Reply
 
Thread Tools Display Modes
 
Old 04-15-2020, 08:50 AM   #1
Bus Geek
 
musigenesis's Avatar
 
Join Date: Jan 2019
Location: Philadelphia
Posts: 3,018
Year: 2003
Coachwork: International
Chassis: CE 300
Engine: DT466e
Rated Cap: 65C-43A
Grade 5 or grade 8 bolts for seats and tether anchors?

The base of my seat is mounted to its pedestal with nine 2" 3/8 bolts. I'm going to get all-new hardware for this, since the original bolts are a bit corroded:

seat bolt.png

I can't tell if this is a grade 5 or a grade 8. What type would normally be used for this purpose?

I also will need to weld in new anchors on the floor for securing the seat belt tethers. These will involve 3/8 bolts (one for the tether on each side) coming up through a hole in the floor, with the heads spot-welded on the underside. Should these two bolts be grade 5 or grade 8? Are there any issued with spot-welding the heads in terms of weakening the bolts?

Lastly, I'm going to be bolting on the rails for my Ford transit van seat on the right side behind the stepwell. There are three bolts per rail and I was planning to use 3/8 here as well, but the holes in the rail could fit larger bolts if that's a good idea; also wondering about grade 5 vs. 8 for these. There will be additional structural pieces for the seat that will also be bolted with 3/8 hardware.

When I rebuilt my floor in the back, I used 3/8 grade 5 bolts in addition to welding, and I'm very comfortable with using this size and type of bolt (have the bits and sockets for it etc.). But I'm not putting my life in my hands with the floor rebuild, whereas with anything related to how the driver seat is attached to the bus, I am, so I'm looking for advice.
__________________
Rusty 87 build thread
musigenesis is offline   Reply With Quote
Old 04-15-2020, 08:51 AM   #2
Bus Geek
 
EastCoastCB's Avatar
 
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 21,520
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
Grade 5 is what I've always found when pulling seats.
__________________
.
Roll Your Own Build Thread
EastCoastCB is offline   Reply With Quote
Old 04-15-2020, 09:22 AM   #3
Bus Nut
 
Join Date: Apr 2019
Location: Savannah GA
Posts: 614
Year: 2003
Coachwork: Bluebird
Chassis: TC2000
Engine: Cummins 5.9 24v
Rated Cap: 54 passenger
It looks like it has three lines on the top. Slightly raised so you should be able to feel them. That would be a number 5 bolt wouldn't it? A number eight bolt has five of those lines.

Unless I'm remembering completely wrong. I took my swivel seats out of my Econoline 2 years ago. Took the bench seat out of the back and replace the bolts after I put new flooring in. That's when I first learned about the lines and I'm pretty sure I had number five. But I will check when I get home later. My rear seat belts attached to this 4 ft channel piece which bolted to the floor of the van. Those were all the same bolts also.
JDSquared is offline   Reply With Quote
Old 04-15-2020, 10:01 AM   #4
Bus Crazy
 
banman's Avatar
 
Join Date: Aug 2019
Location: Ohio
Posts: 1,194
Year: 2002
Coachwork: Thomas
Chassis: Freightliner FS-65
Engine: 7.2L Cat 3126 turbo diesel
Rated Cap: 71 passenger 30,000 gvwr
https://www.nutsandbolts.com/v1-bolt...-markings.html
__________________
David

The Murder Bus
banman is offline   Reply With Quote
Old 04-15-2020, 10:27 AM   #5
Bus Nut
 
Join Date: Apr 2018
Location: NorCal
Posts: 342
Year: 1995
Coachwork: Girardin
Chassis: E-350
Engine: 7.3L Powerstroke
What the law says about seat belts: https://www.law.cornell.edu/cfr/text/49/571.209


What my summary was when I added seatbelts:
  • Seat belt bolts must be at least 7/16" in diameter, 20 threads per inch, Grade 5 or 8 (this would be annotated as 7/16-20)
  • Lap belt bolts must be secured with a 1.7" diameter washer
  • Lap belt mounts should be spaced 16.5" apart, depending on comfort and space for your seat
  • The top shoulder mount must be strong enough to withstand 7kN of force
  • The bottom shoulder mount must be strong enough to withstand 14kN of force
  • The buckle mount must be strong enough to withstand 12kN of force
And I am sure you know not to mount any seatbelts/seats to the bus chassis.
TheArgobus is offline   Reply With Quote
Old 04-15-2020, 10:55 AM   #6
Bus Crazy
 
banman's Avatar
 
Join Date: Aug 2019
Location: Ohio
Posts: 1,194
Year: 2002
Coachwork: Thomas
Chassis: Freightliner FS-65
Engine: 7.2L Cat 3126 turbo diesel
Rated Cap: 71 passenger 30,000 gvwr
Quote:
Originally Posted by TheArgobus View Post
What the law says about seat belts: https://www.law.cornell.edu/cfr/text/49/571.209


What my summary was when I added seatbelts:
  • Seat belt bolts must be at least 7/16" in diameter, 20 threads per inch, Grade 5 or 8 (this would be annotated as 7/16-20)
  • Lap belt bolts must be secured with a 1.7" diameter washer
  • Lap belt mounts should be spaced 16.5" apart, depending on comfort and space for your seat
  • The top shoulder mount must be strong enough to withstand 7kN of force
  • The bottom shoulder mount must be strong enough to withstand 14kN of force
  • The buckle mount must be strong enough to withstand 12kN of force
And I am sure you know not to mount any seatbelts/seats to the bus chassis.
Yup. As an aside -- I was looking at some inexpensive seat belts on ebay and sent a note to the seller: "were these belts in compliance with FMVSS 209...?"
The reply was "we're working on getting those certifications..."
I WON'T be buying those belts -- a very poor place to save $50...

Also, general rule for any given diameter bolt -- fine thread is stronger than course thread in tension.
__________________
David

The Murder Bus
banman is offline   Reply With Quote
Old 04-15-2020, 12:56 PM   #7
Bus Geek
 
musigenesis's Avatar
 
Join Date: Jan 2019
Location: Philadelphia
Posts: 3,018
Year: 2003
Coachwork: International
Chassis: CE 300
Engine: DT466e
Rated Cap: 65C-43A
Interesting: looks like my original bolts are Grade 8 (they either have the six lines or they have three lines and some random accidental marks) but they're definitely 3/8" (and not 7/16"), as were the bolts anchoring the tethers. I think the tether bolts were an after-market modification by previous owners, since the floor had other holes an inch away from the current bolt placements. The seat platform is also new (I think) so maybe whoever did this didn't know they should have used 7/16".

I'm inclined to just go ahead and use 3/8" Grade 8 for everything, since I'm forced to use that on the seat base anyway. I haven't found anything on what size bolt you're supposed to use on the Ford transit ban seat brackets, except one post that said 12 mm is the recommended bolt size (closer to 1/2").

Perhaps the thing to do is to use 1/2" Grade 8 for the transit seat brackets and for the driver's anchor tethers, and 3/8" Grade 8 for mounting the driver's seat base and also for the additional structure to support the transit seat brackets.
__________________
Rusty 87 build thread
musigenesis is offline   Reply With Quote
Old 04-15-2020, 01:20 PM   #8
Bus Geek
 
EastCoastCB's Avatar
 
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 21,520
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
IIRC the federal regs for bus construction call for "grade 5 or 8". IDK. I wouldn't worry over it.
__________________
.
Roll Your Own Build Thread
EastCoastCB is offline   Reply With Quote
Old 04-15-2020, 01:35 PM   #9
Bus Nut
 
Phatman's Avatar
 
Join Date: Jan 2015
Location: Brazoria County, Texas
Posts: 500
Year: 1997
Coachwork: Carpenter
Chassis: International
Engine: T444E
Rated Cap: 32 Passenger
Quote:
Originally Posted by musigenesis View Post
The base of my seat is mounted to its pedestal with nine 2" 3/8 bolts. I'm going to get all-new hardware for this, since the original bolts are a bit corroded:

Attachment 43293

I can't tell if this is a grade 5 or a grade 8. What type would normally be used for this purpose?

I also will need to weld in new anchors on the floor for securing the seat belt tethers. These will involve 3/8 bolts (one for the tether on each side) coming up through a hole in the floor, with the heads spot-welded on the underside. Should these two bolts be grade 5 or grade 8? Are there any issued with spot-welding the heads in terms of weakening the bolts?

Lastly, I'm going to be bolting on the rails for my Ford transit van seat on the right side behind the stepwell. There are three bolts per rail and I was planning to use 3/8 here as well, but the holes in the rail could fit larger bolts if that's a good idea; also wondering about grade 5 vs. 8 for these. There will be additional structural pieces for the seat that will also be bolted with 3/8 hardware.

When I rebuilt my floor in the back, I used 3/8 grade 5 bolts in addition to welding, and I'm very comfortable with using this size and type of bolt (have the bits and sockets for it etc.). But I'm not putting my life in my hands with the floor rebuild, whereas with anything related to how the driver seat is attached to the bus, I am, so I'm looking for advice.
I just extended the back bumper on my shorty, and all the bolts to the frame and bumper were all 1/2” grade 5 bolts.
Phatman is offline   Reply With Quote
Old 04-15-2020, 01:40 PM   #10
Bus Geek
 
musigenesis's Avatar
 
Join Date: Jan 2019
Location: Philadelphia
Posts: 3,018
Year: 2003
Coachwork: International
Chassis: CE 300
Engine: DT466e
Rated Cap: 65C-43A
{ snip ... }

Boy, it is a pain when you make a long post and then add it to the wrong thread.
__________________
Rusty 87 build thread
musigenesis is offline   Reply With Quote
Old 04-15-2020, 01:43 PM   #11
Mini-Skoolie
 
Join Date: Sep 2017
Posts: 14
grade 8

Always use grade 8 for automotive applications, especially when it comes to seats and seatbelts. Grade 8 has way more tensile and shear strength than grade 5.
Ace Wilder is offline   Reply With Quote
Old 04-21-2020, 07:26 PM   #12
Bus Geek
 
musigenesis's Avatar
 
Join Date: Jan 2019
Location: Philadelphia
Posts: 3,018
Year: 2003
Coachwork: International
Chassis: CE 300
Engine: DT466e
Rated Cap: 65C-43A
Quote:
Originally Posted by TheArgobus View Post
Seat belt bolts must be at least 7/16" in diameter, 20 threads per inch, Grade 5 or 8 (this would be annotated as 7/16-20)
Interesting, I decided on 1/2"-20 Grade 8 bolts for mounting my transit van seat (since the factory bolts for these are 12mm, apparently). I figured I would use the same for re-mounting my driver's seat tethers, but I just measured the hole on the floor bracket of the new tether belts I just bought and it's exactly 1/2", so I guess I'm supposed to use 7/16" for these.

Quote:
Originally Posted by TheArgobus View Post
And I am sure you know not to mount any seatbelts/seats to the bus chassis.
Oh yeah, I post that video a lot that shows the bus body sliding forward in a head-on crash. A seatbelt bolted to the chassis would be pretty grisly.
__________________
Rusty 87 build thread
musigenesis is offline   Reply With Quote
Old 04-21-2020, 07:50 PM   #13
Bus Crazy
 
somewhereinusa's Avatar
 
Join Date: Nov 2010
Location: Andrews,Indiana
Posts: 2,154
Year: 1991
Coachwork: Bluebird
Chassis: AARE
Engine: 3116 Cat 250hp
Rated Cap: Just the two of us.
I buy bolts by the pound. I keep quite a few on hand. For the price difference it's not worth using grade 5.
somewhereinusa is offline   Reply With Quote
Old 04-27-2020, 09:41 AM   #14
Almost There
 
Gorzie's Avatar
 
Join Date: Sep 2018
Location: St. Charles County Missouri
Posts: 90
Year: 1997
Coachwork: Bluebird International
Chassis: 3800
Engine: T444e
Rated Cap: 35
I agree, the price difference between grade 5 and 8 is small. I went with a grade 8 bolts for any of my seats or belts. I tend to over engineer anyway. I would rather error on the safer side.
__________________
Michael G.
1997 Bluebird IH 3800 6 window T444e
https://www.skoolie.net/forums/f11/m...ird-28058.html
Gorzie is offline   Reply With Quote
Old 04-27-2020, 09:48 AM   #15
Almost There
 
Gorzie's Avatar
 
Join Date: Sep 2018
Location: St. Charles County Missouri
Posts: 90
Year: 1997
Coachwork: Bluebird International
Chassis: 3800
Engine: T444e
Rated Cap: 35
I forgot to mention I had some seat belts that are certified from seatbeltplanet.com . They are made I Oklahoma and are a veteran owned business if that make a difference to you.
__________________
Michael G.
1997 Bluebird IH 3800 6 window T444e
https://www.skoolie.net/forums/f11/m...ird-28058.html
Gorzie is offline   Reply With Quote
Old 04-29-2020, 03:40 PM   #16
Mini-Skoolie
 
Join Date: Apr 2018
Location: Denver, CO
Posts: 11
Year: 2003
Coachwork: Bluebird
Chassis: 3800
Engine: T444E
Rated Cap: full size w/ handicap
I would use Grade 5 myself... unless I knew that what is being replaced was grade 8 originally. I forget all the proper engineering stuff, but it is not always better to use grade 8 over grade 5. Grade 5 may bend or stretch a little while a grade 8 might just break (although probably at a higher value).
fignasiak is offline   Reply With Quote
Old 04-29-2020, 03:45 PM   #17
Bus Geek
 
musigenesis's Avatar
 
Join Date: Jan 2019
Location: Philadelphia
Posts: 3,018
Year: 2003
Coachwork: International
Chassis: CE 300
Engine: DT466e
Rated Cap: 65C-43A
Quote:
Originally Posted by fignasiak View Post
I would use Grade 5 myself... unless I knew that what is being replaced was grade 8 originally. I forget all the proper engineering stuff, but it is not always better to use grade 8 over grade 5. Grade 5 may bend or stretch a little while a grade 8 might just break (although probably at a higher value).
I've read this as well, and I agree it's best to replace what was there with the same thing. My seat was bolted down with Grade 8 bolts and I have an all-new set of these ready to put in. My seat belt tethers were screwed into the rotten plywood and rusty sheet also with Grade 8 3/8" coarse bolts, but I'm upgrading to Grade 8 7/16" for my new ones.
__________________
Rusty 87 build thread
musigenesis is offline   Reply With Quote
Old 04-30-2020, 09:09 AM   #18
Mini-Skoolie
 
solleks's Avatar
 
Join Date: Apr 2018
Location: CA
Posts: 32
Year: 1995
Coachwork: Bluebird
Chassis: International
Engine: DT466, AT545
Rated Cap: 8 windows
8 if youre the nervous type, 5 if u believe in God
solleks is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 11:51 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
×