MFactory B Series Transmission Shaft Brace Cuff for B16/B18

MFactory Infinitude Shaft Brace Cuff (MFT-INF-TRS-13B) - B-Series

At serious power levels, the problem stops being the gears themselves and becomes the shafts they're mounted on. Heavily loaded gears create radial loads that push the shafts apart, and once that starts happening you get gear alignment problems, accelerated wear, and eventually failure. This MFactory shaft brace locks the shafts together so they can't separate, while still letting them spin freely as designed.

Read This First: It Replaces Fifth Gear

The most important thing on this page. The shaft brace mounts in the position fifth gear occupies, which means you lose fifth. Reverse is retained, so you can still back the car off a trailer or out of a pit box.

Losing fifth isn't a drawback, it's the design. The end of the shaft is the only place you can brace them effectively, and fifth gear is what's there. Trading it for shaft support is the deliberate choice you're making.

So this is for a car where losing fifth doesn't matter. Drag cars, dedicated race builds, and anything that never sees a highway. If your B-series still gets driven on the road, this isn't the right part regardless of how much power you're making.

What Radial Load Actually Does

Worth understanding, because it explains why this exists.

When gears transmit torque, they push against each other. That force acts to separate the shafts they're mounted on, and it scales with how much power you're putting through them.

At stock power, the case and bearings handle it fine. At high power, the shafts deflect enough that gears no longer mesh at the angle they were designed to. Tooth contact shifts to the edge instead of across the full face, load concentrates where it shouldn't, and gears start failing in ways they wouldn't at lower output.

The brace ties the shafts together at their ends so they can't move apart. Gears stay meshed properly, contact stays where it should, and the transmission survives loads that would otherwise be tearing it apart.

Pairs With A Gear Set

This makes the most sense alongside a 1-4 gear set, and the timing is why.

Synchrotech's Pro Series 1-4 sets cover first through fourth and let you either reuse your factory fifth gears or replace them with this brace. If you're already installing gears, the transmission is fully apart and fitting the brace costs you nothing in additional labor.

Doing it later means splitting the case again, which is the expensive part of any transmission job. If a brace is anywhere in your plans, do it while you're in there.

Fitment

1992-2001 B-series transmissions, including:

Acura Integra LS
Acura Integra GS-R
Acura Integra Type R
JDM Integra XSi and RSi
B16 hydro
1999-2000 Honda Civic Si

Part number MFT-INF-TRS-13B.

Who Should Run This

This is for the drag or competition B-series build where power has outgrown what the shafts can handle without help, and where fifth gear was never getting used anyway. It's a part for a specific kind of car, and on that car it's what keeps an expensive transmission together. Be certain you don't need fifth, fit it while the case is already open, and stop worrying about shaft deflection.

Fits: 1992-2001 B-series transmissions (Integra LS, GS-R, Type R, JDM XSi and RSi, B16 hydro, 99-00 Civic Si). Part number: MFT-INF-TRS-13B. Function: locks transmission shafts together to counteract radial load from heavily loaded gears. Important: replaces fifth gear, transmission becomes a four-speed. Reverse is retained.