Solid vs. OEM vs. Poly motor mounts
Solid vs. OEM vs. Poly motor mounts Hey guys,
I'm dropping an LY6/T56 into a 69 GTO and am trying to figure out what mounts to use. I've been told I need to get chevelle frame stands one way or the other, that BOP frame stands do not work.
I like the dirty dingo slider mounts, but they're solid mounts, whereas I'm reading that most people use the Edelbrock, S&P, or BRP mounts with poly bushings.
Can anyone give me a quick rundown of why people use one over the other?
I'd like to buy my adapter plates, mounts, and frame stands this week so i can test fit my motor next weekend or so.
Thanks
Jim
I'm dropping an LY6/T56 into a 69 GTO and am trying to figure out what mounts to use. I've been told I need to get chevelle frame stands one way or the other, that BOP frame stands do not work.
I like the dirty dingo slider mounts, but they're solid mounts, whereas I'm reading that most people use the Edelbrock, S&P, or BRP mounts with poly bushings.
Can anyone give me a quick rundown of why people use one over the other?
I'd like to buy my adapter plates, mounts, and frame stands this week so i can test fit my motor next weekend or so.
Thanks
Jim
I can share my experience in my 4th gen Z28, maybe that will help.
I wanted strength and not to have to worry about replacing motor mounts, but it was a DD - so I went poly.
The tranny mount was poly too but vibration was AWFUL! Went OEM on the tranny mount and was close to stock comfort. My shifter didn't move at all with poly/poly but only a little with the OEM mounts. The fact that the tranny mount is MUCH easier to change sold me on this combo. This was with stock cam so it would have been worse with the cammed motor.
I would think this translates to your platform somewhat. If you care about comfort and the option to put some miles on it, I recommend the poly/rubber combo.
I wanted strength and not to have to worry about replacing motor mounts, but it was a DD - so I went poly.
The tranny mount was poly too but vibration was AWFUL! Went OEM on the tranny mount and was close to stock comfort. My shifter didn't move at all with poly/poly but only a little with the OEM mounts. The fact that the tranny mount is MUCH easier to change sold me on this combo. This was with stock cam so it would have been worse with the cammed motor.
I would think this translates to your platform somewhat. If you care about comfort and the option to put some miles on it, I recommend the poly/rubber combo.
Thanks for the input jmilz.
I was reading the other day about some people that claimed solid mounts resulted in less overall vibration.
everyone says the poly trans mount is a must.
If anyone else can weigh in, I'd love to hear about it.
Jim
I was reading the other day about some people that claimed solid mounts resulted in less overall vibration.
everyone says the poly trans mount is a must.
If anyone else can weigh in, I'd love to hear about it.
Jim
I would caution against mixing solid and rubber/poly anything. Datsun Z cars are notorious for having a poorly engineered front diff mount (IRS rear). It is very tempting to put a solid front diff mount, but then keep the rubber or even poly rear diff mounts. The problem with that is the rear can wiggle a bit whereas the front doesn't. What eventually happens is the solid front mount cracks the front diff cross member resulting in some pretty impressive carnage.
Maybe solid motor mounts and poly trans mount is different, but I would still think going all one way or the other is the way to do it.
I tried a solid rear diff mount on my Z once. It transmitted so much gear noise into the car that I felt physically ill after 10 minutes. It was all high frequency gear noise and not driveshaft vibration. Different car and a worn diff, but I wouldn't lock myself into a solution that can't be switched to something else if need be.
Maybe solid motor mounts and poly trans mount is different, but I would still think going all one way or the other is the way to do it.
I tried a solid rear diff mount on my Z once. It transmitted so much gear noise into the car that I felt physically ill after 10 minutes. It was all high frequency gear noise and not driveshaft vibration. Different car and a worn diff, but I wouldn't lock myself into a solution that can't be switched to something else if need be.
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I would caution against mixing solid and rubber/poly anything. Datsun Z cars are notorious for having a poorly engineered front diff mount (IRS rear). It is very tempting to put a solid front diff mount, but then keep the rubber or even poly rear diff mounts. The problem with that is the rear can wiggle a bit whereas the front doesn't. What eventually happens is the solid front mount cracks the front diff cross member resulting in some pretty impressive carnage.
Maybe solid motor mounts and poly trans mount is different, but I would still think going all one way or the other is the way to do it.
I tried a solid rear diff mount on my Z once. It transmitted so much gear noise into the car that I felt physically ill after 10 minutes. It was all high frequency gear noise and not driveshaft vibration. Different car and a worn diff, but I wouldn't lock myself into a solution that can't be switched to something else if need be.
Maybe solid motor mounts and poly trans mount is different, but I would still think going all one way or the other is the way to do it.
I tried a solid rear diff mount on my Z once. It transmitted so much gear noise into the car that I felt physically ill after 10 minutes. It was all high frequency gear noise and not driveshaft vibration. Different car and a worn diff, but I wouldn't lock myself into a solution that can't be switched to something else if need be.
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Verdad Gallardo There are no cracking issues like in a solid mounted rear end that you were talking about. 
And if you didn't put a poly mount on the trans with the solid motor mounts you would crack the trans bellhousing from chassis flex since a solid trans mount would not flex so the case would. Thousands of people run solid motor mounts with poly trans mounts on the dragstrip everyday with no issues.
And if you didn't put a poly mount on the trans with the solid motor mounts you would crack the trans bellhousing from chassis flex since a solid trans mount would not flex so the case would. Thousands of people run solid motor mounts with poly trans mounts on the dragstrip everyday with no issues.
I think it all just depends on what you want out of the car. I know most people like the poly because they are more durable and less prone to failing than rubber. Though they tend to transmit more vibrations through the body than rubber. Doesn't matter what anyone says they do it's just all perspective on what your comfortable with. The solid I'm not sure about. I know I have ran poly and rubber in my car and I def prefered the rubber. Same with my buddy and his 02' Camaro Ultra-Z with a 427 swap in it.
There are no cracking issues like in a solid mounted rear end that you were talking about.
And if you didn't put a poly mount on the trans with the solid motor mounts you would crack the trans bellhousing from chassis flex since a solid trans mount would not flex so the case would. Thousands of people run solid motor mounts with poly trans mounts on the dragstrip everyday with no issues.
And if you didn't put a poly mount on the trans with the solid motor mounts you would crack the trans bellhousing from chassis flex since a solid trans mount would not flex so the case would. Thousands of people run solid motor mounts with poly trans mounts on the dragstrip everyday with no issues.
although if you run a poly trans though with rubber motor mounts you do have a potenal to crack the trans as the trans is mounted without flex and the motor flexes with the rubber mounts
this is only true if you have a trans mounted torque arm, if you have a body mount ta or no ta then there is no need for a poly trans mount as there no torque or movement on the trans its self
although if you run a poly trans though with rubber motor mounts you do have a potenal to crack the trans as the trans is mounted without flex and the motor flexes with the rubber mounts
although if you run a poly trans though with rubber motor mounts you do have a potenal to crack the trans as the trans is mounted without flex and the motor flexes with the rubber mounts
What ^^ said for cushy DD.
The only issue is that if you like to bang the gears, you are going to have issues with the rubber trans mount failing on you from time to time.
For my DD, it's Poly all-round and for my racer is solid engine poly trans. This combo is not a whole lot worse for vibes (if at all) than full poly.
The only issue is that if you like to bang the gears, you are going to have issues with the rubber trans mount failing on you from time to time.
For my DD, it's Poly all-round and for my racer is solid engine poly trans. This combo is not a whole lot worse for vibes (if at all) than full poly.
