Instructions

Here is a link to Version 3.13 of the instructions.

Video Clips

See video clips to show how to the 920X works.

Tensioning a Cam belt Part 1, Part 2, Part 3, All clips combined.

Tensioning a balance belt Part 1, Part 2, Both clips combined.

Note on the video clips: These short clips will walk you through the steps of using the tool. Many more details, photos and information are provided in the printed instructions that come with the tool. The clips are really just to give you an idea of how the tool works. 

Overview

I created this tool as an alternative to the Porsche's P9201. The P9201 is a well designed tool and can be used to tension both the timing belts and the accessory belts on your 944. It's real advantage is that it is compact and can be used on a variety of applications.

My tool (920X) can be used only to tension the cam & balance belt on your 944. But in a couple of ways, my new tool is better than Porsche's tool. Aside from price, the big difference with my tool is that you can dynamically set your belt's tension. With the Porsche tool, you make a guess at the correct tension setting and then use the tool to measure or verify. After several attempts you will get the correct reading. You may still have to torque offset rollers and do a final check to be sure the tension is still correct. Getting the hang of the P9201 is not difficult but there is some technique required - getting consistent readings with the Porsche tool might be more difficult than you think.

With my tool, things are simpler. Once mounted and calibrated to your engine, just read the gauge and set the belt's tension. Torque the rollers while looking at the gauge. One time, done. That's it. You can even monitor the belt's tension while you make the final torquing of the rollers. You'll be surprised at how sensitive the tool is and how precisely the belt must be set to be correctly tensioned.

FAQS

What exactly comes with the tool?

A tool body  - that attaches to the 944 engine. A gauge that attaches to the body. A fixture that also can be used to attach the tool to the engine - for tensioning the balance belt. Two reference bars - used to take initial readings of the cam belt and of the balance belt. Attaching hardware needed for using the tool on the two belts. A few illustrated pages of instructions.

Which models will this tool work on?

All normally aspirated and turbo 944s & 924S's. Important note: the 920x attaches to the cam belt separator bar. Some of the early cars did not come with the separator bar. After 1986, the separator bar was standard equipment but for earlier cars the bar was added by Porsche to updated water pumps. Any time a pump was changed, the new "updated" pump was to be installed. Most of the older water pumps have disappeared but occasionally one still surfaces. If you are not sure, its best to check your engine before you buy the tool. Here is a link to help you know how to do that.

How does the 920X compare with the P9201?

• First the 920x only works for the 944 cam and balance belt, the P9201 does all belts and for other cars too.

• The 920X costs approximately $150, the P9201 costs over $600.

• The 920X comes with a reference bars, the P9201 requires a calibration bar which costs an additional $45.

• Overall ease-of-use is about the same.

• Consistency of reading is about the same, although P9201 technique is critical and usually requires some  practice to get consistent readings.

How does the 920X work?

The 920X has a small internal spring and an extending rod. When mounted, these parts deflect the belt and a measurement can be made. That measurement represents tension. To get a precise measurement we need the gauge reading at two points. The first is the reference point, shown in this sketch. In order to get that point, we must first insert a reference bar so that we can get a stable reading. The reference bar adds a small amount to the reading but that will be adjusted for. Next, we know the distance from the reference point to the ideal tension point and we know the thickness of the reference bar. For a new cam belt (and the 920X's internal spring), this combined value is 0.173 inches.  We simply add the 0.173 to the reference reading to get the ideal setting. We then remove the reference bar and adjust the belt’s tension until we read the ideal setting. 

 Has the 920X changed since it was originally offered?

Yes, a number of improvements have been made:

•  Spring perches have been improved.

•  Bearings have been upgraded.

•  E-clips are now used in all locations making disassembly possible.

•  A thumbscrew is now employed to capture the gauge in the body.

•  Instructions have been improved several times and are now available as a downloadable PDF.