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Experience with Vibra Technics Fast Road motor mounts
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1522
Location: Somerset, UK

PostPosted: Wed Mar 22, 2017 3:44 am    Post subject: Reply with quote

There must be another issue with your mounts or your engine needs balancing
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1980 931 - forged pistons, Piper cam, CGT turbo, 951 ducted FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife LSD
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Johann  



Joined: 07 Aug 2016
Posts: 163
Location: Netherlands

PostPosted: Wed Mar 22, 2017 7:38 am    Post subject: Reply with quote

A toofah and balancing....aren't those two words mutually exclusive

But seriously, the motor does not vibrate. I actually had the same thought as you, but when I laid my hand on it it was very "calm" with almost no vibration. No more than any other engines I work on. But when I laid my hand on the chassis and suspension struts I could feel vibration. I got the feeling that it was caused by sympathetic vibration or that the mounts amplify vibration.

Above 3k RPM they were actually OK, but below that it was a disaster.
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1522
Location: Somerset, UK

PostPosted: Wed Mar 22, 2017 7:27 pm    Post subject: Reply with quote

I'm not defending the Vibratechnics. I have too many other solid and poly mounts. With a loud exhaust and no sound insulation my whole car vibrates and is noisy. Its too hard to pin point the problem to one item when they all contribute.

I do some 400-600 km journeys. In fact I've done over 1500kms in the last month. But I do use Bose noise cancelling headphones on some.
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1980 931 - forged pistons, Piper cam, CGT turbo, 951 ducted FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife LSD
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CÚdric  



Joined: 27 Aug 2004
Posts: 1663
Location: Sweden

PostPosted: Wed Mar 22, 2017 7:36 pm    Post subject: Reply with quote

You should have listened to my advice .

If you were in contact with VT didnt they have the possibility to make even softer rubber inserts?

I definitely feel a big difference with the VT mounts, not only in lots of vibrations but the drive train response is much better, you notice it alot in autocross when you go on/off trottle all the time to balance the car.

As I wrote before, I probably will go back to modified stock mounts instead, since I want to increase streetability a little bit.
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ideola  



Joined: 01 Oct 2004
Posts: 15486
Location: Woodstock IL

PostPosted: Thu Mar 23, 2017 1:19 pm    Post subject: Reply with quote

I have them on a couple of my cars that I drive on the street. The Club Sport is a harsh beast, and completely stripped out, so not easy to tell there. The 941 is much heavier due to the factory 941 body panels. It has all stock rubber suspension bushings and all of its sound deadening, but it has VT fast street motor mounts. I also have solid brass bushings in the G31 universal coupler, and THAT can be annoying as hell. But I don't have a problem with the motor vibration that you describe.

Both of these engines are highly modified and internally balanced. What I've found from building and prepping several of these is that there is a high degree of variance across individual OEM components, as well as from one motor to the next. Steve may be on to something...maybe your motor is "unbalanced enough" in OEM form that the VT mounts amplify some resonant frequency. I just don't have that problem on the two motors I am running on the street, and it could explain why some people don't report as much of an issue.

Then, there's also personal preference. I don't use any of my cars anything like a daily driver, so I don't really care about the creaks and groans and rattles. It's a 40 year old car, and when I drive it, I'm too busy enjoying the driving experience to worry about whether the car is silent. But I could see where certain things (like the shifter buzz in my 941) would be annoying for long distances or regular use.
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