Innovative Mounts 06-11 Civic Si Rear Engine Mount K-Series

Innovative Mounts 06-11 Civic Si Rear Engine Mount K-Series - Part #90830

The factory rear mount on an FG2 or FA5 Civic Si is the first one to let go. It is a hydraulic mount with a rubber center that splits, and once it does you get wheel hop off the line, a clunk on throttle transitions, and a K20Z3 that rocks back far enough to load the axles. This is the rear mount out of the Innovative 90850 kit, sold on its own so you can replace the mount that actually failed instead of buying four.

What It Is and Why It Works

It is a steel mount with a tapered polyurethane bushing pressed into it, built to bolt into the stock location with factory hardware. The bushing does not tear the way OEM rubber does, and because it is solid poly instead of a fluid-filled hydraulic mount, the engine stops moving under load instead of moving and then catching. On a stock or lightly modified K20Z3 the 75A is what you want. Once you are into a built motor, boost, or regular track use, step up to the 85A. The 95A is for drag and dedicated race cars where noise is not a consideration.

Durometer choice is the whole decision here, and it is the one people get wrong. Every poly mount transmits more vibration than the rubber one it replaces. That is not a defect, it is the trade you make for a drivetrain that stays where you put it.

Specs

Available Options

Fitment

This is the 8th gen Si mount only. It does not fit the non-Si 06-11 Civic with the R18, and it does not fit the 12-15 FB Si.

What to Know Before You Buy

Check the rest of the mounts before you bolt this one in. On a car with 100k miles the rear mount usually fails first, but the passenger side mount and the front torque mount are rarely far behind, and mixing one fresh poly mount with three tired rubber ones moves the problem rather than fixing it. If two or more are shot, the 90850 kit is the better buy.

Pick your durometer for how the car gets driven, not for how much power you want to claim. A 95A mount in a daily driven Si will buzz through the shifter and the seat at idle and on the highway, and that is the number one reason people pull poly mounts back out. If the car sees street miles, stay at 75A.

Install is a bolt-on in the factory location using stock hardware, but support the engine with a jack and a block of wood before you pull the old mount, and torque the bolts with the weight of the motor back on the mount, not hanging from the jack. Once a mount has been bolted down it carries impressions and cannot be returned, so confirm fitment before you put a wrench on it.