1982 GS450 Fork Lowering

[Guest]

Recently started rebuilding my 82' GS450 and I would like to lower the front forks 2"-3". Looking on Progressive Suspension and a few other sites it appears that there is not a lowering kit specifically for the 450.

Can anyone help me out and point me in the direction of a good write up or kit that is out there?

Thank you!

[mmattockx]

3" is a lot to lower it. You will only have maybe 5-6" of suspension travel up front and you are looking to eliminate close to half of it. You will need new springs that are significantly stiffer in order to avoid bottoming the forks over regular road bumps and will have clearance issues with speed bumps and the like. Also realize that you will need to lower the rear by a similar amount or you will end up with super twitchy handling and serious instability issues.

To physically reduce the fork travel is pretty simple, you just need the appropriate length spacer installed under the top out spring to prevent full extension of the fork. I have never seen a lowering kit for these old bikes, but then I haven't looked either. If you haven't yet got a service manual, go to Basscliff's site and download the one for your bike:

http://members.dslextreme.com/users/bikecliff/

If you are unfamiliar with the forks and the top out spring, look at this parts fiche: http://www.partzilla.com/parts/searc...%29/parts.html

The top out spring is #18.


Mark

[bobgroger]

Are you planning to lower the rear an equal amount? If not you might find it pitches you off when you enter a fast corner the first time. Lower will mean quicker steering, but more instability IIRC.

http://bikearama.com/theory/motorcycle-rake-trail-explained/

[HeavyHitters]

Thank you for the feedback and guidance to the resources.

I will likely be adding the Progressive 412's to the rear in 11.5" length, which would be 2" off from where the rear shocks currently sit. So yes, if I lower the forks 2" and add the 412's I would retain the current geometry.

From what I have seen so far, you increase the length of the fork spacer to reduce the overall height? This seems backwards to me.

Any writeups/ pictures showing how to make or install the spacer?

[mmattockx]

From what I have seen so far, you increase the length of the fork spacer to reduce the overall height? This seems backwards to me.

Any writeups/ pictures showing how to make or install the spacer?

I am not talking about the preload spacer that sits on top of the fork springs. The spacer I am talking about goes in the space where the upper and lower fork tubes overlap and it prevents the fork from extending fully. I don't have time at the moment, but can make a quick sketch to explain it tonight and post it here. I would make the spacer out of aluminium myself. It should probably be a machined piece for precision and accurate square cut ends.


Mark

[hillsy]

This.....

[DohcBikes]

Why are you lowering it? Are you 4'8"? Or do you just get a kick out of decreasing the performance of your bikes? Serious questions.

[Steve]

Yep, lowering it that much will severely limit your cornering ability.

I can tell you that from first-hand experience. We just lowered my wife's 850L about half that much. Hagon shocks one inch shorter than stock, Progressive fork springs with stock spacer, but fork tubes slid up almost two inches above the top clamp. Had to shorten the centerstand and sidestand, too, but she fits on the bike much better. I have taken the bike out for some modest rides, there have been no problems with cornering, but I wasn't riding it much harder than she normally does.

.

[steve murdoch]

If it is stability with shorter legs you could also get closer to the ground with altering the seat foam.
Plenty of threads on the subject.