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HELP! 1800 Clutch Bolts

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sikdub Wolfsburg Wizard

571 posts · joined Aug 2002 ·

#628991
Hey All,
I'm getting ready to put my 1800 into my 74 camper but have been held up by a problem. I have got 7mm 1.0mm thread Grade 8 high tensile bolts and when I try to tighten them up to 24ft/lb they will snap a few mm down from the head. What am I doing wrong?

The ones on the clutch beforehand were done up without washers so I have tried both with and without washers. I have tried lubricating the underside of the heads on the bolts with oil to reduce friction but no success. I am tightening the bolts bit by bit from side to opposite side but still manage to break at least one if not more. I have tried this with 2 different clutches also. The bolts will screw all the way into the flywheel without the clutch but break once they get some pressure on them. I have removed the burrs on the clutch bolt holes as well.

Any help is appreciated. I've never come across this before.

Steven

Andy Andy\'s Adventures

2,820 posts · joined Nov 2002 ·

#629043
Only thing I can think of is check the torque is correct? (can you cross check with other books, or check your torque wrench?).
The only book I have handy covers the 1700 motor and calls for 18ft/lb.

Secondly high tensile bolts generally come in grade from 8 to 12, so perhaps try a stronger bolt. Just don't strip the flywheel.

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 ·

#629052
Hi

I cant find any data on the 7mm bolts, but the 8mm ones that were used on 1700 & 2 litres only needed 2.5 mkg or 18 ft. lb.

Steve

vw54 Administrator Always Waiting 4 Friday

16,723 posts · joined Aug 2002 ·

#629074
they should be 8mm x 1.5 thread same as on a stock Beetle 1600
use the washer as it spread the load and acts as a locking mechanism as well

the heads of the bolts should have the number 8 or similar stamped on them
I read it on FACEBOOK so it must be true


http://forums.aussieveedubbers.com/viewtopic.php?tid=91278&page=1#pid848630


http://forums.aussieveedubbers.com/viewtopic.php?tid=63561&page=1#pid624099


http://forums.aussieveedubbers.com/viewtopic.php?tid=4832&page=1#pid452603


http://forums.aussieveedubbers.com/viewtopic.php?tid=60650&page=1#pid574409

dangerous 23 Windows of Awesome

5,901 posts · joined Jan 2005 ·

#629079
For M7 x 1 fasteners:

8.8 grade should not exceed 11 ft.lbs with a drop of oil on the thread.

I would estimate:

10.9 grade 14 ft.lbs

12.9 grade 18 ft.lbs

If you use ANY lube you must REDUCE the torque or the bolt will stretch or break.

Any excess lube should be removed, I like brake Kleen.

Even on 10.9 grade 8mm bolts I would be scared to use 24 ft.lbs.
...perhaps with 12.9 grade, but never with 7mm diameter.
westi wrote:That's mad Alan.

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 ·

#629099
vw54 wrote:they should be 8mm x 1.5 thread same as on a stock Beetle 1600
use the washer as it spread the load and acts as a locking mechanism as well

the heads of the bolts should have the number 8 or similar stamped on them
Hi

1800 cc Kombi motors only used the 7mm bolt, all other air-cooled VWs used 8mm.

Steve

type3lover in the garage...

796 posts · joined Feb 2005 ·

#629102
Are they too long perhaps?
.

sikdub Wolfsburg Wizard

571 posts · joined Aug 2002 ·

#629108
Interesting, thanks for the replies. The bolts aren't too long as they will screw all the way into the flywheel without the clutch attached. Can someone please have a look in their manual to check torque settings definitely for me. I may have misread it. I considered grade 12 bolts but qustioned whether or not this was necessary due to the old bolts being grade 8 also.

Cheers

Steven

1303Steve Scirocco Rare

8,650 posts · joined Aug 2002 ·

#629124
Hi

I have Bentley Kombi manual, it doesn't list the 7mm bolts, only the 8mm ones. I always used 18ft. lb. on the ones on my old bug, which used a 215mm 1800 flywheel.

Steve

dangerous 23 Windows of Awesome

5,901 posts · joined Jan 2005 ·

#629126
11 ft lbs is what I found for grade 8.8 as posted above.
this is for 7mm x 1mm pitch.

That came from a workshop manual.
westi wrote:That's mad Alan.

sikdub Wolfsburg Wizard

571 posts · joined Aug 2002 ·

#629147
Ok i now have got the Gregorys in front of me and can see where I went wrong. 18ft lb is 24Nm. Don't i feel like a dumbass..

Thanks for the help

Steven

1500S Custom Title Time!

1,418 posts · joined Mar 2005 ·

#629172
vw54 wrote:they should be 8mm x 1.5 thread same as on a stock Beetle 1600
use the washer as it spread the load and acts as a locking mechanism as well

the heads of the bolts should have the number 8 or similar stamped on them
Just for reference, do you mean M8 x 1.25 Dave?

DH

vw54 Administrator Always Waiting 4 Friday

16,723 posts · joined Aug 2002 ·

#629221
yeah i can never remember the pitch on metric threads
I read it on FACEBOOK so it must be true


http://forums.aussieveedubbers.com/viewtopic.php?tid=91278&page=1#pid848630


http://forums.aussieveedubbers.com/viewtopic.php?tid=63561&page=1#pid624099


http://forums.aussieveedubbers.com/viewtopic.php?tid=4832&page=1#pid452603


http://forums.aussieveedubbers.com/viewtopic.php?tid=60650&page=1#pid574409

dangerous 23 Windows of Awesome

5,901 posts · joined Jan 2005 ·

#629236
sikdub wrote:Ok i now have got the Gregorys in front of me and can see where I went wrong. 18ft lb is 24Nm. Don't i feel like a dumbass..

Thanks for the help

Steven
That still sounds high.
It is correct for 8mm bolts.
Is that what Gregories quotes for 7mm?

What grade is on the heads, and where did you get replacements?
Might be handy to know.
westi wrote:That's mad Alan.

vw54 Administrator Always Waiting 4 Friday

16,723 posts · joined Aug 2002 ·

#629244
good work charts

Ive got a thread gauge around here somewhere

i proberly have been overtightening them for years just do them up with a socket n bar never broken one yet I have broken a flywheel bolt must have been a weak spot LOL
I read it on FACEBOOK so it must be true


http://forums.aussieveedubbers.com/viewtopic.php?tid=91278&page=1#pid848630


http://forums.aussieveedubbers.com/viewtopic.php?tid=63561&page=1#pid624099


http://forums.aussieveedubbers.com/viewtopic.php?tid=4832&page=1#pid452603


http://forums.aussieveedubbers.com/viewtopic.php?tid=60650&page=1#pid574409

sikdub Wolfsburg Wizard

571 posts · joined Aug 2002 ·

#629647
dangerous wrote:
sikdub wrote:Ok i now have got the Gregorys in front of me and can see where I went wrong. 18ft lb is 24Nm. Don't i feel like a dumbass..

Thanks for the help

Steven
That still sounds high.
It is correct for 8mm bolts.
Is that what Gregories quotes for 7mm?

What grade is on the heads, and where did you get replacements?
Might be handy to know.
The grade listed on the heads is 8.8 and the bolts were purchased from Coventry Fasteners. They are the same as the ones that were holding the clutch on beforehand. Am just waiting for some more to turn up now.

Steven