Timing belt stretch. Readjust timing belt after some miles?
08-26-2018, 11:12 AM
#1
Burning Brakes
Thread Starter
Timing belt stretch. Readjust timing belt after some miles?
Since the stock tensioner doesn't take up slack I'm guessing the belt needs retensioned after some time. How long do people normally wait to do this? I've got less than 100 miles since the belt was done on my blue car right now.
08-26-2018, 12:30 PM
#2
Drifting
The WSM says to check tension after 1000km or around 600 miles. That’s what I do, but I’ve seen posts saying the belt has actually done most of its break on a lot earlier within a few hundred mile.
WSM good enough for me, and you have the belt warning system in case anything’s going badly wrong.
WSM good enough for me, and you have the belt warning system in case anything’s going badly wrong.
08-26-2018, 03:40 PM
#4
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The card that used to come with a new Porsche tuning belt said to readjust in 1500-2000 miles, which is what we recommend.
If a new factory belt is set to 5.0 wirh the 9201 tool, by 2000 miles it will have stretched to ~3.8. The belt light is very reliable and predicable and will light ~3.2, so the belt light will not come on, during this time.
We've check many factory belts before 1500 miles and found that they will not be fully stretched until that point.
Of course, if you run any other belt than a factory belt, they will stretch much quicker and need adjustment earlier.
If a new factory belt is set to 5.0 wirh the 9201 tool, by 2000 miles it will have stretched to ~3.8. The belt light is very reliable and predicable and will light ~3.2, so the belt light will not come on, during this time.
We've check many factory belts before 1500 miles and found that they will not be fully stretched until that point.
Of course, if you run any other belt than a factory belt, they will stretch much quicker and need adjustment earlier.
08-26-2018, 09:20 PM
#6
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I've never had or used a Kemph tool, so I'm not going to be of any help.
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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!
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08-26-2018, 11:07 PM
#8
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Regardless (maybe) of miles 6 months seems to be enough. This for a storage climate that sees actual temperature changes. Might or might not apply in SC. Certainly not CA.
08-27-2018, 12:49 AM
#10
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Notes on various belt types from the PKT-S manual:
A new belt will stretch to create approximately 2 mm (or more) additional piston extension after about 1000 miles.
Continental belts are thicker (2.56 mm) and install with less T/D extension than Gates (2.49 mm) but both will stretch to be about equal. The Gates Racing belt is thinnest (2.39 mm), has the largest initial T/D extension but stretches less, and takes longer to stretch.
(Flennor belts are made by Gates.)
A hot engine will show approximately 2 mm less piston extension than a cold engine.
Continental belts are thicker (2.56 mm) and install with less T/D extension than Gates (2.49 mm) but both will stretch to be about equal. The Gates Racing belt is thinnest (2.39 mm), has the largest initial T/D extension but stretches less, and takes longer to stretch.
(Flennor belts are made by Gates.)
A hot engine will show approximately 2 mm less piston extension than a cold engine.
08-27-2018, 01:59 AM
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