Honda CB750 Sandcast
The Restoration Shop => Front End and Suspension => Topic started by: the-oz-slider on October 26, 2020, 08:58:59 pm
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Hi all, Im dismantling my K0 front end and for the life of me I cant get the seals out of the fork lowers. I have the circlip out and have applied lots of heat, some gentle mechanical persuasion courtesy of a plastic hammer applied carefully to the lip of the lowers and no luck...........
What do I do next please?
Thanks
Al
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As long as you are sure the circlip is out, then you can begin to use more force. It usually take a few good tugs on the fork tubes to get an old seal out. Ive never needed heat. Just use the fork tube like a slide hammer and it will loosen up.
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yes circlip is definitely out- it was rusty and broke when I pulled it out....
no luck yet I had another go at them this morning and pulling the tubes simply wont work.
Ive even loosened off the damper rod slightly, thought that might help.......
Im at a loss what to do next
Al
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Are you giving it a good wack when you yank on the fork tube? I'm not gentle when I do this. It is like pulling out a wheel bearing with a slide hammer. A lot of force is used!
Confirm that there is nothing in the groove that circlip sat in that could be blocking the seal. The seal is rubber/plastic, so it should not have bonded to the form leg.
I bit of penetrating oil sitting over night might help.
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oh woe is me....
I had the original forks off the ugly chopper dismantled and all the brass sleeves, bottom circlip and bleed sleeve are all trashed, so I had another set of forks that I thought were pre-72 that I was going to get the parts out of.......
Well the second set of forks arent what I thought they were - they are later with the fork tube captured by the damper rod. As soon as I released the damper rod fully the forks came apart as they should.
My apologies for wasting your time.
Next question though. Where can I buy the brass top sleeves, lower circlips, damper/bleed sleeve etc, preferably as a complete kit?
Thanks and apologies again
Al
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No worries.
I have never seen them sold as new parts. I may be mistaken about that. I've only ever found them as used parts. eBay has lots of used forks usually!
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CMNSL has everythung new at the usual nose-bleeding prices, so Ill guess Ill go with them.
Al
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No, CMSNL is out, too expensive even for this bike....so Im still on the hunt for the damper collar, top sleeve and the little circlips that keep the damper collar in place on the lower fork leg if anyone has any spares please.
Al
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well I bit the bullet, held my nose and ordered all new lower fork parts from CMSNL - almost $400 CAD and no doubt Ill get raped at the border to the tune of likely another 20% damnit.....
Al
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Absolutely horrendous prices from these thieves. I used to buy parts from them years ago until they started pricing their parts using telephone numbers. Used K0 fork leg for US$800 is just plain theft IMHO. You have my sympathy. Just for others info, the internals of the K1 are more or less the same.
Cheers
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More woes for my forks....
I bit the bullet and bought all the circlips and snap rings and sleeves etc from CMSNL and after going thru the packages when they arrived yesterday, there are circlips with two different part numbers that are in fact identical, damnit......
But on sorting out what was correct and what wasnt [one of the circlips used to secure the damper sleeve is too large to do the job] I installed everything and it seems that the fork tubes I bought from Vintage CB750.com are incorrect.
The distance between the two lower circlip grooves [the circlips that control the damper sleeve] are too close together [32mm+/- apart] so once the circlip is in place the damper sleeve cant float as it should.
If someone has a set of early forks dismantled would you be so kind as to measure the distance between the circlip grooves on the bottom end and also the distance from the very bottom of the fork leg to the third groove please?
Also, if anyone has a good set of the top bronze sliding bushes that sit under the seal available I'd appreciate being able to find a pair that are better than my ex-chopper-fork worn out ones....
Thanks
Al
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UPDATE FOR THOSE WHO MAY FACE THIS PROBLEM
I purchased new fork tubes from Vintage CB750.com and all new damper and guide sleeves and circlips from CMSNL at their typically outrageous prices, but so be it.
When I assembled the forks using the information gleaned from this site and the various manuals and experts on the SOHC forum, I had a problem in that the damper sleeve was fully covering the damper bleed holes and couldnt move either direction.
So I flipped the damper sleeve upside down and it now works with the bleed holes being covered/uncovered as needed as the forks go up and down.
According to the manuals this is wrong but it works so Im leaving it as is.
Second issue is that my bronze top guide sleeve is stuffed, so Im off to see a machine shop today to see if they can make me 10 sets at a reasonable price. The clearance on my top sleeve varies from 1/32 to 1/16" at various point around my chopper forks.
Thankfully the bottom tolerance inside the lower fork case is OK, it seems the top sleeve took all the pain from the super-extended forks.
If I can get these top sleeves manufactured at a reasonable price Ill offer the remainder for sale at my cost. There surely must be demand as Ive searched worldwide for replacements and CMSNL is the only known source, currently at 67.00 euros each, which is about $100 CAD.....
Al
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Sorry but I don't have a spare. There is one for sale on ebay at the moment with the correct part number but it's "huge" money. Here's the link
https://www.ebay.com.au/itm/Honda-CB-750-Four-K0-Ball-Immersion-Pipe-Brass-NOS-Guide-Front-Fork-Pipe/293500344641?hash=item4455fbd941:g:u1IAAOSwngBeX2YQ
I spoke to a fellow who rebuilds K0, K1 and K2 bikes and here is his easy solution. Use a K1 item and have approx 2mm turned off the top collar part. They are the same dimensions other than that. The K1 uses the larger fork seal (diameter only) so have your machinist do that adjustment and the issue is solved. These K1 guides are a little longer but he said that's not a problem and actually provides a little more support to the tube action
If anyone else has a solution then please assist
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thats a great solution as I have four of the later model sleeves....I can get new ones machined from bronze for $70 each and was considering getting 10 made which would reduce the price to $50 each, and then offering them for sale to members. I surely cant be the only one who has major slop at the top sleeve on K0-K1 forks, and can't justify the 67 Euro bill from CMSNL, plus shipping, plus duty and taxes.....
$50 CAD, thats about 19 US dollars isnt it?? ;D
Al
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well that didnt achieve much ...I went looking for my four top sleeves and cant find any of them. Mind its -25 here today so I didnt look too hard.
I have one in my hot paws, but if anyone has one or two of these they can part with I'd appreciate a PM...
Thanks
Al
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OK, Ive given up trying to find good used parts so have committed to a local CNC machine shop to make 10 [5 sets/pairs] of the top bronze sleeve Honda Part number 51451300000.
Ill list the parts in the ' for sale' section.
Thanks everyone for the input.
Al
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Try the K0 Facebook group More going on there than this site
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I ran into this myself, I have a set of early fork 46mm lowers (ugly as the dirt I found them in) but cleaned up well. Apparently I have no 46mm early fork hardware to assemble them with. Probably another display of my earlier ignorance of what I had. The new plan is to buy new tubes and use cut down 48mm parts to rebuild them.