Bottom engine mount bolts 10mm

[BRT-GTR]

Hi All
       I've just noticed that the 10mm bottom engine mount bolts, temporarily installed by previous owner to ship bike (GTR),  are too long and obviously not right. Luckily he didn't tighten them or he could broken the crankcase.
Installed bolts are 38mm long and have a distinct 45 degree pointed taper on the front end. So where should these be used - Lower fork bridge?.   Did find the kick start clamp bolt in one of the fork holes. 
 In the box of bolts that came with the bike are two normal ended 10mm bolts 32mm long . Are these the correct lower mounting bolts for the engine. This is where the parts list lets you down. I would appreciate your help.   
In due course I think I will measure all the bikes bolts and screws and mark their head type, thread diameter, thread length and pitch bolt length etc and produce a list for the GTR/GTO or mark them in the parts list / manuals. I am sure this would be a great help to someone in my position with boxes of bits and bolts. Has anyone already done this ?. If you have can I have a copy.

Bridgestone did use some not so standard thread pitches, particularly on bolts 5mm and below although you can't fault their logic. Course or fine threads where needed to suit application. They really did go to town when designing all the bikes, its only now after a lifetime of engineering I appreciate the detail they went into. Wonderful. It must have been a great place to work for a committed engineer.

Bewitched (by the GTR), bothered ( Its hot here)  and bewildered, Many Thanks ,  Brian.   I just love being a member of this whacky site.

[ziggy stardust]

The bolts with the 45 deg taper (point) fasten from underneath, vertically through the chassis into the engine.

The non ISO threads have been covered many times on the forum with the 5mm X .9mm pitch being the most controversial.

Z

[BRT-GTR]

z
Thanks for that, so they were in the right place after all . I will have to ckeck the depth of the holes and clean the internal threads. They were reluctant to go all the way in and I didn't want to force them
 regards Brian      Have sent you an email.

[ziggy stardust]

Yes I got that, thanks very much.

Z

[disc_valve]

Begfore you go at the bottom bolts with a big spanner, check that they are the correct pitch. The bottom bolts were 10mm * 1.5 pitch, whereas the other 10mm bolts on the bike are 10mm * 1.25. If you fit a 1.25 pitch bolt in a 1.5 pitch hole, it won't screw in very far.

My dodge when inserting these bolts was to tighten them carefully with a single plain washer undernweath and confirm that the bolt head tightens down onto the washer. (If the bolt is tight but the washer is loose, it's too long and bottoming in the hole). Having confirmed the bolt is teh correct llength, I then remove it and re-fit with an additional spring washer as well as the plain washer.

I don't know about the tapered end on the genuine bolts, as I used my GTR came with a pair of imperial sized bolts in the bottom hole (obviously owned by a bodger) and I had to order the correct bolts from my nuts-and bolts man. The tapered end may have been to aid assembly as the bottom bolts can be a bit awkward to line up when mountng the engine.

Graham

[ziggy stardust]

Graham, are you implying that Dennis was a bodger?

Z

[BRT-GTR]

Graham,
             When you say big spanner is that a 12'' or 24'' wrench? cos I'll have to take the 48''extension bar off.
Only joking. Thanks for your reply, good advise, very comprehensive (This is the sort of detail us newbies or in my case returning after a 42year ownership gap, need) but I'm now confused/worried.
According to Z these are the right dimension bolts ( 10 X 38mm) with a pointy end and the Parts List does confirm the size in this instance - didn't look before- but bolts installed by previous owner do have a 1.25 pitch not 1.5. I noticed, when under the bike,they were not fully home with maybe 10mm of shank exposed, so pulled them out.
  Obviously the tapped holes are almost impossible to see with the engine in the frame.To save a lot of rambling, by me, I will take the engine out (needs to come out anyway) and have a close look at the pitch. They will go in a couple of threads by hand but the rubber mounts don't line up too well and I would normally expect to have 4/5 threads home before getting the spanners on them.
Thanks for all your help Guys , I'll let you know how I go on.
 Will post some pictures of GTRs as received.

Brian.

[ziggy stardust]

Here is a close up of my re plated bolts showing one of the two lower engine bolts with the taper, the only other tapered bolts I can think of are the drive chain tension ones.

Z

We would all like to see your GTR/s as received Brian, how long before yours looks like this one?

[BRT-GTR]

 Thanks Z, my lower engine bolts look exactly like that with a matching thread count, I.E. 14 shown.
Graham, I value your help and expertise but having whipped my donor engine out (only a few hand tight bolts), Well I say engine, empty cases really. Well I say empty cases they did leave some alloy castings bolted to the frame !! The lower engine bolt holes are definitely tapped 10X1.25mm pitch thread and the above bolts can be screwed in all the way by hand but I will use your technique to ensure they are tapped deep enough when re-assembling.
 If some 'previous owner' to be polite put in  3/8 Whit bolts in your motor they could appear to have a 1.5mm pitch. I've no doubt we are talking about the same bolts. Did they do a mod at some stage?
  Had had a look at setting up a gallery but it's not immediately obviously to me what to put in where. These computer systems quite never work as you think they should but easy when you know how. Will have another go.

Brian