Paul M wrote: Tue Mar 14, 2023 10:10 am
I think this is such a smart tool design. Worked very well for me. Of course the BSB tension is still a bit of a mystery, but comparing with the cam belt helps to dial in a very good guesstimate.
I personally tensioned the new BSB to about a 135 degree twist. I also noted the tension of the old BSB coming off and snugged it up a bit to compensate for the newness. The P.O. of this car had a good mechanic so I'm thinking they were really in the proper range for used belts. As a Porsche mechanic explained; the BSB feels a bit looser than you'd perhaps think.
I'm very confident everything is good, but it all started with having a good initial tension for the cam belt which this tool was so wonderful for. Do I sound like a fan?
Awesome! Thanks for the feedback -- please help spread the word about it My plan is to develop a companion for the balance shaft. The b/s does feel loose when tensioned to spec. They tend to whine as you approach and exceed the upper tension spec. So fairly easy to hear when it's too tight, and because it feels so loose when within the spec range, I doubt many people would say "that feels about right" when the belt is under spec.
p.s., I posted an alternate version of the tool in the first post and need to explain what it is. Stay tuned on that. It's the same tool, so no more or less accurate, but uses heat-set threads for a longer-lasting torque wrench drive port.
Re: New 3D-Printed 944 Timing Belt Tensioner Tool
Posted: Tue Mar 14, 2023 10:42 am
by Paul M
Yes I was thinking of filing the 3/8" opening there for clearance. Then JB Welding in a square 3/8" ID metal sleeve to combat the wear the torque wrench provides. Wouldn't be too hard to fab something like that up. However I didn't find it necessary under limited use.
Re: New 3D-Printed 944 Timing Belt Tensioner Tool
Posted: Tue Mar 14, 2023 6:54 pm
by Tom
Here is a video showing an alternate version of this tool. This version replaces the 3/8" ratchet drive socket with a bolt, for a longer-lasting tool. It uses a heat-set thread insert by McMaster-Carr, as linked below, along with a short M10x1.5x15 bolt. With the bolt torqued into the tool to about 10-15 ft. lbs, you can then use a 17mm socket on the bolt to turn the tool. Otherwise, everything works the same as the original version of the tool. The original is still perfect for most people working on their own cars, but if you need a tool that will stand up to frequent and repeated use, this alternate is for you.
Prior to using this tool I have always been tensioning by feel and although I never experienced any issues, I was always curious what "new" vs "used" tension might feel like. I noticed that by tensioning the belt such that the water pump can barely turn by hand yields a "new" belt tension spec, while a "used" tension would result in being able to turn the water pump with much less force (moderate force). I find this tool to be a good compromise between buying an expensive tensioning tool and doing it by hand - but surprisingly you can get very close results by hand!
Big thanks Tom
This is a great video -- not sure if I missed it or was just too busy to respond when it was first posted, but very much appreciate seeing one in action like this! Would love to see someone with a factory tool or Arnnworx tool compare the two, but I suppose people who have those tools aren't going to be super motivated to try this one.
Hi Tom,
When using this tool, do I need to rotate the crank backwards a bit like mentioned in Clarks garage before measuring the tension?
Prior to using this tool I have always been tensioning by feel and although I never experienced any issues, I was always curious what "new" vs "used" tension might feel like. I noticed that by tensioning the belt such that the water pump can barely turn by hand yields a "new" belt tension spec, while a "used" tension would result in being able to turn the water pump with much less force (moderate force). I find this tool to be a good compromise between buying an expensive tensioning tool and doing it by hand - but surprisingly you can get very close results by hand!
Big thanks Tom
This is a great video -- not sure if I missed it or was just too busy to respond when it was first posted, but very much appreciate seeing one in action like this! Would love to see someone with a factory tool or Arnnworx tool compare the two, but I suppose people who have those tools aren't going to be super motivated to try this one.
Hi Tom,
When using this tool, do I need to rotate the crank backwards a bit like mentioned in Clarks garage before measuring the tension?
Yes! Follow all the factory procedures to set up the belt for testing. Everything about testing/setting the tension is the same other than the tool. :!
Re: New 3D-Printed 944 Timing Belt Tensioner Tool
Posted: Thu Mar 16, 2023 9:31 am
by iamgerry86
This is amazing! I can't wait to give this a try! Thank you so much!
My plan is to develop a companion for the balance shaft. The b/s does feel loose when tensioned to spec. They tend to whine as you approach and exceed the upper tension spec. So fairly easy to hear when it's too tight, and because it feels so loose when within the spec range, I doubt many people would say "that feels about right" when the belt is under spec.