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Author Topic: Cb 750 fork seals  (Read 4494 times)

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Bob H

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Cb 750 fork seals
« on: December 19, 2005, 02:47:01 AM »
Hi,
Can someone please advise on the correct way up for the fork seals, I was given an old cb 750 last week & after a few years a  garden the fork oil has been contaminated with water & changed to black goo. I have a manual but the diagram isnt clear.
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Offline ofreen

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Re: Cb 750 fork seals
« Reply #1 on: December 19, 2005, 05:41:07 AM »
The closed side faces up.

Greg
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Greg
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Offline HondaMan

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Re: Cb 750 fork seals
« Reply #2 on: December 21, 2005, 07:19:27 PM »
The side with the spring does down.
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Offline superchode

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Re: Cb 750 fork seals
« Reply #3 on: March 08, 2006, 01:18:30 PM »
hey guys, just going to resurrect this thread for a quick sec to make sure i don't make a mistake.

picked up some replacement seals for my '78 750F and one side seems to have a groove in it, while there's a metallic ring visible on the other side. i realize this explanation sucks but perhaps someone could make it clear which side is which and which side goes where?
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Offline dusterdude

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Re: Cb 750 fork seals
« Reply #4 on: March 08, 2006, 01:29:53 PM »
chode,you`re thinking too hard brother,1 side of the seal is closed and the other is open where the spring and lip are visiible.the seal goes in the leg closed side up.you should/might be able to read numbers on the closed side
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mark
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Offline superchode

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Re: Cb 750 fork seals
« Reply #5 on: March 08, 2006, 01:33:54 PM »
well the confusion comes in because going by that explanation - the previous owner had them in upside down.

leaked like a bastard... and dirty as hell... i have some picks i can throw up late tonight.

that would certainly explain why the seals themselves looked OK when i pulled them... even though they were pouring out fluid when we rode the thing.
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Offline dusterdude

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Re: Cb 750 fork seals
« Reply #6 on: March 08, 2006, 01:44:17 PM »
yep,that will do it everytime,glad you got it figured out
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mark
1972 k1 750
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1 1/2 gl1100 goldwings
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Offline superchode

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Re: Cb 750 fork seals
« Reply #7 on: March 08, 2006, 02:07:46 PM »
i appreciate the help.
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Offline Clyde

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Re: Cb 750 fork seals
« Reply #8 on: March 08, 2006, 03:09:02 PM »
Some good fork seals have a spring both sides. They have two lips  and a spring to keep the oil in and a small lip with a smaller/lighter spring to keep the dust out.
Other seals just have a small lip with no spring for the dust (these are the ones referred to as having a groove). They also have two main lips and a spring for oil retention
Very cheap seals will only have one lip for the oil and a small lip for dust
Regds Clyde
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Offline superchode

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Re: Cb 750 fork seals
« Reply #9 on: March 09, 2006, 07:00:15 AM »
the new ones i got have springs on both sides - i put the side with writing on it (should be the closed side) up. this appeared to be opposite to the orientation of the seals put in by the PO - which looked good, but leaked very badly.

there's a slight gouge out of one of the seal seat walls... but it's not over the entire height of the seal - hopefully things will still be oil-tight. new clips hopefully tonight, then the forks go back together.

when adding fluid - i bought two plastic measuring cups and was just planning on measuring the fluid out such that the amount is about proper and equal in each cup - then pouring it into the forks. should this be good enough or should i be looking at some sort of measuring device to slide down into the fork assembly?
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Offline mick750F

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Re: Cb 750 fork seals
« Reply #10 on: March 09, 2006, 07:48:16 AM »
   Your method for adding fork oil is fine. Do you know the proper amount? I can't recall it off the top of my head and my manual is at the shop.

Mike
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Offline superchode

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Re: Cb 750 fork seals
« Reply #11 on: March 09, 2006, 07:57:39 AM »
the FAQ says 5.1 ounces for a '78K... i imagine the amount for the F is the same... i only have a generic clymer service manual for SOHC 750s, not sure if it lists model specific amounts or not. if someone could post a definitive number, i'd appreciate it.
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upperlake04

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Re: Cb 750 fork seals
« Reply #12 on: March 09, 2006, 08:21:31 AM »
Super - the Haynes manual states fork oil capacity as 145-155 cc (4.9-5.3 oz) and 135-145 cc (4.6-4.9 oz) refill after draining.  D.
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Offline superchode

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Re: Cb 750 fork seals
« Reply #13 on: March 09, 2006, 08:24:39 AM »
so somewhere near 5.1 ounces would be just about right after full dissassembly and reassembly, yes?
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upperlake04

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Re: Cb 750 fork seals
« Reply #14 on: March 09, 2006, 08:28:52 AM »
thats what I would put in
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Offline Dave Wyatt

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Re: Cb 750 fork seals
« Reply #15 on: March 10, 2006, 07:56:46 AM »
I would add new oil, cycle the forks a few times, drain, and then refill.  Just to be sure any contaminates were out.  I know you've had this apart, but a little wasted oil to flush things one last time would not hurt. 

Also, if you have not refilled yet, I would suggest using ATF instead of fork oil.  I used it in my bike, the seals quit leaking, and it rides nicer.  I still have my new seals on the shelf and might actually use them some day.
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Dave Wyatt
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Offline superchode

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Re: Cb 750 fork seals
« Reply #16 on: March 10, 2006, 09:12:06 AM »
i had already flushed the forks fairly well when they were apart.

i filled them with ATF... the weight should be about right and it'll make the seals swell a bit. the price is right for that stuff as well.
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Offline superchode

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Re: Cb 750 fork seals
« Reply #17 on: March 10, 2006, 10:38:03 AM »
here's some pics of the project:

http://www.3cpu.org/gallery/750_repair

can see the old seals in there somewhere...
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