Topic: Another Fork Seal Thread - 750 K6

[oldhatt45]

OK, so I finally got back to work on my 750 K6.

I pulled the forks and started on the left fork.
Drained the fork oil out. (See first picture.) What came out after sitting for 26 years wasn't bad.  Still looked like Oil (Bel-Ray 30wt fork oil) and just a little bit of sludge.  But altogether, the quantity that came out was about 145ml. I figure the other 5ml is probably there as well, since when last filled I put in 150ml in each leg.

I removed the Circlip easily, then used an electric impact wrench to remove the 6mm allen head bolt from the bottom.  That was a little harder, but it came out without damage. 

I then pulled the fork tube out of the lower and was hoping the fork seal would come out, but it didn't.
So I read a bunch of threads dealing with fork seals.  Only a couple of ideas.  One to use some heat and another to use a C-Clamp.  So unless anyone has any other ideas, tomorrow will go buy a small C-Clamp.

Also, for those that are interested, I took a picture of the fork seal as it sits right now.  Hopefully you can see that this Original 1976 Seal is seated just below the circlip and has about 3/16 inches of space below it to the visible lip inside the fork leg. 

Hope someone has some ideas on getting the Fork Seal out without damaging the tube.

THanks,

Charlie

[vames]

Seal puller -- available at any local auto parts store. Just put something to protect the upper lip of the fork slider when you're leveraging against it. Doesn't hurt to heat up the edge of the slider little bit before you do it.

[PeWe]

I used a heat gun and warmed it up from the outside. Then a large srewdriver without scratching the inside or bendmatks on outside. I used the old bigger seals 13.2mm thick. I tried the 11mm sold everywhere first but they are crap, leaked direct.
David silver has the better 13.2mm, stiffer and stable, same type I installed 1983, hard to remove
Honda PN: 91255-341-305, Size: 35 x 48 x 13.2
Partnumber in the old service bulletin from Honda about fork seals, mentioned here by Dream750. http://forums.sohc4.net/index.php?topic=135862.0

When you compare these from David silver numbered 91255-341-305 with the other lower ones, Honda marked bag or not you will notice that this is quality, no question which side up when its obvious. The bulletin has picture

http://www.davidsilverspares.co.uk/parts/by-part-number/partnumber_91255341305/

When mounting these, use a heat gun hande make the fork tube seat realy warm, Oil the outside of the seal and use a 46-47mm 3mm thick short pipe as a tool when you hammer these down with a heavy hammer. The circlips have to be mounted correctly to avoid scratches in the chromed fork legs and future leak.

I followed the instruction of the spring manufaturer when filling oil. Fork completely collapsed without springs oil up to 140mm from upper level. My forks wanted about 200ml each. I used a large syringe with a hose, lenght 140mm from bottom. Then easye to fill oil. I sucked oil with syringe, hose ensured exact 140mm from top.

[oldhatt45]

vames and PeWe,

Thanks!

I used the wife's hair dryer and warmed up the leg and then used a tire iron with a nice smooth curved end to pop the seal out by tapping the tire iron with a hammer.  I taped the shank of the tire iron so it wouldn't scratch, bend or mess up the leg.  Only took a few taps and it came out nicely.

I read the service bulletin in the thread by Dream750.  It looks like it applies to the K2's.  Not sure if it applies to the K6 I have.  You mention the size of the seal you used from David Silver Spares as being 35X48X13.2 . 

I measured the seal that I just took out.
OD = 48.06mm
ID = 34.99mm
Height = 10.95mm

A while back I ordered a couple of fork seals.
They measure out at
OD = 48.04mm
ID = 34.23mm
Height = 10.95mm

They both look like they are single lipped.
I looked at the ones you mention and can't tell if the 13.2mm is single or double lipped. 
Intuitively I would think that the double lipped seal would be better, but wondering about something I read about "stiction" and was wondering if the double lipped seals would affect performance?

Given that my old seals were still pliable and not leaking after 38 years, and performed well when I last rode the 750, I'm wondering if changing over to the 13.2mm high seal is really the right thing to do?

Also, I noticed that my old seals did not seem to have any springs in them, while it looks like the new one I have does.  Wonder if that makes any difference? 

I plan  to order the David Silver part 91255-341-305 as you suggest, but I believe I may be overthinking this whole thing.

Thanks,

Charlie

[BobbyR]

OK great job on getting the seal out without busting everything up. The next step should be to inspect the chrome on the fork tubes. The rule of thumb is if you can feel a defect with your fingernail, it will cause a leak.
In any event, polish them. The smoother the better.

[oldhatt45]

BobbyR,

Thanks, The chrome on the tubes is in excellent shape.  I plan on polishing them anyhow and appreciate your reminding me to do it.    I do have some lite pitting up in the area between the triple trees (under where the headlight ears sit, and was planning to use some JB Weld to smooth those pits out. 

what about polishing the other internal parts of the fork?  Does that or should that be done as well?

Thanks,

Charlie

[BobbyR]

Charlie, just de gunk the inside. The real sealing takes place between the chrome and the rubber. Honda OEM seals are best.

[dhall57]

Bobby's right Charlie, OEM is the way to go. If the part or parts can still be got from Honda I go that route no question.

Ive ordered alot from http://www.servicehonda.com/ over the years for my Honda's and always got good service. Most of the time their prices are about 30% off list. Forks don't leak on my 750K6 but I went on and got these the same time I got and replaced fork seals on my 750KO so I would have them when needed. The KO seals are a different # and size and won't work on the 6.

[PeWe]

....
I read the service bulletin in the thread by Dream750.  It looks like it applies to the K2's.  Not sure if it applies to the K6 I have.  You mention the size of the seal you used from David Silver Spares as being 35X48X13.2 . 

I measured the seal that I just took out.
OD = 48.06mm
ID = 34.99mm
Height = 10.95mm

A while back I ordered a couple of fork seals.
They measure out at
OD = 48.04mm
ID = 34.23mm
Height = 10.95mm

They both look like they are single lipped.
I looked at the ones you mention and can't tell if the 13.2mm is single or double lipped. 
Intuitively I would think that the double lipped seal would be better, but wondering about something I read about "stiction" and was wondering if the double lipped seals would affect performance?

....

I plan  to order the David Silver part 91255-341-305 as you suggest, but I believe I may be overthinking this whole thing.

Thanks,

Charlie

MY bike is a K6. Check the depth of the seat for seal in lower fork just for sure. My is  about 14mm under circlip grove.
I doubt it will not leak with the 11mm seal. I bought that seal from CycleX together with new fork tubes. I saw how it leaked direct before using the bike.
I thought it was oil used during assembly. My first ride showed different.

I checked here on the forum how the seal should be mounted and direction of the lip. Checked many times and checked again when replacing it. Could not seee it was wrong done.

The double lipped is very stable, the 11mm very flimsy. I ordered Honda OEM but when I saw that the seals looked as the leaking one i used have removed I went for the thicker double lipped. I remembered it direct when it was that type I had used + 30 years ago.  No leak, replaced it when I bought new fork tubes.

Order both and compare... you will understand what I mean when holding them side by side.

[oldhatt45]

PeWe,

I don't doubt you and your experience.

Can I ask a couple of questions?  (And some of them may be dumb questions.  LOL )
1.  You said that you ordered new tubes.  Did you check the new tubes for roundness and straightness??
2.  Did you check the fork legs (lowers) for roundness?
3.  Did you check the fork legs (lowers) for straightness?
4.  Is or was there any problem with aligning the forks?  (Possibly if the forks were not aligned it could cause stress or tension on the seals causing one or both to leak?)
5.  Was the alignment of the triple trees checked?
6.  Did both of the fork seals leak or just one of them?

It just seems to me that the 11mm seals that came on your K6 (& my K6) did the job at some point and at least theoretically should continue to do the job unless there is something wrong.  As with many things, I am scratching my head about why you are having the problem with the 11mm seals.  I don't doubt that there is a problem, but I can't help but wonder why.

Thanks,

Charlie
PS:  I did order the 13.2mm seals and will definitely compare them before reassembling my forks!

[PeWe]

It does not leak with the thicker ones. The leaking ones felt leaky direct before mounting the forks into the triple tree.
I did not measure the new fork tubes. New should be OK.
The lowers were good back in the days and had no leak, no reason to measure. I checked the seat for scratches and used thin layer of not hardening sealer just for sure. No sealer with the thicker ones, only fork oil 10-30 (Motorex)
http://www.motorex.com/index.cfm?oid=1147&lang=en&webtoolDbTemp=eintragDetail&kategorieId=12&eintragId=98

For me its clear when comparing the seals, night and day in quality. I'll order extra of them just for sure if I'll find another bike to repair.

Strange that the most common fork seal today is what was replaced for many years ago documented by the Service Bulletine that introduced the new thicker one. It should be opposite.

One thing was changed when I replaced the seals. The springs adjustment were too soft for me, added 15mm distances according to the spring manufacturers recommendation. Soft fork should not cause a leak within 20-30km on the road.
Both fork pipes at same level at upper tree mount. Difficult to do it wrong I aligned everything before final tourqe.

Best thing is to compare, all mechanics will most likely see the for me huge difference.

I'm sure that many guys here have used the 11mm version without any issues when there are no direct complaints about leaking forks with rather new seals.

[oldhatt45]

PeWe,

Thanks for the response.

When you say that it should not be leaking when you changed to the firmer fork spring setting, I am Wondering if the added "pre-load" of 15mm on the springs could have some effect on pressure inside the forks???
Kind of like putting pressure on the fork oil and the pressure is going to be relieved at the weakest point???  Or maybe the spacers you added are occupying expansion room for the fork oil??? But maybe I am over thinking this, again?

Your experience is making me think about this very seriously.  And yes, I agree that the newer 13.2mm seals should probably be the more used option.  But then if you remember, I did mention the "stiction" thing.  It could be that the "stiction" is causing people to think about more friction and less than optimum fork performance?? 

It is an interesting topic.  I wish that some of the folks with more experience would chime in and maybe give us more insight into the different issues and problems.

Thanks,

Charlie

[oldhatt45]

Bump.....

Anyone else have any thoughts on the topic or the info here in the thread???

THanks,

Charlie