Anyone know what the difference is between these two motor mounts? (Page 1/1)
82-T/A [At Work] JAN 06, 02:55 PM
So, for those who do not know...

86-88 Automatic 4-cyl Fieros, and all 88s, got a revised front Engine Mount. It was called a "hydraulic" replacement mount. Specifically, it has fluid within the rubber that's supposed to help isolate sound and vibration from the motor to the frame (and thus the rest of the car).

Many newer cars come with this now, so it's nothing super special, but it's part of what makes "newer" cars much more refined sounding and feeling than older cars... which also lacked the CAFE and CARB standards that tended to pervade the rest of the country (sound silencers in the intake, muffler resonance-elimination cans, etc.).


I was looking on the Fiero Store website, and happened to notice the OEM one that they sell:

https://www.fierostore.com/...0%20%20OEM&d=312&p=1




And then the aftermarket replacement one they sell:

https://www.fierostore.com/...0%20%20OEM&d=312&p=1




The OEM one (top) is $350, while the aftermarket one is $20.


A few months ago, I was looking to replace the one on my daughter's 85, and wanted to go with this new one... only to find out it won't work. It'll fit the engine of course, but they used a different mounting plate on the subframe so unless I modify it ... it's not going to fit. The one I ordered was on Rock Auto and said it was "Hydraulic" ... I think I paid $43 for it (minus shipping).

Am I to assume these two motor mounts are the same, and the only reason why the GM one is more expensive is because it's original (as in, would be concourse correct)? Just curious if anyone happens to know...
Raydar JAN 15, 09:35 PM
The OEM one is filled with a gel, or something similar, while the replacement is solid rubber. Theoretically, the gel-filled mount will absorb vibration better.
Fiero store charges $350 for it because someone (not me) will buy it.
I can't speak to the one on Rockauto, but the price is more realistic.
And yeah... the 88 cradle "shelf" is different. Kind of strange how they mix-match the part for different applications, like that.
Unless it's used for the goofy uni-mount that 86-88 4 cylinder automatics used at the tranny end. One mount under the crank. One mount on the very far end of the trans. And a dog bone. My old automatic 88 Duke used to beat hell out of my trunk wall.

[This message has been edited by Raydar (edited 01-15-2025).]

TakeTwo JAN 18, 06:38 PM
My buddy has a 15$ ebay 3rd party mount in his '86 4 banger and i asked what the mileage on it is since he installed over 19k miles its very smooth riding car.

I guess the F.S. has the last of he OEM stock hence the pricing? I'd def just get the solid mount or something from Rodney if he still sells them.
82-T/A [At Work] JAN 18, 08:09 PM

quote
Originally posted by Raydar:

The OEM one is filled with a gel, or something similar, while the replacement is solid rubber. Theoretically, the gel-filled mount will absorb vibration better.
Fiero store charges $350 for it because someone (not me) will buy it.
I can't speak to the one on Rockauto, but the price is more realistic.
And yeah... the 88 cradle "shelf" is different. Kind of strange how they mix-match the part for different applications, like that.
Unless it's used for the goofy uni-mount that 86-88 4 cylinder automatics used at the tranny end. One mount under the crank. One mount on the very far end of the trans. And a dog bone. My old automatic 88 Duke used to beat hell out of my trunk wall.



Yeah, my daughter wanted to be a bit more unique with her Iron Duke, and I was only too happy to go along with it, so we've been trying to make it run as smooth as possible. We almost used the 88 engine we had, because it actually came with the balance shaft, and then we wouldn't have had to "convert" her 85's engine to serpentine... but she wanted to keep the original motor.

I have to say, it runs pretty damn well. We had them balance it, but also found an original Grand Am harmonic balancer, and as many other things as we could find to help the engine run more smoothly. It's really quite decent. But yeah, we were hoping we could use the "hydraulic" motor mount too... but it didn't fit the subframe. Oh well...



quote
Originally posted by TakeTwo:

My buddy has a 15$ ebay 3rd party mount in his '86 4 banger and i asked what the mileage on it is since he installed over 19k miles its very smooth riding car.

I guess the F.S. has the last of he OEM stock hence the pricing? I'd def just get the solid mount or something from Rodney if he still sells them.



Yeah, we were hoping to upgrade to the nicer motor mount, but we just went with the stock solid rubber replacement one. Thanks!