750 Commando Crankshaft reassembly hardware question: Is new hardware really needed?

rwanz · Mar 15, 2023

l know "better safe than sorry" but is there really a need to replace the hardware when bolting the crankshaft back together? The workshop manual doesn't specify. I know, what's a few more bucks when you're this far in...but man, money is tight these days and if everything is tightened up to specs is there a real need? Just looking for some experienced input before I put my gentle Sunday rider back together.

hhh · Mar 15, 2023

IMO, only con rod nuts need to be replaced amongst all the fasteners if they're in good shape unless you're pushing it to its limits. Don't forget the locking plates, regardless of Loctite application.

marshg246 · Mar 15, 2023

rwanz said:
l know "better safe than sorry" but is there really a need to replace the hardware when bolting the crankshaft back together? The workshop manual doesn't specify. I know, what's a few more bucks when you're this far in...but man, money is tight these days and if everything is tightened up to specs is there a real need? Just looking for some experienced input before I put my gentle Sunday rider back together.

I guess it depends on whether they have been punched. If so, then at least the nuts will take damage while undoing so should be replaced. Since I don't know if the last guy was a human or gorilla, I replace all.

baz · Mar 15, 2023

rwanz said:
l know "better safe than sorry" but is there really a need to replace the hardware when bolting the crankshaft back together? The workshop manual doesn't specify. I know, what's a few more bucks when you're this far in...but man, money is tight these days and if everything is tightened up to specs is there a real need? Just looking for some experienced input before I put my gentle Sunday rider back together.

I've heard the school of thought that says your used crank bolts/con rod bolts are tried and tested
New ones are not

ludwig · Mar 16, 2023

hhh said:
.. Don't forget the locking plates, regardless of Loctite application.

There seems to be some confusion about these locking plates.
A while ago, I read this on a restoration blog:
".. look at the second picture - the last person to work on it didn't bend the tabs! " (quote)

750 Commando Crankshaft reassembly hardware question: Is new hardware really needed?

I have read that remark about the tabs before. (originally they were never bent over)
Even if it was the first crankshaft that person ever saw, he should have wondered why there are no locking tabs on the other 3 bolts.
The locking plates are only there to keep the central dowel in place, not to secure the nuts.
They are soft metal, and I don't use them. Not suggesting that you shouldn't , but there are some more competent than me, who don't use them either.
I also prefer to reuse the original nuts and bolts , if in good condition, over new ones.

SteveA · Mar 16, 2023

When I worked on my first Commando crank in '75.....when they were easy enough to come by about 20 miles away....I didn't even think about replacing the bolts...nuts had been staked by 'someone' so yes.

And I certainly would not have known at that time that there were different sizes used in different models.

With my current crank, last time I stripped it I asked the maker, Steve Maney, if I should change them, and he said no!

I did change the nuts though, even though they had never been staked, and I used ARP.

Do I have a good technical reason for choosing ARP? No. I just happened to have some.

marshg246 · Mar 16, 2023

SteveA said:
When I worked on my first Commando crank in '75.....when they were easy enough to come by about 20 miles away....I didn't even think about replacing the bolts...nuts had been staked by 'someone' so yes.

And I certainly would not have known at that time that there were different sizes used in different models.

With my current crank, last time I stripped it I asked the maker, Steve Maney, if I should change them, and he said no!

I did change the nuts though, even though they had never been staked, and I used ARP.

Do I have a good technical reason for choosing ARP? No. I just happened to have some.

Did you use ARP washers with the nuts?

milfordite · Mar 16, 2023

NO, simple answer. Those "locking" plates are only there so that the locating pins don't move.

Fast Eddie · Mar 16, 2023

ludwig said:
There seems to be some confusion about these locking plates.
A while ago, I read this on a restoration blog:
".. look at the second picture - the last person to work on it didn't bend the tabs! " (quote)

I have read that remark about the tabs before. (originally they were never bent over)
Even if it was the first crankshaft that person ever saw, he should have wondered why there are no locking tabs on the other 3 bolts.
The locking plates are only there to keep the central dowel in place, not to secure the nuts.
They are soft metal, and I don't use them. Not suggesting that you shouldn't , but there are some more competent than me, who don't use them either.
I also prefer to reuse the original nuts and bolts , if in good condition, over new ones.

What do you use in place of them to keep the dowels in place Ludwig ?

marshg246 · Mar 16, 2023

milfordite said:
NO, simple answer. Those "locking" plates are only there so that the locating pins don't move.

So, why does the workshop manual say to bend them over?

seanalex · Mar 16, 2023

marshg246 said:
So, why does the workshop manual say to bend them over?

Maybe this was the factory way to ensure they'd have to be replaced every 20,000mi when they shear off. Good service dept conspiracy.

SteveA · Mar 16, 2023

marshg246 said:
Did you use ARP washers with the nuts?

No washers, Steve didn't fit washers, I didn't fit washers. No Tab plate either, but I think he locates the dowel another way (blind holes?). Can't remember.

I will be pulling it out shortly to change main bearings. Will see how it is.

Steve had also told me that late in production they had moved to what he called 'aircraft nuts'. Right or wrong, I figured ARP would be pretty close, and like I said, I had some.

No good reason not to use the ones originally supplied with it. If I have any doubts, they will go back.

SteveA · Mar 16, 2023

Fast Eddie said:
What do you use in place of them to keep the dowels in place Ludwig ?

Glue

SteveA · Mar 16, 2023

marshg246 said:
So, why does the workshop manual say to bend them over?

View attachment 104747

'use vice grips' Yeah, go on then, that'll work!

Along side a suggestion that you might change one crank cheek on it's own.......not a particularly useful manual is it?

hhh · Mar 16, 2023

SteveA said:
'use vice grips' Yeah, go on then, that'll work!

Along side a suggestion that you might change one crank cheek on it's own.......not a particularly useful manual is it?

I'm surprised it doesn't say "mole grips."

SteveA · Mar 16, 2023

hhh said:
I'm surprised it doesn't say "mole grips."

That's a brand name!

hhh · Mar 16, 2023

SteveA said:
That's a brand name!

So is "VICE-GRIP."

SteveA · Mar 16, 2023

hhh said:
So is "VICE-GRIP."

Seems to get used as the generic in the UK!

hhh · Mar 16, 2023

SteveA said:
Seems to get used as the generic in the UK!

I learned my British from BLMC manuals.

marshg246 · Mar 16, 2023

SteveA said:
No washers, Steve didn't fit washers, I didn't fit washers. No Tab plate either, but I think he locates the dowel another way (blind holes?). Can't remember.

I will be pulling it out shortly to change main bearings. Will see how it is.

Steve had also told me that late in production they had moved to what he called 'aircraft nuts'. Right or wrong, I figured ARP would be pretty close, and like I said, I had some.

No good reason not to use the ones originally supplied with it. If I have any doubts, they will go back.

ARP nuts and bolts that I've seen have a radius that requires the ARP washers or they don't sit flat. I'm no expert on ARP and have only used the cNw sets, but those will not work properly without the special ARP washers.