Author Topic: 750 K2 Strip & Rebuild - help please  (Read 20982 times)

Offline Lobo

  • Lobo
  • SOHC Master
  • Posts: 1568
  • Lobo
    • View Profile
    • Lobo
Re: 750 K2 Strip & Rebuild - help please
« Reply #195 on: July 26, 2022, 10:31:28 PM »
Thanks gents.

Nige, slightly struggling with your explanation/ logic as surely a torqued nut/bolt combination will behave as a ‘unit’, though I agree the fastener end planer forces will be higher at the floating end of the casting…
Maybe I’ve the wrong D washers, but certainly they provide no restrictions to the passage or siting of the bolt through the constant bore size….. as I mentioned; they’re currently rattling! (bolts tight but not checked wrt torque value yet)
« Last Edit: July 27, 2022, 02:22:47 AM by Lobo »

Offline Lobo

  • Lobo
  • SOHC Master
  • Posts: 1568
  • Lobo
    • View Profile
    • Lobo
Re: 750 K2 Strip & Rebuild - help please
« Reply #196 on: July 27, 2022, 02:22:20 AM »
Tips pls on compressing the rear shock springs wrt dismantling the units? Have looked eBay but concerned the jaws of all I see too bulky to engage the lower part of the spring (ie next to the damper)

Have tried 4x decent tie-wraps and ratcheting down… but too much force required methinks.

Offline K2-K6

  • Grogu
  • *
  • Posts: 5234
    • View Profile
Re: 750 K2 Strip & Rebuild - help please
« Reply #197 on: July 27, 2022, 08:16:04 AM »
Thanks gents.

Nige, slightly struggling with your explanation/ logic as surely a torqued nut/bolt combination will behave as a ‘unit’, though I agree the fastener end planer forces will be higher at the floating end of the casting…
Maybe I’ve the wrong D washers, but certainly they provide no restrictions to the passage or siting of the bolt through the constant bore size….. as I mentioned; they’re currently rattling! (bolts tight but not checked wrt torque value yet)

 ;D I can understand struggle, my explanation was a bit rambling Simon. I know what I want to say but putting words to it more challenging. 

Another go, essentially it's a compromise joint and so will have different views on deployment as I see it. Ideally the centre of the bolt "wants" to be dissecting the circumference of the fork stanchion to be a best design. Some do actually do that with a relief in the bolt that has to be placed in situ before the stanchion goes in to give correct load line with least possibility of distortion. 
With the honda one here, as you tighten the bolt it wants to banana shape itself away from stanchion centre (pushing the bolt shank inwards toward the stanchion) which the D washer may help prevent.  Also to stop the casting gap closing too much.
Guess they are trying to get workshop to do it up without snapping the casting as the stanchion is all but incompressable. If they've accommodated that with geometry in any way then it's advisable to assemble as the manual. If there's not a convincing reason to deviate then that would be wise.

Just checked an original fit 750 K2 and the D washers are definitely clamped tight when joint is secured.

Offline Oddjob

  • SOHC Jedi
  • Posts: 4296
    • View Profile
Re: 750 K2 Strip & Rebuild - help please
« Reply #198 on: July 27, 2022, 11:22:41 AM »
You may be vastly overstating this, Honda changed the design to a 7mm bolt and ditched the D washer. It appears they were trying to reduce the diameter of the bolt head to a 10mm instead of 12mm so that you couldn't tighten it as much thus breaking the casting. The castings didn't break at the bolt, they broke halfway round the casting, which would point to overtightening. The D washers I think were installed in the first place so that when they went rigid the bolt was tight enough.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline Lobo

  • Lobo
  • SOHC Master
  • Posts: 1568
  • Lobo
    • View Profile
    • Lobo
Re: 750 K2 Strip & Rebuild - help please
« Reply #199 on: July 27, 2022, 12:53:03 PM »
Thanks Nige / Ken; I guess I’ll just stick with the parts manual drawings; if for no other reason than originality.

I’m away from the bike now for a couple of weeks; but do balk at doing the clampings up ‘D washer tight’: yesterday evening I went to my comfort limit wrt what I reckon a M8 Stanchion bolt in an alloy casting should take. (I did though pre-measure the D washers at 2.3mm thickness - maybe there’s an issue here?)

I’ll stick a torque wrench on it later and double check my wrist calibration…

Cheers!

Offline taysidedragon

  • SOHC Master
  • Posts: 1318
    • View Profile
Re: 750 K2 Strip & Rebuild - help please
« Reply #200 on: July 27, 2022, 02:41:24 PM »
Thanks Nige / Ken; I guess I’ll just stick with the parts manual drawings; if for no other reason than originality.

I’m away from the bike now for a couple of weeks; but do balk at doing the clampings up ‘D washer tight’: yesterday evening I went to my comfort limit wrt what I reckon a M8 Stanchion bolt in an alloy casting should take. (I did though pre-measure the D washers at 2.3mm thickness - maybe there’s an issue here?)

I’ll stick a torque wrench on it later and double check my wrist calibration…

Cheers!

If the nut is tight but the D washer is still loose, the nut, or the head of the bolt must be catching on something else and tightening on that. Maybe part of the yoke casting? Are the bolt head and nut the original sizes across the flats? Any increase in size might cause a problem.  Just a thought.
Gareth

1977 CB400F
1965 T100SS

Offline Seabeowner

  • SOHC Pro
  • Posts: 986
    • View Profile
Re: 750 K2 Strip & Rebuild - help please
« Reply #201 on: July 27, 2022, 06:55:30 PM »
Tips pls on compressing the rear shock springs wrt dismantling the units? Have looked eBay but concerned the jaws of all I see too bulky to engage the lower part of the spring (ie next to the damper)

Have tried 4x decent tie-wraps and ratcheting down… but too much force required methinks.
I did the 500 shocks using plenty of ingenuity and a couple of ratchet straps. Fixed the shock upright and fixed the straps to an anchor points either side. You can wind the straps up inside the shroud by a turn.
Phil
1971  CB500K0  Candy Jade Green or Candy Gold
1973  CB500K1  Candy Ruby Red
1975  CB550F1   Shiny Orange
1978  CB550K     Excel Black

Offline Lobo

  • Lobo
  • SOHC Master
  • Posts: 1568
  • Lobo
    • View Profile
    • Lobo
Re: 750 K2 Strip & Rebuild - help please
« Reply #202 on: July 27, 2022, 09:10:40 PM »
Thanks Gareth: pretty certain of no issues other than my reluctance perhaps. I did consider the fresh paint within the yolk; but I did have to Dremel-scotchbrite much of that away simply to get the stanchions through. A bit of me still wonders whether the D washers are undersized?

Seabe.. like the sound of that and will give it a try. Many thanks.

Offline K2-K6

  • Grogu
  • *
  • Posts: 5234
    • View Profile
Re: 750 K2 Strip & Rebuild - help please
« Reply #203 on: July 27, 2022, 10:26:12 PM »
Thanks Gareth: pretty certain of no issues other than my reluctance perhaps. I did consider the fresh paint within the yolk; but I did have to Dremel-scotchbrite much of that away simply to get the stanchions through. A bit of me still wonders whether the D washers are undersized?

Seabe.. like the sound of that and will give it a try. Many thanks.

Aah, that may have an impact on the washers, any paint in the bore will push the gap apart where the washer sits.

In manufacturing the bore is made all but identical to the OD of the stanchion and then the cut made. If it's not done in this way then the bore (if too big or small) won't have the same circular shape as the fork leg and not be able to clamp effectively. Any additional coating in there will give error.

Offline Oddjob

  • SOHC Jedi
  • Posts: 4296
    • View Profile
Re: 750 K2 Strip & Rebuild - help please
« Reply #204 on: July 28, 2022, 01:58:10 PM »
I seem to recall the D washers are 2.3mm thick as standard so it doesn't sound like that's the problem.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline K2-K6

  • Grogu
  • *
  • Posts: 5234
    • View Profile
Re: 750 K2 Strip & Rebuild - help please
« Reply #205 on: July 28, 2022, 02:55:49 PM »
You may be vastly overstating this,

You're probably right Ken, but while the world and his dog concern themselves with, variously, meltdown, invasion, no gas supplies, rail strikes etc etc and all other frivolous malarkey,  we can come to the relative peaceful and far more serious subject of discussion as to how the nuts and bolts really should be arranged  ;D

Also via an intercontinental motorcycle forum no less, I'm sure we'll be able to sort it out.   :)

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
  • Grogu
  • *
  • Posts: 8206
    • View Profile
Re: 750 K2 Strip & Rebuild - help please
« Reply #206 on: July 28, 2022, 03:19:48 PM »
Here is one of our 750/4's
Have you got a Unicorn top yoke fitted Simon?

[ Guests cannot view attachments ]
« Last Edit: July 28, 2022, 03:23:56 PM by Nurse Julie »
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Lobo

  • Lobo
  • SOHC Master
  • Posts: 1568
  • Lobo
    • View Profile
    • Lobo
Re: 750 K2 Strip & Rebuild - help please
« Reply #207 on: July 28, 2022, 11:48:02 PM »
Thanks Julie, unsure what a Unicorn yoke is, but afaik mine is just plain old 1973 Honda. Appreciate the photo. Nothing has changed wrt this area (other than fresh powder coat) and I can’t bloody remember how the D washers were at tear-down.

The stanchions are DSS patterns …. gave Trig the old ‘ uns. (restoring the UK based bike from my work place in Brunei was a problem back then!)

Q1. Wrt the mostly cleaned away paint, should the stanchions be a fairly tight slide in, or easy insertion? Mine are tight, needing a fair amount of pushing and twisting.
Q2 - do you preferably torque them, or use the D washers as an indication of final clamping?

I might be wasting everyone’s time here as not yet put a torque wrench on them, which will happen in a couple of weeks now. Regardless, a big thanks.
« Last Edit: July 28, 2022, 11:50:36 PM by Lobo »

Offline Lobo

  • Lobo
  • SOHC Master
  • Posts: 1568
  • Lobo
    • View Profile
    • Lobo
Re: 750 K2 Strip & Rebuild - help please
« Reply #208 on: August 13, 2022, 09:35:19 AM »
Back from my hols and checked the torque on those 7mm / D washer top yolk today.. were bang on at 8ft lbs. Ie the washers still rattle.
It got me thinking deeper - surely if these washers tighten up you can’t be certain that the stanchion is fully clamped? Are they not provided as a simple yolk-crack saving device?
I’ve cleaned away 80% of the powder coat (more or less bare metal showing) and honestly don’t want to go more. Those washers have about 0.2mm rattle slack - it’ll do me… unless I’m missing something critical here.

Wrt to the rear shocks, they are fully checked, cleaned and as good as new. I never was able to compress the springs enough to access the lock-nut to upper mount, mainly because 50% of said spring is inaccessible under the chrome skirt. 3 stout tie-wraps over 1/2 the spring afforded me just enough to do the job.
With the twin top collars removed I noted the upper mount was about 0.5mm too large to pull through the upper holes in the chrome skirts - at 4 circumferential points - and so ground away a minuscule 0.25 mm notch at each point with the Dremel. (I wish I’d tried heat… the interference was so minimal it might have worked?) The top mount  then pulled though and gave me access to the lock nut / disassembly.

A horrible job due my puny muscles compressing the unit against my  flabby gut - glad it’s bloody done.


« Last Edit: August 13, 2022, 12:36:06 PM by Lobo »

Offline Lobo

  • Lobo
  • SOHC Master
  • Posts: 1568
  • Lobo
    • View Profile
    • Lobo
Re: 750 K2 Strip & Rebuild - help please
« Reply #209 on: August 20, 2022, 01:48:01 AM »
Slow progress… too many distractions.

Anyways, when I dismantled the bike the cylinder head breather was to atmosphere. Now I note the parts manual (part # 11 uppermost) shows a clip on each end of this… so where does it connect to pls?
 
I’m pretty certain the oil tank breather connects to the (lower) crankcase vent, ie that hole’s accounted for 😂.

Ta.
« Last Edit: August 20, 2022, 02:05:44 AM by Lobo »

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal