Engine Mount Bolts

[DewCatTea-Bob]

Sourcing SAE bolts in 3/8 grade 8 seems do-able from stock in some places. "

____ After my second stock-type 8mm-bolt busted, (both at the thread just at the inside edge of it's nut), I then got a 3-ft length of 3/8ths" threaded-rod and cut a piece to length, for the job.
Later, I found a number of long-length 10mm-bolts (within my mass of used parts), which were long enough for the job, (but required some drilling of the holes, for them), so I just used one of them when-ever I needed a bolt for the (upper-rear w-c motor-mount) job.
__ Until now, I never really bothered to try to figure-out where I might have gotten them from, but I recall always suspecting that they were 250-DUKE cylinder/head-bolts. However those are about 250mm long, so the ones I found & used were likely from either 200 or 160 engines.
Whatever, they were Italian-made and strong enough for their new job !
__ Other than that, I really have no other recommendations for replacement-bolts. _ But I don't see where any bolt thicker than 8mm needs to be especially strong for this job, (as the common threaded-rod I once used, held-up well enough!).


Dukaddy-DUKEs,
-Bob

[MotoMike]

Sourcing SAE bolts in 3/8 grade 8 seems do-able from stock in some places. "

____ After my second stock-type 8mm-bolt busted, (both at the thread just at the inside edge of it's nut), I then got a 3-ft length of 3/8ths" threaded-rod and cut a piece to length, for the job.
Later, I found a number of long-length 10mm-bolts (within my mass of used parts), which were long enough for the job, (but required some drilling of the holes, for them), so I just used one of them when-ever I needed a bolt for the (upper-rear w-c motor-mount) job.
__ Until now, I never really bothered to try to figure-out where I might have gotten them from, but I recall always suspecting that they were 250-DUKE cylinder/head-bolts. However those are about 250mm long, so the ones I found & used were likely from either 200 or 160 engines.
Whatever, they were Italian-made and strong enough for their new job !
__ Other than that, I really have no other recommendations for replacement-bolts. _ But I don't see where any bolt thicker than 8mm needs to be especially strong for this job, (as the common threaded-rod I once used, held-up well enough!).


Dukaddy-DUKEs,
-Bob

Bob
Looks like you might be right on the head bolts. the parts manual shows them to be 10mm x253mm. Those come up on the bay quite often. thanks.

Mike

[MotoMike]

Also in looking at the 350 parts list, the 350 head bolts are 10mmx263mm so one from a 250 for the upper rear and one from a 350 for the lower rear would fit the bill nicely. If you have rearsets, then two from the 250 sound about right.

[MotoMike]

Well even the best laid plans. I did not see from purusing the parts books that an alignment bushing resides at the case union at the upper rear mounting bolt location. Consequently, drilling if the bushing decides to spin is not likely. So I have reassembled it with the 5/16 inch bolt back in place.
So, are there any positioning bushings in the front engine mounting holes?

guessing that Ducati must have made a bushing with a 10mm hole in it if they changed that upper rear bolt to 10mm in production. So the cases must be split to effect the change to a 10 mm bolt unless you get luckh and drill out the bushing without it spinnning.

[DewCatTea-Bob]

" So, are there any positioning bushings in the front engine mounting holes? "

____ You now have me doubting my memory on these details but, first off, what makes you think these things you've come-up with?
As I'm sure that I myself had chosen all my previous wording carefully enough to prevent most misinterpretation.
__ I've never tried to use 10mm bolts at the front-mounts, so I can't say whether there may be any such issue as you're concerned with at the front-end.
However, as I had mentioned in the past about the upper-rear location, the only drilling that needed to be done (in order to fit a 3/8ths" threaded-rod), was to the mount-holes in the frame itself (only!).
And to fit a 10mm-bolt, I had to use a 3/8ths drill-bit, (in some cases), to drill-out just a mere shaving of internal-metal from the motor's hole.
__ So I'm wondering where you got the notion that there would be any much more to it -(my recommended-modification) !?


Hopeful-Cheers,
-Bob

[MotoMike]

" ... first off, what makes you think these things you've come-up with?...

Hopeful-Cheers,
-Bob

the drill 3/8" x 12' stops about a quarter inch from the center seam on either side. spins, but does not bite.

when you insert a 3/8 inch bolt in one side, its threads will engage what I assume to be the bush. then looking through the other side with a light, you can see the reduced diameter and see it move when you move the bolt.

the gasket for the case has a large hole in this location.

regards,
Mike

[DewCatTea-Bob]

" the drill 3/8" x 12' stops about a quarter inch from the center seam on either side. spins, but does not bite.
when you insert a 3/8 inch bolt in one side, its threads will engage what I assume to be the bush. then looking through the other side with a light, you can see the reduced diameter and see it move when you move the bolt.
the gasket for the case has a large hole in this location. "

____ Well all that is more than sufficient to reach your conclusion.
It's been a long time since I've done it myself, so I couldn't recall those likely facts but, I do know that I myself never ran-into that problem (either with using an extended 3/8ths drill-bit from either side, or a std.length 3/8ths-bit from both sides) !
__ To deal with this issue you've encountered, I'd suggest using two 3/8ths ream-bits for reaming-out the impasse from both sides at once.
But in lue of that, if you could get a pair of 1mm thick sleeve-bushings at least 10mm long, they could be used to sleeve-up your 8mm-bolt at both ends, so as to make for a more solid connection between the motor-case & frame-mounts.
I myself probably wouldn't bother to go through this extra trouble for the 250 or 350 but, the 450 is such a shaker that I wouldn't give-up if there's any reasonable way possible to go-through with the desired affixing-modification.


Dukaddy-DUKEs,
-Bob

[MotoMike]

"

__ But in lue of that, if you could get a pair of 1mm thick sleeve-bushings at least 10mm long, they could be used to sleeve-up your 8mm-bolt at both ends, so as to make for a more solid connection between the motor-case & frame-mounts.

Dukaddy-DUKEs,
-Bob

Ha. wouldn't you know that I have done exactly that Bob. I used sleeve spacers 1"x 5/16". I peened one end slightly to keep it fro vibrating into the channel, so they stay at the outter ends. they are a close fit and will hold me over until I decide if I will take on the two drill method you describe. Hadn't thought of that. thanks.

[DewCatTea-Bob]

" I peened one end slightly to keep it fro vibrating into the channel, so they stay at the outter ends. "

____ As I've mentioned before, you're my kind of people. _ As most would never bother.
I was also concerned that if such spacers were not long enough, that they may move out of intended position (between both the motor-case & frame mounts), and thought that it would be best if they had flange-lips (only at one end of each, of course), but figured you'd not be able to find such spacers as that, so I didn't bother to mention that added detail.


" until I decide if I will take on the two drill method you describe. "

____ When shopping for the pair ream-bits, don't let both be the type which have cutting-teeth at their front-end, as there are also ream-bit types with a smooth/flat end. _ Or if you can find one of them to be made for reverse-direction reaming, then that could work too.


Hopeful-Cheers,
-Bob

[jbcollier]

Over the counter stainless (SS) is very low grade and galls quite easily. However, high grade SS is available though not cheap. Google ARP. I wouldn't bother myself, grade 8 (3/8) or grade 12.9 (10 mm) with Copaslip will work just fine. I have seen nylocks vibrate loose, I lock wire most fittings on my single.