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#Post#: 338--------------------------------------------------
Flywheel bolts
By: Tim Watson Date: August 23, 2012, 5:29 pm
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Hey folks.
Just wondering if anyone has come up with a better item for the
flywheel cover plate to clutch bolts. I'm sure we are all aware
that the standard ones are made of slightly mature cheese, then
bend and snap. The issue I seem to have is that they are an odd
size, so was just wondering if anyone had any good info on where
we can get some better quality bolts to stop this happening.
Any advice or info will be greatly received.
Thanks.
Tim
#Post#: 341--------------------------------------------------
Re: Flywheel bolts
By: mitlom Date: August 24, 2012, 4:31 am
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Hi Tim,
Interesting you should mention this as I was doing a load of
reading and searing of t'internet yesterday on this very topic!
It seems that some people have had issues whilst others running
similar spec engines have not ???
The bolts in question are10.9 grade so are not a bad grade of
fastener, the thread is M7 x 1.0 so alternatives in a higher
grade such as 12.9 are not going to be readily sourced
unfortunately. I know there has been mention of drilling out
the M7 thread and tapping to a larger thread but this would need
a significant amount of machining of both the flywheel and the
pressure plate. The alternative would be to fit a number of
solid steel dowels to both the flywheel and pressure plate which
again would require additional machining but potentially a
better solution?
The final thing worth pointing out is that it has been suggested
that one of the issues that contributes to the failure of these
bolts on high reving engines is the use of NON lightened
flywheels and that by lightening the flywheel you will prolong
the life of these M7 fasteners, I would also suggest fitting new
items when re-building an engine and also modifying the pressed
steel gearbox to engine back plate to provide an access hole so
that the bolts can be cheked without removing the gearbox ;)
Tim
#Post#: 482--------------------------------------------------
Re: Flywheel bolts
By: chrismc Date: October 7, 2012, 1:47 pm
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I managed to shear 6 out of 9 with a missed gear change on my
old ITB'd 16v- scary biscuits :o
I have known other valvers to do the same- though only those
with 2L bottom ends & revving to 7800 instead of the KR 7200
limit
Maybe an issue of the slightly increased torque combined with
the weak bolts & poor stock locating dowel.
I used to own the OP's 16v & that flywheel has been lightened &
modded with 2 steel dowels & the bolts were correctly
torqued/loctited on assembly- however at a recent Curborough
sprint day we attended I sensed all was not well :-\
It also has a 2L block so we shall have to do some
investigations!
An access hole in the bellhousing is what my 2 16v trackday
friends have gone for
#Post#: 1010--------------------------------------------------
Re: Flywheel bolts
By: daligh Date: October 18, 2013, 5:46 am
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I looked at this issue a a couple of years ago and make the
following observations:
The 1988 the VWMS brochure lists the standard bolt for the
flywheel/cover-plate joint: N 100 134 01
The 1989 supplement and the Group A Workshop Manual list an SP
part number: N 100 134 01 SP
The Manual assembly instructions refer to these as 'Special
Bolts' and it does not suggest using Loctite 'Blue' on these
bolts, but does advocate its used on the cover-plate/crankshaft
bolts.
The Sachs Performance clutches, 606 & 616, are made from 5.5 mm
thick material, not the 5 mm of the standard unit. This extra
0.5 mm adds 30% more flexural stiffness to the bell of the
cover-plate and, because of the better production quality of the
these clutches, the threads formed are more than 0.5 mm deeper.
These units use a three plate drive link so the bending forces
transmitted between pressure-plate and cover bell are less than
with a single plate link.
The VWMS assembly uses a 2.5 mm thick intermediate plate at the
cover-plate/crankshaft joint which reduces the flex in this
area.
All VWMS Mk2 documents I have seen call for a standard flywheel.
The rev limiter for these engines is pre-set to 8200 rpm.
As the bolted joint between cover-plate and flywheel is designed
to transmit radial shear loads through friction at the interface
any flexing local to the bolts will tend to 'work' the joint so
loosening could occur.
#Post#: 1016--------------------------------------------------
Re: Flywheel bolts
By: mitlom Date: October 18, 2013, 5:30 pm
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I recently had the opportunity to tour the ARP manufacturing
facilities in California and following some discussion with
Jason I am in the process of drawing the standard OEM fasteners
and sending them to ARP for them to evaluate some uprated items
;)
#Post#: 1021--------------------------------------------------
Re: Flywheel bolts
By: GEL Date: October 19, 2013, 7:02 am
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Excellent info and progress guys :)
#Post#: 1068--------------------------------------------------
Re: Flywheel bolts
By: Smudge Date: October 22, 2013, 3:16 am
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[quote author=GEL link=topic=66.msg1021#msg1021 date=1382184127]
Excellent info and progress guys :)
[/quote]
^ This ;D
#Post#: 1085--------------------------------------------------
Re: Flywheel bolts
By: daligh Date: October 24, 2013, 4:40 am
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Tim Moll mentions people cutting inspection holes in the pressed
steel shield between clutch pressure plate and block.
I did this a few years ago and photos below should be self
explanatory:
[URL=
HTML http://s899.photobucket.com/user/daved96/media/clutchhole001JMR_zps40f8d164.jpg.html][IMG]http://i899.photobucket.com/albums/ac193/daved96/clutchhole001JMR_zps40f8d164.jpg[/img][/URL]
[URL=
HTML http://s899.photobucket.com/user/daved96/media/clutchhole002JMR_zps2c128d39.jpg.html][IMG]http://i899.photobucket.com/albums/ac193/daved96/clutchhole002JMR_zps2c128d39.jpg[/img][/URL]
[URL=
HTML http://s899.photobucket.com/user/daved96/media/clutchhole003JMR_zpsa817bbb0.jpg.html][IMG]http://i899.photobucket.com/albums/ac193/daved96/clutchhole003JMR_zpsa817bbb0.jpg[/img][/URL]
#Post#: 1123--------------------------------------------------
Re: Flywheel bolts
By: TSC Date: October 26, 2013, 8:35 am
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I've popped flywheel bolts even on a mostly standard 1.8 KR,
with a lightened flywheel only, on track - so I'm not surprised
they go on something a bit revvier. Only found out when I heard
a rattle from the gbox coming off track. Thought the box was
eating itself, but no - flywheel bolts rattling around. I do
drive like a prick though, in a car not prepared for it. Give me
a dose of that Loctite, eh Dave?
#Post#: 1135--------------------------------------------------
Re: Flywheel bolts
By: RobT Date: October 26, 2013, 12:21 pm
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The reverse flywheel is a daft idea. Bin it and fit an 02a
setup.
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