I responded in your original thread in the Autocross section, but I wanted to get the info here, as well.

The AWR mount is perfectly legal for STF autocross. I've done the measurements and posted a note with pics and the calcs here.

Please update the original post in the thread so as not to further this misconception. Thanks!

Sorry Andy - I dont check this forum much anymore. I will edit to avoid misinformation. Thank you for your research!

 

[robmilkshakes]

Yesterday I picked up my new mount and received the 60A urethane from mcmaster-carr so I will try this and report back in a few days with my results!

 

[eyeballs]

I almost forgot about this...I need to get this done to mine someday. What did the new mount from mazda and the urethane cost?

 

[robmilkshakes]

I almost forgot about this...I need to get this done to mine someday. What did the new mount from mazda and the urethane cost?

Mazda list price is ~$30-$35, you can get it online for a wholesale price of ~$25. I got mine locally for wholesale price since I work for another dealer and after shipping the urethane cost me about $35. Mine should have cured enough by now to install so in the next few days I'll pop it in and see how it is.

 

[Ryno666]

Looks like skateboard wheels wich are also measured in durometer and made of polyurethane. hmmmmm....

 

[George Patches]

I have just done this same modification to my car. I modified the instructions and used blue painters tape instead of duct tape. It was easier to remove without damaging the polyurethane, but still required care. If I were to do it again, I would cut a piece of paper to fit the one side and tape that down so there would be no adhesive in direct contact with the polyurethane.

 

[George Patches]

So just to update this, the clutch take up is definitely improved from stock, but not as much as the AWR mount. The shifting feels stock, which I never personally had a problem with, but going back to this after having the AWR I definitely notice it's not as sharp. For me it's a good compromise of performance improvement, but not much more NVH. With the clutch engaged the slop of the drivetrain coming on and off the throttle is improved, but the NVH over stock is not noticeable to me. There is a vibration at idle that was not there when stock, but after a week or so I'm used to it and it doesn't bother me. If you daily your car, this is a great compromise. My fuel economy is back above 40 MPG average since I can drive below 2000 rpms again.

 

[George Patches]

Bumping this thread as I'll be doing this again but with 80A instead of 60A.

 

[utmorpheus]

/r/ update

 

[eyeballs]

I sent George a PM as I am curious too. I want to try the 80D in lieu of my AWR mount. If I could just decrease some of the vibrations of initial clutch engagement from a stop, and low rpms with AC on I'd be happy.

 

[n8myton]

I had the same thoughts as you guys a few weeks back and PM'd George as well. Here are his thoughts. I'm still on my AWR mount, which I think has gotten a bit better with some combination of mileage and summer temps rising into the 90s recently. Still a bit more NVH than I'd like, but tolerable. Maybe I should go back to stock for a week for a reminder of what I'm missing.

I actually tired it first a few years ago and had similar results to you. I sold it someone else on the forum after I fully disclosed my results to them. He got the same results, but said he'd only use it for autocross events so it worked out. The 80A is an order of magnitude less vibration than you're getting now with the AWR, but for nearly stock like NVH I'd still recommend 60A. The vibration with the 60A filled mount was barely more than stock, not noticeable unless you're very observant.

Interesting. I have the AWR 70A and I get very slight vibration at idle (<1k), heavy vibration&shaking at around 1.2-1.5k, and resonating engine drone at 3.5k. Have you tried the AWR mount? I'm considering getting rid of it because it's a bit much for a daily.

Hey,
You posted some about your experiments with urethane filled motor mounts for your Mazda 2. I'm curious if you ever ended up trying a 80A fill, and if so what sort of results you found?
Thanks,
Nate

I picked up a bad vibration at idle sometimes, it's borderline streetable. I don't really like it, but I can live it right now. However, the bad vibration is only a dead idle, everywhere else it's completely fine. I don't feel the 80A is enough of an improvement over the 60A to warrant doing it. If I were to do it over I would go 60A.

-George

 

[eyeballs]

Thanks for posting that up, Nate. I wonder how the 80a filled mount compares with the AWR as far as throttle response and shifting go.

 

[utmorpheus]

George sold it to me, I am selling it now. The vibration is just too much for a DD. I've lived with it for two years but it's to the point where I'll give up some shift quality to not have my entire dashboard rattle when I start from a dead stop.

 

[eyeballs]

Sounds like its about the same as the 70 duro AWR mount. I filled my OE mount last night with the 60A stuff. Taking the 2 on a family road trip soon and will swap mounts before we leave.

 

[eyeballs]

Swapped out the AWR for my OE mount yesterday. I filled it with the 60D stuff from mcmaster-carr. Super easy to do, came out great. Results? Meh. Vibrations all gone, but so is the fun. It's probably better than the OE was before the mod, but I already miss the AWR mount. If only I had a button inside the car to push and change the mount stiffness. For those that don't mind a moderate amount of vibration during clutch engagement into 1st and at idle with AC on, get the AWR!

Here's how my stock mount came out: