HPI trans mount
Le Mans Master
Joined: Oct 2008
Posts: 8,891
Likes: 981
From: Whitby Ont.
Le Mans Master
Joined: Oct 2007
Posts: 9,683
Likes: 3,437
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
I have nothing to compare to other than stock mushy rubber, but with the AMT engine and diff mounts there is some noise, but no where close to helicopter sounds. There is less rubber and its stiffer rubber so more noise and vibration is to be expected. The main thing I notice now which I didnt before is that between 65-85mph on the highway I can hear the gears in the trans whining a little (think old school trans am race car with straight cut gear whine, but not as loud). It only happens on maintenance throttle, not accelerating or decelerating. I also notice the sound of the drive shaft spinning if I stop at a light and let the clutch out with the car in neutral. Both sounds go away though with the radio on, so its really not THAT noticeable.
Le Mans Master
Joined: Oct 2008
Posts: 8,891
Likes: 981
From: Whitby Ont.
I have nothing to compare to other than stock mushy rubber, but with the AMT engine and diff mounts there is some noise, but no where close to helicopter sounds. There is less rubber and its stiffer rubber so more noise and vibration is to be expected. The main thing I notice now which I didnt before is that between 65-85mph on the highway I can hear the gears in the trans whining a little (think old school trans am race car with straight cut gear whine, but not as loud). It only happens on maintenance throttle, not accelerating or decelerating. I also notice the sound of the drive shaft spinning if I stop at a light and let the clutch out with the car in neutral. Both sounds go away though with the radio on, so its really not THAT noticeable.
Le Mans Master
Joined: Oct 2007
Posts: 9,683
Likes: 3,437
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Yeah, vibration and ride are like asking for best tire and oil. Its all subjective really. My car is focused on track use (delrin bushings, loud exhaust, stiff shocks, etc) without losing too many creature comforts (AC, radio, nice interior). The extra vrbration to ME was minimal and something I could live with. May not be the case for everyone.
Drifting
Joined: Feb 2002
Posts: 1,630
Likes: 125
From: Park Ridge Illinois
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
No Hostility Be Happy
Joined: Aug 2018
Posts: 10,068
Likes: 7,387
From: South Hill Wa
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
I just ordered an HPI. I would like to have tried the AMT but it's just priced out of my range right now. Especially since I already have the AMT engine mounts.
Will definitely report back if there are annoying noises or harshness.
Will definitely report back if there are annoying noises or harshness.
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Melting Slicks
Joined: Nov 2016
Posts: 2,305
Likes: 1,581
From: East Metro (Twin Cities) Minnesota
St. Jude Donor '21
I have had mine for over a year. Plenty of seat time. I do notice a little gear noise at certain RPM, perhaps a tiny bit of vibration but a lot less movement and much less drivetrain shake if I break em loose - in situations where previously I would have had much more.
I would do it again!
T4L
I would do it again!
T4L
Le Mans Master
Joined: Jul 2007
Posts: 6,094
Likes: 3,467
From: Oswego IL
Finally got an HPI diff mount. Going to put it on when we install the coilovers soon. On stock suspension with my Hankooks, the driveline bounce is BAD, even when hitting the throttle from a low roll. Hoping the new mount combined with the coilovers will help tame things down.
Drifting
Joined: Nov 2019
Posts: 1,265
Likes: 381
From: SC
How do you like the AMT engine mounts? I have them but haven’t installed them yet.
No Hostility Be Happy
Joined: Aug 2018
Posts: 10,068
Likes: 7,387
From: South Hill Wa
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
They're not as bad as I expected them to be vibration wise. They are as close to being a solid motor mount without being a solid motor mount.
The reality of it is for me I think I prefer the stock mounts for all around driving enjoyment but I needed a good quality short mount that won't melt for my engine/blower/hood combination.
My wife drives this car as well on occasion and she has not complained about it so it's really not too bad.
I will also say they are a major pain in *** to install. Especially if you have headers. Plan on dropping the cradle down. Just bite the bullet. You will be done way faster. Once I did that I had them installed in like a half hour less reassembly.
Drifting
Joined: Nov 2019
Posts: 1,265
Likes: 381
From: SC
They're not as bad as I expected them to be vibration wise. They are as close to being a solid motor mount without being a solid motor mount.
The reality of it is for me I think I prefer the stock mounts for all around driving enjoyment but I needed a good quality short mount that won't melt for my engine/blower/hood combination.
My wife drives this car as well on occasion and she has not complained about it so it's really not too bad.
I will also say they are a major pain in *** to install. Especially if you have headers. Plan on dropping the cradle down. Just bite the bullet. You will be done way faster. Once I did that I had them installed in like a half hour less reassembly.
The reality of it is for me I think I prefer the stock mounts for all around driving enjoyment but I needed a good quality short mount that won't melt for my engine/blower/hood combination.
My wife drives this car as well on occasion and she has not complained about it so it's really not too bad.
I will also say they are a major pain in *** to install. Especially if you have headers. Plan on dropping the cradle down. Just bite the bullet. You will be done way faster. Once I did that I had them installed in like a half hour less reassembly.
1st Gear
Joined: May 2008
Posts: 1
Likes: 0
Has anyone had issues with these causing extreme drivetrain noise at about 2.5k-3k rpm? The mount does its job, definitely a driving improvement but just cruising it sounds like a Huey helicopter is landing on top of me at certain RPM. Everything is tight and both pads are making contact with the crossmember.
Melting Slicks
Joined: Nov 2016
Posts: 2,305
Likes: 1,581
From: East Metro (Twin Cities) Minnesota
St. Jude Donor '21
Just curious if you found any kind of solution, either modification to mount or different mount. I just installed the HPI mount and I am having really bad vibrations in the same RPM range (2.5k-3.5k). I'm really torn because the driveline shake is now gone (woo hoo!), but this vibration is so bad it feels like it could cause other damage to the car.
The problem: Big soft squishy rubber engine mounts (2) and the stock squishy (1) rear diff mount really do isolate almost all engine, torque tube, transmission and differential noise and vibration from the passenger area very nicely. All of these systems are mechanical devices that by default vibrate and transmit noise. NOTHING does nearly as good of a job as the stock squishy mounts at isolating the noise - but under hard use - they deflect ALOT - which sucks.
Screw the magnetic shocks - GM, develop some magnetic mounts PLEASE. FIRM when you hammer it, soft when you're Cruising!!
Toys
Drifting
Joined: Aug 2003
Posts: 1,994
Likes: 1,330
From: Des Plaines, Il
6th Gear
Joined: Dec 2022
Posts: 6
Likes: 0
yeah I can see that. I'm not a fan of the amt stuff on street cars. I have hinsen mounts. I'm 900-1000whp and would love to get the hpi mount, but the nvh people are talking about makes me wonder if they're using it with stock motor mounts which are leaning on the hpi mount really hard or something causing the helicopter noise.
Drifting
Joined: Sep 2017
Posts: 1,961
Likes: 693
From: Avon Lake OH
I have Hinson 3/8" shorter motor mounts along with the HPI mount (has able to modify the factory bracket so I could keep the mass dampener donut on the drivers side of the differential. The engine is basically a warmed over LS6 (+400 RWHP). I have a TMOD shifter box with poly bushing and a Hurst shifter. The flywheel/clutch is a factory stock LS3/LS7 unit. I also have a full set of aFe/PDAFT poly suspension bushings as well as stock Z51 springs and DRM Bilstein B8 shocks. I run 275/295 tires on 10/11" wide 18 rims. Yes there is some vibration and noise that gets transmitted into the chassis from all these changes. Is it bad, no. Is it tolerably, yes. If this was a long distance highway cruiser would it get annoying, most definitely YES! But that isn't what my car was built for, its as close to a dual purpose GTS coupe as possibly, ready for use on fun to drive roads, some street use as well as track day events. As always YMMV.