What the fork?

[BigDaddyD]

I'm looking to do my first fork rebuild this weekend on my '77 GS750 and I was wondering if I could get some info as to what I'm in for?

I have the new seals and a new set of Progressive Springs.

Are there any special tools I'm going to need?
The manuals list like one or two, but it seems there are ways around having to use them.

Also, is there a trick to setting spring pre-load?
These forks will give me a dual disk setup, and I wanted to make sure i have the pre-load correct for the extra stopping power.

On my old forks I used a slightly heavier oil weight with the stock springs, since I'm a heavier rider and stock oil weight was too squishy, and I didn't pre-load the springs.
It helped with the ride, if not being a little too stiff over bumps, but the bike seems to still dive alot if I ever had to really grab the brake. I was just wondering if pre-loading the newer springs and using lighter oil will fix these probs.

Thanks!

[Guest]

one special tool you need to hold the inner fork tube while undoing the allen bolt at the bottom can be made out of long socket extension bars and the sparkplug socket OR out of a threaded rod with nuts that take spanner size 19mm - there is a picture somewhere posted by steve

old seals can be a pain to take out if they have coroded to aluminium, but you can use heat gun to assist removal, or some people just burn the seals (but i hate that smell)

spring preload you can achieve by inserting spacers but as you noted that'll make for a bumpy ride at low speed compression. there's no way around it other than going for a cartridge type fork inserts.

[boathead]

http://www.thegsresources.com/_forum/showthread.php?t=144719&highlight=boathead

the above thread shows some pics of the tool needed, as well as an alternative. i got my tool all crafted only to find out that my 650 didn't need it. not sure about a 750. anyway, i am a newbie in every sense of the word, and i was able to pull it off. so good luck.

ultimately what i found was this: the springs themselves provided sufficient pressure against the dampening unit to hold it in place and stop it from turning on me when i put the allen wrench to it. perhaps you'll find the same.

[Steve]

- there is a picture somewhere posted by steve

Here are the pictures posted by that "Steve" guy:





Using 1/2" all thread, the nuts are 3/4" across, which is pretty darn close to the 19mm you need. Leave some thread sticking out of one end, put that end into the fork. The threaded rod sticking out will help center the tool where you need it.

Setting the preload is mainly for getting your ride height correct. That assures that you have most of your suspension travel available. The amount that the front end dives under braking is really just a function of spring strength. Preload will add a little to the initial strength, but not to the overall strength. Switching to Progressives is a good move there.

Oil viscosity does not change how far the front dives, either, it only affects how fast it dives. With your admittedly increased gravitational attraction, you will probably do well with Progressive's recommended 15w oil. I have found it too uncomfortable for my use and have switched to 10w.

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[Nessism]

Steve's tool is neat an alll but as long as you have a spark plug socket with the hex on the bottom and a couple of extensions you will be good to go.

[Steve]

Yeah, they have to be LONG extensions, but they will work. Also helps if you tape them together so they don't come apart.

I did not have enough extensions, and I had read about the all-thread tool on another forum before I heard about Nessism's trick with the spark plug socket.

If you don't already have the extensions, check the price on them. The all-thread and four nuts is less than $10.

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[gert du prez]

I also made the tool of which Steve put out a post: it is very handy, cheap and easy to make yourself, and it works... One suggestion though, tape off or smoothen the thread between the left and right nuts (the long space in between), as you can damage your inner fork tubes threads when inserting this tool...

[Dogma]

I used an impact wrench instead of the special tool. It worked. Easy to chew up the screw if you don't get the bit in there though.

[BassCliff]

Hi,

For further reference, I found this on some guy's website:

Fork Seal Replacement
(by Mr. Matchless)


Thank you for your indulgence,

BassCliff

[zanza14x]

Hey, sounds like you're in for a good time this weekend. I myself am no self proclaimed expert, but I just replaced my fork seals and cleaned and put new oil in my forks this last weekend, aka-took everything apart and back together. Took me all of a couple of hours because it was my first time. I am not sure if this will help, but as far as a visual guide besides all of the outstanding info already provided here, I found this comparable video to be very helpful. (Btw I ride a '78 GS550)

http://www.youtube.com/watch?v=pV5ZkIBtrns

Hope this helps, and best of luck!

[jwhelan65]

Just did mine a few weeks back, there is an exploded view on my bench so you can see how it comes apart. You will also need a retaining clip pliers to remove the c-clamps that hold the seals down, you can pick one up at Lowes or Home depot

http://www.thegsresources.com/_forum/showthread.php?t=135310&page=22