Timing belt tensioner difference??
07-07-2007, 11:38 PM
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Timing belt tensioner difference??
can someone explain the difference between the "spring tensioner" in my 1987 S, and the earlier kinds? Does it make it any easier to replace or retension? Should I buy the timing belt tool kit from rennbay?? Pictures and stuff would help a ton! thanks!
07-08-2007, 06:28 AM
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I believe. The spring tensioner auto tensions the timing belt. And the eariler models dont have it. I have read on this forum that people dont trust the auto tensioner and still use a tool to tension the belt like the newer models.
07-08-2007, 07:17 AM
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The early system used eccentric pulleys to adjust the tension on the belt. One would have to rotate the tensioner until it created the proper tension, then tighten the bolt down to hold it like that.
The later spring tensioner system looks completely different and uses a spring loaded tensioner to actively push a pulley against the belt to create the tension.
The spring tensioner is good because it is always setting a tension onto the belt (i.e. it can't undo itself or come loose like an eccentric tensioner) but it's bad because it is possible for it to break and totally let go of the timing belt. Also it sometimes doesn't provide the right AMOUNT of tension.
The old eccentric tensioner is good because it is basically fail proof (trusty). It's bad because you have to manually set the tension, check, retension, recheck, reretension, rerecheck.
The bottom line: late tensioner is hi-tech but annoying, the early tensioner is more rudimentary but better. If you keep your auto tensioner good and fresh, then dealing with the timing belt on an auto-tension car (spring tensioned 944s or hydraulic tensioned 968s) is easier than on a regular tensioner car (944 through 86). Altogether and as a whole, the old simple system is easier to deal with though. HTH.
And yes, you can't do a belt job without at least the 27mm offset wrench for the BS tensioners and (if your car is pre 87) the t-belt tensioner as well. It is also good (but not necessary) to have the pin wrench for the BS pulleys, and a flywheel lock. Lastly, you need a tool to measure tension - either the P9201, the Arnnworx 920X, or the basic Kricket. If you're going to buy tools check out www.arnnworx.com as well as rennbay. They both have awesome stuff but I think Arnn's special 920X tension tool is the tool of the year.
The later spring tensioner system looks completely different and uses a spring loaded tensioner to actively push a pulley against the belt to create the tension.
The spring tensioner is good because it is always setting a tension onto the belt (i.e. it can't undo itself or come loose like an eccentric tensioner) but it's bad because it is possible for it to break and totally let go of the timing belt. Also it sometimes doesn't provide the right AMOUNT of tension.
The old eccentric tensioner is good because it is basically fail proof (trusty). It's bad because you have to manually set the tension, check, retension, recheck, reretension, rerecheck.
The bottom line: late tensioner is hi-tech but annoying, the early tensioner is more rudimentary but better. If you keep your auto tensioner good and fresh, then dealing with the timing belt on an auto-tension car (spring tensioned 944s or hydraulic tensioned 968s) is easier than on a regular tensioner car (944 through 86). Altogether and as a whole, the old simple system is easier to deal with though. HTH.
And yes, you can't do a belt job without at least the 27mm offset wrench for the BS tensioners and (if your car is pre 87) the t-belt tensioner as well. It is also good (but not necessary) to have the pin wrench for the BS pulleys, and a flywheel lock. Lastly, you need a tool to measure tension - either the P9201, the Arnnworx 920X, or the basic Kricket. If you're going to buy tools check out www.arnnworx.com as well as rennbay. They both have awesome stuff but I think Arnn's special 920X tension tool is the tool of the year.
07-08-2007, 03:15 PM
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so the spring should tension the belt by itself? Then what do i do if it isnt the right tension? Theres no way to adjust the tension on a spring tensioner is there?
07-08-2007, 04:02 PM
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To add to Arash's post: The spring pulley doesn't "actively" tension the timing belt like, for example, the hydraulic tension pulley on the 968.
The spring pulley needs to be locked in place after the tension is set so that it cannot move.
When you replace the belt, you push the pulley in and lock it. Once you have reinstalled the belt and tensioner, you release the springed tensioner so that it takes up the slack, lock it, rotate the engine a couple times, release the springed tensioner again so that it takes up the added slack, and then lock it.
Once locked, it cannot adjust the tension on its own.
If I remember correctly, the rule of thumb is that if you can twist the timing belt only a quarter turn with two fingers, it’s close to proper tension.
The spring pulley needs to be locked in place after the tension is set so that it cannot move.
When you replace the belt, you push the pulley in and lock it. Once you have reinstalled the belt and tensioner, you release the springed tensioner so that it takes up the slack, lock it, rotate the engine a couple times, release the springed tensioner again so that it takes up the added slack, and then lock it.
Once locked, it cannot adjust the tension on its own.
If I remember correctly, the rule of thumb is that if you can twist the timing belt only a quarter turn with two fingers, it’s close to proper tension.
07-08-2007, 04:33 PM
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In this picture you can see the blue-highlighted bolt is the pivot point. The red bolt is the locking mechanism.
Loosen both the blue and red bolts and the spring will push outwards on the belt. Then, tighten both the blue and red bolts to lock the pulley in place.
Loosen both the blue and red bolts and the spring will push outwards on the belt. Then, tighten both the blue and red bolts to lock the pulley in place.
Last edited by The DareDevil; 07-08-2007 at 04:54 PM.
07-08-2007, 04:51 PM
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Originally Posted by The DareDevil
In this picture you can see the blue-highlighted bolt it the pivot point. The red bolt is the locking mechanism.
Loosen both the blue and red bolts and the spring will push outwards on the belt. Then, tighten both the blue and red bolts to lock the pulley in place.
Loosen both the blue and red bolts and the spring will push outwards on the belt. Then, tighten both the blue and red bolts to lock the pulley in place.
thank you! this is exactly what i wanted to know!! I love rennlist...
