Topic: DIY/budget motor mount "rebuild"

The motor mounts on my Caliber were completely shot after Buttonwillow. The engine was banging all around every time we shifted by the end of the race.

I took out the beat up motor mount, cleaned it up with brakeclean, let it dry out and then filled it full of 3M 590 polyurethane.

I left all the old beat up stock rubber in there, and just filled up all the voids with the 3M poly.

The 3M 590 poly is very thick in the tube...it broke my cheap caulk gun and I had to quickly go buy a heavy duty caulk gun to finish the job.

I'll let it cure for a month before I install it in the car.

https://i.ibb.co/vLtzKcv/IMG-1616.jpg

EPA Racing - #40 Supercharged Dodge Caliber

Re: DIY/budget motor mount "rebuild"

I dunno why not just buy a new one?

"get up and get your grandma outta here"

Re: DIY/budget motor mount "rebuild"

First off, I'd do the same even if I got a new one. I checked and there are no solid mounts for my car, so filling the stock mount (even a new one) with 3M poly is still a good idea for a track car.

Also, budget. Trying to keep this car under the overall budget cap.

EPA Racing - #40 Supercharged Dodge Caliber

Re: DIY/budget motor mount "rebuild"

I did something similar on an Audi GT once. Granted, that was a vibration prone 5 cylinder engine. But it broadcasted enough extra vibes into the structure that the subframe bolts started backing out, and one of the control arm bolts did also.

I added Loctite and subtracted the homemade solid mount shortly after.

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Re: DIY/budget motor mount "rebuild"

Limonaid wrote:

First off, I'd do the same even if I got a new one. I checked and there are no solid mounts for my car, so filling the stock mount (even a new one) with 3M poly is still a good idea for a track car.

Also, budget. Trying to keep this car under the overall budget cap.

fixing broken parts doesn't go against the cap.

"get up and get your grandma outta here"

6 (edited by bobnowoc 2020-12-23 07:35 PM)

Re: DIY/budget motor mount "rebuild"

Motor mount doesn't count to the cap.   And if it did, no body would ever see it

Former Captain
1996 Crown Vic. #55
Team Racing Cosmo

Re: DIY/budget motor mount "rebuild"

Man this crowd is weird sometimes. Sometimes cheap fixes are held on pillars as literal mechanical genius. Other times they're criticized as being ultra dumb. Always fun to guess which it'll be before scrolling into a thread.

I've done the fill worn mounts with urethane trick before. The Daytona front engine mount was wearing out and letting the engine rotate too much. New ones were harder to find so I filled it. Good enough for what we're doing. And honestly it was way easier and faster than it would have been to try and wrestle the old mount out of the metal bracket and get a new one in that was still designed to flex more than I wanted for a car on track.

20+ Time Loser FutilityMotorsport
Abandoned E36 Build
2008 Saab 9-5Aero Wagon
Retired - 1989 Dodge Daytona Shelby 2011-2015 "Lifetime Award for Lack of Achievement" IOE, 3X I got screwed, Organizer's Choice

8 (edited by Guildenstern 2020-12-24 05:01 PM)

Re: DIY/budget motor mount "rebuild"

There are a couple "certain" members of the crowd. We just nod and smile at them mostly when it's not our money they're spending.

Mistake By The Lake Racing (MBTL)
88 Thunderbird "THUNDERBIRDS ARE GO!", Ex Astris, Rubigo / Semper Fracti
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2018 Route Sucky-Suck Rally Miata, 2019 World Tour Of Texas 64 Newport

Re: DIY/budget motor mount "rebuild"

I never knew the  urethane was stronger than the factory material.

"get up and get your grandma outta here"

10 (edited by Limonaid 2020-12-25 10:16 AM)

Re: DIY/budget motor mount "rebuild"

bobnowoc wrote:

Motor mount doesn't count to the cap...

Mr.Yuck wrote:

fixing broken parts doesn't go against the cap.

I don't think this is technically true.

While I am reasonably sure that, at least on a class C car, no BS judge would say anything about it or penalize me for going over budget even if it was pointed out to them, I believe that motor mounts do indeed count toward the cap, at least the captive type that I have where there is no chance of the motor going anywhere because the rubber in the mount is dead.

I'd like to be wrong on this.

EPA Racing - #40 Supercharged Dodge Caliber

Re: DIY/budget motor mount "rebuild"

Mr.Yuck wrote:

I never knew the  urethane was stronger than the factory material.

I don't know that it is stronger than the factory material, but I am reasonably sure that polyurethane + a worn out mount is better than a worn out mount by itself.

EPA Racing - #40 Supercharged Dodge Caliber

Re: DIY/budget motor mount "rebuild"

Limonaid wrote:
bobnowoc wrote:

Motor mount doesn't count to the cap...

Mr.Yuck wrote:

fixing broken parts doesn't go against the cap.

I don't think this is technically true.

While I am reasonably sure that, at least on a class C car, no BS judge would say anything about it or penalize me for going over budget even if it was pointed out to them, I believe that motor mounts do indeed count toward the cap, at least the captive type that I have where there is no chance of the motor going anywhere because the rubber in the mount is dead.

I'd like to be wrong on this.

If your broke a harmonic muffler bearing in a race, the replacement cots would not be added to you car.

"get up and get your grandma outta here"

Re: DIY/budget motor mount "rebuild"

Mr.Yuck wrote:

If your broke a harmonic muffler bearing in a race, the replacement cots would not be added to you car.

Wheel bearings and mufflers are exempt per the rules.

The car "runs fine" with worn out motor mounts. And for my car, the rubber part of the mounts could fail completely and the engine would be no more likely to separate from the car in an accident, so I don't see that my motor mounts would be budget exempt.

Again, I'd like to be wrong on this.

EPA Racing - #40 Supercharged Dodge Caliber

Re: DIY/budget motor mount "rebuild"

a. Fixing parts during the race doesn't count, because you aren't turning laps.

2. I'm sure that a motor mount is not the only thing holding the car back from an overall win.

D. I'm also pretty sure nobody cares what you spend on a Caliber. Those things are rental grade terrible, even if you get the tarted up "S" model or whatever it was.

That guy

Re: DIY/budget motor mount "rebuild"

Mr.Yuck wrote:

I never knew the  urethane was stronger than the factory material.

It's not a universal answer of "yes it's stronger" or "no it's not". Different cars have different mounts. A lot of utility cars have mounts that allow some engine movement because it hides vibrations better. Great for driving to the store, terrible for flipping WOT to no throttle over and over. These mounts are designed as a pin floating inside the larger mount attached with some rubber and a bunch of air space. That design lets them flex in a certain way. By filling in those mounts with urethane you stiffen them up by a large margin and help stop the engine bouncing around.

for example, this was the daytona front engine mount. After 5 races or so the thrashing of repeatable smashing the engine back and forth broke it down and essentially separated the middle pin from the rest of the mount. Filling it made it better than brand new for track use.

https://ic.carid.com/anchor/products/2615_6.jpg

20+ Time Loser FutilityMotorsport
Abandoned E36 Build
2008 Saab 9-5Aero Wagon
Retired - 1989 Dodge Daytona Shelby 2011-2015 "Lifetime Award for Lack of Achievement" IOE, 3X I got screwed, Organizer's Choice

Re: DIY/budget motor mount "rebuild"

Limonaid wrote:
bobnowoc wrote:

Motor mount doesn't count to the cap...

Mr.Yuck wrote:

fixing broken parts doesn't go against the cap.

I don't think this is technically true.

While I am reasonably sure that, at least on a class C car, no BS judge would say anything about it or penalize me for going over budget even if it was pointed out to them, I believe that motor mounts do indeed count toward the cap, at least the captive type that I have where there is no chance of the motor going anywhere because the rubber in the mount is dead.

I'd like to be wrong on this.


By the letter of the rules, 4.2.1 does NOT exempt motor mounts.  As a general rule the judges are using a "sniff test" for budget items.  Does it make the car faster?  (or more accurately, does it make the team think the car will be faster?)  Then it counts as a budget item.

Motor mounts are weird.  Sometimes they make the car safer (I could point out a certain wrench+strap mount solution from Sputnik/NSF as an counter example).  Sometimes they make the car faster, especially in front drive cars where they can accidently be part of the suspension response.

The correct procedure for fixing broken parts is to email Judge Phil (or Judge Eric, I suppose since Phil doesn't know the teams nearly as well these days) and ask for a residual to cover the mounts.  If you replaced them track side during a previous race, just have your story ready.
Showing up with brand new motor mounts and no paperwork is asking for special attention during BS.

Apparently my name is really "Craigers".  Who knew?
We might be yellow, but at least we are slow
I'm a WINNER!