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Dogbone transmission pendulum mount replacement - mk4 VW
Dogbone pendulum mount removal and/or new bushings
This page shows how to remove or rebuild the dogbone mount (pendulum mount) on a mk4 VW Jetta.difficulty: 2/5
The engine hangs from 2 engine mounts. One is on the transmission and the other is under the power steering reservoir. The 3rd engine mount, the pendulum mount, aka, dogbone mount, lets the engine rotate a little bit while holding it steady. You may want to replace the dogbone mount for a variety of reasons. The most common ones are: you just installed a downpipe and you're hearing a metal grinding/rubbing noise or you want to reduce wheelhop. A stiffer dogbone mount will reduce engine movement and will help reduce downpipe rubbing (the new bushings keep the engine from rotating as much) and reduce the possibility of wheelhop. The downside is that stiffer engine mounts transmit more vibration and noise to the cabin.
You could buy an aftermarket dogbone bushing kit which includes only replacement bushings or a replacement OEM-stiffness dogbone. These are normally poly mounts which are harder than rubber mounts. Another option is the 034 motorsports mount sold by 034 motorsports. The blue mounts the author originally had were about 90 durometer, the yellow Forge ones are about 70 durometer, the 034 motorsports rubber dogbone is about 50 durometer. The stock dogbone mounts are about 40 durometer and all other mounts will cause some more noticeable vibration.
Richard55 made his own stiffer dogbone mount by putting something solid inside the original dogbone mount rubber.
hydraulic jack and jack stands rated for your car
always replace bolts:
n 102 683 02 , n 905 970 05? or n 905 970 01? (long alignment plate bolt), n 102 466 03, available as a kit
new stock dogbone mount VW# 1j0 199 851 n
034 motorsports rubber dogbone mount
Raise the car, make sure it's secure on the jack stands, apply the parking brake and chock the wheels, and make sure it's safe before getting underneath the car.
Use a hydraulic jack to support the transmission. This helps with alignment and reinstallation. Make sure it's not carrying the weight of the car since the jack stands should be supporting the car.
Remove the black alignment plate first (2x 16mm bolts), then remove the dogbone mount (2x 13mm bolts).
If you are using a replacement dogbone then put the new dogbone on and see the last picture for torque specs. If you are installing a bushing kit then remove the 1x 16mm bolt compressing the bushings onto the dogbone.
The author used blue poly and yellow Forge bushings. Here is a comparison with the black stock bushings. The aftermarket ones are slightly taller than the black stock ones so you'll need to squeeze things together when you reassemble the mount. The author's comments on the blue bushings "The blue poly ones are stiffer than you could possibly imagine, and I wasn't even able to compress the 2 blue pieces into the dogbone mount. I ended up using the bigger blue bushing, and the smaller black stock bushing. This worked, but the car definitely gained some nasty interior vibrations." Yellow bushings "I ordered the Forge dogbone mount. They are softer than the poly ones (70 durometer rating) but definitely firmer than stock. The ride is beautiful! With my idle at 800rpm (more like 790), you can hardly tell a difference. You feel the engine a bit more, but it's definitely not intrusive. Plus, my wheelhop is almost completely gone (it's still there a wee little bit, but tonnes better than it was stock!). Also, my downpipe doesn't rub at all. If anything, I might loosen up the compression bolt to 10ft-lbs, just to smooth it out a little bit more."
On a diesel, I suspect that the idle roughness would be worse than on a gasoline engine. In other words, I would choose a stock dogbone or 034 motorsports rubber dogbone mount. Even the 034 motorsports rubber mount has been reported to give some additional vibration over stock since it's harder. In addition, you shouldn't drive in a manner to cause wheelhop. Wheelhop is when the tires quickly grip then let go, in a bouncing motion. It's caused by a combination of suspension, tire grip, and power. You can never power your way out of wheelhop so if you feel the wheels bouncing up and down rapidly, get off the throttle since wheelhop destroys drivetrains.
If they come with grease then lube up the bushing-metal contact areas. Put the smaller piece in first, and line up the 'grooves' in it with the ridges in the metal (the grooves go downwards).
There is a lopsided nut that goes into the end of the compression bolt. The lip on the edge of the head goes on the outside. If you put this nut in the other way, the compression bolt won't line up with the threads and it's not going to go in.
The compression bolt doesn't quite reach the little nut so you must squish the entire dogbone mount and then turn the compression bolt to get the threads to catch. This might work better in a vice but the author just used his body weight.
Torque the compression nut to 12ft-lbs, some blue loctite would help keep it in place. Pictured below is the replacement with torque specs (they are single use stretch bolts).
Here is Richard55's dogbone mount mod.
When I took the dog bone off the trans I thought I may as well, do a mod on it. You can pay big dollars for a upgraded dogbone that is stiffer than the stock one, but what if you could do the same or close for only $1.00 yes only $1.00. Here is how and it is easy. You can make it as stiff as you like. You can choose any color you want, I chose black as I think it will show less dirt. lol
Go to one of the big box stores and buy one square of industrial floor tile. This is all you will need in supplies. Get back home quick and get the sheet metal sissors out. You can use and exacto knife if you don't have the scissors.
This is a picture of the before and after mod. lol It looks the same as it looks the same lol. This is the after as it is clean.
Unscrew the thru bolt at the top of the dogbone.
Please have a good set of wood clamps handy as you will not get it back together with out something like these.
You are looking for the rubber part of the dogbone. Use this as the template for you inserts It has an indent on the bottom and this is where you will place your pieces of cut out tile.
Cut at least two pieces of tile to fit inside this piece of rubber. You can use as many as you like, the more you use the stiffer it gets. Less rebound on the rubber. I use two pieces as this is where I like the feel.
Now get the wood clamps out and squeeze it together and start the thru bolt. The capture nut that the thru bolt attaches to will go in two ways. Look at it prior to starting the mod. It will go in both ways but the bolt will only start when it is in correctly. So if you are cussing and can't get it started this is why. Now you are stiff again lol.
Finished mod all cleaned up and ready to install.