Bolt/screw - diameters & lengths.

[BRT-GTR]

Hi All,
         I know there are a few threads on the forum on this topic but I've just spotted something in the Parts Manual that may be of help to anyone rebuilding a GTR or possibly any of the BS models for the first time.
 I bought one and a half GTRs in a largely dismantled state and was presented with a large box (100s) of random screws/bolts/nuts/washers etc. Also included were a lot of imperial sized screws and bolts which didn't help. Now its pretty obvious in most cases what diameter of bolt should be used either based on the hole diameter in a part or the tapped thread diameter in other  parts but it is not always obvious what length of screw should be used.
The workshop manual does include some of the screw lengths in the assembly instructions but does not give provide this information in a most cases. I was able to work out where the special stepped bolts go using the parts manual and previous knowledge of the bikes.    I found the kick start clamp bolt (that also acts as the lever pivot stop)  in the lower fork bridge,  the lower engine mount bolts with the bevelled end had also been misplaced. :'( A few bolt dimensions are given under the part name in the Parts Manual, I.E. 6X18 hexagon bolt but most are described as Hexagon Bolt A or B which doesn't help.  :'(

   I'm sure many of the established forum members will already know this but I've just realised that in most cases the second four digits of the screw or bolt part number in the Parts Manual represent the diameter and length of the fixing.  . In the case of washers it indicates the hole diameter and outside diameter of the part and there's a tremendous variation in washer sizes on these machines. I wish I had spotted this earlier, it would have saved me a lot of detective work!.

 As an example check out the two 6mm screws that hold together the handlebar switch cases, parts 10 &11 on page 34 of the Parts Manual. One is 14mm long the other is 16mm long with the shorter one to the front. You have to look very carefully at the lower case to even see that the front flange is thinner than the rear flange.

  Anyone looking to order a new set of cross head screws for the engine cases can find all the screws lengths in the manual, you don't have to measure them which I was planning to do. 
  I will add a note for new members. Before ordering any standard generic screws/bolts , check the pitch of the existing thread. 6 and 8mm screws on BS machines match the ISO standard with 1.0, 1.25mm pitch respectively but 3, 4, 5, 10 & 12mm screws may be non ISO.

Hope this helps, Brian the Brit

[slawsonb]

Just added to my bookmarks. Thanks Brian...
...bert

[CL-100]

I'm glad this info has been posted again for those that may have missed it previously. I believe that Graham decoded this in an earlier post and this is how I was able to know what size hardware to buy for my last restoration.

I've found that all the 5mm screws have the 0.9 pitch which is not the standard for today. They can be bought in bright zinc at "Mr Megapack" on line but his pricing on shipping to the US is no bargain.  (He's in the UK)  As far as the larger bolts go I finally bought a thread pitch gauge to measure the threads before buying. It seems like today's threads are coarser than they were during BS manufacturing.

Thanks Brian for posting this. This kind of info always save many from some of the frustration when putting these great bikes back on the road.

[husker]

Thanks Brain, I just learned something new to me.

[alan86a]

Thats a great piece of info Brian it's going to save me loads of time.
Leading on from there i'm wondering if anyone has compiled or knows of a list of known screw sets for any Bridgestones, my particular interest is the Gtr.

[BRT-GTR]

Hi all,
        Thanks for the comments guys, glad to help. I been studying the Parts Manual for at least a year, can't believe I didn't notice the screw information earlier.
 CL-100, I'm in the UK, it's somewhat ironic to see you complaining about UK-US shipping costs.  .   Here in blighty, 99% of our BS parts (new & old) have to come from the States with your high shipping costs + import tax + VAT + customs handling charge. We envy your access to parts and complete bikes, very few came to the UK in the late 60's (33 GTR's). 

Alan86a, I asked about GTR screw packs 12 months ago on this forum and got no response. Odd ones are offered on the internet but tend to be Allen headed screws which I don't want. If you make a list please post on here.

For those of you without a pitch gauge I've checked out the pitch of the remaining screw diameters on the GTR to complete the list as follows:-
     3mm Dia   -   0.6mm pitch  JIS      location - Inside h/bar switch cases, fuel tap.
     4            -   0.75  JIS                               -  points & points plate.
     5            -   0.9   JIS                              - various
     6            -   1.0  ISO                               - various
     8            -   1.25  ISO                             - various
     10          -   1.25  JIS                              - rear & lower engine mount bolts,  bottom rear shocks
     12           -   1.5   JIS                            -  foot rest mounts, top rear shocks.
Not an exhaustive list but will cover 99% of GTR bolts & screws.

Brian the Brit.
     

[OldSwartout]

Hi all,
         I been studying the Parts Manual for at least a year, can't believe I didn't notice the screw information earlier.

I've been messing with Bridgestones and the parts manual for 55 years and never realized the connection between part number and size and length. 

[CL-100]

Brian,
When I was doing my last restoration the only place I could find that 5mm cross head screw with the 0.9 pitch was the Megapack guy there in the UK. Even then he can't get them in stainless. By the time I bought the screws and paid for shipping they ended up costing about one dollar per screw.  That's a lot more than I'm used to paying for new hardware.  Especially for zinc. I "bit the bullet" and purchased enough to last me for a while.

I do sympathize with you guys over there in the UK for having to order most parts from the US.  From what I can tell, your taxes for purchases would make a lot of enthusiasts choose a different hobby.  Given that, hats off to you guys for persevering on behalf of Bridgestones.

Rowland