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D1R Supercharger Kit belt tension
#1

Over the years of having this kit out there, there have been a number of continuing questions about the belt tension. There have also been some pulley failures. I thought I would take a minute to address this.



The pulley failures are a result of too much belt tension. The Dayco pulley used is designed to service 100k miles of use. This assumes that there isn't too much side loading on the bearing. Unfortunately some installations have resulted in too much side loading. I now know how this happens, and it is a direct result of failure to follow instructions.



The instructions clearly tell the installer to use the center link of the OEM tensioner if the belt is too tight. I have always said that less tension is needed on the belt than in stock configuration. I guessed about 80% of the tension setting would do it. Regardless, if there is more tension than stock, which can easily be read with any of the tools, then clearly it is too much. Many of the installations resulted in the use of a prybar to get the Tensioner that came with the kit installed, with some really struggling to get it in there. This is a clear indication that it is too tight. This is the point at which the center link should be changed to the OEM unit, and be used with the heim joints and jam nuts that came with the kit.



Failure to take this step has resulted in a number of pulley failures. I thought it was 12, but after going back over my records, it seems more like 8 or 9. Still that is too many. This is completely avoidable.



Further, the Belt Guard may require the bolt holes to be drilled out larger, so that the Belt Guard may be raised to create further clearance from the belt. It may also need a bit of "tweaking" to create clearance. This will in no way reduce the effectiveness of the Belt Guard.



In the end, the belt need only be tight enough so as not to slip. Slippage will show up on a boost gauge.



If it makes anybody feel better, I too created a failure by over-tensioning the belt. That's how I figured this out.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



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#2

Hmmm, I followed the instructions to the letter, but perhaps my instructions were an "early edition"? They are Revision 3s.



Here's all the excerpts related to the belt and tensioner from my copy. There are no references to using a different center link on the tensioner, but there are references to using a pry bar to get the tensioner to fit (thereby tightening the belt even more). Maybe these were updated since... is there a new revision I should download?



[Image: Tension.png]
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#3

yeah - it's on the site. i know i've talked about this a number of times, starting way back when the first pulley failed. the instructions have included this since august of 2012.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#4

p.s. - we are now on version 5. version 4 brought in the bit about the tensioner. i edit the instructions as i find things that make them better. it's part of a constant ongoing attempt to improve a product, just as have been the retrofit of some parts that were in early versions.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#5

Most people would obfuscate about problems with anything they designed, but not our Flash, I'm proud of him! Psst,psst, any SC kits kicking about buddy. No? Well, I think its very poor that there are any problems with the kit! Its totally unacceptable.... unless you rake in the attic and come up with an SC kit for moi! Cheers.



Andy
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#6

Page 26



"Tip: Cut a notch as shown below in the Adaptor Hose as necessary to create at least

2mm clearance between the charge pipe and the belt"



Is not shown below.



MN
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#7

crap! i have no idea what happened to that. i'll get in there and fix it.



basically you cut a 3/16" wide 1" long semi-circle "notch" in the edge of the hose, on the small end, which will fit into the corner of the tight bend of the charge pipe, allowing you to insert the charge pipe farther into the adaptor hose, which moves the charge pipe away from the belt guard.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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#8

[color="#000000"][size=2]Bob,[/color][/size]

[color="#000000"][size=2]I knew right away what you meant and why. However, since no photo in the installation instructions, my mechanic apparently ignored your instructions/suggestions when installing. As a consequence, the charge pipe was exerting a side load on the belt cover which in turn exerted a side load on one of the pulley, which then started to fail.[/color][/size]

[color="#000000"][size=2]Maybe you could also incorporate your technical bulletins in the installation instructions and maybe add a check list and a trouble-shooting section.[/color][/size]

[color="#000000"][size=2]MN[/color][/size]
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#9

there is really no chance the charge pipe hitting the belt guard would have any effect on the pulley. even if you were smack up against the belt guard, it wouldn't affect the pulley. they don't touch each other al all. you would have to be rubbing on the pulley for that to happen, which would have made a hell of a racket.



more likely, he also ignored the instructions about the tensioner, which resulted in the belt being too tight, thereby putting too much stress on the pulley bearing.



if the pulley fails, you will have to replace the pulley. you will need to shave .035" off one face of the replacement so that it will clear the mounting plate. contact me directly for more information.



since there are no current plans to make any more kits, incorporating the tech bulletins at this time would serve little purpose. however, it would certainly be something to do with any hypothetical subsequent kits.
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94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com



"It isn't nearly as expensive to do it right as it is to do it wrong."
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