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Motor Mounts - Moving to Poly

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Old 07-28-2011, 11:31 AM
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Default Motor Mounts - Moving to Poly

Well looks like I have worn out another set of motor mounts. These liquid filled mounts just do not seem to be all that durable. Or maybe it is just me. Instead of fulfilling the definition of insanity (doing the same thing over and over while expecting a different result) we have decided to take a slightly different route.

We are going to drain a set of motor mounts and fill with liquid poly urethane and let it harden before installing. Apparently the MB guys in Europe have been doing this for awhile on certain models.

This should keep me from having to replace these things every 25k miles or so and should reduce engine movement. Downside will be increased NVH - although I do not know to what extent at this point.

Not an exact fit but these links will give you an idea of what I am talking about:

How To Make Universal Motor Mount Inserts

Prothane Suspension Parts - Part Number DIYMMI - Do It Yourself Motor Mount Inserts - Liquid Urethane
 
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Old 07-28-2011, 12:21 PM
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Default Re: Motor Mounts - Moving to Poly

Keep us informed on how this goes.
 
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Old 07-28-2011, 01:08 PM
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Talking Re: Motor Mounts - Moving to Poly

Remember that I used a SS cable to limit the motor mount flex on the driverside for stress, which I have been known to cause........Woody FYI
 
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Old 07-28-2011, 01:52 PM
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Default Re: Motor Mounts - Moving to Poly

How could anyone forget your cable I need to find pictures of it and look at it again. My one concern when I first saw this was the stress on the SC.

I was looking through your gallery and only saw the picture of the cable wrapping around the frame but do not see on of it over the motor. Do you have more pictures?
 

Last edited by SRT6_Roadster; 07-28-2011 at 02:12 PM.
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Old 07-28-2011, 03:11 PM
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Default Re: Motor Mounts - Moving to Poly

Humm, interesting invention. I wonder how well it works.

Les
 
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Old 07-28-2011, 03:29 PM
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Talking Re: Motor Mounts - Moving to Poly

The SC motor cable was just for the one day for the track, I went ot the SS cable and its still there. Woody
 
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Old 07-28-2011, 06:46 PM
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Default Re: Motor Mounts - Moving to Poly

Waldig - can you post pictures of your new setup? I looked in your gallery and did not see them.
 
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Old 07-30-2011, 12:11 PM
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Default Re: Motor Mounts - Moving to Poly

Waldig- Any chance of getting pictures of the way you have routed the chain?

So the shop that is taking care of my motor mounts did a bit of investigation and they have decided to go with #80 poly urethane on the motor mounts. I am a bit concerned that this may transmit too much vibration but the shop thought it would be okay. Plus they were worried that anything less just would not hold up with the torque the motor is putting out.

Should have a report on the car Tuesday or so. If the motor mounts are transmit too much vibration we will try a different strength compound in the old motor mounts.
 
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Old 07-30-2011, 12:36 PM
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Talking Re: Motor Mounts - Moving to Poly

I added a ss cable not chain and used it to loop over the motor mounts groove and under the frame support, motion I have - stress I dont there is slack 1" Woody
https://www.crossfireforum.org/galle...grade_0311.JPG

ENJOY< woody

Larger photo in the gallery: Fuel system upgrades (031)
 
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Old 07-30-2011, 01:02 PM
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Default Re: Motor Mounts - Moving to Poly

Wow.... took a while to track that picture down! I will save the rest of you some time. Here ya go.

 
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Old 07-30-2011, 03:28 PM
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Default Re: Motor Mounts - Moving to Poly

Thanks I saw that picture but was trying to figure out how had it wrapped. Now with the additional explanation about being wrapped over the motor mount groove I think I understand. Although I do not have the car to look at right now.
 
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Old 07-31-2011, 08:52 AM
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Default Re: Motor Mounts - Moving to Poly

I haven't experienced this problem so far, but maybe it is just happening with the clutch/manuel transmissions. I did experience this in my younger years on my '69 Z-28. The rubber mounts wouldn't hold up. We cabled the torque side down. I had a cable made up with loops. I bolted one end to the frame, the other to the block with about an inch of play...never lost another motor mount... I did this with my big block '71 Camaro as well...same results. Any hardware can make you cable, and it is a cleaner look. I have even seen them chained down...
 
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Old 07-31-2011, 10:53 AM
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Default Re: Motor Mounts - Moving to Poly

doc the mounts on these cars are the weakest i have ever seen. replaced 13dogs srt-6 mounts and they were completely dry. i really like this idea and if i can find some older mounts i would try it myself. new mounts are about 100$ a set
 
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Old 07-31-2011, 11:02 AM
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Default Re: Motor Mounts - Moving to Poly

I guess I will have something else to do while she is up in the air...but, I haven't noticed any real torque over...I will check them out...let me know how the home-made kind work out...
 
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Old 07-31-2011, 11:13 AM
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Default Re: Motor Mounts - Moving to Poly

I never really noticed an issue with my mounts... and I gave my car absolute hell.

Why not look into solid mounts? you only noticed the increased vibration at idle... I have them on my 240 and my turbo civic and i absolutely love them
 
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Old 07-31-2011, 12:06 PM
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Default Re: Motor Mounts - Moving to Poly

Originally Posted by Infinite
I never really noticed an issue with my mounts... and I gave my car absolute hell.

Why not look into solid mounts? you only noticed the increased vibration at idle... I have them on my 240 and my turbo civic and i absolutely love them
when you get 375 ft/lbs of torque in your xfire you will see it then. as for solids thats a race only mod and not suited for the street. the poly mount idea is a very nice medium between the 2
 
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Old 07-31-2011, 01:32 PM
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Default Re: Motor Mounts - Moving to Poly

well, i guess i drive race cars on the street lol.

We have a write up a friend did on how to mold your own poly mounts from liquid urethane... I'll see if I can dig it up for you
 
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Old 08-01-2011, 11:15 AM
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Default Re: Motor Mounts - Moving to Poly

My STR6 driveline chirps often with the 1st to 2nd shift. Not sure if this is motor mounts or tranny mount, or both. It wouldn't hurt to replace both, I guess.
 
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Old 08-01-2011, 01:03 PM
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Default Re: Motor Mounts - Moving to Poly

Is there any way to visually inspect them w/o removing them? Mine feel like they've softened over the years, I feel it especially on the 1-2 shift, and putting around town... I can feel a lot of "give" in the powertrain. Perhaps it's my imagination, but...
 
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Old 08-16-2011, 07:33 PM
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Default Re: Motor Mounts - Moving to Poly

Originally Posted by JHM2K
Is there any way to visually inspect them w/o removing them? Mine feel like they've softened over the years, I feel it especially on the 1-2 shift, and putting around town... I can feel a lot of "give" in the powertrain. Perhaps it's my imagination, but...
Try rocking your engine from side to side. If it moves pretty easily it is time for new mounts.
 


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