Need torque spec for 8 hub bolts in flywheel center

road.ripper

road.ripper

Petty Officer 2nd Class
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Messages
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1970 merc 650 65hp 4 banger

center hub broke on my flywheel cause the previous owner didnt torque them right .
does anyone know the torque value on these 8 - 5/16 bolts on the hub ?

i have a manual but i cannot find the torque for these bolts ,wouldnt want my work to fall apart .
 
j_martin

j_martin

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Re: Need torque spec for 8 hub bolts in flywheel center

road.ripper said:
1970 merc 650 65hp 4 banger

center hub broke on my flywheel cause the previous owner didnt torque them right .
does anyone know the torque value on these 8 - 5/16 bolts on the hub ?

i have a manual but i cannot find the torque for these bolts ,wouldnt want my work to fall apart .
Click to expand...

From Machine Tool Help
5/16" Steel Hex Head
Grade 5, 18 TPI, 17ft/lb
Grade 5, 24 TPI, 19ft/lb
Grade 8, 18 TPI, 25ft/lb
Grade 8, 24 TPI, 29ft/lb

Use a little locktite on it. I'd use red, blue would probably be OK.

In normal maintenance those bolts should not be removed. The proper way to remove the flywheel is at the center spline with a special puller.

hope it helps
John
 
road.ripper

road.ripper

Petty Officer 2nd Class
Joined
Jul 11, 2009
Messages
118
Re: Need torque spec for 8 hub bolts in flywheel center

awsome thanks John
i found the hub broken after i removed the flywheel , so disassembly was required ( definitly not desired ) .

i tried to torque them to 15 ft/lb the third bolt snapped , although i did get it out , i realized i should use new grade 8's because of damage to the old hub center.
off to get them tomorrow , Again thanks for the specs John
Is there a site you found that on ?
Road.
 
j_martin

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: Need torque spec for 8 hub bolts in flywheel center

road.ripper said:
awsome thanks John
i found the hub broken after i removed the flywheel , so disassembly was required ( definitly not desired ) .

i tried to torque them to 15 ft/lb the third bolt snapped , although i did get it out , i realized i should use new grade 8's because of damage to the old hub center.
off to get them tomorrow , Again thanks for the specs John
Is there a site you found that on ?
Road.
Click to expand...

http://www.machinetoolhelp.com/Repairing/bolt-torque-chart.html

One usually comes with any torque wrench you buy, also.

It's unlikely the grade 8 bolt was that damaged if it looked good. Hardened bolts are subject to corrosion stress cracking, however. I always replace them if there's any rust on them.

hope it helps
John
 
road.ripper

road.ripper

Petty Officer 2nd Class
Joined
Jul 11, 2009
Messages
118
Re: Need torque spec for 8 hub bolts in flywheel center

The hub is all done and torqued same with the center nut, timing is done , just have to install the new harness, and the new prop and fire it up ..
thanks for the specs and the help

Road
 
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