High Performance Tranny Mount Bushings

[Kentetsu]

I replaced my tranny mount with another stock unit a couple of years ago, but I was still not happy with the results. The amount of movement in the shifter between gas on/gas off was considerable, even though my motor mounts were also new.

In addition to this, while performing very fast shifts from 1st to 2nd gear in autocrosses, the movement would sometimes throw me off a bit. I've put up with it for a couple of years now, but finally got fed up enough to do something about it.

Enter Ryan from Shook Motorsports ( http://shookmotorsports.com ) They are now offering performance bushings for the FB tranny crossmembers, so I thought I'd give them a shot. I'm very glad that I did!

The bushings appear to be of high quality, and the price is right since they are cheaper than the cost of a new tranny mount and perform better than stock.

Installation: There are two types of FB tranny mounts, and while either version is a simple install, the older type is easier than the newer. With the old type, the bushings are not actually inserted into the mount, so removal and installation are very straight forward. With the newer style, the old bushings will have to be pressed out, and the new ones pressed in (easy).

Although I installed the new bushings using the old type of mount, I'll also walk through the procedure of removing the stock bushings from the newer mount as well.

First off, here's a shot of the bushings and hardware I received from Shook Motorsports:

[Kentetsu]

...and now, on to the installation.

Once the car is up in the air, support the tranny with a jack and a block of wood (the camera was tilted, not the jack :

[Kentetsu]

Now, to get at one of the bolts that hold the tranny mount onto the chassis, you may have to remove a section of the exhaust shielding. I used an angle grinder and cutoff wheel to cut a notch out of that area years ago, and it has been a huge timesaver ever since. I highly recommend this minor mod.

You can just make out the notch, right above the presilencer in this photo:

[Kentetsu]

Pressing out the bushing on newer type of mount:

I used a vice and a combination of one large, and one small socket to press the stock bushing out.

Once that was done, I was left with some rubber residue in the mount, so out comes the torch and a drill mounted wire brush to clean things up:

[Kentetsu]

Here's a few shots showing the difference between the two types of mount. Make sure you know which version you have when you place your order

[Kentetsu]

And here are a couple of shots showing the placement of the new bushings, using an old style mount:

[Kentetsu]

And finally, the finished product reinstalled on the car:

[Kentetsu]

The results:

Since the installation I've participated in three autocross events. Shifter movement is noticeably reduced, and (this is a seat of the pants gut feeling) it seems that the shifts are slightly quicker and more accurate.

In daily driving I have not noticed any increase in vibration. And the shifter movement from gas on/gas off has been greatly reduced. Everything just feels a bit tighter all around.

Overall I'm very happy with this (albeit minor) upgrade and the improvements that have come from it. So if you are are looking to tighten things up in this manner, I have no problem recommending these bushings to you.

And I'd like to thank Ryan for putting up with all of my stupid questions along the way. Despite all of my attempts to make this more difficult than it turned out to be, he was very patient with me and was of great assistance.

[j_tso]

Thanks for posting this, I'm going to replace the big block tranny mount and will probably put these bushings in while it's all out.

I'm sure if the big block was made out of delrin or polyurethane there'll be more vibrations.

[PercentSevenC]

Hmm... interesting. I'd been thinking of trying a stock tranny mount with a bolt through it to try to reduce the movement, but this seems like an altogether better idea.

[Kentetsu]

Thanks guys. While this is obviously not a huge mod, I'm still very happy with the results.

I mean, why replace with stock when there's a better option at an even lower cost? I think you guys will like this.

[Jeff20B]

Mazda's competition motor mounts, which provide a 40% increase in stiffness over stock, really should be considered first if shifter, and therefore engine+tranny movement is offensive. Next stiffer option are hockey pucks which are closer to 60% increase. Anything after that is really very stiff, and if your engine has any natural vibrations (such as rotors not within 10 grams of each other, flywheel or pressure plate not quite perfect etc), the vibrations can actually wear down the threads inside your front cover where the front mount bar bolts thread in to the aluminum.

If you prefer stock motor mounts, get yourself the RB torque brace.

Tranny mounts really should be considered as secondary to motor mounts, I think.

[Kentetsu]

Good point Jeff. The thing is, I was looking for a way to reduce the shifter movement without increasing the transmission of the engine vibrations. A 40% increase in motor mount stiffness would no doubt add at least 40% more vibration into the chassis.

That's why I was glad these mounts showed up. Since they sit on the outboard ends of the tranny mount, they can increase stiffness without a noticeable increase in vibration. So far I'd say these things have hit the nail on the head.

[orion84gsl]

I have an RB torque brace no longer being used. Hint, hint.

[Kentetsu]

Originally Posted by orion84gsl

I have an RB torque brace no longer being used. Hint, hint.

My first thought would be, if it's so great why aren't you using it anymore?

I hope you can make the Lansing race Chris, can't wait to see the ride...