ST170 MTX75 Gearbox Conversion

We constantly get asked about our 5 speed MTX75 gearbox conversions on the ST170. This time we thought we would do a write up with various pictures highlighting the differences and issues faced.

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The vehicle in question is a 2004 ST170. These come with a 6 Speed Getrag gearbox and Dual Mass Flywheel (DMF). Being a 2.0 Zetec there is no real reason to have a DMF, and we suspect this was Ford's way of capping performance to create a market for the 'ST' badge when compared to the 'RS'.

The regular 2.0 Zetec runs a much better ratio gearbox, the very strong MTX75. Along with a solid flywheel. So even from the Ford parts bin, you dont have to spend a fortune replacing the original ST170 DMF & Clutch.

First we removed the ST170 Gearbox, Clutch and Flywheel

Next we compared the 2.0 Solid Flywheel to the ST170 DMF. Showing the difference in depth. We also took note of the difference in flywheel bolt size, the bolt on the left is 2.0 zetec, the bolt on the right is ST170 DMF.

The 2.0 Solid Flywheel bolts straight to the ST170 engine with clearance to the crank sensor as expected. Use the original 2.0 zetec solid flywheel bolts. Again, the 2.0 zetec clutch must be used due to different input shaft size on the MTX75. The original 2.0 or ST170 clutch bolts can be used.

Next we took the MTX75 and Getrag and sat them together to show the size difference and mount differences

As you can see from the pictures, the MTX75 is actually much bigger despite being 5 Speed. The gearbox mounts are completely unique to the gearbox so you require the MTX75 mount when carrying out this conversion

As you can see in the above picture, the ST170 slave cylinder is the same bolt pattern as the MTX75 slave cylinder.

The MTX75 will bolt up using the same bolts as removed from the Getrag. Using the MTX75 gearbox mount the gearbox will bolt back up the the vehicle as before. You will notice the powersteering pipes will be very tight around the back of the gearbox, due to the MTX75's additional depth. Routing the pipes diagonally over the back of the box gives enough clearance.

Next its on to the driveshafts. We compared the size difference between the ST170 shafts and 2.0 zetec. They are completely different both in length and spline size gearbox end. The hub end is the same, but as shown in the picture, the ST170 tripod bearing is larger than the 2.0 zetec so will not fit in the tripod housing. (Note: A 2.0 Zetec Tripod bearing will fit in an ST170 Tripod Housing)

So for this conversion the MTX75 driveshafts must be used. We also noted the centre bearing carrier is in a different position. So you also need to fit an MTX75 long driveshaft centre bearing carried in order to fit the o/s driveshaft.

Two final points you will find in this conversion is the difference in reverse light switches, both in location and length. The ST170 is longer and has a triangular plug. The MTX75 is shorter and this particular one doesnt have a triangular plug. We will be offering an adaptor kit for this shortly. Email 8BallTuning@mail.com for info

The 2nd point is the speedo pick up, again located in different places, but use the same sensor and plug, so its a direct plug and play. The only difference is the sensor location on the MTX75 is right next to the ST170 exhaust. Its down to your own discretion if you fit a small heatshield to it.

In order to utilise the 5 Speed gearbox you need to use the MTX75 gear cables because it has lift up reverse. The ST170 cables will physically fit, but not operate correctly. Its only 4 nuts under the gearlever to remove and two on the cable bracket.

So there you have it, the inexpensive way to avoid DMF repair bills, increase performance and driving feel. Keep your MTX75 in good health with oil changes every few years (Depending On Use) and it will take most things you throw at it.

Uprated Gearbox Oil Available Through Us

Full Conversion Available As A Drive In Drive Out Option

Contact Us On 0345 548 8801