Adelaide65SS
Silver Supporting Member
Posts: 80

Loc: South Australia
Reg: 06-20-11
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01-13-25 11:09 PM - Post#2877065
Whilst cleaning up these 4 bolts (7/16 UNF) I note that they are all not full length threaded.
I think their codes are 3859094 and 3859095.
The threads on two of them are no good so I need to replace however so far all I can seem to find new (easily) are full thread.
I assume the unthreaded portion sits more neatly through the strut rod and control arm for metal on metal rather than thread on metal contact.
Do you think the fully threaded bolt will function the same in this situation or should I try to source the partly threaded versions.
I understand GM did this for a reason so my gut tells me to keep the same but not sure if it is anything to worry about.
Thanks
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DHMelton
"3rd Year" Silver Supporting Member
Posts: 447

Loc: Central Arizona
Reg: 04-10-22
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01-14-25 06:49 AM - Post#2877074
In response to Adelaide65SS
Find longer bolts with an unthreaded shoulder and cut the excess thread length off, and bevel the cut end threads using a grinder of some sort.
Inexact rule of thumb is thread length needs to excess 4 times the diameter before you start getting an unthreaded shank. So probaly 2.25"- 2.5" long bolts should start getting unthreaded portions.
Doug
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sz0k30
"16th Year" Gold Supporting Member
Posts: 631

Loc: Oakland Co., Michigan
Reg: 10-12-08
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01-14-25 07:06 AM - Post#2877076
In response to DHMelton
Use the bolts you can get & don't worry about it.
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65_Impala
Very Senior Member
Posts: 5046
Reg: 12-29-02
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01-14-25 10:09 AM - Post#2877084
In response to Adelaide65SS
Put grade 8 bolts in and torque them down. They will clamp well enough there won't be any part movement against the threads to matter.
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