Major issue with Kempf timing belt tensioning tool/ results of comparison tests
11-19-2004, 11:50 AM
#31
928 Collector
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Cool Mark 
... Garth it does all move. Those washers move and they vibrate. This is where oil comes in. It dampens and lubes those movements. I just looked at a very worn tensioner. Shaft worn; washers worn and inside of tensioner worn. How is that, if nothing moves? Remember the front of the unit is loose and moves in and out with the boot on the tensioner arm.
Mark, about washers .... I don't recall but I believe there is a thick washer there.
... Garth it does all move. Those washers move and they vibrate. This is where oil comes in. It dampens and lubes those movements. I just looked at a very worn tensioner. Shaft worn; washers worn and inside of tensioner worn. How is that, if nothing moves? Remember the front of the unit is loose and moves in and out with the boot on the tensioner arm.Mark, about washers .... I don't recall but I believe there is a thick washer there.
11-19-2004, 12:22 PM
#32
Track Day
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Spare tire
How's about a spare tire for a 89 928s. recently found out hard way spare belongs to 87 or 86 model it dont fit 89.......any info or even a swap with the one i have.......
11-19-2004, 12:41 PM
#33
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Mark,
The small coil spring on the tensioner push rod does not accomodate arm movement. It is part of the tension warning system. As long as there is adequate belt tension, the spring is compressed, allowing solid electrical contact from the tensioner arm to the tensioner body. When belt tension is too low, the spring pushes the push rod out enough to break the electrical contact, setting the belt warning.
The bimetallic Belleville washers act as a short, stiff spring that gets slightly shorter when it gets hot.
The small coil spring on the tensioner push rod does not accomodate arm movement. It is part of the tension warning system. As long as there is adequate belt tension, the spring is compressed, allowing solid electrical contact from the tensioner arm to the tensioner body. When belt tension is too low, the spring pushes the push rod out enough to break the electrical contact, setting the belt warning.
The bimetallic Belleville washers act as a short, stiff spring that gets slightly shorter when it gets hot.
11-19-2004, 02:51 PM
#34
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Thread Starter
ahhh, Interesting!
Now we know!! thanks
MK
Now we know!! thanks
MK
Originally Posted by WallyP
Mark,
The small coil spring on the tensioner push rod does not accomodate arm movement. It is part of the tension warning system. As long as there is adequate belt tension, the spring is compressed, allowing solid electrical contact from the tensioner arm to the tensioner body. When belt tension is too low, the spring pushes the push rod out enough to break the electrical contact, setting the belt warning.
The bimetallic Belleville washers act as a short, stiff spring that gets slightly shorter when it gets hot.
The small coil spring on the tensioner push rod does not accomodate arm movement. It is part of the tension warning system. As long as there is adequate belt tension, the spring is compressed, allowing solid electrical contact from the tensioner arm to the tensioner body. When belt tension is too low, the spring pushes the push rod out enough to break the electrical contact, setting the belt warning.
The bimetallic Belleville washers act as a short, stiff spring that gets slightly shorter when it gets hot.
11-19-2004, 03:07 PM
#35
Rennlist Member
Thread Starter
RESULTS from calabrating Kempf tool with factory tool
Spent a good hour testing , rotating the engine, and comparing the two tools. This tool was from a well known porsche shop, which takes very good care of the tools. first i checked the tension that i had guessed at by hand and it was 4.0 with the POS porsche tool. Then, i checked with the Kempf tool and it was in the window, but on the first 1/4 of the window. tighten it up by hand as tight as i could go and then a 1/8 further, and it was right at 5.0. rotated the engine again, 5.1. checked with the kempf tool and it was at the last 3/4 of the window. tightened the system up after more validation tests, for which the factory tool was always right around 5.0. kemp tool was +/- about a 1/4 of a window depending on angle and how i moved the tool to the cam housing surface. Then, after tighting the tensioner bolt, i checked again, after feeling that both bolts were moving and it may have changed the tension. sure enough, it was at 6.1. then, used this as an opportunity to check with the Kempf tool again, and it was just near the end of the window. double checked and verified this, then loosened, checked to 5.2 or so, verified with kempf tool and rotated engine again, reverified and buttoned it all up.
By the way, being off 1-2 teeth toward the pulley did force the kempf tool to read 1/8 of a windo higher. not much, and certainly not as much as first seen. after i got good with the kempf tool (and im already pretty good at the factory tool) i was able to calabrate to the point where i feel comfortable using only the kempf tool.
so, bottomline, on an S4,use the kempf tool make sure its oiled and set the tension to 3/4 toward the end of the window. the window range can be 4.0 all the way to 6.0. I dont know if 4.0 is dangerous for slip, and who knows when too tight make the belt groove out the pulleys, but over my 15 years of 928 ownership and lots of race miles, anthing around 5 seem to wear things well and not break the belt (or allow it to slip, with exception of my last race where that could be due to tensioner warning sensor strip broke and maybe got caught up in the pulley, worn belt, or lack of oil in the tensioner.)
I should also add that its important that whom ever is testing and/or comparing the 9201 with the Kempf is proficient in the use of it. the real trick here is to find a slight click sound. you can get a click, but it can be kind of quiet and muffled. that gives an incorrect value (and not repeatable and this is what the original test team probably found) however, in my tests, when i only used the clean readings, the 9201 was very accurate and repeatable. (+/- .1-.2)
i give the kemp tool a range of 4 to 6 in the window compared to the 9201. this means, just get near the max of the window and you are in the 5.2-5.6 range, which i imagine is good for the first initial setting.
Thanks for all the comments and concerns!
By the way, i may drill a hole in the bottom of the cam cover and use the Kempf tool and a short shaft to check tension. i think it will be a very accurate way to at least check the 1000mile tension if not verify the tension at any time without having to remove the covers.
(using the flat part of the tensioner and a shaft up toward the belt, push until the spring is stretched and the tool bottoms out. mark the movemement, compare next time!)
Mark
Firing the ole Holbert car up tomorrow AM and doing a freeway run!!!!
By the way, being off 1-2 teeth toward the pulley did force the kempf tool to read 1/8 of a windo higher. not much, and certainly not as much as first seen. after i got good with the kempf tool (and im already pretty good at the factory tool) i was able to calabrate to the point where i feel comfortable using only the kempf tool.
so, bottomline, on an S4,use the kempf tool make sure its oiled and set the tension to 3/4 toward the end of the window. the window range can be 4.0 all the way to 6.0. I dont know if 4.0 is dangerous for slip, and who knows when too tight make the belt groove out the pulleys, but over my 15 years of 928 ownership and lots of race miles, anthing around 5 seem to wear things well and not break the belt (or allow it to slip, with exception of my last race where that could be due to tensioner warning sensor strip broke and maybe got caught up in the pulley, worn belt, or lack of oil in the tensioner.)
I should also add that its important that whom ever is testing and/or comparing the 9201 with the Kempf is proficient in the use of it. the real trick here is to find a slight click sound. you can get a click, but it can be kind of quiet and muffled. that gives an incorrect value (and not repeatable and this is what the original test team probably found) however, in my tests, when i only used the clean readings, the 9201 was very accurate and repeatable. (+/- .1-.2)
i give the kemp tool a range of 4 to 6 in the window compared to the 9201. this means, just get near the max of the window and you are in the 5.2-5.6 range, which i imagine is good for the first initial setting.
Thanks for all the comments and concerns!
By the way, i may drill a hole in the bottom of the cam cover and use the Kempf tool and a short shaft to check tension. i think it will be a very accurate way to at least check the 1000mile tension if not verify the tension at any time without having to remove the covers.
(using the flat part of the tensioner and a shaft up toward the belt, push until the spring is stretched and the tool bottoms out. mark the movemement, compare next time!)
Mark
Firing the ole Holbert car up tomorrow AM and doing a freeway run!!!!
Last edited by mark kibort; 11-19-2004 at 03:32 PM.
11-19-2004, 03:15 PM
#36
Rennlist Member
Originally Posted by heinrich
Cool Mark ... Garth it does all move. Those washers move and they vibrate. This is where oil comes in. It dampens and lubes those movements. I just looked at a very worn tensioner. Shaft worn; washers worn and inside of tensioner worn. How is that, if nothing moves? Remember the front of the unit is loose and moves in and out with the boot on the tensioner arm.
.
... Garth it does all move. Those washers move and they vibrate. This is where oil comes in. It dampens and lubes those movements. I just looked at a very worn tensioner. Shaft worn; washers worn and inside of tensioner worn. How is that, if nothing moves? Remember the front of the unit is loose and moves in and out with the boot on the tensioner arm..
Forget the speed reading and go for accuracy
- your note is largely in agreement with what I had stated - "Close, but not entirely correct - the 35 belleville washers are 'along for the ride', being captive on the rod from the top piston which is centered in the well of the lower piston - see the copper coloured stack between the two pistons in the center image. The 4mm deep well in the lower piston ( with the O-ring and check valve) allows enough slack under compression, or belt tension, to prevent the centering rod from bottoming out. This leaves the 7 opposed groups of 5 washers each captured by the rod to act as a powerful spring that absorbs and dissipates the harmonic energy of the TB into the oil, tensioner walls - and so on ..."
- especially the last line , ' act as a powerful spring ... dissipating energy into ...'
Wally P also noted. "The bimetallic Belleville washers act as a short, stiff spring that gets slightly shorter when it gets hot."
I suspect there is more agreement than seemed evident.
11-19-2004, 11:28 PM
#38
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As I've stated before, I've spent several hours checking, comparing, and double checking my 9201 tool (w/calibration bar) against two different Kempf tools...and it always came up the same on my '85S...that is, the 5.2 setting is just "barely outside" of the Kempf tool window. Not sure where the variation is but that's the way it is on my car. If I set my belt tension in the center of the Kempf window, it would probably be OK for the average bear...but more like a 4.0 setting...not close enough for me. So I use the Kempf tool to "ball park" the setting...knowing where 5.2 is on my tool...then verify the setting with the harder-to-use-in-that-tight-space 9201 tool. There may be something to the variation thing from car to car? Doesn't take much.
Harvey
Harvey
11-23-2004, 07:34 PM
#39
Rennlist Member
Thread Starter
one last possible issue
Ok, its all back together and road tested for a few days. sounds good, but one small issue. Im leaking that gear oil from what looks to be, the tensioner . all i can think of is that i didnt fill the tensioner when i had tension on the belt and when it was full, as the belt was cranked down, it pushed the fluild out the rubber dust/oil cover ( i even reinstalled it with the little spring sleal on the inner diameter) since on the 3rd day of driving around, the oil flow is getting less , im pretty sure thats what it is. i know i should have rebuilt the tensioner, but all that would have changed would be that gasket to the block and the new o ring. since it is not leaking out the bolt, and not seeping out the block, i think the leak is just an over fill.
any comments??
thanks for all the help on this one. Now, the ole Holbert car has the new timing belt, new tensioner sensor, new oil boot cover and some new oil in there too. runs great, wonder if the timing is right now because it seems like its running better. (but then it always runs better just after i wash it)
Mk
any comments??
thanks for all the help on this one. Now, the ole Holbert car has the new timing belt, new tensioner sensor, new oil boot cover and some new oil in there too. runs great, wonder if the timing is right now because it seems like its running better. (but then it always runs better just after i wash it)
Mk
Originally Posted by mark kibort
Spent a good hour testing , rotating the engine, and comparing the two tools. This tool was from a well known porsche shop, which takes very good care of the tools. first i checked the tension that i had guessed at by hand and it was 4.0 with the POS porsche tool. Then, i checked with the Kempf tool and it was in the window, but on the first 1/4 of the window. tighten it up by hand as tight as i could go and then a 1/8 further, and it was right at 5.0. rotated the engine again, 5.1. checked with the kempf tool and it was at the last 3/4 of the window. tightened the system up after more validation tests, for which the factory tool was always right around 5.0. kemp tool was +/- about a 1/4 of a window depending on angle and how i moved the tool to the cam housing surface. Then, after tighting the tensioner bolt, i checked again, after feeling that both bolts were moving and it may have changed the tension. sure enough, it was at 6.1. then, used this as an opportunity to check with the Kempf tool again, and it was just near the end of the window. double checked and verified this, then loosened, checked to 5.2 or so, verified with kempf tool and rotated engine again, reverified and buttoned it all up.
By the way, being off 1-2 teeth toward the pulley did force the kempf tool to read 1/8 of a windo higher. not much, and certainly not as much as first seen. after i got good with the kempf tool (and im already pretty good at the factory tool) i was able to calabrate to the point where i feel comfortable using only the kempf tool.
so, bottomline, on an S4,use the kempf tool make sure its oiled and set the tension to 3/4 toward the end of the window. the window range can be 4.0 all the way to 6.0. I dont know if 4.0 is dangerous for slip, and who knows when too tight make the belt groove out the pulleys, but over my 15 years of 928 ownership and lots of race miles, anthing around 5 seem to wear things well and not break the belt (or allow it to slip, with exception of my last race where that could be due to tensioner warning sensor strip broke and maybe got caught up in the pulley, worn belt, or lack of oil in the tensioner.)
I should also add that its important that whom ever is testing and/or comparing the 9201 with the Kempf is proficient in the use of it. the real trick here is to find a slight click sound. you can get a click, but it can be kind of quiet and muffled. that gives an incorrect value (and not repeatable and this is what the original test team probably found) however, in my tests, when i only used the clean readings, the 9201 was very accurate and repeatable. (+/- .1-.2)
i give the kemp tool a range of 4 to 6 in the window compared to the 9201. this means, just get near the max of the window and you are in the 5.2-5.6 range, which i imagine is good for the first initial setting.
Thanks for all the comments and concerns!
By the way, i may drill a hole in the bottom of the cam cover and use the Kempf tool and a short shaft to check tension. i think it will be a very accurate way to at least check the 1000mile tension if not verify the tension at any time without having to remove the covers.
(using the flat part of the tensioner and a shaft up toward the belt, push until the spring is stretched and the tool bottoms out. mark the movemement, compare next time!)
Mark
Firing the ole Holbert car up tomorrow AM and doing a freeway run!!!!
By the way, being off 1-2 teeth toward the pulley did force the kempf tool to read 1/8 of a windo higher. not much, and certainly not as much as first seen. after i got good with the kempf tool (and im already pretty good at the factory tool) i was able to calabrate to the point where i feel comfortable using only the kempf tool.
so, bottomline, on an S4,use the kempf tool make sure its oiled and set the tension to 3/4 toward the end of the window. the window range can be 4.0 all the way to 6.0. I dont know if 4.0 is dangerous for slip, and who knows when too tight make the belt groove out the pulleys, but over my 15 years of 928 ownership and lots of race miles, anthing around 5 seem to wear things well and not break the belt (or allow it to slip, with exception of my last race where that could be due to tensioner warning sensor strip broke and maybe got caught up in the pulley, worn belt, or lack of oil in the tensioner.)
I should also add that its important that whom ever is testing and/or comparing the 9201 with the Kempf is proficient in the use of it. the real trick here is to find a slight click sound. you can get a click, but it can be kind of quiet and muffled. that gives an incorrect value (and not repeatable and this is what the original test team probably found) however, in my tests, when i only used the clean readings, the 9201 was very accurate and repeatable. (+/- .1-.2)
i give the kemp tool a range of 4 to 6 in the window compared to the 9201. this means, just get near the max of the window and you are in the 5.2-5.6 range, which i imagine is good for the first initial setting.
Thanks for all the comments and concerns!
By the way, i may drill a hole in the bottom of the cam cover and use the Kempf tool and a short shaft to check tension. i think it will be a very accurate way to at least check the 1000mile tension if not verify the tension at any time without having to remove the covers.
(using the flat part of the tensioner and a shaft up toward the belt, push until the spring is stretched and the tool bottoms out. mark the movemement, compare next time!)
Mark
Firing the ole Holbert car up tomorrow AM and doing a freeway run!!!!
11-23-2004, 07:55 PM
#40
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Hopefully Jay will confirm, but I was told to use the middle of the window for 16V cars and the upper part of the window for 32v cars.
Has worked for both of my cars over the past two years.
Has worked for both of my cars over the past two years.
11-23-2004, 07:58 PM
#41
Rennlist Member
Originally Posted by mark kibort
...... should have rebuilt the tensioner, but all that would have changed would be that gasket to the block and the new o ring. since it is not leaking out the bolt, and not seeping out the block, i think the leak is just an over fill.
any comments?? ....
Mk
any comments?? ....
Mk
11-23-2004, 08:01 PM
#42
Rennlist Member
Thread Starter
Like i said, in the middle to the beginning area, i coorelated to 4.1 or so on the 9201 tool. anything over half is probably going to be ok, until the end, where that can be 6.0. looks like the safe bet is the back 1/4 of the window. half way only got me to 4.5ish.
Im pretty good with the 9201 tool getting very consistant readings. its easy to use on the race car, as there is nothing in the way for tests too!
MK
Im pretty good with the 9201 tool getting very consistant readings. its easy to use on the race car, as there is nothing in the way for tests too!
MK
Originally Posted by John Veninger
Hopefully Jay will confirm, but I was told to use the middle of the window for 16V cars and the upper part of the window for 32v cars.
Has worked for both of my cars over the past two years.
Has worked for both of my cars over the past two years.
11-23-2004, 08:20 PM
#44
Rennlist Member
Thread Starter
I dont have the calibration bar, but the tool is in the box and the shop is one of the best. plus, when i did measure 4.0 with the Kempf tool showing just in the window by 1/4 of the width, the belt did feel loose even by the old traditional twisting techquique. im sure its not off , if any. Plus i did have the tension light go on last year, tightened the belt 1/2 turn just before the SpeedGT laguna race in 2003, Light never came back on , and later checked the belt to be 5.7. So, if anything, the tension tool is on the soft side.
mk
mk
Originally Posted by John Veninger
Did you have and use the calibration bar to set the 9201 or just use it out of the box from the shop?