Help: Nighthawk 750 clutch mishap

I have a 92 nighthawk 750 with a worn out clutch. I bought the discs
and plates and springs, and the silly socket that honda says you need
to remove the big nut that holds on the clutch plate (but NOT the
thing that holds the plate from spinning, because people told me I'd
be able to wing it.)

Went in to do it, and lo and behold, the big nut that holds the plate
on is "staked" (manual's word) to the shaft it's theaded onto (the
input shaft for the trans). "Staked" turns out to mean the nut has a
thin shoulder which is hammered into a groove in the input shaft after
the nut is torqued down. I tried to pry up this indent using an awl
and a tiny screwdriver, only to have it snap off half way (the bent
bit of the nut, NOT the screwdriver), leaving the remainder
more-or-less hammered down between the nut and the shaft.

So I thought, "Gee, I got a fair bit of it out, maybe a little
persuasion on the nut will snap off that last little tab" Wedged a
bar across two of the shafts that the springs slip over and put the
funny socket on the big nut, applied persuasion, and SNAP--broke off
one of the little shafts that the springs sit over.

So here I am with a snapped inner clutch plate and a big nut that is
seemingly STUCK on the shaft. I put it back together and went to the
bar.

What do I do? I'm going to buy the stupid honda gizmo for holding the
plate from spinning, which should hopefully keep from snapping the
other 3 shafts. Have to replace the broken plate, of course--but how
do I get the goddamn nut off? The shaft has a groove, like for a
woodruff key, but now the little shoulder of the nut is more-or-less
hammered inside it. I'm thinking maybe I can use a tiny drill to
drill out the bit that's hammered in? Any suggestions?

Thanks all.

-Luke

 

But, it is possible to block the clutch basket from turning while you loosen

I can't get at anything to wedge. Until this stupid nut comes off,
there's no room to access anything. I'm going to buy the tool and
lower my risk.

The shop manual says to "unstake the clutch center nut", which had me
expecting something like a woodruff key. Turned out that they (Honda)
used a punch or similar tool to just hammer part of the nut down into
the groove. "Unstake" is all the guidance they give. My initial
thought was to use a dremel and just cut the whole damn nut off, but I
don't want to damage the plate behind it (I'd rather not have to
replace TWO of these stupid plates).

I'm going to go to home depot and check out dremel items, but I think
the drill makes the most sense. I'd appreciate any and all
suggestions, of course.

-Luke

 

Completely "unstaking" a mechanical part that has been secured by softer metal

It can't be IMPOSSIBLE or else changing the clutch would be
impossible. A huge pain in the ass, yes. I ended up buying a carbide
dremel cutting bit (looks like a mean, mean drill bit, but designed to
cut sideways through hardened steel instead of drill) and cut a notch
down through the cut to where it was staked. Looks like I succeeded
in cutting out the entire staked bit, but I'll need the gizmo from
honda to find out.

Good idea about locking the rear wheel with wood. The nut is supposed
to have 80 ft lbs of torque on it--I wouldn't think that would be
enough to hurt anything inside the tranny... I may give it a shot
tonight. I actually ordered the little tool this morning, but maybe
they can return it.

-Luke

 

How come nobody has mentioned the use of an impact wrench on the nut?
Should be able to loosen the nut while holding the clutch assembly
without putting any stress on other components??? What am I missing?
mike

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The nut in question is dead center in the clutch basket and there is no
problem getting to it with the clutch cover removed. On a unit
construction engine like the DOHC CB750 there is no space between the
engine and the transmission because both are in the same enclosure.

Easiest thing to do is to simply have someone apply the rear brake while
you take the nut off.

 

Use Blue loctite, if you want it off again
Rob.
| >From: (luke)
|
| >It can't be IMPOSSIBLE or else changing the clutch would be impossible
|
| What I should have explained was that the staking process by using a punch
will
| locally work harden the material that is punched...
|
| The big nut holding the clutch inner sleeve onto the transmission
mainshaft is
| what was "staked" isn't it?
|
| If you grind away the staked area on the nut, you will be obliged to stake
it
| in another spot, since you've ground away the work-hardened part...
|
| But, when you go to reinstall that old used nut, guess what part of the
nut is
| going to line up with the groove that looks like it's meant for a Woodruff
key?
|
| Won't you need a new nut?
|
| The alternative to a new nut is the use of the thread locking compound
called
| "Loctite"...
|
| You could use red Loctite, after degreasing the threads with alcohol or
brake
| cleaner, but, if you ever need to remove the nut again, you may have to
use a
| torch to burn away the Loctite, and you may find that subsequent attempts
to
| remove and reinstall the nut feel like the nut is cross-threading on the
| shaft...
|
| That's a spooky feeling...
|
| Red Loctite can be some nasty stuff, and a friend once described the use
of
| green Loctite as "the kiss of death", you can never remove a geen Loctited
part
| again, according to him...
|
| >Good idea about locking the rear wheel with wood. The nut is supposed to
have
| 80 ft lbs of torque on it--I wouldn't think that would be enough to hurt
| anything inside the tranny... I may give it a shot tonight.
|
| The transmission is designed to transmit 300 to 400 foot pounds of torque,
in
| first gear, and can easily survive heavy shock loads from rough shifts and
| riders popping wheelies, you won't hurt the gears by tightening the nut to
the
| specified torque...
|
|
| # * 0 * #
| ^
|
|
|

 

I can't get at anything to wedge. Until this stupid nut comes off,
there's no room to access anything. I'm going to buy the tool and
lower my risk.

The shop manual says to "unstake the clutch center nut", which had me
expecting something like a woodruff key. Turned out that they (Honda)
used a punch or similar tool to just hammer part of the nut down into
the groove. "Unstake" is all the guidance they give. My initial
thought was to use a dremel and just cut the whole damn nut off, but I
don't want to damage the plate behind it (I'd rather not have to
replace TWO of these stupid plates).
[/QUOTE]
My initial thought is to find a chisel that's the width of the groove,
and use that to wedge the nut material out of there.

That worked for me on my Acura Integra (wheel hub nuts were staked, used
a small screwdriver instead of a chisel). Of course, when I went to
repeat the process on my friend's Integra, it turned out that the guys
at the Honda shop had hammered that nut on with full impact-wrench
force. I snapped a socket extension (1/2" thanks) trying to remove it
before we just drove it to a muffler shop.

If you go for a power tool, you need to be REAL careful. If you go for
the dremel, you are going to be pretty limited in what you use: the
cutting wheels often won't get into the space you've got, grinding tools
are either too big, or easily worn out (like the deburring head that I
wiped out working on my friend's aforementioned Integra).

Good luck.

--
Later,
John



'indiana' is a noun. Leave only the noun between @ and .edu to reply

 

What I should have explained was that the staking process by using a punch
will
locally work harden the material that is punched...

The big nut holding the clutch inner sleeve onto the transmission mainshaft
is
what was "staked" isn't it?

If you grind away the staked area on the nut, you will be obliged to stake it
in another spot, since you've ground away the work-hardened part...

But, when you go to reinstall that old used nut, guess what part of the nut
is
going to line up with the groove that looks like it's meant for a Woodruff
key?

Won't you need a new nut?[/QUOTE]

Every application I've ever seen a staked nut in demanded a new nut
after you removed the old one. I wouldn't want to re-use an old staked
nut anyway...

As you said (in the snipped bit) Loctite is NOT the way to go here.

--
Later,
John



'indiana' is a noun. Leave only the noun between @ and .edu to reply

 

My initial thought is to find a chisel that's the width of the groove,

Chiseling it ended up pushing the "staked" metal back underneath the
rest of the nut, therefore making it impossible to unstake.

I've got the thing off now. I used this dremel cut off bit, # 9901
Tungsten Carbide Cutter. It looks like a blunt, thick drill bit and
is designed to cut sideways, not drill. Because I tried to chisel it
and ended up pushing it underneath the thick body of the nut, I had to
cut through the whole nut to unstake it. I would REALLY recomend to
anyone trying this to simply grab this dremel bit and cut off the
staked bit. It would only take about 20 seconds and then you'd be
free of a huge hassle. Don't risk creating a larger problem by
chiseling and prying and deforming the nut--just grind off the staked
bit while it's right there and easy to get at.

As far as the air wrench (if I had one): It would work fine getting
the nut off (once it's unstaked) but there's no way to properly torque
it when reassembling. I tried to order the fancy holding tool from
honda, then in the mean time successfully got the nut off using the
wood in the back wheel method. This morning I found out Honda can't
get me the tool for some reason, so I'm going to reassemble with the
wood method.

Thanks everyone for all your input... imagine, a reeky thread that's
on topic and useful through out! I'll post a note of success when
I'm done.

-Luke

 

Chiseling it ended up pushing the "staked" metal back underneath the
rest of the nut, therefore making it impossible to unstake.[/QUOTE]

Ah. The nuts that I unstaked had enough material to slid the chisel
underneath that this wasn't a problem. Glad you got it out, though.

I really should invest in a Dremel or similar. <sigh> They're pretty
useful...maybe after the start-of-semester bills are all paid off.

Thanks for the tip on the cutter part. I'm keeping that one around.

--
Later,
John



'indiana' is a noun. Leave only the noun between @ and .edu to reply

 

So, I've got the new pressure plate and am reviewing the procedure so
all will go well tomorrow, when I notice that the manual lists no
torque specs for the clutch lifter plate bolts (the 4 bolts that go
through the cross shaped plate and ultimately hold the springs on).
It says:

"Install lifter plate bolts and tighten finger-tight... check that the
pressure plate seats flush against the friction disc... tighten
lifter plate bolts securely in two or three steps and in a crisscross
pattern".

Generally I have a sense of what "secure" means, but with springs it's
awfully goddamn ambiguous. Guidance, anyone?

And no, it's not in the torque specs anywhere in the manual.

Thanks.

Luke
92 nighthawk 750 eager to be riding again

 

These are some relatively small machine screws, are they not?
Something like 6mm? And they do not actually torque down only against
the springs, they do put the springs under compression, but the screws
bottom out against the cross shaped lifter plate and the mounting
bosses in the clutch basket.

My recollection is that the torque spec is surprisingly small, best
measured in inch-lbs. I would use Loctite on them in any case.

As to whether the torque spec is in the manual- I would find that
somewhat unusual. Most manuals (including all my Honda manuals)
have a chart near the front of general torque values for fasteners
by diameter, for those that are not otherwise explictly called out
in the text.

My Honda CM400T manual also omits an explicit torque value for the
clutch lifter plate screws. This tells me to consult the Standard
Torque Specifications chart on page 1-5:

Size ft-lb
------------------------------
5mm bolt and nut 3-4
6mm bolt and nut 6-9
8mm bolt and nut 13-18
10mm bolt and nut 22-29
12mm bolt and nut 36-43
5mm screw 3-4
6mm screw 5-8
6mm flange bolt and nut 7-10
8mm flange bolt and nut 14-22
10mm flange bolt and nut 22-29

Since these are 6mm machine screws (I am guessing from memory),
I would torque them to 5-8 ft-lbs. Your situation may vary, and I
strongly urge you to measure the screws in question, and consult the
standard torque chart in your Honda CB750 manual.

For whatever it is worth, the clutch repair section of the Clymer
manual (which came with the bike, I didn't buy it) says to torque
the 'Camplate bolt' to 6-9 ft-lb.

 

These are some relatively small machine screws, are they not?

Yeah, I didn't realize they bottomed out when the cross shaped thing
touches down against the plate... or rather, I knew they would IF it
did, but I thought they'd give much more resistance to tightening and
feel "secure" before then. So, problem solved.

Got eveything back together, including a new cable to replace the old
stiff one (previous neglect and misery made it pretty unresponsive to
lube) and went out today... you know, I may have spent more than I
needed to and wasted a hell of a lot of time, but even aside from the
enjoyment of learning about it and doing it myself and knowing
that--eventually--it was done right, the feeling of finally getting
back on the bike and opening it up, that acceleration, and the feel of
the clutch lever in my hand actually doing what it ought to do...
that's just completely worth it. Had a big stupid grin on my face the
whole time. Tomorrow will see an early rise and a nice loooooong
ride... making up for lost time.

Thanks everyone for your help... and sorry about not cross-posting
between regular reeky and here--it just didn't occur to me.

-Luke