Kempf setting / @ post #96, where for Gates Racing Belt?
10-04-2010, 12:26 PM
#18
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Thread Starter
Gates regular? Seemed very durable. I'm switching to them on mine.
Mark the odo, drive it 1000 miles and when we retension we can shoot for just a hair above middle of window.
Or wherever the team here decides is better.
Mark the odo, drive it 1000 miles and when we retension we can shoot for just a hair above middle of window.
Or wherever the team here decides is better.
10-04-2010, 12:38 PM
#19
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Dave
10-04-2010, 01:07 PM
#21
Burning Brakes
10-07-2010, 12:42 PM
#22
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As proud new owner of the Gates Racing belt (thx to Roger), I'd be interested as well. In the street car you can probably be save by the PKtensioner. However, my buddy wants to get the belt for his racer and likes to stay with the factory tensioner. Anyone out there who is racing the PKtensioner?
Marc
Marc
10-07-2010, 02:41 PM
#24
Former Sponsor
I went back and looked at the engine that I have on the stand, with Roger's new Gates Racing belt. I also studied another one of Roger's Gates Racing belts that is not installed on an engine. Huge difference in belt stiffness, when compared to a stock Porsche belt.
I'd have to guess that every measuring tool we have for belts is going to have to be "recalibrated" for this belt. Certainly the Kempf tool, which measures "twist" is not going to work. The 9201 tool, which measures the amount of "flex" between two different (very close together) points, is going to be inaccurate. Any of the audible tightness tools that measure tightness dependant upon sound is going to be inaccurate, because the belt has a completely different "sound" when it touches anything (sounds like a piece of hard plastic....or a sheet of carbon fiber). Doesn't sound like rubber, at all.
I have no idea how Ken's tensioner is going to work with this belt. It would seem that this belt would need "more" tension force to keep it tight, because it is so stiff.
Additionally, the cam timing numbers, when one assembles an engine, advance the camshaft on the driver's side more than the camshaft on the passanger side, because there is way more belt stretch at the crank pulley than there is between the two cam gears (the smaller crank gear is "exerting the force" that both moves and stretches the belt.) A belt that doesn't stretch as much will naturally need different cam timing set-up numbers. (I compensated for this, when I assembled the engine I put this belt on...but had to guess at how much different the stretch would be.
The other thing that will be interesting is to see how this belt works with the hard anodized cam gears. Initially, I'd think that this belt would be far more abrasive than the stock rubber belt.
Time and careful study will answer all of these questions.
I'd have to guess that every measuring tool we have for belts is going to have to be "recalibrated" for this belt. Certainly the Kempf tool, which measures "twist" is not going to work. The 9201 tool, which measures the amount of "flex" between two different (very close together) points, is going to be inaccurate. Any of the audible tightness tools that measure tightness dependant upon sound is going to be inaccurate, because the belt has a completely different "sound" when it touches anything (sounds like a piece of hard plastic....or a sheet of carbon fiber). Doesn't sound like rubber, at all.
I have no idea how Ken's tensioner is going to work with this belt. It would seem that this belt would need "more" tension force to keep it tight, because it is so stiff.
Additionally, the cam timing numbers, when one assembles an engine, advance the camshaft on the driver's side more than the camshaft on the passanger side, because there is way more belt stretch at the crank pulley than there is between the two cam gears (the smaller crank gear is "exerting the force" that both moves and stretches the belt.) A belt that doesn't stretch as much will naturally need different cam timing set-up numbers. (I compensated for this, when I assembled the engine I put this belt on...but had to guess at how much different the stretch would be.
The other thing that will be interesting is to see how this belt works with the hard anodized cam gears. Initially, I'd think that this belt would be far more abrasive than the stock rubber belt.
Time and careful study will answer all of these questions.
10-07-2010, 03:27 PM
#25
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Hmmm...
It would appear that running with the Gates racing belt and PKtensioner would be charting new territory. I think I'll stick with the more conventional route for now with the factory tensioner and standard Gates or Porsche belt.
As we are on the topic of belt tensioners, which vendor sells a kit for rebuilding the factory tensioner?
It would appear that running with the Gates racing belt and PKtensioner would be charting new territory. I think I'll stick with the more conventional route for now with the factory tensioner and standard Gates or Porsche belt.
As we are on the topic of belt tensioners, which vendor sells a kit for rebuilding the factory tensioner?
10-07-2010, 03:42 PM
#26
Roger has that stuff too. I'd not be worried about the Pk tensioner, lots of them on the road.
10-07-2010, 03:49 PM
#27
Race Car
Dan
'91 928GT S/C
475hp/460lb.ft
10-07-2010, 04:36 PM
#28
I don't have an answer to that, or any ideas either.
10-07-2010, 04:55 PM
#29
Rennlist Member
Greg, I have a Kempf tool, and measured it and two others against a 9201, all three of the Kempf tools had significantly different readings.
You bring up a point that I never would have thought of, how the stiffness of a belt would affect your belt tension measurements.
You bring up a point that I never would have thought of, how the stiffness of a belt would affect your belt tension measurements.
Also, this is why a lot of belt tension measurement is done by audio frequency. More accurate, more repeatable. And if you look up vibrating string theory, you'll see why. Just adding this as an ex-electric bass maker.
10-07-2010, 05:31 PM
#30
Former Sponsor
But Greg, have you tried measuring three 9201's against one Kempf tool? I'm not really being facetious, just thinking about statistics.
Also, this is why a lot of belt tension measurement is done by audio frequency. More accurate, more repeatable. And if you look up vibrating string theory, you'll see why. Just adding this as an ex-electric bass maker.
Also, this is why a lot of belt tension measurement is done by audio frequency. More accurate, more repeatable. And if you look up vibrating string theory, you'll see why. Just adding this as an ex-electric bass maker.
I agree on the audio frequency. I'd be thrilled if someone has a audio frequency value, for Roger's Racing belt. That would solve everything, for me. However, as I stated earlier, this belt is going to have a different "tune" than the factory belts.