Author Topic: 350 Engine Bolt Markings  (Read 1430 times)

0 Members and 1 Guest are viewing this topic.

Offline slawsonb

  • Trade Count: (0)
  • Master Registered Bridgestone Member
  • *****
  • Posts: 1351
350 Engine Bolt Markings
« on: October 22, 2015, 05:16:19 PM »
I just disassembled my fourth 350 engine and am curious about the significance of the markings on the engine bolts (the 17 that hold the cases together). I have seen 6, 6T, 7, and 7T on the heads. My earliest engine (01351) had only 6 and 6T. The latest (07875) is the only one of these I have seen a 7T on. The other two (in the 035xx range) had a mixture of 6, 6T, and 7. Does anyone know what these markings are intended to signify? The bolt sizes are all 6 and 8mm. It's a quandary.  ;D
...bert
« Last Edit: October 22, 2015, 10:31:13 PM by slawsonb »

Offline Sye

  • Trade Count: (0)
  • Full Bridgestone Member
  • ***
  • Posts: 172
Re: 350 Engine Bolt Markings
« Reply #1 on: October 23, 2015, 05:28:18 AM »
It signifies the grade of steel the bolt is made from and its tensile strength.

Grade 6 is now obsolete but grade 7 is as follows:

Medium-carbon alloy steel, quenched and tempered.
Minimum tensile strength in thousands of pound-force per square inch = 133.
Be nice - feel good

Offline slawsonb

  • Trade Count: (0)
  • Master Registered Bridgestone Member
  • *****
  • Posts: 1351
Re: 350 Engine Bolt Markings
« Reply #2 on: October 23, 2015, 11:07:30 AM »
Thanks Sye. Any idea about the "T"? I guess I'm used to more contemporary markings (tic marks on the head). Was this a Japanese marking technique? Used in the 60's and 70's?
...bert

Offline BRT-GTR

  • Brian
  • Trade Count: (0)
  • Master Registered Bridgestone Member
  • *****
  • Posts: 632
Re: 350 Engine Bolt Markings
« Reply #3 on: October 24, 2015, 09:38:05 AM »
              Aaaaarrrrrrrrrrrrrggggghhhhhh!!!!.     'Step away from the bolt/screw minefield',  Bert. lol.

    The more research you do , the more confused you will get.  :D ;D :D

   I did find this, 'The markings such as 7T (other common ones are 4T and 9T) are Japanese Industrial Standard (JIS) grades and indicate 1/10 of the nominal tensile strength in kgf/mm2'.  
    I've seen references to the 'T' meaning max torque but it's more likely to refer to max Tensile strength as Sye states and I guess was used up to the adoption of ISO heads and thread forms around 1971. .
         Brian.
« Last Edit: October 24, 2015, 09:44:38 AM by BRT-GTR »
Unspoiled by progress.

Offline slawsonb

  • Trade Count: (0)
  • Master Registered Bridgestone Member
  • *****
  • Posts: 1351
Re: 350 Engine Bolt Markings
« Reply #4 on: October 24, 2015, 12:42:12 PM »
But Brian, you know I love a good minefield. ;D
Thanks...itch scratched.
...bert

Offline BRT-GTR

  • Brian
  • Trade Count: (0)
  • Master Registered Bridgestone Member
  • *****
  • Posts: 632
Re: 350 Engine Bolt Markings
« Reply #5 on: October 24, 2015, 01:26:16 PM »
         Kaboooooooooooom !!, damn, found one.    ;D ::)            Brian
Unspoiled by progress.

 


Gallery


Views:17
Comments (3)
By: mybridgestones

Views:43
Comments (2)
By: OldSwartout

Views:60
Comments (2)
By: AlanJohn

Views:38
Comments (0)
By: AlanJohn

Classifieds

Bridgestone GP 100 Muffler

Price: $80.00
Date: 12/03/2017 12:52 pm
Time Left: 79d 13h 41m
4 motorcycles for sale
Price: $0.00
Date: 12/02/2017 02:41 pm
Time Left: 78d 15h 31m
1969 Bridgestone dual 175

Price: $0.00
Date: 11/29/2017 11:17 am
Time Left: 75d 12h 6m
1969 Bridgestone dual 175
Price: $0.00
Date: 11/29/2017 11:13 am
Time Left: 75d 12h 2m

Recent Downloads added

How to build a 149 mph 350GTR....
Rating: (None)
Filesize: 7154.56KB
Date: April 18, 2017, 08:25:38 AM
Bridgestone 100 Sport Brochure
Rating: *****
Filesize: 937.72KB
Date: July 08, 2015, 12:58:53 PM
BS 100 Sport Australian Brochure
Rating: *****
Filesize: 937.53KB
Date: June 29, 2015, 06:40:40 PM
Bridgestone 350 GTO - Moto L├ęgende May 2003
Rating: *****
Filesize: 9429.41KB
Date: April 22, 2015, 04:18:43 PM

Powered by EzPortal