All good stuff G , I read it from start to finish ,observed and understand the various methods to tension the belts and after thinkin about it all I have come to only one conclusion.................you need to get out more .
What I did for belt tension was to pull the cover off my Toyota MR2 engine and my ford Capri engine , set the tension with the spring loaded tensioners , felt about how tight the belt was ( very similar on both engines ) and then did the Paso about the same . The belt needs to be tight enough so its not flapping about and not so tight that its stretched . I think that as long as its about right its all good , problem is that you cant put "about right" in a tech publication so there needed to be some spec and , as you can see several people had a go at this in different ways . I would be stunned if there was a seat of the pants difference between 110hz and 140hz , like the belt wearing faster , or the associated bearings wearing faster , or even the bike going faster . I would think , being that the belt is toothed and doesn't rely on friction ( like a V belt ) to provide the drive it doesn't need to be as tight as you might 1st think .
G , your observations are interesting and do shed a bit of light on the subject , I hope others who have not changed their own belts will now have a go because it really aint rocket science

Hi G,

To be honest, it scared me a bit reading this but I have another question related to this topic: Which belt (brand and type) did you use?
Contemporary timing belts should last longer than those of the 70-ties and 80-ties.
Need to change mine, so interesting to know which ones to order .....

Sure you did your math on those

Frank

Personally I'm fine with the allen key method. I have everything needed for the tuning programs but just never seem to have the time to give it a go. Spring tools wear out so never put much faith in them.

Frank, I could tell you which belts I used but that wouldn`t help you. As you can see I have converted to round tooth belts & pulleys. The original ones have square teeth.

Thanks voor de information. It helps . The next time I'm working on the belts I'll be sure to double check. Until now I used the same allen key for used and new belts .

Hi G,

I know but are there different qualities from Dayco and Gates or do they have only 1 quality?
Also is Gates better or similar to the Dayco quality?
Why did you change the hexagonal teeth to rounded?
Where do they come from (monster)?

Just interested to know if it makes sense to change them.

Frank

the belts I`m using are 73710051A which are for 600/695/750 ie/dark (68 teeth/reinforced). The main reason for changing the belts to round tooth ones was that I had adjustable round tooth cam pulleys and the engine was about to being rebuild so I only had to change the crankshaft pulleys. I had a shop do this. If I had known back then that one (!) of these belts would cost €47 while the original ones are €18-22 ea. I wouldn`t have done it and would have rather sold the adjustable pulleys and bought some for square teeth.
While I do think round toothed belts generally roll better over the pulleys than square toothed belts this or any quality aspect was not a reason for me to change them.
Gates, Dayco, Flennor, Conti imho it doesn`t make much difference as you chance them every two (or three) years anyway.

Nice writeup, covered everything.

I have only one thing to add. I use sonic tensioning on my 4v bikes. I tried several methods, none successful (simple things like fluorescent lights cause false readings with some programs). Tried several free iPhone apps, none worked well.

Then, I bought TE Tuner for the iPhone, $3.99, and that simply worked. Easy to use, no microphone needed. Just hold the microphone end of the iPhone in close, and pluck the belt.

I too use the 5mm allen wrench method for the 2v motors. But you've got to be careful. It's easy to "force" a 6mm, and think the belt is too loose. The 5mm should push thru fairly easily.

careful when using a phone. The frequency response of the built-in mic should be known. Many are not suitable unless you use a proper external microphone.
http://blog.faberacoustical.com/2009/io ... omparison/

Good job as always , thanks G.

Hail to the inventor of transparent timing discs with black printing