Progressive fork springs

[lurch12_2000]

I recently decided to replace my stock 31 yr old stock fork springs on my '80 GS1000G. A little info...the stock springs were about 17" long (at least now after 31 yrs) with a 3" metal spacer and I used 10psi air. I assumed the stock 10w oil was probably still in use but can't be sure. The ride was soft and a little mushy in the corners and tended to dive on hard braking. Sag was a little over 1.5" and unweighted fork length was just under 6".
I followed the directions included with the new Progressive fork springs for an 850G and cut the provided PVC for a 1.75" new spacer as there was no recommendation specifically for a 1000G listed. I did not use any air pressure and went with new 15w fork oil. After installing everything my sag was less than an inch, unweighted fork length was 6 3/8" and the ride was a little jittery and stiff, but the diving on braking eased up considerably along with a much tighter feel on the corners. This was with solo riding or 2 up riding and a full tank. I only weigh about 165lbs and barely over 300lbs combined with my wife. But I didn't like the total feel after 100+ miles and pulled the spacers out and cut 3/8" off each of them. I figured 1/4" would be a waste of time but thought a 1/2" trimmed off would be too much right away. My fork length was now 6" with about 1 3/8" sag. After my 70+ miles of commuting today, I felt the ride was more comfortable overall, along with a tighter feel in turns and not much dive on harder braking.
Overall, the bike is more sure footed but I am not necessarily satisfied with the overall ride.
Anyone else with a 1000G, progressive springs and about my weight tell me what measurement they used when cutting for spacer length?
I have fiddled with the original rear shocks and settled on the #3 setting for dampening and 4th stiffest (out of 5) for spring preload. I'm holding off replacing the rear shocks as I've tried those $75 MDI cheapo shocks on an '83 1100G I owned and think they are a waste of $ and not ready to spring for $300 shocks if my stockers are still doing the job for now.
Any other input is welcome.

 

[Nessism]

The spacers should be just even with the top of the forks. When the caps are installed a small amount of preload will be applied then.

The sag you site is about right. Maybe you need some 10 weight oil? Oil viscosity varies by brand so keep to the same brand and maybe try an experiment with one grade lighter.

 

[lurch12_2000]

The spacers should be just even with the top of the forks. When the caps are installed a small amount of preload will be applied then.

The sag you site is about right. Maybe you need some 10 weight oil? Oil viscosity varies by brand so keep to the same brand and maybe try an experiment with one grade lighter.

With the forks off and fully extended the 1.75" spacer was about half way up the cap threads and required a little pressing down to start the threading. At 1 3/8" they were even with the bottom of the thread at full extension and didn't require pushing down to start threading. In neither situation were they even with the top of the fork tube? I would think once the bike is resting on both wheels without a rider the preload would be present. Remember, at 1.75" spacer length the ride was pretty stiff.

 

[Steve]

Remember, at 1.75" spacer length the ride was pretty stiff.

I agree with the suggestion to try 10w oil. :clap:

I really think the "pretty stiff" ride was not due to spring rate, but rather, lack of ability to move smoothly. Switching to 10w oil will help considerably.

The previous owner of my Wing had installed Progressive springs in the forks and installed the recommended 15w oil. I found that after a couple of hours on the road, my wrists would hurt, due to the constant jarring over the irregularities in the road. I switched to 10w oil and can now handle 700-mile days with NO problems.

.

 

[tkent02]

If you want smoooth forks, get cartridge emulators.

 

[lurch12_2000]

If you want smoooth forks, get cartridge emulators.

I had those on the Connie I had (PO installed) and they were nice enough, but the forks on that bike could have used a fork brace at higher speeds (over 80 mph) on curves as it wallowed a bit.

 

[lurch12_2000]

The spacers should be just even with the top of the forks. When the caps are installed a small amount of preload will be applied then.

The sag you site is about right. Maybe you need some 10 weight oil? Oil viscosity varies by brand so keep to the same brand and maybe try an experiment with one grade lighter.

That will be my next remedy if I decide to keep fine tuning for now. At least I can use the drain screws and fill to measure with the forks on since I already removed the fork tubes, turned upside down to completely drain and swished some mineral spirits to clean out what was there.