Aftermarket Fork Springs for GS450 + Rear Shock Size Question

[JRHemmen]

I'm looking into replacing the fork springs on my '80 GS450L with something more heavy duty. I'm rather tall and large, and don't know how the stock springs would do. The bike is hardtailed currently, so I'll be replacing the rear shocks sometime soon as well. Is there a good aftermarket option for these front forks? I looked at sonic springs and I saw they had springs for the GS550 and GS500, but nothing smaller than that. Would the 500 springs be compatible without any sort of modification? Also, does somebody have a measurement for the rear shocks on the 450? Since mine is hardtailed its hard to tell where the swingarm originally sat, or if it would need changed to accommodate my size.

 

[Guest]

Give Sonic a call. They've got great customer service and will help in anyway they can. The owners a member here. Pretty darn sure the stock shocks on that bike will be the same as most others, 13". I checked Progressive Suspension and they list the shock for your bike at 13" as well. Progressive lists a front spring for your bike, as well as the rear shocks. If I were given the choice I'd be taking the Sonic (straight rate spring) for sure but being a hard tail I'm not sure if you care about performance at all, maybe the progressives (progressively wound spring) would be fine.

 

[tkent02]

Be careful on the Progressive shocks. You can get whatever spring rate you want, but the damping is set up for the big heavy bikes, it will ride hard as a rock on the lighter 450.

I haven't found any designed for light bikes like the 450, let me know if you find anything because I need some for mine. The front is easy, Sonic fork springs in an appropriate rate, cartridge emulators and it will ride pretty nice.

 

[JRHemmen]

Be careful on the Progressive shocks. You can get whatever spring rate you want, but the damping is set up for the big heavy bikes, it will ride hard as a rock on the lighter 450.

I haven't found any designed for light bikes like the 450, let me know if you find anything because I need some for mine. The front is easy, Sonic fork springs in an appropriate rate, cartridge emulators and it will ride pretty nice.

I did a real quick search, and I'm not sure about this website or this brand, but here's a 13" shock that has springs sold separately depending on size. They have bikes in the 360-650cc range, but the GS450 and 550 aren't listed. Hope that might help.

https://www.denniskirk.com/progress...n-eye-to-clevis-12-1204b.p58340.prd/58340.sku

 

[tkent02]

Those are eye to clevis, the 450s need eye to eye. They probably have them but ask about the damping.

 

[JRHemmen]

Those are eye to clevis, the 450s need eye to eye. They probably have them but ask about the damping.

Oh, yea. I see that now, sorry. I'll keep looking around and respond here if I find anything that provides a better fit than the ~$90 ones on eBay.

*edit* Here's a set on the same site thats a 13" eye to eye. It lists the GS450 (1980-1983) as a compatible vehicle with a specific shock for it.

https://www.denniskirk.com/progress...3-in-eye-to-eye-12-1202b.p58338.prd/58338.sku

 

[tkent02]

The $90 Ebay ones are out, they ride brutally hard on a big bike.

 

[RichDesmond]

...Is there a good aftermarket option for these front forks? I looked at sonic springs and I saw they had springs for the GS550 and GS500, but nothing smaller than that. Would the 500 springs be compatible without any sort of modification?...

Unfortunately, we don't have anything in stock for the 450. The fork tubes are quite skinny and our smallest springs, which are 24mm OD, won't fit into the tubes.
Race-Tech may have something for you, or we can do a custom set (which might actually be cheaper than Race-Tech's off the shelf ones).
Shoot me a pm or email if you would like to discuss further.

 

[Guest]

850G shocks drop right on a 450; they're a bit stiff, but with 5 way preload and 4 way damping I find them OK on the softest settings. I weigh about 165 so if you're 200 or more they might be just right. Finding a pair might be a challenge, but??? I think all the G models have eye to eye shocks, but I've only owned the 850.

The forks respond well to having an inch or two cut off the springs and a spacer - PVC pipe - added. I seem to recall cutting about 1.5" off and a two inch spacer, but it's been a long time. If you cut too much off, the coils will bind before you get full travel. Cut the closer wound end.

 

[bwringer]

850G shocks drop right on a 450; they're a bit stiff, but with 5 way preload and 4 way damping I find them OK on the softest settings.

That's just what we did last summer for Larry D's GS450 -- I happened to have a set of fairly low-mileage stock 850G shocks on the shelf that were in decent shape but getting sort of bouncy and overwhelmed on the porky 850.

We slapped them on the fo-fiddy, and they actually work mostly okayish under us healthy corn-fed Americans. Much better than the stock 450 shocks anyway.

We ended up installing Progressive fork springs -- as Rich mentioned, they're lil' biddy boogers.

For the rear, another option might be Hagon shocks -- they use shock bodies with various damping profiles, so the "soft" profile might work out pretty well. A little over $200, though.

 

[tkent02]

I like that idea, anyone have a nice old set of stock 850G shocks laying around?

Anyone want a damned near new set of Hagons for an 850G or 1100G?

 

[JRHemmen]

So it looks like putting on the stock 850 shocks is my best bet. I'm seeing them on ebay for $30-$60, does that seem like a decent price?

 

[Guest]

So it looks like putting on the stock 850 shocks is my best bet. I'm seeing them on ebay for $30-$60, does that seem like a decent price?

The ones currently listed by 'mistermonkeyclaw' for $32.70 look really nice. The shafts look in great shape and that is what's most critical. The others look pretty pooched to me?..

If I needed a set I'd pounce. Although I haven't actually bought from him, I've come close, and he seems to be a respected and fair dealer. Plus, I like buying from places like Appleton, Wisconsin. Low overhead; short riding season.

 

[JRHemmen]

The ones currently listed by 'mistermonkeyclaw' for $32.70 look really nice. The shafts look in great shape and that is what's most critical. The others look pretty pooched to me?..

If I needed a set I'd pounce. Although I haven't actually bought from him, I've come close, and he seems to be a respected and fair dealer. Plus, I like buying from places like Appleton, Wisconsin. Low overhead; short riding season.

Just ordered them. $47.70 shipped. Thanks everyone for all the help!

 

[herostar]

Did you ever figure out a front spring solution? Is Progressive really our only option for front springs?

 

[cowboyup3371]

Herostar, check out Sonic Springs; the owner is a member here and they are very good springs

 

[sam000lee]

I have progressive springs in my '81 GS450 and love them. Made world of difference. I have Sonic Springs in my '77 GS750 which were also HUGE improvement. The GS450 is a little stiffer but I don't find it overly so.

 

[Guest]

Herostar, check out Sonic Springs; the owner is a member here and they are very good springs

Rich got here in post #8. Apparently they don't have springs small enough to fit in the 450 fork tubes...

For those not liking the progressive suspension option you can cut several inches off the more closely wound end of their springs which will up the spring rate and give you a more linear rate throughout the stroke. If you want to get fancy and try to achieve a desired rate there are spring rate calculators online that will let you figure out how much to cut off and what you will end up with for a rate.


Mark

 

[cowboyup3371]

Rich got here in post #8. Apparently they don't have springs small enough to fit in the 450 fork tubes...

Mark

Thanks. That is the problem with a thread that is a year and a half old (this started Jan 2016) and I now see he said that last year. Of course Rich also offered for the OP to have custom ones made so that might also be an option.

 

[Guest]

I run Ikon progressive rate springs up front and Ikon shocks on my 450 and have done for nearly 6 years now and they've been great, however I've always wondered if the front was bit soft. I had to put the preload on 2 on the shocks a few years ago and have had the damping on 2 for a while too. I just have the standard 15w fork oil in at the standard 150mL capacity.

I finally tried adding some preload spacers last weekend to the forks (4 x 10c pieces each leg which is ~7mm) and had my first real fun ride yesterday, and much improved. I did go up to 3 for damping on the rear shocks too as they then felt soft compared to the forks. The whole ride was much better, the front felt more planted and on the occasions I find the limits of the front suspension where it starts to weave in faster sweepers, that's now all gone and it just tracks nicely.

Anyway, my 2 cents on the 450 after market suspension equation