Topic: Lowering Forks

[Zeke]

Hey All:

I've got a 1980 650 C -- and the forks on the C model are longer than they were on the original standard model.

I'd like to lower them -- seems like the bike would handle better with a bit more weight on the front tire.

What is involved in making this happen?  I've got a second pair of forks from a 1982 650 (dual disks and air assist!) that I can shorten if this is possible.

I thought I might be able to just let an inch or so slip thru the triple clamps but it looks like the handlebars are in the way.

Thanks,

Zeke

[neckyzips]

hey,
a inch or so is a great deal when you start screwing with the geomentry of the forks! try letting them down a little at a time, say a 1/4 inch or 1/2 inch and see what happens... if you start cutting the tops of the forks off, well, you will need shorter springs if you go more than an inch, and dont forget that rod that goes through the whole fork assembly... best option, if you want better handling: drop the forks or rather drop the frame on the forks a bit at a time, making sure you do the same amount on both sides obviously... if you want stiffer forks try getting a pvc coupler from the hardware store about an inch or so long, take the caps off the forks and insert it in note: get the closest fit you can find, i used to do this to fzr's all the time, put a washer in on top of the spring, with a about a half inch hole in it then the pvc. you will see a noticable difference! but i wouldnt screw with trying to make the forks shorter. but thats just me.

[Terry in Australia]

Cut an inch off the springs. Cheers, Terry.

[Zeke]

Thanks for the replies, guys.

Bear in mind that the 650 came in a few different packages -- the standard 650 had shorter forks with less travel -- that's kind of what I'm shooting for.  I'm not trying to do anything that hasn't been done already.

I don't know why they gave the 650 custom longer forks -- I guess they were going for more of a cruiser look.

Zeke

[frostypuck]

every set of forks that I've seen that have been lowered thru the triple clamps have bent at the upper clamp. Bad bad idea. I second the suggestion of taking out the springs and cutting an inch off. Also, you may find a spacer inside, that you can mess with to adjust.
Chris in Boston

[Zeke]

every set of forks that I've seen that have been lowered thru the triple clamps have bent at the upper clamp. Bad bad idea. I second the suggestion of taking out the springs and cutting an inch off. Also, you may find a spacer inside, that you can mess with to adjust.
Chris in Boston

Huh.  I guess that would mean that there is either the wall thickness of the stanchions is thicker at the top or else there is a secondary sleeve inside or something to deal with the clamping force...

No matter, I can't let the tubes slip in the clamps as I've pointed out the handlebars are in the way.  Cutting the springs sounds like a good way to at least try it -- but if the forks were to extend all the way (say with zero gravity  ) wouldn't something weird happen?  Basically the first inch of travel would be unsprung, right?

I'd like to take them apart to check it out but I hear to replace the seals you need some special press or something to put it together....

Anyone else have something to add?

Zeke

[frostypuck]

No special tools needed to get the seals in or out. Just be careful to not gouge the inside of the forks when prying out the old seal. Then when you place the new seal in, use the old seal on top of it to assist driving the new one in to place. One of those plastic hammers and a piece of 2X4 help to get it in straight.
Later,
Chris in Boston

[Terry in Australia]

Nike. (Just do it) Nothing bad is gonna happen, as anyone who has ever actually gotten the front wheel of one of these bikes off the ground will tell you, when it eventually comes back in contact with terra firma, the ensuing shift in gravity will try to bury the front wheel under the exhaust sytem, so losing an inch of spring length will be the least of your worries as you attempt to resist the urge to shift your own mass over the handlebars!

I personally have never gotten the front wheel more than an inch off the ground on any of my sohc-4's, but I'm almost brought to tears as I recall an incident involving a suzuki GS1000 based drag bike engine that I fitted into a stock GS1000 road bike rolling chassis, and not being totally familiar with this monster's 140 BHP at the rear wheel, inadvertantly performed the "Mother of all Wheelies" in my street before pulling in the clutch and completely bottoming the front suspension, as my testicles flattened themselves against the fuel tank while I launched myself forward and almost kissed the front fender.

Surprisingly, while all this was going on, I never even considered whether cutting my fork springs down would have an adverse effect in this particular situation, ha ha! Nike. Cheers, Terry.  

[Zeke]

Haha Terry, thats a damn funny story!!  Almost as good as that one with the Valkyrie and the Squirrel of Doom!!

Thanks for the advice.  This is my first road bike, but I've had my share of dirt bikes and rebuilt the Marzocchi forks on my mtn bike several times.  In those cases I have left the ground.....

In the case of my SOHC, it was just a what if scenario...

Zeke

[basz500]

What if you cut a bit out of the springs, and then compensated for that by installing a spacer on the bottom side of the damper?  You would probably need a longer bolt that holds the damper to the lower leg.  This should get rid of "slack" when you take weight off the front end.
I'm looking at my CB500 book, so the setup of your forks might be slightly different, but the theory should hold true.