Kempf tool VS porsche 9201 tool PROBLEMS HERE!
08-11-2011, 09:12 AM
#31
Addict
Rennlist Member
Rennlist Member
Dare I say that both tools measure the torque applied to the belt to move part of it a certain distance. You also need to ascertain the time taken to take the reading to compute the horsepower required.
08-11-2011, 02:32 PM
#33
Rennlist
Basic Site Sponsor
Basic Site Sponsor
im actually pretty good with the tool, but thanks for the heads up. yes, i spun the engine several revolutions. yes, it did change the measurement slightly. a little higher after rotation a few times.
i tried the tool from almost on the pulley itself to toward the water pump. you just got a picture of one of many of the testing spots. the results were no that different when the kempf tool said "max window setting, or near 5.0". I actualy put the center cover on for a sec, becase i always use that as a reverence point too.
I also can get it to click, see the setting and then tighten the bolt to reach the desired setting. seems like a good way to do it, and I cant see any drawbacks to that, unless you do.
anyway, I just measure the differences in belts as the little round shaft fits into the belt between the teeth. its 1mm thicker, so basically, the older belt adjustment will be WAY too tight if you use the 9201 too. if you have ever used it on older models and set it to 5.0, the tension is really more like 7.0,
I used several simple ways to verify this. one way n particular was to fit both the belt and the adjustment tool in the tool itself and see what the needle did. it was between 1.5 and 2 off on the gauge!!
i tried the tool from almost on the pulley itself to toward the water pump. you just got a picture of one of many of the testing spots. the results were no that different when the kempf tool said "max window setting, or near 5.0". I actualy put the center cover on for a sec, becase i always use that as a reverence point too.
I also can get it to click, see the setting and then tighten the bolt to reach the desired setting. seems like a good way to do it, and I cant see any drawbacks to that, unless you do.
anyway, I just measure the differences in belts as the little round shaft fits into the belt between the teeth. its 1mm thicker, so basically, the older belt adjustment will be WAY too tight if you use the 9201 too. if you have ever used it on older models and set it to 5.0, the tension is really more like 7.0,
I used several simple ways to verify this. one way n particular was to fit both the belt and the adjustment tool in the tool itself and see what the needle did. it was between 1.5 and 2 off on the gauge!!
__________________
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
08-11-2011, 02:33 PM
#34
Rennlist
Basic Site Sponsor
Basic Site Sponsor
so, clearly the old timing belts should NOT be tightened with the 9201 tool. think of all the WRECKED timing belts, pulleys..........etc . !!!!!!!!!!!!!!!!! its not a stretch that I may have just accidentially figured out why. who has old and new enigines next to each other, spare old and new belts laying around and has used the kemp tool and the 9201 on a old motor with belt assembly. by tightening the old belt with the 9201 to 5.0, you are essentially tighting the belt to 7.0 that would explain the grooved out cam pulleys, now wouldnt it?????
i think the manal just says twist the belt to 45 degrees and call it a day or something on the older models, right?
i think the manal just says twist the belt to 45 degrees and call it a day or something on the older models, right?
BTW...I've had my 9201 tool since I took the very first belt off of my first 928 engine....back in 1979.
08-11-2011, 02:34 PM
#35
Rennlist
Basic Site Sponsor
Basic Site Sponsor
update: Just thought about it for awhile. since the belt just doesnt fit the 9201 the same, you have to MAKE it the same. I did this by puttiing some tape around only ONE side of the tensioner tool 9201 roller and made it apear to the belt, in the same way that the HTD belt would . when i did this, the tension goes up by 1 full point. anyway, im full window on the kempf tool now, and with the tape on the 9201 roller, its at 4.0. but before when i had the 9201 at near 4 , the tape made the result near 5.5.
anyway, there might be subtle differences in the belt as well. im a little puzzled on how to set it, but feeling a little better after figuring out the belts being held differently, is a huge issue and needs to be addressed.
anyway, there might be subtle differences in the belt as well. im a little puzzled on how to set it, but feeling a little better after figuring out the belts being held differently, is a huge issue and needs to be addressed.
08-11-2011, 02:49 PM
#36
Rennlist Member
Thread Starter
08-11-2011, 02:52 PM
#37
Rennlist Member
Thread Starter
08-11-2011, 02:58 PM
#38
Rennlist Member
Thread Starter
So, by measuring the belt with the porsche tool 9201, at what I have set at 4.0 (notice, i havent shown anything over 4.0), when you use the Kempf tool, its so far over the window, its in the next county!
point is, the kempf tool is not that far off. i mocked up something to simulate the thicker belt of the HTD design, and found that the gauge reads about 1 to 1.5 higher, just based on belt construction and size.
So, why at 3.0 or so, does the kempf tool go off scale showing very very tight.
yet, when used on a HTD type, does both the tool and the Kempf tool coorelate equal?
Do you just set the old bugger belts at 4.0 with the tool? maybe this is too much tension vs the original design and WSM instructions. you can see my concern. its not that much of a stretch to question what is going on here vs the HTD versions.
point is, the kempf tool is not that far off. i mocked up something to simulate the thicker belt of the HTD design, and found that the gauge reads about 1 to 1.5 higher, just based on belt construction and size.
So, why at 3.0 or so, does the kempf tool go off scale showing very very tight.
yet, when used on a HTD type, does both the tool and the Kempf tool coorelate equal?
Do you just set the old bugger belts at 4.0 with the tool? maybe this is too much tension vs the original design and WSM instructions. you can see my concern. its not that much of a stretch to question what is going on here vs the HTD versions.
08-11-2011, 04:31 PM
#39
Inventor
Rennlist Member
Rennlist Member
08-11-2011, 06:22 PM
#40
Addict
Rennlist Member
Rennlist Member
both equate to measuring the force required to deflect the belt sideways a given amount which increases the tension in the belt. This indiectly gives an indication of the tension initially present.
The kempf gauge will read high if you use it anywhere other than midspan between the tensioner pulley and the cam pulley. This is due to the increase in torque required to physically twist the belt regardless of the tension in it. Easiest way to understand this is to hold a belt in your fingers with about 1" of belt between your hands and then twist 90 deg letting your hands move closer together as you twist - no increase in tension but quite hard to twist. Repeat with hands a foot apart - very easy to twist.
Have you lubricated the pivot pin in the kempf tool recently ?
The kempf gauge will read high if you use it anywhere other than midspan between the tensioner pulley and the cam pulley. This is due to the increase in torque required to physically twist the belt regardless of the tension in it. Easiest way to understand this is to hold a belt in your fingers with about 1" of belt between your hands and then twist 90 deg letting your hands move closer together as you twist - no increase in tension but quite hard to twist. Repeat with hands a foot apart - very easy to twist.
Have you lubricated the pivot pin in the kempf tool recently ?
08-11-2011, 08:50 PM
#41
Rennlist
Basic Site Sponsor
Basic Site Sponsor
I can still count, on a single hand, how many timing belt failures I've ever seen, in my entire 928 history (now, literally thousands of vehicles).....and still have a couple fingers left over. I can even include the one CRaP belt that skipped on a race engine that backfired cold...and still have fingers left.
I've got a pretty good list of things that happen to the 928 model vehicles that people need to be concerned with...and the stock tensioner design still isn't anywhere on that list.
08-11-2011, 10:05 PM
#42
Rennlist Member
Would downshifting at too high of a speed for the gear possibly be a cause for a belt to skip teeth on one of the cam gears? Especially if the belt were a little loose?
08-12-2011, 01:12 AM
#43
Rennlist
Basic Site Sponsor
Basic Site Sponsor
That's tough to answer. Lots of different things can go wrong, then there is a true mechanical overrev. I've personally seen 911s blow up the clutch, bend valves, break rocker arms, I can see where the belt could slip on a cam sprocket, on a 928.
08-12-2011, 01:17 AM
#44
Addict
Rennlist Member
Rennlist Member
08-12-2011, 01:20 AM
#45
Rennlist Member
I had two occasions where the red mist descended on my brain and in my excitement I went into Muncie 4spd mode and pulled it into 1st at too high of a speed.
I'm just trying to figure out what happened on mine.
I'm just trying to figure out what happened on mine.