Here is a link to a Version 4.00 of the instructions (for tools made beginning Jan 1, 09).
Here is a link to Version 3.13 of the instructions.
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. Some numerical values, used in the clips, have changed with update to the tool.
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. 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 with the Porsche tool, you will get to an acceptable reading. You may still have to torque offset rollers and do a final check to be sure the tension is within the acceptable boundaries. Getting the hang of the P9201 requires a steady hand and 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.
What exactly comes with the 920X tool?
A tool body - that attaches to the 944 engine.
A machinist's 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.
Which Porsche models will this tool work on?
All normally aspirated and turbo 944s, 944S, 944S2 & 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 (a.k.a. guide rail). 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 identify an updated versus non-updated water pump.
How does the 920X compare with the P9201?
First the 920x only works for the cam and balance belt of the 944 and 924 cars mentioned above, 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. The P9201 is hand held and requires no set-up, the P920X must be mounted to the engine and a initial reference reading made.
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 deflection measurement can be made. That measurement represents tension. To get a precise measurement we need the gauge reading at two points. The first is an initial or reference point, shown in this sketch. In order to get that point, we must insert a reference bar. A reading with the bar gives us a reading that effectively represents no-deflection. Next, we know the distance from the reference point to the ideal tension point and we know the thickness of the reference bar, so we simply add the 0.173 to the reference reading to know the ideal setting. With that, 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.
A small diameter, cam belt roller is now used for better fitment with the engine.
Instructions have been improved (several times) and are now available as a downloadable PDF. Please feel free to review these instructions and become familiar with the tool BEFORE YOU BUY.
