Grade 8 Hardware
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Tourer
Joined: Aug 2014
Posts: 302
Likes: 49
From: Gambrill, MD
Grade 8 Hardware
Hey Folks!
The factory parts catalog for my '93 Ultra says that the rocker box cover socket head screws are: "P/N 882, Screw, 1/4-20 x 7/8, knurled socket head., Grade 8 Steel"
Are they really Grade 8 steel? Do they need to be? They only need to be torqued to 10-13 ft-lbs so it seems like overkill.
I'm asking because I'd like to buy chrome replacements which are readily available in 18-8 stainless (Bolt Depot, McMaster-Carr, etc.), but harder to find in chromed Grade 8 (although I did find them on the "Allen's Fasteners" website).
-Dave
The factory parts catalog for my '93 Ultra says that the rocker box cover socket head screws are: "P/N 882, Screw, 1/4-20 x 7/8, knurled socket head., Grade 8 Steel"
Are they really Grade 8 steel? Do they need to be? They only need to be torqued to 10-13 ft-lbs so it seems like overkill.
I'm asking because I'd like to buy chrome replacements which are readily available in 18-8 stainless (Bolt Depot, McMaster-Carr, etc.), but harder to find in chromed Grade 8 (although I did find them on the "Allen's Fasteners" website).
-Dave
Last edited by drm1978; Feb 5, 2020 at 08:15 PM.
Grand HDF Member
Joined: Nov 2009
Posts: 4,315
Likes: 1,663
From: Tampa
Harley does not use Grade 8 on anything in the rocker box. I've taken tons of them apart, and broken some based on too much torque even though it was was in spec.
Go buy some good replacement Grade 8 fasteners at Fastenal or something where you know you're getting Grade 8.
Oh, and to answer your question Grade 5 is plenty strong for rocker box work, although most of the allen head cap screws I can find locally are black oxide with no grade level (although they're hard as hell).
Go buy some good replacement Grade 8 fasteners at Fastenal or something where you know you're getting Grade 8.
Oh, and to answer your question Grade 5 is plenty strong for rocker box work, although most of the allen head cap screws I can find locally are black oxide with no grade level (although they're hard as hell).
Road Warrior
Joined: Dec 2015
Posts: 1,826
Likes: 1,047
From: Southwest Desert
Just buy a new set from Colony, or Drag specialties. You'll get all chrome bolts and washers and the correct gaskets to go under the top washer. Last time I tried to piece together a set and Harley was out of the little gaskets. eBay is great for this as a source. And the chrome bolts look a lot better. 
https://www.ebay.com/itm/FXR-FXRT-Ch...oAAOSwwhxcAHWO
https://www.ebay.com/itm/FXR-FXRT-Ch...oAAOSwwhxcAHWO
Last edited by SirHarley; Feb 5, 2020 at 09:21 PM.
Seasoned HDF Member
Joined: Nov 2009
Posts: 15,705
Likes: 22,718
From: Farmington ,MS
Harley does not use Grade 8 on anything in the rocker box.
Oh, and to answer your question Grade 5 is plenty strong for rocker box work, although most of the allen head cap screws I can find locally are black oxide with no grade level (although they're hard as hell).
Oh, and to answer your question Grade 5 is plenty strong for rocker box work, although most of the allen head cap screws I can find locally are black oxide with no grade level (although they're hard as hell).
Once upon a time... before cheap Chinese crap...all socket head cap screws were grade 8...they didn't come in any other grade...still are if you go to a bolt store...
Last edited by Tom84FXST; Feb 6, 2020 at 09:14 AM.
Stellar HDF Member
Joined: Feb 2007
Posts: 2,558
Likes: 280
From: Russellville, Arkansas
No need for Grade 8 Allen bolts there. Any stainless steel Allen bolts will do. Same goes for primary cover too.
But, one does need to pay attention to proper length and the shoulder of the bolt. The shoulder is designed to burden the load/stress area.
Same goes for nuts on the ends of bolts...there should be at least three threads past the nut.
Lock washers are always next to the head or nut.....when used in conjunction with washers.
Bolts look simple....but theres a lot that goes into them.
I worked in the Aviation field and saw many incorrect fastening techniques. I see same things applied to general machinery including Harleys.
But, one does need to pay attention to proper length and the shoulder of the bolt. The shoulder is designed to burden the load/stress area.
Same goes for nuts on the ends of bolts...there should be at least three threads past the nut.
Lock washers are always next to the head or nut.....when used in conjunction with washers.
Bolts look simple....but theres a lot that goes into them.
I worked in the Aviation field and saw many incorrect fastening techniques. I see same things applied to general machinery including Harleys.
Seasoned HDF Member
Joined: May 2008
Posts: 21,146
Likes: 12,713
From: South Carolina
The factory did not call for any grade 8 socket head screws in the early Evo manuals, but the spec for the small socket head screws that hold the rocker box cover changed from part number 852 to 882 for the `91 model year (grade 8).
The 5/16-18 hex head bolts have always been specified as grade 8 (Part numbers 3500-3501).
The 5/16-18 hex head bolts have always been specified as grade 8 (Part numbers 3500-3501).
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