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25 September 2007

ECS Dogbone Mount Insert Installed

This particular part is available from several vendors. I preferred the one from ECS. because they include a new stretch bolt, where some of the other vendors don't. More on that below.





Unlike some of my other installations, I'm not going to do a step-by-step with pictures description of installing this part. The reason is that excellent documentation already exists from ECS (PDF). I'll just add some personal observations.

First, this thing is a lot larger than I had imagined it from pictures. I imagined it being about 3/4 as big as it actually is.

Second, it's a lot squishier than I anticipated. I thought it would be pretty much rigid, and was really surprised when I found how flexible it is. I thought, "you've *got* to be kidding - how can you push this in?" I'm not used to pushing things into a tight opening that aren't pretty rigid, no matter how much lube is involved.





With the car raised I removed the original bolt in the 'dogbone' mount. The original bolt takes a 21mm socket, and came loose much easier than I thought it should. I lubed up the insert, and lined it up on the rubber bushing. It started in pretty easily, then no amount of arm force would budge it. Time for Plan B.

Plan B was a hydraulic bottle jack. I set it against the edge of the insert and jacked it enough to push the insert in a few milimetres, then backed it off, repositioned and repeated. This worked great, and working in small increments got the whole insert firmly seated into the bushing.

The small washer goes INSIDE the hole in the insert, then the larger disk on top of it. The bolt supplied requires a 22mm socket.

If you're not familiar with stretch bolts, the idea is that the bolt is designed where the threads pull the bolt down and stretch the neck so that the head of the bolt applies extra tension against the fastening surface. It takes advantage of the tensile properties of the bolt, but at the same time it inherently weakens the bolt. Therefore, a stretch bolt must not be tightened more than spec, and must never be re-used.

The way a stretch bolt is tightened is with two separate steps: It's tightened to a specified torque value, and then 'angle torqued' for a specified amount. In the case of this bolt used in the insert, it is first tightened to 74 pounds-feet of torque, then it is rotated for an additional 90degrees (no more, no less) (expressed as 74 lbs-ft + 1/4 turn, or 74 lbs-ft + 90deg.) Tightening this bolt to 74 lbs-ft was easy enough with a torque wrench, but that last 90deg turn was a bitch. I wasn't taking any chances, so I coated the threads with LocTite Threadlocker (BLUE) before I assembled it.




Having installed the insert, I'm kicking myself for not having done it earlier. Seriously, it's the best $40 you can spend on the car. For anyone who claims that it increases any vibration, I have one question: "what are you, nuts?". This smoothed out everything quite noticeably. It idles smoother, and got rid of a lot of the lurching and generally crappy feel when starting off or shifting. When people say it improves the feel of shifts, it's not the actual 'shift' that feels any different, it's the clutch engagement *after* the shift that's improved. This is definitely $40-worth of value and improvement in feel. Now I'd like to do the full VF-Engineering engine mount kit, but I'm not sure that it has the same cost-benefit as just this insert alone.

I highly recommend this for anyone with a manual-transmission A3 (or GTI or GLI).

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