[Cloud9...68]

There's been a lot of discussion about belts lately, so I thought this would be a good time to start a thread about something I've alluded to before, and which has always puzzled me. Everybody knows it's recommended to periodically re-tighten our balance shaft belts, typically once a year. This would seem to make sense, because being made of rubber, the BS belt will of course stretch some over time. But my question is, is it really practical and realistic to re-tighten it?



The reason I ask is that unless you're one of the 0.01% of 968 owners who owns a P9201 tool, I maintain that it's virtually possible to accurately tighten the belt from the degree to which it has loosened in a year's time, to the specified tightness. You would basically have to loosen it, go through the whole procedure of setting the clearances and deflections, and hope you end up with it better that it was before you started. Unless this is something you do on a regular basis, like once a month, the variation in the average 968 owner's ability to get the tightness correct far exceeds any loosening that occurred over the past year.



So, is it just a matter of semantics? In other words, when we say "re-tensioning" of the belt, do we really mean, "take-it-all-apart-and-go-through-the-whole-procedure-once-a-year"?



And I even question how much the belt actually stretches, and here's why: Several years ago, when I was driving my car virtually every day, I replaced the belts. I set the BS belt a little too tight, because it whined noticeably when I first started it, but the whine went away completely after driving for about five minutes. No problem, I figured, because as it loosens, the whine should go away on its own. Except it never did. I gave it several weeks, and this was over the hot summer, and the whine never decreased one iota, or even a smidge (which is significantly less than an iota...). I finally went back in and loosened it and got the whine to go away. But I never re-tightened it after that, and since have changed it out.



When I rebuilt my engine, I used a P9201 tool that someone loaned me to tension my BS belt, so I'm sure I got it perfect, and based on my prior experience, I've very reluctant to go back in and re-tighten it, for fear of making it worse, since I no longer have access to the tool. But as always, I can be convinced of the error of my ways with data.

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[flash]

as somebody who did not retension the belt, i can tell you what happens when it isn't done. not pretty.



it really isn't all that tough, and you really don't need the tool, though for those who don't have the sensitivity in their hands that is required, it is likely the only way to do it.



the key is not to have the belt too loose. obviously if it is too tight it will make noise, but too loose and it can skip a tooth or worse yet, get buggered up and take out your timing belt.



the next time i have mine off, i am going to make a tool that will set the correct tension. i have a design already, and it won't cost much to make. i just didn't get around to it the last time.



as for the process, you only have to remove the cover to get to what you need. it's not a terribly complicated or time consuming process. the lower cover is a bit of a drag, but i think i have a mod for that too. film at 11 on that.

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[WJH]

I got the ArnnWorx tool. I find it easy to use. I've got an 85.5 944, 88 951, and the 968 that I do belts on. It was well worth the money. I'm not big on the "I can feel what's right" method. The results of being incorrect are far too great. I just consider it another tool in the box that one needs to work on these cars.

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[Cloud9...68]

Thanks, but to be honest, you guys didn't really answer my questions, or address my concerns, so I'll try to re-state them:



1. Is there any way, without a tool, to determine how loose your belt is, and then tighten it appropriately? In other words, can the average 968 owner be expected to take off their belt cover, test the tightness of the belt by feel, determine it is too loose, and then, without taking everything apart and starting over, tighten the belt until it is at the correct tightness? Or, do you have to assume that it's dangerously loose after a year, and undo everything, re-set the clearances and deflections, and re-tighten the belt? Do the whole job, minus actually removing the belt, once a year, in other words?



2. I agree that it's possible to develop a feel for how tight the belt needs to be, but not without a lot of practice and regular repetition. Unless you own a fleet of 968's that have had their belts replaced on a staggered interval, I don't see how that's possible in practice.



3. Any comments on my experience from a few years ago? If the belt truly stretches over time, why didn't my new, freshly-installed belt in the middle of a Texas summer, stretch enough to have the slightest impact on the whine that resulted from my setting it a little too tight initially?



The thing that would really answer my questions would be if anyone here used a P9201 tool to set their belt tightness initially, and then tested the tightness with the same tool a year later. Anybody out there fit that description? Did the belt loosen to a measurable degree? WJH, have you done this with your Arnworx tool?



The bottom line is that I'm very skeptical that it's possible for anyone who doesn't do this on a regular basis to make an accurate determination as to the looseness of their balance shaft belt without an appropriate tool, and then go in and tighten it the correct amount, by feel. But again, I'd love to be proven wrong, as there's an awful lot at stake. My plan is to go ahead and replace my belts, which are about three years old, but have less than 2000 miles on them, this Fall.

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[WJH]

To check tension, you have to loosen the balance belt idler. You can then check with the gauge. If it is not in spec, you will need to adjust the tensioner roller. Watch their video and read the instructions. It is very straightforward.



As you stated, I too doubt the ability of anyone to tension by feel. Even if they do it for a living, without the tool how do they know they are right?



I don't have enough miles on my 968 balance shaft belt to recheck the tension. Perhaps before the end of the summer.

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[GT917]

Interesting post ! What are the consequences of an untightened BS Belt ?

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[Bulti]

Cloud, I agree with all your concerns. The method I use is to tighten the belt until it starts whining. Then slacken it until the whining is all but gone, but not completely. When the engine heats up (after 2-3 minutes) the whining dissapears completely.



I know, it is a bit trial and error and not exact science, but this way I know the belt is definitely not too loose. When the engine is cold and the outside temp also, and there is no more whine, it's time to retighten.



However, I am currently using Conti belts and they seem to be more temp sensitive... So maybe this method does not work with Gates.

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[Bulti]

[quote name='GT917' timestamp='1405586085' post='160185']Interesting post ! What are the consequences of an untightened BS Belt ?[/quote]



Worst case scenario: BBS jumps off a sprocket and gets caught up in the camshaft belt. Cam belt snaps, valves out of sync, pistons hitting valves. Wallet hurting big time.

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[Cloud9...68]

Bulti,



Have you actually experienced your belts getting quieter over time? That definitely wasn't the case with mine when it was wining a bit for the first few minutes of driving, but I've always used Gates, so as you say, maybe there's a difference in the communicativeness between manufacturers (kind of like with tires).



So to try to distill it even further, what I'm saying is that anybody with any experience working on cars can take a belt they've just installed, set the clearances and deflection per the manual, and get the tightness pretty close to correct, even without a tool. What I'm questioning is the ability of anybody, even someone who does these jobs all the time, to take a belt that was replaced a year ago, assess its tightness without using a tool, conclude that it's gotten too loose, and then go in and tighten it the correct amount.

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[Bulti]

Re 'quieter over time': my belt certainly is quieter now than when I installed it last year during winter. It definitely needs less time for the (slight) whining to go away. When hot outside there isn't any whining anymore. I will see next winter, when temps go down again, if the belt starts to make more noise again. If not, I conclude it stretched and I will set it again to 'slight whine'-mode :-)



For me, just a little noise means that the belt isn't too loose, and that's the important thing.. Off course, too tight would be bad also, but then the whining is just way too present and irritating.



Re 'setting tension without a tool': I can totally agree with your statement. A human being is no robot and an arm is no calibrated torque wrench. But the belts tension isn't very critical (I believe Flash made a similar remark in a different thread, and I can't see why he wouldn't be right), so without a tool, trial and error it is



Bottom line: the noise is my (cheap but effective?) insurance. Hope I don't regret it. Time will tell.

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[Cloud9...68]

Makes sense, and I've been through a similar experience. The first time I replaced my belts, I set the BS belt too tight, and it whined loudly, all the time, so went back in and loosened it. Another time, as I said, it was only slightly tight, and only whined for the first few minutes of driving. Maybe I didn't wait long enough to allow it to stretch enough for the whining to go away.



The other problem I'm having with all this is that I must be doing something wrong in the tightening procedure, because I've always had a lot of trouble getting the belt clearance and deflection, and the tightness of the belt itself, to all hit their correct values simultaneously. I'd set the clearance and deflection, then as I tighten the belt by rotating the tensioner roller, the clearance and/or deflection would move out of spec, so then I have to do it all over. And over. And over. And once I finally have everything close, it all falls apart when I tighten the tensioner roller. The last time I did it, it was with the engine on a stand, with the P9201 tool, and with a pair of dial gauges to monitor the deflection and clearance, and it still took me two very frustrating hours. Sheesh - it didn't take me that long to time my cams!

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[Bulti]

Lol, know what you mean. First two times test driving it skipped some teeth. Then the whining was too loud and didn't go away and so on. I'm sure that somebody who does the job regularly, it would still be a frustrating job, but a shorter one ;-)



Look at it this way: it's only every 4 years one has to change it, and if you need to do it more often, it only serves experience. Maybe you should offer to do 944/968 belt jobs in the whole of Texas and become an ace!

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[Cloud9...68]

Well, I feel better that I'm not the only one who has trouble with this - no other part of the job has ever caused me any grief - I never got the marks out of sync, or had much trouble getting the new timing belt on, etc. But the fact that some, such as WJH, have said that getting the belt clearance, deflection, and tightness simultaneously correct is "straightforward" makes me think there must be a trick that I'm not aware of. Those who find this quick and easy to do, please enlighten the rest of us!

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[flash]

here is an easy way to learn how to do this:



go out and buy a cooking scale. you know, the one that measures in grams and ounces.



using your finger, press on the scale. see what it says. now without looking, push on the scale again, with the goal of hitting the same pressure. repeat until you can get it 4 out of five times.



once you have it set right using the tool, use this method to teach you how to determine much pressure is required when pushing on the belt toward the water pump,

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[Cloud9...68]

That sounds like a good technique. Do you think it's accurate enough to allow someone to discern the difference between a correctly tightened belt, and one that's been on a car for a year?

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[flash]

it may or may not still be tensioned correctly after a year. that is why it needs to be checked and retensioned as needed.



as for the noise going away after time, it all depends on just how tight it was, how hot you get it, what kind of belt you started with, and how old it was. i've seen them go quiet, and i've seen them not.



yes, i think it would be accurate enough. it would be every bit as accurate as using the tool, considering they both work essentially the same way.

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[Cloud9...68]

OK, but we're still not addressing the heart of my concern/question, which is:



I know the belt will shrink some over time



I'm not convinced it's possible to accurately discern whether it's shrunk enough to warrant re-tightening



I seriously question the ability of any amateur, or even professional, mechanic to get it any closer to the ideal tightness after checking a belt that's run for a year, than when they checked it



This isn't a mechanism where you can just turn a screw clockwise and tighten things right up. As soon as you loosen the tensioner roller, everything moves, so you're pretty much stuck going through the whole deflection/clearance/tightening procedure. It's a crap shoot whether you will be able to get everything any closer to the correct settings than before you started.



Sounds like it has "waste of time" written all over it to me, but again, I could be convinced otherwise.

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[flash]

no, it stretches over time, not shrinks. the belt loses its elasticity over time.



getting this is no different than being able to put food on a fork and into your mouth without bending the fork or ramming it out the back of your throat. you know how much pressure to apply. you just need to learn how and where to do that on the belt, and be able to repeat it accurately. it's really not that hard. in 30 years i have never used a tool to adjust a belt of any kind, and they have always been right.



as example of being able to do this kind of thing, my wife brought home 2 packs of tee shirts the other day. the hanes pack had 7 shirts and the fruit of the loom pack had 8. she asked which shirt was lighter. i weighed each pack in my hands, and said they weighed the same, so the FOL would be lighter, but to verify, i put them on a postal scale. both packs weighed the same 3lbs (within 1/2 ounce).



if you do something enough, your muscles learn. it's called muscle memory programming.



the issue i suppose os the practicality of learning this. it may be easier to buy the tool.



as for necessity, given how many issues we've seen..................

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[Cloud9...68]

I meant stretch, not shrink. Major typo. But I'm going to stop participating in this thread, because obviously I'm not explaining myself. I'm not talking about being able to tension a belt properly, even without a tool. I get that. What I don't get is how anybody can discern whether a belt has stretched over the course of time (say a year). I agree that it stretches. I just seriously doubt that it stretches enough to be able to accurately detect, and then reliably correct. I'm done.

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[WJH]

[quote name='Cloud9...68' timestamp='1405645353' post='160220']

I meant stretch, not shrink. Major typo. But I'm going to stop participating in this thread, because obviously I'm not explaining myself. I'm not talking about being able to tension a belt properly, even without a tool. I get that. What I don't get is how anybody can discern whether a belt has stretched over the course of time (say a year). I agree that it stretches. I just seriously doubt that it stretches enough to be able to accurately detect, and then reliably correct. I'm done.

[/quote]

That is why you use the tool. If it has stretched, the tool will know! Seriously, get the tool and sleep well at night. LOL

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