Motor mount ???
Thread Starter
Le Mans Master
Joined: Apr 2000
Posts: 5,981
Likes: 0
From: Houston,Tx. USA
Motor mount ???
DUmb question....how da ya know if motor mount(s) are needed; all of a sudden I'm getting a lot of a vibration like motion from the front of the car at idle. It's a L-48, so it's not a huge cam, but feels like it; or feels like a bad miss; but the car seems to run pretty good.
Le Mans Master
Joined: Jun 2004
Posts: 9,289
Likes: 16
From: Skippack PA
St Jude Donor '13
Best thing to do is get up under and look at them. If they're split badly enough to cause the motor to jerk around there should be visible evidence. You could also watch the motor while somebody stomps on the gas for you, but the "how much" it moves is rather subjective.
If they're the original motor mounts since it's a fairly inexpensive and easy thing to do you might just want to replace them. Better safe...
If they're the original motor mounts since it's a fairly inexpensive and easy thing to do you might just want to replace them. Better safe...
Burning Brakes
Joined: Jun 2005
Posts: 764
Likes: 2
From: THE OLDER I GET THE BETTER I WAS! NORTHERN ONTARIO
Originally Posted by TheKomoman
You could also watch the motor while somebody stomps on the gas for you, but the "how much" it moves is rather subjective.
If they're the original motor mounts since it's a fairly inexpensive and easy thing to do you might just want to replace them. Better safe...
If they're the original motor mounts since it's a fairly inexpensive and easy thing to do you might just want to replace them. Better safe...
You might want to check the Transmission mount as well.
Burning Brakes
Joined: Sep 2005
Posts: 1,078
Likes: 0
From: Santee CA
If they look like they're torn or look compressed, it's probably time to replace them.
They can be replaced with polyurethane mounts, which might be a good idea if you've got a high torque engine; otherwise you might just tear them out again by putting a good load on it.
It's a relatively simple install; put a jack underneath it with a 2x4 on it to jack up the engine a bit when you go to take off the mounts; that should give you enough lift amount and enough surface area to get the engine up. The wood will also act a bit like a cushion so you won't mess up the oil pan when lifting.
They can be replaced with polyurethane mounts, which might be a good idea if you've got a high torque engine; otherwise you might just tear them out again by putting a good load on it.
It's a relatively simple install; put a jack underneath it with a 2x4 on it to jack up the engine a bit when you go to take off the mounts; that should give you enough lift amount and enough surface area to get the engine up. The wood will also act a bit like a cushion so you won't mess up the oil pan when lifting.
Le Mans Master
Joined: Jun 2004
Posts: 9,289
Likes: 16
From: Skippack PA
St Jude Donor '13
Originally Posted by G dad
You might want to check the Transmission mount as well.
I meant to mention that. The tranny mount on my 80 was separated. That explained the big thump though!
Race Director
Joined: Mar 2001
Posts: 11,601
Likes: 0
From: San Francisco CA
St. Jude Donor '07
I did this over summer!
Pretty much you power brake with the hood open and see how much the engine moves. If the mount is split, it's VERY obvious. I do like the poly mounts though. Very shiny and should last a whole lot longer than the rubber.
Pretty much you power brake with the hood open and see how much the engine moves. If the mount is split, it's VERY obvious. I do like the poly mounts though. Very shiny and should last a whole lot longer than the rubber.
Safety Car
Joined: Jun 2002
Posts: 4,738
Likes: 2,485
From: Buckeye, AZ
St. Jude Donor '12-'13
Another method to check we used to do years ago is to put the car in drive with the brake on and mildly brake torque it. You will see the engine twist up if the mounts are broke.
Burning Brakes
Joined: Sep 2005
Posts: 1,078
Likes: 0
From: Santee CA
Something I forgot to mention with Poly bushings:
Because the poly bushings are more firm, if you install them you will notice a little bit of vibration at idle, or at RPM just above idle (ie takeoff from a dead stop).
However, that takeoff is going to feel more solid with those polyurethane bushings, because more of the energy is being transferred into the frame for resistance.
Because the poly bushings are more firm, if you install them you will notice a little bit of vibration at idle, or at RPM just above idle (ie takeoff from a dead stop).
However, that takeoff is going to feel more solid with those polyurethane bushings, because more of the energy is being transferred into the frame for resistance.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski