New 3D-Printed 944 Timing Belt Tensioner Tool

[944recognizer]

Just got a new to me 944 and want to change out the timing belt and not destroy the engine. This is my initial post so I can download the file. Thanks!

[Supernaut]

Anyone have an extra McMaster threaded heat set insert? I'd prefer not to buy a 25-pack!

I had a friend print me two of the tools, if someone sends me a couple of inserts I'll send the extra assembled tool to whoever they want me to.

[Tom]

Anyone have an extra McMaster threaded heat set insert? I'd prefer not to buy a 25-pack!

I had a friend print me two of the tools, if someone sends me a couple of inserts I'll send the extra assembled tool to whoever they want me to.

As luck would have it, I need to order more. If you can wait until next week, I can send you one. Also, I've come up with yet another drive port that does not require an insert and should last a long time. Instead of the square, 3/8" drive port, it has an M12 triple square port. I did a test print in ABS with 8 walls and it held over 15 ft lbs with no damage to the tool -- so it should hold up a long time without any of the rounding-out issues that happen over time with the square port. If printed in a Nylon-CF, it would likely last as long as the threaded insert. You will need an M12 triple square tool, but unlike the threaded insert (and its weirdly short M12 bolt), you can get an M12 triple square socket at your local auto parts store any day of the week. I'll post that STL in the morning...

[Tom]

Here's a new version of the tool that bridges the gap between the original version and the one I sell with the metal thread insert.

944 Belt Tool Triple Square by CP.stl

It uses an M12 Triple Square socket to drive (like the bolts use on the flywheel). These sockets, shown below, were once fairly hard to find, but can now be found online or at most national auto parts stores for about the price of a Cheeseburger. Print the tool with 8 or more walls and 75% or more infill, and be sure to install the screws for the belt-deflection tab. Just about any filament should be fine really (no TPU of course) -- though a CF filament would likely last even longer. With those settings in standard ABS, I tested the tool to 15 ft lbs. with no issues -- very strong, no deforming in the port, etc. This tool is used just like the original in the video, so should never see more than 7 ft. lbs. -- and should last the life of the car.

triple square tool image.jpg

triple-square.gif

[Daloia20]

This looks awesome!!!

[Supernaut]

Anyone have an extra McMaster threaded heat set insert? I'd prefer not to buy a 25-pack!

I had a friend print me two of the tools, if someone sends me a couple of inserts I'll send the extra assembled tool to whoever they want me to.

As luck would have it, I need to order more. If you can wait until next week, I can send you one.
(snip)

That would be great - Too bad I did not think of this a couple of weeks ago when I bought the throttle body reseal kit from you, could have just thrown the inserts in there!

[944er]

fixture.jpg

I was curious how much torque the spline version of the tool would support, so I printed a test fixture. This is PLA printed at 100% infill. The tool I used is from the Sedy set purchased on Amazon, though other brands appear to be the exact same Chinese version. Actual failure torque will vary with material used and tool fitment, of course.

With the tool pressed in by hand, the fixture supported 25 ft-lb torque, and failed when tested at 30. The splines in the fixture (and therefore the belt tension tool) go quite deep, and this triple-hex bit only engaged the outermost 1 cm. So, I drilled out the sheared section and tapped the bit in lightly with a hammer for another test. This time it made it to 35 ft-lb, and started failing at 36. I'm sure a triple-hex bit with a longer engagement surface would support even more torque.

It is definitely good enough to tension a belt, with significant safety margin.

[t36]

When using this tool, is it similar to the ArnnWorx or Porsche tool where you remove slack/tension from the upper run? (between cam and crank). I believe porsche's tool says to turn counter clockwise 10 degrees.
Or Is this tool to be used after turning the crank clockwise and landing on TDC - where there would be no slack on the upper run?

[Tom]

When using this tool, is it similar to the ArnnWorx or Porsche tool where you remove slack/tension from the upper run? (between cam and crank). I believe porsche's tool says to turn counter clockwise 10 degrees.
Or Is this tool to be used after turning the crank clockwise and landing on TDC - where there would be no slack on the upper run?

Use it just like the factory tool -- i.e., rotate the motor 2 full revolutions, then back up 10 degrees, then measure.

[t36]

When using this tool, is it similar to the ArnnWorx or Porsche tool where you remove slack/tension from the upper run? (between cam and crank). I believe porsche's tool says to turn counter clockwise 10 degrees.
Or Is this tool to be used after turning the crank clockwise and landing on TDC - where there would be no slack on the upper run?

Use it just like the factory tool -- i.e., rotate the motor 2 full revolutions, then back up 10 degrees, then measure.

awesome! thanks Tom!