Fork seals on '82

Fork seals on '82

Postby cross » Thu Feb 20, 2014 2:56 am

Hi Guys,
My forks are seeping oil and since i need to take the wheels off to install new tires, it would make sense to disassemble them and change oil and seals.
Is there anything else inside that usually needs changing?
I read on here on recommendations for oil and amount of it. There is so much info that i got lost. :think:
I'm 5'9" and 170#, not aggressive rider but like to lean it a bit in the corners so i guess soft would not be too good for me, maybe medium, medium+ on firmness but of course, rear needs to match.
Second, there is a drop of oil on the bottom of the rear shock as well, are they rebuild-able too?
Any suggestions welcomed.
:text-thankyouyellow:
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Re: Fork seals on '82

Postby daves79x » Thu Feb 20, 2014 6:38 am

So looks like you got the info on the front forks. Use 10 wt to 6 inches from tube top, springs out and fork collapsed. This is more than Honda calls for. Rear shock is junk even with rebuild - if you can even still get the seal. Spring for a real shock.

Dave
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Re: Fork seals on '82

Postby cross » Thu Feb 20, 2014 11:59 am

And is anything else usually needed beside seals and dust caps? Or recommended to replace?
That would be 10w fork specific oil?
Also, i didn't pull the side cover to check ignition before u poured new oil in the engine, how much oil will it come out if i remove it now?
Its probably not related to ignition but i still would like check things, as #4 pipe is not nearly as hot as the other ones.
I'm thinking its probably the carb.
You can hear it running here
viewtopic.php?f=102&t=8735

Thanks
Sasha
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Re: Fork seals on '82

Postby daves79x » Thu Feb 20, 2014 12:51 pm

No, fork rebuild is straight by the book, except for oil level. No oil will come out the crank cap. Carbs are for sure the problem with #4. I can tell you for what it's worth that a complete carb rebuild will be the best money you'll ever spend. There are clearly issues that can't be fixed with external fiddling. You'll never know how sweet the bike is until you do that.

Dave
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Re: Fork seals on '82

Postby cross » Thu Feb 20, 2014 3:49 pm

I read the manual and will follow the procedure i just wanted to minimize down time by ordering all parts needed.
I spoke with Mike Nixon and will be delivering carbs to him this weekend for a rebuild.
Any specific brand/type of fork oil?
Thanks Dave for answering all my questions
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Re: Fork seals on '82

Postby daves79x » Thu Feb 20, 2014 5:54 pm

I like Bel-Ray fork oil either 7wt or 10wt - 7wt is hard to find.

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Re: Fork seals on '82

Postby cross » Thu Feb 20, 2014 6:05 pm

Thanks
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Re: Fork seals on '82

Postby cross » Fri Feb 21, 2014 12:57 am

Dave,
Local bike shop has both, 7w and 10w.
What is the difference when using 7 vs 10?
I also ordered honda seals and dust caps.
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Re: Fork seals on '82

Postby NobleHops » Fri Feb 21, 2014 1:12 am

Lay in some mineral spirits too, and fill up the fork legs and flush with the stuff a few times. I just did my 400F forks and it took roughly forever to get them squeaky clean, and you likely won't be in there again (hopefully!). I can't recall what the CBX uses, but the 400F uses copper crush washers to seal the drain screws and also the damper rod screws. You can (should) re-anneal those if you intend to reuse them by heating them till red hot with a propane torch and then quenching them in cold water, then lightly wire-wheeling off any scale that forms.

Measure the free length of those springs while they're out, compare to the spec in the manual!
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Re: Fork seals on '82

Postby daves79x » Fri Feb 21, 2014 6:27 am

Nils - good info. Yes, you need to clean the internals and especially the lowers of all crud - and there will be a lot. 7wt is closer to Honda's spec of ATF, but most guys use 10wt. Break the damper rod holder bolt loose before removing the cap.

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Re: Fork seals on '82

Postby cross » Fri Feb 21, 2014 3:56 pm

So using the 10w leads to stiffer fork?

Thanks guys, you've been of lots of help.
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Re: Fork seals on '82

Postby Larry Zimmer » Sat Feb 22, 2014 11:44 am

Sasha,
One of the most important things to do while the forks are apart is to inspect the surface of the upper tubes that slides in the seals. Inspect for ANY scratches and nicks. This is the most common cause of seal weeping/leaking. Most things can be polished using 400 and 600 grit paper. If scratches are relatively deep, start with a 220 or 280 grit. Finish with the 600. Use any light oil on the paper when polishing. Be certain to polish 'around' the tubes NOT up-and-down.
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Re: Fork seals on '82

Postby cross » Tue Mar 11, 2014 1:21 am

I got mu forks apart and cleaned them up.
Few things that i will need to get are the circlips and backup plates/washers as they are rusty.
This was much easier than I thought.
I measured my springs and they are just shy of 21", books states that if they are shorter than 22.2" to replace them.
There was however 1" spacer from PVC pipe on the top.
Now, should I be considering new springs or just use them with spacers that they came with
I originally wanted gold valve emulators with my springs but I'm not sure on how complicated it is to install them.
Now that my springs are shorter, how much difference there really is with gold valves and stock springs and gold valves with their rave tech springs?
When I was pushing the tube down to drain the oil, it was pretty hard to compress them.
Anyone have experience with these?
Thanks
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Re: Fork seals on '82

Postby NobleHops » Tue Mar 11, 2014 2:02 am

cross wrote:I got mu forks apart and cleaned them up.
Few things that i will need to get are the circlips and backup plates/washers as they are rusty.
This was much easier than I thought.
I measured my springs and they are just shy of 21", books states that if they are shorter than 22.2" to replace them.
There was however 1" spacer from PVC pipe on the top.
Now, should I be considering new springs or just use them with spacers that they came with
I originally wanted gold valve emulators with my springs but I'm not sure on how complicated it is to install them.
Now that my springs are shorter, how much difference there really is with gold valves and stock springs and gold valves with their rave tech springs?
When I was pushing the tube down to drain the oil, it was pretty hard to compress them.
Anyone have experience with these?
Thanks


I'm going to guess those springs are not stock, and so may be uprated, and that would possibly make the free length measurement in the manual not useful. Racetech springs (for example) are shorter for the same given spring rate, hence their use of spacers and the ability to tune the preload with the spacer and also and make room for the emulator/adaptor stack. Clean them and count the coils. Racetech might be able to walk you through figuring out the spring rate of what you have by making a few measurements of them and coil count. If the springs ARE good, then you're home free. With the fork apart the installation of the emulators is really pretty easy. Drill the damper rod and chamfer the edges, adjust the spring/screw on the emulator as directed by their calculator, stack the emulator on the little adapter they'll sell you, drop it in on top of the damper rod, drop the spring on, then the spacer, and done.

I just did this on my 400, let me see if I can recycle a post on the topic...

N.
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Re: Fork seals on '82

Postby NobleHops » Tue Mar 11, 2014 2:10 am

Hope this helps.

This is fork seal replacement and RaceTech Gold Valve cartridge emulators being installed in a Honda CB400F fork. Not a CBX, so there may be differences, this is offered here to help picture how the emulator install goes.

---

OK, it was Fork Night around the garage tonight. On the agenda was rebuilding the forks, installing new seals, re-annealing the copper washers on the damper bolts, and installing RaceTech Gold Valve Cartridge Emulators. Everything in hand, everything is spotless and good to go.

Image

First up, scratch my a$$ for a bit and think of the best sequence to do it in.

First, loosen up the gold valves and verify their state of tune. I settled on 3 1/2 turns on the spring after reading the tuning guide. You hold the screw with a hex driver, loosen the jam nut, then back out the screw till the spring is just barely slack, then screw in the appropriate amount of turns on the screw into the body of the valve to tension the spring, then tighten the jam nut while holding the screw to lock it in place.

Image

These bushings are furnished to adapt the gold valves to the top of the damper rods.

Image

With the valves ready, time to drill and chamfer the damper rods.

Image

RaceTech calls for the existing two holes to be drilled out to 1/4" and then two more holes to be drilled 10mm up the damper rod, at a right angle. Then chamfer and deburr the edges, get them good and clean.

Minorly fiddly without v-blocks and a vise for the drill press, no big.

Image

...
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