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P9201 alternative

 
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Eric P  



Joined: 21 Jun 2017
Posts: 93
Location: NY, USA

PostPosted: Fri Aug 18, 2017 1:56 am    Post subject: P9201 alternative Reply with quote

So I've been reading a lot and can't find a definitive answer from somebody who has actually used this tool as to whether this will work on our cars. It looks like there are four common ways that people set the timing belt tension.

- With the P9201 factory tool (correct way)
- With the arnnworx tool (might not work with auto tensioner, not sure)
- With a krikit tool, which appears to be difficult if not impossible to get accurate readings with the 924S
- With the 90 degree twist method, which seems somewhat subjective

So the most widely accepted method is of course to use the factory tool which will run you over $600. I found what appears to be an possible alternative but I haven't heard of anyone using it on their 924S or 944.


Link to amazon listing: https://www.amazon.com/Supercrazy-Universal-Engine-Tension-Timing/dp/B00J8R5BQO/

It looks like these are available for anywhere between $20 and $60 depending on where you buy them. If you search for "Universal timing belt tension tool", they're all over ebay, amazon, sears, ecstuning, etc. It looks like you can order them in different scales depending on what units you prefer. I found a few listings (both ebay and ECS tuning) that state that these will work on the 924 and 944, and from that presumably the 924S? Does anyone have experience with these? Are they worth the $20 or so or are they junk?

I doubt I'll be doing this enough to justify a $600+ tool, but I bought this car because I enjoy doing the work myself. I feel that I could get the belt close enough with the auto tensioner and twist method but I'd really like the peace of mind to know it's correct. Could this be a cheap alternative to double check my work?

Edit: Added the Arnnworx tool to my list
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1980 924 NA, US model
1987 924S, US model
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Eric P  



Joined: 21 Jun 2017
Posts: 93
Location: NY, USA

PostPosted: Tue Aug 22, 2017 7:43 am    Post subject: Reply with quote

I just ordered one of these and I'm determined to get it to work.

I've found the following documents on how to use this tool:



And also the chart referenced in the instructions above:

http://www.uniortools.com/docs/258774.pdf

Now I just have to find the correct belt spec for the 924S and 944. I might as well find the spec for the 924 NA too as long as I'm diving into this. Since this tool measures a deflection at a predetermined force (Nm), it doesn't correlate to known values for the other tools listed out there:

P9201- No units, just arbitrary numbers specified by porsche.
According to Clark's Garage:
New cam belt:4.0 +/- 0.3 units
Used Cam belt:2.7 +/- 0.3 units
Old style Balance Shaft belt (15 mm wide): 2.7 +/- 0.3 units
New style Balance Shaft belt (18 mm wide): 3.5 +/- 0.5 units

Krikit- measures belt tension -somehow (?) by converting deflection at a predetermined force. I can't find the "click" force listed online or the deflection/lb readout ratio for that matter.
What I found online:
New cam belt: 40 lbs
Used Cam belt: 35 lbs
New/used Balance Shaft belt: 35 lbs (no mention of belt width)

Arnnworx- Actually has a deflection listed in the instructions, but the spring force isn't listed and neither is the spacing between the prongs that support the edges of the belt.
New cam belt: .X90" to .X97"
Used cam belt: .X01" to .X05"
New/used balance shaft belt: .X06" to .X14"


Why is this so overly complicated? Short of buying another tool and checking with both against eachother, is there any way to convert these numbers? Can anyone a bit smarter than I am help me convert these known specs into something a bit more useful?

I'm hoping to find a cheap, accurate, and easily repeatable way to measure the belt tension. I think this tool has potential if I can iron out the details.
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1987 924S, US model
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