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Probably about the same, I guess the new belt has the potential to be shorter so in theory would require more shims on the inside?

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I maybe wrong but isn't it the case that you may need to move some shims to either side to get the right fit.

Edited by Beaky
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Correct Beaky. Put more inside the pulley to slacken the belt, less inside to tighten. Most important is to make sure that are all used. In all likelihood you'll find the same amount in/out as before will be about right. Be careful not to crush/distort any.

Chris

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7 hours ago, sheep911uk said:

I am going to replace the fan belt, I know there are 6 washers used to adjust tension but putting a certain number either side but what’s the split for a new belt?

Interesting - there were only four on mine. Two either side.

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funny enough i have seen 5 or 6 shims mentioned in genuine porsche literature, which I have never gotten to the bottom of. I have always used 6, but i read 5 in an owners manual not that long ago and it was not the first time ive seen that.... I'll see if I still have it (I have a couple of manuals, plus loads of tech books). 

A good trick, is a tiny smear of grease on the shims on the outside so they stick to each other then you can put them in "as one", then when you tighten dont use the special pulley holder (yet), simply tighten the nut, turning the engine (which turns the pulley), checking the shims have not fallen to one side (where you then accidently squash them), then when you get to the point that all you are doing is turning the engine with your spanner, then put the special pulley holder on and finish tightening the belt.

Finally of course check belt tension (just twist 90 deg mid way at longest point) Complete by looking at the belt while reving the engine while at the engine and see if it still seems "loose"

 

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Ooooh that grease tip is nice! I'm always having trouble with the shims shifting before I can tighten things up and end up having to use some percussive maintenance to straighten out a distorted shim.

I always start off with 6 shims on the inside before tightening things up with a new belt on. After some time as the belt stretches/wears I move shims to the outside to maintain tension until eventually I end up with all 6 shims on the outside.

One mechanic who was told to tighten my belt (before I learned how to do it) insisted that any shims not on the inside should be kept as spares! I told him all 6 must be on the car otherwise there is the danger of the pulley bottoming out, he didn't listen so I learned to do it myself and he was forbidden from the owner of the garage from touching my car again. One other tip after fitting and checking the tension is to turn the engine over by briefly turning the ignition key but not starting the car. After that go back and check the tension again.

When I first started to change my fan belt I kept having the belts becoming loose ever so quickly. I found out the reason for this was over-tightening the nut holding the pully in place. Get yourself a torque wrench and use the correct torque settings. After I learned that lesson I never suffered that issue again.

One last tip, get a bit of rag and put it under the main pulley to catch anything that may fall, I learned this after dropping the main nut down into the recess where the bottom pully is located, it was NOT fun trying to retrieve it.

Another last tip, I always buy genuine Porsche fan belts from my OPC, they fit better and last longer, at least, that's my personal opinion.

Edited by SurlySurdi
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3 hours ago, sheep911uk said:

Thanks how do you know what the correct tension is?

The Bentley manual states 5mm deflection at mid point with finger pressure. Hardly definitive but there you go.

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11 hours ago, SurlySurdi said:

Ooooh that grease tip is nice! I'm always having trouble with the shims shifting before I can tighten things up and end up having to use some percussive maintenance to straighten out a distorted shim.

I always start off with 6 shims on the inside before tightening things up with a new belt on. After some time as the belt stretches/wears I move shims to the outside to maintain tension until eventually I end up with all 6 shims on the outside.

One mechanic who was told to tighten my belt (before I learned how to do it) insisted that any shims not on the inside should be kept as spares! I told him all 6 must be on the car otherwise there is the danger of the pulley bottoming out, he didn't listen so I learned to do it myself and he was forbidden from the owner of the garage from touching my car again. One other tip after fitting and checking the tension is to turn the engine over by briefly turning the ignition key but not starting the car. After that go back and check the tension again.

When I first started to change my fan belt I kept having the belts becoming loose ever so quickly. I found out the reason for this was over-tightening the nut holding the pully in place. Get yourself a torque wrench and use the correct torque settings. After I learned that lesson I never suffered that issue again.

One last tip, get a bit of rag and put it under the main pulley to catch anything that may fall, I learned this after dropping the main nut down into the recess where the bottom pully is located, it was NOT fun trying to retrieve it.

Another last tip, I always buy genuine Porsche fan belts from my OPC, they fit better and last longer, at least, that's my personal opinion.

as above indeed, and it says porsche on the side of the belt which is nice (but they really do fit better), good tip on the torque wrench, i always use one on everything (engine/suspension) but never on the belt, i'll keep that in mind and try next time

10 hours ago, sheep911uk said:

Thanks how do you know what the correct tension is?

i do all belts such that if you can just twist it 90 degrees then it is tight enough, that said I always also start the engine, and rev it looking at the belt, if you see it "flap" then its not tight enough, and your alt bearings while whine if its over tight

Edited by Strictly
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