Transmission Mount
Buyer's Guide

The transmission mount is the small block of rubber or urethane between the tail of the transmission and the crossmember. Its whole job is to locate the back of the drivetrain and soak up the torque twist and vibration so it never reaches the floor pan. It is one of the cheapest parts on the car and one of the most ignored, right up until it tears and the driveline starts slamming on every shift.

Two questions decide which mount you buy: do you want stock comfort or do you want the drivetrain held tight, and how much power and abuse is the mount going to see. The first picks rubber vs polyurethane. The second decides whether a stock-style mount is enough or whether you step up to a performance mount. Everything else is fitment to your exact vehicle.

Polyurethane vs Rubber — The Decision Tree

Rubber (OE-Style) Transmission Mounts

The factory mount is bonded rubber. It is soft, it isolates vibration well, and the cabin stays quiet and smooth. The tradeoff is that rubber is compliant, so under hard torque the drivetrain moves more, and rubber degrades: it dries, cracks, gets oil-soaked, and delaminates over the years. For a daily driver where comfort matters, a quality rubber mount is the right call.

Buy a rubber mount if: it is a daily driver or family vehicle, you want the quietest and smoothest ride, and you are just replacing a worn-out original.

Polyurethane Transmission Mounts

Polyurethane is much firmer. It holds the drivetrain far more precisely, resists oil and heat better than rubber, and lasts longer under abuse. The tradeoff is honest: poly transmits more vibration and noise into the cabin, so you will feel and hear more of the drivetrain, especially at idle and low rpm. For a performance car, a truck that tows, or anything that has torn a rubber mount, poly is the upgrade.

Buy a polyurethane mount if: you make more power, you race or tow, you are tired of replacing torn rubber, or you want the drivetrain held tight for cleaner shifts.

There is a middle path: many poly mounts come in different durometers (hardness). A softer poly gives most of the durability with less buzz than a race-hard one. If you daily the car but want it to hold up, a mid-durometer poly or a poly-filled OE-style mount is the compromise a lot of people land on.

Signs Of A Bad Transmission Mount

A failing mount is one of the most common causes of a driveline clunk, and it is cheap to confirm. Watch and listen for these:

• Clunk or bang when shifting into gear (drive or reverse) or when getting on and off the throttle. The torn mount lets the drivetrain lurch and slam.
• Driveline vibration that gets worse under load or at certain speeds, because a collapsed mount changes driveshaft angle.
• Thunk over bumps or during hard braking as the unsupported trans tail moves and taps the crossmember.
• Visible cracks, tears, or separation in the rubber, or a mount that is soaked and swollen with oil.
• The drivetrain lifts noticeably when a helper eases the vehicle in gear and you watch the mount from below. Movement is normal, but a big jump means it is done.

The quick shop test: from underneath, put a pry bar on the trans tail and gently lever it while watching the mount. If the two halves pull apart or the rubber is split, replace it. Also check the mount bolts, a loose mount mimics a bad one.

Rubber vs Poly — Side By Side

Browse rubber transmission mounts

Browse polyurethane transmission mounts

When To Upgrade For A Performance Build

Stock mounts are tuned for stock power. Add torque, sticky tires, and hard launches and a soft rubber mount lets the drivetrain rock enough to change driveshaft angle, load the U-joints, and even yank on shift linkage. That is the point to step up.

• You added real power or a stall converter. More torque twist means the mount works harder. Poly holds it.
• You launch hard or race. Repeated shock loads tear rubber. A firm poly or a reinforced mount survives it.
• You tow or haul heavy. Sustained load and heat cook rubber. Poly resists both.
• You keep tearing stock mounts. If you are on your second or third rubber mount, stop buying the same part and step up.

One caution: do not go straight to the hardest race mount on a street car and then complain about the buzz. Match the durometer to how you actually drive it. A mid-hardness poly is usually the sweet spot for a street-and-strip build.

Check performance transmission mounts

How To Choose By Vehicle

Transmission mounts are application-specific. The bolt pattern, height, and stud spacing all have to match your transmission and crossmember, so a mount is not one-size-fits-all. Before you buy:

• Match the exact transmission, not just the vehicle. A truck can leave the factory with more than one transmission, each with its own mount.
• Confirm stud vs bolt-hole style and the spacing. Some mounts use a center stud, others bolt through.
• Check the height. A mount that sits taller or shorter than stock changes driveshaft angle and pinion angle.
• Buy the right hardware. Replace crusty mount bolts while you are under there, and torque them to spec.

Find a transmission mount for your vehicle

FAQ

Can a bad transmission mount really cause a clunk on shift?

Yes, it is one of the most common causes. A torn mount lets the drivetrain lurch when you engage a gear or get on and off the throttle, and that lurch lands as a clunk. Confirm it with a pry-bar check before replacing anything more expensive.

Will polyurethane make my car uncomfortable?

You will feel and hear more drivetrain, especially at idle. On a dedicated performance car that is a fair trade. On a daily driver, a softer-durometer poly or a good rubber mount keeps it livable.

Do I need to support the transmission to change the mount?

Yes. Support the transmission with a jack and a block of wood, take the load off, then unbolt the mount and crossmember. Never let the trans hang on the shifter or lines while you swap it.