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korfmach
Samba Member
Joined: February 28, 2014
Posts: 264
Location: Fort Collins, CO
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 Posted: Thu Apr 23, 2015 10:44 pm Post subject: Flywheel / pressure plate balance |
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Hi everyone...putting a new clutch disc in the Bleeding Trout. I followed the Bentley advice of marking the bolt holes so that the pressure plate could be reinstalled in the same orientation on the flywheel. Then I used some solvent to clean off the pressure plate and (of course) erased my marks.
1) Is the PP/flywheel balance relationship super critical, and
2) if so, is there a method to re-establish the correct relationship between the two that preserves the rotational balance?
Hope this description is adequate.
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1989 Westy
2016 Golf TSI
Gone, but not forgotten:
1974 Dorper Baywindow, "The Bleeding Trout"
1998 Jetta TDI, "Trixie"
1987 GTI, "Heike"
1974 Thing, "The Luftwaffel"
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curtis4085
Samba Member
Joined: July 22, 2011
Posts: 4806
Location: Colorado
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| Posted: Thu Apr 23, 2015 10:51 pm Post subject: |
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Critical to a long engine life!! If balanced correctly the shop that did it should have out indexing marks on the flywheel and pressure plate.
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scrivyscriv
Samba Electrician
Joined: October 04, 2011
Posts: 3344
Location: Memphis
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| Posted: Fri Apr 24, 2015 5:31 am Post subject: |
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The shop that balanced my parts used white paint for alignment marks, so maybe hopefully you still have something there? If it goes on any other way... the balance job is worthless.
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 13491
Location: West Coast, USA
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| Posted: Fri Apr 24, 2015 6:17 am Post subject: |
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Are they apart or still together currently?
Most shops use a punch or engraved indexing mark. Look for dots that match up.
If they're apart, take them to a balance shop and explain what happened. You'll basically be paying for a balance, but instead of removing material, they'll be trying to balance it six different ways and finding the original index.
Robbie
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kreemoweet
Samba Member
Joined: March 13, 2008
Posts: 4097
Location: Seattle, WA
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| Posted: Fri Apr 24, 2015 9:09 am Post subject: |
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The OP gives no indication that his flywheel and PP were balance-matched (and I doubt if they were from the factory), so reinstallation position
is not an issue. Given that it is quite rare for any bus to have such balance-matched parts, it is not only not "super-critical", but I would say not
even "important".
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korfmach
Samba Member
Joined: February 28, 2014
Posts: 264
Location: Fort Collins, CO
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| Posted: Fri Apr 24, 2015 1:52 pm Post subject: |
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Thanks all for your input. I was concerned about the balance just because my Bentley says one should mark the PP position WRT to the flywheel.
I took the flywheel to a machine shop today--it was in pretty good shape but I figured I might as well get it resurfaced since it was already out. The machinist said the same thing as Kreemowheat...it's not balance-matched so reinstallation position doesn't matter.
_________________
1989 Westy
2016 Golf TSI
Gone, but not forgotten:
1974 Dorper Baywindow, "The Bleeding Trout"
1998 Jetta TDI, "Trixie"
1987 GTI, "Heike"
1974 Thing, "The Luftwaffel"
1974 Ghia
1966 Ghia |
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 13491
Location: West Coast, USA
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| Posted: Fri Apr 24, 2015 2:32 pm Post subject: |
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| korfmach wrote: |
| The machinist said the same thing as Kreemowheat...it's not balance-matched so reinstallation position doesn't matter. |
This is both correct and incorrect. So I guess it's neither...
Reinstallation DOES matter! Your flywheel is likely not perfect, and your pressure plate is not perfect either. (That is, if your engine was not professionally balanced.) So there is an installation position that would actually help out your engine, if the balances are offset. The opposite is true as well; if both heavy sides of both pieces are on the same side, you'll head/feel more vibration, and engine life will be shortened.
The problem lies in "how do you know?" So you'll have to take a guess. And you have a 1/6 chance of getting it best, a 1/6 chance of making it worse, and a 2/3 chance of making it just OK. If you are the adventurous/OCD/caring type, you can make a mark NOW, and change it every time you pull the engine. Or pull the engine to change it, if when you put it back in the vibration is worse. If you put it back in and the vibrations are LESS, go buy a lotto ticket.
What size flywheel/clutch/ pressure plate are you running? If 200mm, then you might have to deal with the crap Sachs plates that are on the market today, and don't line up with the flywheel perfectly.
Robbie
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