Here are informal video clips to demonstrate using our tension tool on a Porsche 944 Turbo.
Version 6.1 Cam Belt Tensioning Demo is a short (1.5 minutes / 40 MB) download that goes through the key steps of using the tool on a Porsche 944 cam belt.
Version 6.1 Balance Belt Tensioning Demo is even shorter (30 seconds / 25 MB) download that goes through the key steps of using the tool on a 944 balance belt.
Porsche 944 (all models/years including S, S2 & Turbo)
Unlike the other tension tools, we include printed instructions and have a download facility so that you have access to the latest changes. Yes, occasionally there are changes. Sometimes these have been corrections but mostly they are suggestions or clarifications that our users send to us to help support the 920X. Here is the link to see / download the most current version of the instructions - Version 6.183.
This link is the change log for the instructions. It has overview notes and is a general history of how the instructions have been revised.
Our tool is better - Earlier tension tools were not designed to give you a moment-by-moment reading of your belt tension adjustment. To use the Porsche recommended tool, you would guess/set the belt's tension, mount the earlier tool and then test the tension. If the reading wasn't what you wanted to see, you would remove the tool (dis-mount), adjust the tension and then re-mount the tool and re-test. This cycle of mount, test, dis-mount, adjust, mount, re-test... is maddening.
We wanted a different approach: pre-set the belt, mount the tension tool, read the gauge and adjust the belt's tension per the active reading on the tool. Remove the tension tool. Done.
Next there is cost. Our tension tool only $170 and we can ship it, from here in the United States, right away.
Most of the calibration work is done during assembly but this simple reference bar allows the customer to know the tool is ready to go. We provide it for free instead of selling as an add-on with our tool.
On the underside of our reference bar there is a hand-written number. That number is used to ensure the tool is calibrated. Its easy to do; just insert the bar as shown and rotate the gauges outer ring until the large needle points to the number.
Here we are re-tensioning a cam belt on a 944 turbo (the 87 & 88 turbo engines use a spring-loaded tensioner to assist with pre-setting the cam belt tension). Note that reading of x09 which is outside of the range for a used cam belt (x01 to x05). A number like this (larger than the acceptable range) means the belt is too loose. Now if we had trusted this engine's spring tensioner to set our belt we would have been well outside the Porsche tension specification. This problem is typical of the spring tensioners on the 87-88 engines, the springs get weak from fatigue and this contributes to belt failures.
Here we are adjusting the balance belt tension. The large gauge and range markers make it easy to read.
Make it easier to use - less setup time, minimize errors, no worksheets, no math, no on-engine adapters or attaching hardware.
Make it so that the user performs a short set-up, clips the tool onto the belt and adjusts the tension while looking at the gauge - no more adjust, then check; adjust, then check... that is needed with other tension tools.
Use off-the-shelf parts and get the price as low as possible.
Provide simple Reference Bar without any add-on to price.
Use precision pivot hardware and a spring that places deflection force over a greater range so tension can be adjusted moment-by-moment while reading the gauge.
Make it usable on 924S, 944NA, 944S1/S2, 944 Turbo, 968 (balance belt only).
Why does the applicability of this tool no longer include the 928?
Like any business, we are constantly adjusting our approach to the marketplace. In this case, we saw much greater interest in our tools from the 944 community than from the 928 crowd. So, we simply chose to focus more of our attention on our primary customer.
I just installed a new balance belt on my 944. I'm not yet very familiar with this engine so I put the 920X onto the belt and then began adjusting from the loosest possible setting. As I slowly tighten the belt, the large needle swings through more than a full rotation. Since the needle passes through the desirable deflection range more than once, how do I know which time is the one to use.
When we made our video we randomly chose a pre-set for the balance belt that was somewhere in the middle between too-loose and too-tight. As it turns out, this was closer to the too-tight side and in the video we just loosened the belt till the large needle first crosses into the range markers. Its usually that easy but we should have been more specific about our set-up.
This problem, and others like it, became known to us as "pre-set problems" and to address them we went through a few changes to our procedure. On the balance belt we suggest the the belt be pre-set to a point where it is obviously too tight. Then when the tension tool is placed on the belt the adjustment is to loosen the belt until the large needle first crosses into the range markers, just as the video shows.
For the cam belt, we devised a visual check that is done when the tension tool is first attached to the cam belt. We think of it as the cam belt "arch" and is shown in step 3 of the 944 cam belt procedure (also shown in the image below).
How can the acceptable ranges for a 944 balance belt (.x06 to .x14) be so close to the acceptable range for a used cam belt (.x01 to .x05) - we all know the cam belt is much tighter than the balance belt?
True, the tensions of the two belts are very different. But the tension reading is also affected by characteristics of the belt such as belt thickness, width, flexibility etc. In this case the thickness of the two belts are different.
You mention that a reading higher than the acceptable range indicates a loose belt. This seems backward, shouldn't higher tension be indicated by a higher reading number?
Yea, it does seem backward but remember we are measuring tension by applying a deflecting force and then measuring the deflection. If the belt is loose, the deflection will be greater, hence the greater number on a loose belt.
If I somehow damage some part of my 920X, can I get replacement parts?
Yes, we can provide replacement parts for the tool. Just contact me via email. Note; replacement of most 920X parts will require the tool to be returned to us for calibration set up - if you [original owner] pay the shipping, we do the work for free. We actually like to see our tension tools find their way back into our shop for an occasional tune-up or upgrade. We offer this at a very low cost.
No, it could be made to work that way but we wanted a simple rule concerning belts with nubs - if it has nubs, then the center roller must be inserted on the nub side of the belt, we also use a smaller roller to help avoid situations where a reading is inadvertently taken with the roller resting on top of the nub (instead of between them). In cases where nubs are on both sides of the belt and the tool will read the same now matter which way it is oriented.
Actually, the Porsche Workshop Manual (WSM) does do this at least for the 944 cam belt, but doesn't really describe what is happening. They say move the crank clockwise to TDC and then 1-1/2 tooth back. That backward motion is what moves the slack and that is critical. Without this step the acceptable ranges would be very small. But, reliably getting all of the slack to one span is the source for most errors. We wanted the user to see and understand the importance of this. Since our tool can provide a moment-by-moment reading, we can see and control this variable and thereby achieve more consistent readings.
On the 944 balance belt, the WSM does not mention moving the slack but we do in our instructions. We ask the user to grasp and pull on the upper span of the belt. We added this during development because this helped with getting consistent readings.
I used the tool but it didn't seem to work at all during the move-the-slack part of the procedure (944 cam belt). I would rotate the crank but the reading stayed the same. What's wrong?
Its likely that the tension tool is positioned in a place where the tool is making contact with the nut on the separator bar stud. Other possibilities are that you rotated the crankshaft clockwise (instead of counter-clockwise) or that the belt is preset too-tight. We added details to the instructions to help identify preset problems (looking for the arch in the cam belt).
The instructions and video clip mention the separator bar stud as a help for finding the attach point for the 920X to the 944 cam belt; but my car does not have the separator bar. How do I know the exact location along the span to place the 920X?
The pictures shown on this webpage and the instructions can give you a general idea of where the tension tool will work best. Beyond that, you should be looking for a place where contact with with surrounding engine parts does not occur. For the early 944 cars with no separator bar, the placement location along the upper span is not as specific. You should still be watchful though for other potential contact points, such as the the plastic belt cover seen in the image below. Try to avoid or keep this contact to a minimum.
Can the 920Xv6 be used for tensioning the ribbed AC compressor belt and or the power steering belt?
Yes - Ribbed Belt: see the image below for how to use it (this info is not included in the printed instructions). No - Power Steering Belt: that V-belt varies in thickness from one manufacturer to the next and the belt thickness affects the deflection measurement.