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Motor Mount Repacement

belize1334

Well-known member
Joined
Nov 18, 2003
Messages
3,316
Location
Bozeman, MT
So I'm finally in a position where I have to bite the bullet and get some poly motor mounts. But, I've heard horror stories about the vibration from Prothanes and I'm not gonna shell out hte coin for Avid's 62A mounts.

I'm thinking that the solution may be to run prothane front, left right, and then leave the rear OEM. It seems like that way I'd get 90% of the benefit but without as much noise in the cabin. Has anybody run 3 of 4 mounts that would care to comment on their experience?
 

dsmer06

Well-known member
Joined
Feb 27, 2008
Messages
636
Location
Des Moines, IA
I ran 3 mounts for over a year. I noticed a little extra vibration, but I got used to that within a couple days. Even with all 4 mounts and no balance shafts I don't think it vibrates excessively.
 

gramkrakr89

Well-known member
Joined
Jan 25, 2010
Messages
308
Location
Bunker Hill, WV
Some people use prothane front & rear mounts and stock trans & side mounts...

The front & rear mounts are what control most of the engine "bucking", and they're attached to the sub-frame and front crossmember, not directly to the body... apparently leaving the trans and side mounts stock rubber helps keep the body-shaking vibrations to a minimum, while the prothane front & rear mounts stop the bucking.

quite honestly, I've run both kinds of mounts in 689, and the vibration wasn't all that bad after switching from all stock to all prothane... The vibration is more than most people would like to commute with every day, but it's totally acceptable for a vehicle that would actually need them...

I still run counter-balance shafts. /ubbthreads/images/graemlins/hsugh.gif
 

belize1334

Well-known member
Joined
Nov 18, 2003
Messages
3,316
Location
Bozeman, MT
I was under the impression that the rear mount was the biggest culprit for vibration. You think that the sides are worse? They're definitely gonna be poly so if the rear isn't a big contributor then I'll go for broke.
 

VR_IV_MR

Well-known member
Joined
Dec 4, 2007
Messages
283
Location
Queens, NY
Anyone have the durometer rating on the stock rubber mounts? Just curious of how it compares to the 62A, 75A, and 90A...
 

belize1334

Well-known member
Joined
Nov 18, 2003
Messages
3,316
Location
Bozeman, MT
Unfortuately the OEM mounts aren't solid so they're softer than the durometer rating of the rubber would imply. And I don't know the rating of the rubber... though I've heard the number 40a thrown around for OEM rubber mounts on other makes and models.
 

VR_IV_MR

Well-known member
Joined
Dec 4, 2007
Messages
283
Location
Queens, NY
Ok cool.. so 62A is still stronger than stock.


What about the power range for the different durometers?

For example...

Stock good up to 200whp
62A good up to xx whp
75A good up to xx whp
90A good up to 1k whp?
 

belize1334

Well-known member
Joined
Nov 18, 2003
Messages
3,316
Location
Bozeman, MT
Just got off the phone with prothane. They say 68A for their mounts. So that's stiffer than Avid's 62A but not as stiff as the 75A available from both Avid and Drop Engineering.

Avid says 62A is good for up to 400whp but that's a pretty narrow view of things. Technically even the OEM mounts will handle that... but the engine will roll like crazy. The question is, how much engine play can you stand for a given level of vibration in the cabin. And I'm still not sure which mount causes the most noise or if that's even a sensible question to ask...

Edit: I've also been doing a bit or research, mostly on Wikipedia, and it seems that in the range of 50A-80A, durometer rating is approximately proportional to the square root of elasticity. So, for example, you can figure that 68A is roughly 20% stiffer than 62A under a linear deflection...
 
Last edited:

gramkrakr89

Well-known member
Joined
Jan 25, 2010
Messages
308
Location
Bunker Hill, WV
As it is said... "Verily, if thou desireth to make for thyself an omelet, thou shalt breaketh a few of thine own eggs"

cabin comfort /ubbthreads/images/graemlins/uhh.gif engine stability
 

I have a poly mount in the front and the rest are nice stock ones. I am happy with it and the engine seems to stay nice and solid and there is little vibration in the chassis.
 

minneSNOWta

Well-known member
Joined
May 14, 2011
Messages
363
Location
Eagan, MN
Quote:
I put the stainless steel version in my GVR4 and I love them. My install went a bit easier than yours though cause I had them all installed in less than 1hr by myself. I'd recommend to anybody installing these to leave everything loose till they're all in position, then torque them down.

With new OEM mounts all around, my motor was moving so much that the driveline hit the exhaust mount bracket. With the Drop mounts, there's virtually zero movement and no more rubbing.



Quote:
I love mine! Got the stainless steel mounts with green bushings. My 2.3 used to flex my new OEM stock mounts so far that the driveline would hit one of my exhaust hangers. That's a thing of the past. I'm not even that unhappy with the vibrations that transferred to the engine bay. I have nothing good to say about Avid Racing as a whole so Drop Engineering is the only option for a replacement mount in my opinion.



Does anyone here use Drop Engineering mounts? I found the quotes above on "Tooners" by RvlutionMtrsprt who has a GVR4. The big "L" bracket seems to be shortened, but I am unsure about the compability with the front and rear mounts. Garfield had a post as well on "Tooners" listing them for 1G T/E/L and Galant 89-92. Emailed Drop to see if there is compability and they say they don't know anything about it.
 

ktmrider

Well-known member
Joined
Sep 10, 2007
Messages
3,124
Location
Portland, OR
^^ Yes the front mount bracket is different between the TEL and GVR4 vehicles. Search "344" for more info.

Inserts/bushings are the same tho.
 
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