Front rotor fastener torque

[wally anderson]

I'm replacing a front rotor. The service manual page 5-42 shows fastener torque of 35 ft/lbs. They are 1/2 fine thread (20) and grade 8. They seemed
way tighter than 35 ft/lbs when removing. Bolt torque charts read 65 to over 100 ft/lbs for this size fastener. Dumb question but is the manual
right?

--
Wally Anderson
1975 Glenbrook
Megasquirt 455 port injection science project
Omaha Nebraska
Bob Stone hydroBOOOOST
Greater Midwest Classics
GMCES
http://wallyandsue.blogspot.com/

 

[Jim Hupy]

It's not the bolts. It's the rotors. They are cast. 5 ea. 1/2" diameter
grade 8 bolts
@ 35 Pounds feet should hold em fine.
Jim Hupy

> I'm replacing a front rotor. The service manual page 5-42 shows fastener
> torque of 35 ft/lbs. They are 1/2 fine thread (20) and grade 8. They seemed
> way tighter than 35 ft/lbs when removing. Bolt torque charts read 65 to
> over 100 ft/lbs for this size fastener. Dumb question but is the manual
> right?
>
> --
> Wally Anderson
> 1975 Glenbrook
> Megasquirt 455 port injection science project
> Omaha Nebraska
> Bob Stone hydroBOOOOST
> Greater Midwest Classics
> GMCES
> http://wallyandsue.blogspot.com/
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[Matt Colie]

> It's not the bolts. It's the rotors. They are cast. 5 ea. 1/2" diameter grade 8 bolts @ 35 Pounds feet should hold em fine.
> Jim Hupy

>
> I'm replacing a front rotor. The service manual page 5-42 shows fastener torque of 35 ft/lbs. They are 1/2 fine thread (20) and grade 8. They
> seemed way tighter than 35 ft/lbs when removing. Bolt torque charts read 65 to over 100 ft/lbs for this size fastener. Dumb question but is the
> manual right?
> --
> Wally Anderson

Wally,

The only reason for torque on a fastener like that is to be certain it is stretched enough to stay put. A lower grade fastener would have worked just
fine as the suggested assembly load is no problem for anything above grade 3. They are probably Gr.8 because that is a low cost litigation stopper
and that is all it is.

Matt
--
Matt & Mary Colie - Members GMCMI, GMCGL, GMCES
'73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
Now with both true Keyless and remote entry
SE Michigan - Twixt A2 and Detroit

 

[wally anderson]

> > It's not the bolts. It's the rotors. They are cast. 5 ea. 1/2" diameter grade 8 bolts @ 35 Pounds feet should hold em fine.
> > Jim Hupy

> >
> > I'm replacing a front rotor. The service manual page 5-42 shows fastener torque of 35 ft/lbs. They are 1/2 fine thread (20) and grade 8. They
> > seemed way tighter than 35 ft/lbs when removing. Bolt torque charts read 65 to over 100 ft/lbs for this size fastener. Dumb question but is the
> > manual right?
> > --
> > Wally Anderson
>
> Wally,
>
> The only reason for torque on a fastener like that is to be certain it is stretched enough to stay put. A lower grade fastener would have worked
> just fine as the suggested assembly load is no problem for anything above grade 3. They are probably Gr.8 because that is a low cost litigation
> stopper and that is all it is.
>
> Matt

Thank you 35 ft/lbs it is.
--
Wally Anderson
1975 Glenbrook
Megasquirt 455 port injection science project
Omaha Nebraska
Bob Stone hydroBOOOOST
Greater Midwest Classics
GMCES
http://wallyandsue.blogspot.com/