In the past several months I have seen a number of “HOT ROD” 911s all complaining of various abnormal noises. These noises have been described as anything from cam chain noise, to 5th gear noise, to ring and pinion noise. Are all these cars just getting noisier? Are gear surfaces failing? Or are these owners just becoming less tolerant of an inherently noisy car? Well no, most likely not. All of these cars have shared one common factor. They all had solid engine and/or transmission mounts recently installed.
Solid 911 Engine Mount
In many of the cases, one pair was installed a month or so prior to the second pair, causing the gear noise to “become progressively worse”. In reality, the gear noise did not change at all. It was the insulation between driver and drive train that changed.
You might ask yourself why someone would intentionally install a device into his or her car that would make it so unbearable to drive? The answer is quite simple. Solid drive train mounting has many advantages; increased chassis rigidity, increased throttle linkage feel, more positive shift feel, indefinite mount life (no rubber to deteriorate), and low price (about $100.00 per set steel or aluminum).
The one sizable disadvantage, however, is the incredible increase in drive train noise and vibration. Such an increase for a dedicated racecar is not a real problem. For a car that serves a dual role as both street and track car, it can be a large one.
Fortunately there are two different compromise options between the soft stock mounts and the completely rigid, solid mounts. The first compromise is a factory mount known as the Carrera “CLUB SPORT” mount. It was designed for the Carrera “CLUB SPORT” option (M637). This car was essentially a lighter, high performance, stripped version of the standard ’87-’88 Carrera. The premise was to build a car that was set up for club racing right out of the box. This is the car where our compromise component comes from. The (M637) engine mounts are considerably stiffer than the stock mounts, yet still offer some sonsiderable dampening not available from solid mounts.
911 Club Sport Engine Mounts
So you’re thinking, ” A limited production racing part, it’s got to cost a fortune.” Well, sit down because you’re not going to believe this. The stock cushy motor mount part #911.375.043.00 lists for about $155.00. The (M637) “CLUB SPORT” mount part 911.375.043.07 lists for about $90.00 Yes, that’s right, twice the part, 2/3rds the price! A true Porsche rarity! These mounts will probably be the last ones you will ever have to replace.
The second option are WEVO semi solid mounts.
These are beautifully manufactured aluminum pieces with silicone type pillows as they call the that do the dampening.
These pillows come in two color/firmness levels. Blue is the original stiffer option and black is the softer option.
Either option lists for about $85 each.
As a side note solid mounts will cause severe running issues with carbureted 911s or 914/6 cars.
The vibration causes problems with the needle/seat float system and will cause the float levels to overflow.
So if you have just got to have the ultimate in rigidity, go out and buy yourself a set of solid mounts. If you want more rigidity but don’t want to feel as if you’ve been placed inside the drive train, try some club sport mounts or the semi solid mounts. After all, life is just a series of compromises, isn’t it ?
P.S. If you have a convertible you don’t need to upgrade to these mounts because the factory did it for you!