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The title says it basically, I can’t find out what the scale is of the Porsche timing belt tension tool P9201 (Stäger tool)
The only thing we know is that Porsche calls it “Belt Units” but I can’t get my head around it that after years and years of these cars being maintained by us. Nobody ever found out what the scale represents. Also at diverse 944 forums I came to a dead end..
So I became a (Google) detective I’ve searched everywhere but can already tell you I still don’t know what it is, but I found some interesting information that I would like to share here, and maybe with some information you guys have we can figure it out?
First thing I found out, that some of you probably already knew is that the tool is used on more vehicle makes. As far as I found right now: Porsche, Volvo, BMW, Ferrari & Ducati
This gave me a few leads, on this (http://www.ducati.ms/forums/11-ducat...ng-tool-4.html) Ducati forum somebody states that the tool Ducati uses to set timing belt tension is the same as used on 944. But this is only one person I can find who said that… “I'm going to be testing it against the Porsche factory tool (which uses the scale as the Ducati tool)”
Then here (http://www.ducatisportingclub.com/showthread.php?t=5172) I read that the factory tool of Ducati is this one (https://rennlist.com/forums/924-931-...ts-no-56k.html) a tool made by Löwener. “the SPX Lowener belt tension gauge is the one as supplied to Ducati. In other words, it's the right tool for the job I'm sure that other tools will do the job just as well but whichever one you go for, make sure that it is graduated in "Lowener" units. All the belt tension figures supplied by Ducati in their workshop manuals are in "Loweners"”
Löwener seems to be a recognised used scale for belt tension. You can find the Löwener scale back in various documents like this one (http://www.autodataonline.com.au/Thi.../tbtension.htm) (note here, the P9201 Stäger tool displayed here for BMW and Volvo seems to have a different scale then our P9201 Stäger tool has, don’t know why…)
But 1+1=2, so if all above would be true then you could say the scale used on our tool is Löwener, they also have roughly the same reach. But I need more prove to be able to believe this.
Ok, then I thought maybe Löwener and Stäger are the same guy/company. So what do we know about Stäger (or Staeger ä=ae) well we know he is called Friz and used to live on:
Fritz Staeger
Zossener Str. 56/58
D-1000 Berlin 61
Tel:030/693 1204
(http://forums.pelicanparts.com/porsc...djustment.html)
You can look it up on google street view, the building does not say much. Also I could not find a company that carries the name orso.
Number 1&2 look like our P9201, maybe a less “refined” version
But for the rest the Patents don’t seem to tell us something about the scale, most informative part about the scale I’ve found was this:
Die Erfindung betrifft eine Vorrichtung zur Messung der Spannung von Riemen, bei welcher ein paar von im Abstand voneinander angeordneten auflagegliedern an eine Seite des Riemens ablegbar sind, ein zwischen den auflagegliedern an die gegenüberliegende Seite des Riemens ablegbares Tastlied unter durchbiegung des Riemens um eine vorgegebene strecke eindrückbar ist und als Maß für die riemenspannung die dazu erforderliche kraft mittels eine meßfeder und eines mit der meßfeder über mechanische wegübersetzungsmittel gekuppelten, auf die Verformung der meßfeder ansprechenden anzeigeinstument messbar ist.
Translates roughly to:
The invention relates to a device for measuring the tension of the belt, in which a pair of spaced apart pins/pads can be put to one side of the belt, and a pin/pad (that you can lay on the belt) between the two support members on the opposite side of the belt. The deflection of the belt by a predetermined pressed distance is a measure of the belt tension, the force required is measured by a measuring spring and coupled with the range spring by mechanical connection, to the deformation of the measuring spring.
partly Google translate, and partly my own. Out of old technical German (so not perfect)
so we know how it works. But can’t find in which unit you read it out.
But there are a few interesting things, the scale on the gauge on the drawing in patents is not always the same. Fig.1 has 0 - 9 and Fig.4 has 0 - 45. Which fits again with the BMW (11.2.080)& Volvo (9988500) scale? Used here: http://www.autodataonline.com.au/Thi.../tbtension.htm
Okay, so what next. Well two of the patents changed owner in 1992 to : “Owner name: FERNSTEUERGERAETE KURT OELSCH GMBH, 1000 BERLIN, D”
And this is a company that still exists: http://www.fernsteuergeraete.de/en/
But the tensionmeter is not something they seem to sell any more.
So, long story short… we still don’t know the scale used by Fritz Stäger.
But we could try to contact the company that owns the patents right now.
Or we could go for the more hands on approach and get a P9201, and test it together with a bunch of other devices preferably that measure in a documented scale or Newton’s. Or make a test rig where you can measure the tension in the belt using a springscale and see what the P9201 reads, I would like to do this, but I don’t have a P9201. But maybe someone close to me (The Netherlands) has one and wants to do an experiment? I can get my hands on a Seem tronic tension gauge
Curious what you guys can add to this story, anyways thanks for reading
And I will be posting this same story on some Dutch and German forums, maybe the community can solve this mystery
Porsche sells a nice piece of spring steel, 9201/2, to calibrate the 9201.
Here's the 9201 with the calibration bar, and how you load it up on the 'paddles' of the 9201 and take a measurement with it. Spec on the calibration bar is 4 belt units.
My setup for this measurement may be flawed but I think it'll give a ballpark measurement. I'm holding the left side paddle on the height comparator- Here's the zero measurement with 0 belt units of force on the bar:
And 0.022" of downward deflection with 4.6 belt units on the gauge. Next step is to measure the force required to deflect the bar X amount. Greg has a spring dyno with a dial gauge mount at his shop that should work to give us the spring constant. Then we can calculate pounds per belt unit.
Real engineers, please point out the error(s) in my approach!
The title says it basically, I can’t find out what the scale is of the Porsche timing belt tension tool P9201 (Stäger tool)
The only thing we know is that Porsche calls it “Belt Units” but I can’t get my head around it that after years and years of these cars being maintained by us. Nobody ever found out what the scale represents. Also at diverse 944 forums I came to a dead end..
So I became a (Google) detective I’ve searched everywhere but can already tell you I still don’t know what it is, but I found some interesting information that I would like to share here, and maybe with some information you guys have we can figure it out?
First thing I found out, that some of you probably already knew is that the tool is used on more vehicle makes. As far as I found right now: Porsche, Volvo, BMW, Ferrari & Ducati
This gave me a few leads, on this (http://www.ducati.ms/forums/11-ducat...ng-tool-4.html) Ducati forum somebody states that the tool Ducati uses to set timing belt tension is the same as used on 944. But this is only one person I can find who said that… “I'm going to be testing it against the Porsche factory tool (which uses the scale as the Ducati tool)”
Then here (http://www.ducatisportingclub.com/showthread.php?t=5172) I read that the factory tool of Ducati is this one (https://rennlist.com/forums/924-931-...ts-no-56k.html) a tool made by Löwener. “the SPX Lowener belt tension gauge is the one as supplied to Ducati. In other words, it's the right tool for the job I'm sure that other tools will do the job just as well but whichever one you go for, make sure that it is graduated in "Lowener" units. All the belt tension figures supplied by Ducati in their workshop manuals are in "Loweners"”
Löwener seems to be a recognised used scale for belt tension. You can find the Löwener scale back in various documents like this one (http://www.autodataonline.com.au/Thi.../tbtension.htm) (note here, the P9201 Stäger tool displayed here for BMW and Volvo seems to have a different scale then our P9201 Stäger tool has, don’t know why…)
But 1+1=2, so if all above would be true then you could say the scale used on our tool is Löwener, they also have roughly the same reach. But I need more prove to be able to believe this.
Ok, then I thought maybe Löwener and Stäger are the same guy/company. So what do we know about Stäger (or Staeger ä=ae) well we know he is called Friz and used to live on:
Fritz Staeger
Zossener Str. 56/58
D-1000 Berlin 61
Tel:030/693 1204
(http://forums.pelicanparts.com/porsc...djustment.html)
You can look it up on google street view, the building does not say much. Also I could not find a company that carries the name orso.
Number 1&2 look like our P9201, maybe a less “refined” version
But for the rest the Patents don’t seem to tell us something about the scale, most informative part about the scale I’ve found was this:
Die Erfindung betrifft eine Vorrichtung zur Messung der Spannung von Riemen, bei welcher ein paar von im Abstand voneinander angeordneten auflagegliedern an eine Seite des Riemens ablegbar sind, ein zwischen den auflagegliedern an die gegenüberliegende Seite des Riemens ablegbares Tastlied unter durchbiegung des Riemens um eine vorgegebene strecke eindrückbar ist und als Maß für die riemenspannung die dazu erforderliche kraft mittels eine meßfeder und eines mit der meßfeder über mechanische wegübersetzungsmittel gekuppelten, auf die Verformung der meßfeder ansprechenden anzeigeinstument messbar ist.
Translates roughly to:
The invention relates to a device for measuring the tension of the belt, in which a pair of spaced apart pins/pads can be put to one side of the belt, and a pin/pad (that you can lay on the belt) between the two support members on the opposite side of the belt. The deflection of the belt by a predetermined pressed distance is a measure of the belt tension, the force required is measured by a measuring spring and coupled with the range spring by mechanical connection, to the deformation of the measuring spring.
partly Google translate, and partly my own. Out of old technical German (so not perfect)
so we know how it works. But can’t find in which unit you read it out.
But there are a few interesting things, the scale on the gauge on the drawing in patents is not always the same. Fig.1 has 0 - 9 and Fig.4 has 0 - 45. Which fits again with the BMW (11.2.080)& Volvo (9988500) scale? Used here: http://www.autodataonline.com.au/Thi.../tbtension.htm
Okay, so what next. Well two of the patents changed owner in 1992 to : “Owner name: FERNSTEUERGERAETE KURT OELSCH GMBH, 1000 BERLIN, D”
And this is a company that still exists: http://www.fernsteuergeraete.de/en/
But the tensionmeter is not something they seem to sell any more.
So, long story short… we still don’t know the scale used by Fritz Stäger.
But we could try to contact the company that owns the patents right now.
Or we could go for the more hands on approach and get a P9201, and test it together with a bunch of other devices preferably that measure in a documented scale or Newton’s. Or make a test rig where you can measure the tension in the belt using a springscale and see what the P9201 reads, I would like to do this, but I don’t have a P9201. But maybe someone close to me (The Netherlands) has one and wants to do an experiment? I can get my hands on a Seem tronic tension gauge
Curious what you guys can add to this story, anyways thanks for reading
And I will be posting this same story on some Dutch and German forums, maybe the community can solve this mystery
Why do you care?
"Belt Units" works fine for me. I get the tool out, check the calibration, set the belt tension, and put the tool back in it's box.
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
I care because I find it interesting. It's not rocket science, and it should be doable to figure it out.
And it would be cool for the community to know I thought...
And then you can use every tool too measure it and your not forced to buy the Porsche tool just because the scale is unknown.
I just thought I could help some people with it....
This will not help, probably, but some years ago I loaned Kempf tool to one person who has all kinds of measuring devices at his work place. He measured it and IIRR result was 10kN. I have actual number somewhere. Number is obviously how much spring gives resistance when tool is rotated to proper tension.
I care because I find it interesting. It's not rocket science, and it should be doable to figure it out.
And it would be cool for the community to know I thought...
And then you can use every tool too measure it and your not forced to buy the Porsche tool just because the scale is unknown.
I just thought I could help some people with it....
Sounds like a god reason, to me.
I've bought several 9201 tools over the years....it only takes one mechanic to run it around the timing gear (under the belt) to make it junk.
I personally think the Ducati "sonic" method is the way to go...
The title says it basically, I can’t find out what the scale is of the Porsche timing belt tension tool P9201 (Stäger tool)
The only thing we know is that Porsche calls it “Belt Units” but I can’t get my head around it that after years and years of these cars being maintained by us. Nobody ever found out what the scale represents. Also at diverse 944 forums I came to a dead end..
:
Curious what you guys can add to this story, anyways thanks for reading
And I will be posting this same story on some Dutch and German forums, maybe the community can solve this mystery
====Potential Solution====
I needed to use my P9201 to document the OEM belt tension on a couple of LifeCycles that I needed to do some alternator work on.
LifeCycles use a long, flat poly belt w/6 ribs to engage the flywheel to the alternator pully, both of the latter grooved to engage said ribs,
and they're allegedly set at the factory to ~65lbs via the factory's belt tension gauge.
But my P9201 was out of cal, & Googling uncovered the need for a 1.5mm hex to complete the cal,
but I also came across your question,
will try to get you in the ballpark ::
The poly belts in question measured 3.35 BU & 3.6BU per P9201 w/fresh cal,
so avg = 3.475 BU, ergo 65lb/3.475BU = 18.75lb/BU.
So a 944's drive belt for balance shafts tightness of '2.7BU' likely correlates to approximately 50.5lb.
Then, assuming that my 18.75lb/BU number is in the ballpark, AND assuming Rob Edwards noted 0.022''(= 0.5588mm) deflection actually reflected an accurate 4.0BU (75lb = 34.02Kg) cal bar (meaning, if his P2101 had been in cal at the time that he’d still have gotten the same 0.022'' deflection and a 4.0BU reading), we know the force F applied by the belt (in the middle of a 85mm belt span the P2101 provided) causes belt deflection BD,
such that : F x C = BD
Meaning C= (0.5588mm / 34.02Kg) = 0.016426 mm/Kg.
But it’s the P2101's micrometer gearing (MG) yields BU’s, then : F x C x MG = 4.0BU,
So MG = 4.0BU / (34.02Kg x 0.016426 mm/Kg) = 7.15 BU/mm,
Leading to : F x C x MG = tension of belt in BU’s.
Hope that helps.
I work in a lab where we do some reverse engineering and have set up measurement standards for V&V testing. My suggestion for limiting error and simplicity of traceability would be to have a calibrated 9201 with cal bar setup and then take a 928 timing belt cut it so it can be hung from a mount like a hanging rope. Have calibrated weights of 50lb and 100lb and then attach / hang the 50lb weight on the timing belt place the 9201 on the belt and check the resultant BU. Repeat for 100lb and 150lb
This simple test should result in good data.
Since I bought 550 Maranello about year ago I have been looking into belt tension setup they have. Originally 456, 550 and some V8 Ferrari's used basically same tool as 9201 but with different scale. Haven't been able to find out actual tool or even picture of its dial. In any case they updated procedure when 575 and 612 came around and used Ducati frequency listening tool which measures frequency of belt vibration when it is hit with normal screw driver or something similar. There are two different procedures for Hz measurements for V12 cars. First way to do it is to just take Hz reading from longest part of belt. Later they updated to two separate measurements for single belt, one from longest and another from second longest part of the belt and then two Hz numbers are counted together. Normal phone with hands free mic and $0.99 sound visualization software provides very good setup for the job. So no need for $1K Ducati tool or anything else expensive. Single measurement is around 160Hz and dual is at 330Hz range. Similar measurement style is used for aux belts also, alternator is 160-170Hz with new belt. Way back 20+ years ago before Kempf tool existed there was sound file available at internet for setting 928 cambelt. Hz method works on 928's also but back then it was done by ear so margin of error was big.
Once I get far enough on 550 belt job I'll try Kempf tool on it once again just for the hell of it to see how it corresponds to Hz numbers. Same thing next time doing 928 belts. Interesting to see what Hz number is for those. Different manufacturer belts might cause different Hz when tightness is same. In 550 that's not an issue as practically everyone uses whatever Ferrari sells so all measurement are done against same make belt.
Red shows clear peak at 135Hz. Measurement is from 5 years old belt which was soaked in oil from leaking cam seal so its not really same as new belt values.
10-29-2015, 10:43 AM
The P9201 Scale mystery
I’ve searched everywhere but can already tell you I still don’t know what it is, but I found some interesting information that I would like to share here, and maybe with some information you guys have we can figure it out?
(so not perfect)
