Progressive Spring install

[zephyr_bike]

Edit: Wow, these feel incredibly stiff, like there is almost no give. What should the ride feel like now? I'll do a test ride tomorrow, what's should I be looking for?

With the progressive springs and my spacer in they are only about 2mm above the threads inside the forks. The stock springs were 300mm ABOVE the top of the forks. Does this sound normal?

I changed the oil out, took out about 200mL and added in about 300mL giving me an air gap of 120mm on each fork.

[fetor56]

The manufacturer tells u the amount of Preload required.
With Sonic Springs it's 1/2",which means the top of the spacer is 1/4" below fork height,so when u do-up your 3/4" deep fork nuts u have your correct 1/2" preload.
Your 2mm above sounds a little high(out by 7mm) but NOT entirely crazy.The 300mm for stock springs sounds about right.

[zephyr_bike]

Cool, thanks.

I followed these instructions http://gstwins.com/gsboard/index.php?topic=25706.0

I was saying I'm 2mm above the bottom of the fork threads. So I think I'm exactly where I'm supposed to be based on what you said and the instructions. I was just shocked at the difference! (bad pun)

[tialloydragon]

If you have your preload set right, it will feel like a whole new motorcycle.  I had stock forks that would bottom out in a shallow pothole and would dive badly during braking ( I am 190lbs.).  I installed progressive springs and fixed both issues.

[zephyr_bike]

I'll take it out for a spin in the next few hours. My bike would dive really bad during breaking and I'm 165lbs. I also felt very loose in corners. That's why I decided to do this mod.

My spacers were 4.75cm which with the new springs were about an inch less than the stock springs and spacers.

[zephyr_bike]

Sanity check please:

I currently have:
140mm air gap (no springs, no washer)
40mm spacer (think this is 18mm too short??)
46cm progressive spring
50mm distance washer to top of fork
12mm fork cap height

So with a 20mm preload I should have a 58mm spacer? I think last night while working on this watching the caps game I meant to do that but added 2mm instead of 20mm (doh!)

[spray____]

I just installed some sonic springs a few months back, and the instructions that came in the box described doing it this way, which was very simple:

[zephyr_bike]

Thanks for the image. That's exactly what I did and the bike felt like it was bottomed out the entire time I was riding it. Is there such a thing as a hard front?

I increased the preload by 18mm last night, rode this morning, and it feels very aggressive still but it wouldn't be terrifying to hit a bump on the highway now.

[spray____]

From what I understand, the other thing that will affect the stiffness of the forks is the amount of oil vs air. The air will compress under weight, the oil not so much. So if your forks are too firm you could try less oil. Inversely if they are too soft (bottoming out) add some more oil and see if that helps.

[Joolstacho]

Not at all impressed with that.
These spring kits are not cheap, surely it couldn't be that hard for them to supply correct length spacers for a 'standard' setup on the GS.
(If you wanted to fine-tune preload you might then start packing or cutting spacer length, but I would have thought they could have supplied a good standard setup).
Sounds to me like they're doing it the easy way, just supplying a generic kit that probably covers dozens of bike models, and then expecting the buyer to do the work on the preload/spacer.

[fetor56]

Not at all impressed with that.
These spring kits are not cheap, surely it couldn't be that hard for them to supply correct length spacers for a 'standard' setup on the GS.
(If you wanted to fine-tune preload you might then start packing or cutting spacer length, but I would have thought they could have supplied a good standard setup).
Sounds to me like they're doing it the easy way, just supplying a generic kit that probably covers dozens of bike models, and then expecting the buyer to do the work on the preload/spacer.

Probably.................welcome to 2013. 

[gsJack]

Are you talking about Progressive Suspension brand progressive rate springs?  If so I've run mine for 130k miles in my 97 and 02 GSs.  The spacer is only about 3/4-1" long and oil level is 5.5" (140mm) below the top of the tube which the sheet that came with the springs said was max height of oil to be used.  Suzuki spec was 3.9" (99mm) below the top of tube with stock springs.  Oil level is measured with forks compressed and springs removed. 

It's about 10 years since I saw them when I transferred them from the 97 to the 02 GS.  If your oil is too high they might bottom out on oil and seem very stiff and possibly blow the seals in use.  The newer F models have different design forks made in Spain but it's been said here that the same # Progressive springs fit.  Sheet that came with springs said most motorcycles need 3/4-1" preload.

[RichDesmond]

Not at all impressed with that.
These spring kits are not cheap, surely it couldn't be that hard for them to supply correct length spacers for a 'standard' setup on the GS.
(If you wanted to fine-tune preload you might then start packing or cutting spacer length, but I would have thought they could have supplied a good standard setup).
Sounds to me like they're doing it the easy way, just supplying a generic kit that probably covers dozens of bike models, and then expecting the buyer to do the work on the preload/spacer.

It is that hard.   All the aftermarket spring companies do it this way, for good reason. The big problem is that you don't always know when the manufacturer makes a change that would affect the spacer length. For example, early in the second gen SV650s run Suzuki changed the top out spring length. Unannounced, undocumented change unless you happened to look at the fiche and see the different part number.
The only way to be certain of the spacer length is to have a complete fork leg for every year of every model that you carry springs for. Possible, yes, but very very expensive. That cost would have to get passed on to the customer.
Figuring out the proper spacer length is easy and quick, most customers would rather do that than pay $40-50 more for a set of springs.

[Joolstacho]

Yep, fair enough Rich, I realise it must be big job covering so many models and variations particularly when there are 'undocumented' changes as you say.
We're lucky to have companies like yours supplying aftermarket parts.
Grovelling apology to Rich... (I'd better keep on the good side of him 'cos Im going to up for a set myself soon) 

[RichDesmond]

Yep, fair enough Rich, I realise it must be big job covering so many models and variations particularly when there are 'undocumented' changes as you say.
We're lucky to have companies like yours supplying aftermarket parts.
Grovelling apology to Rich... (I'd better keep on the good side of him 'cos Im going to up for a set myself soon) 

No apology needed! I'm sure many people were thinking along the same lines, so I appreciate the chance to explain the "why" behind what we do.

[zephyr_bike]

I forgot to update this but it was just too much oil in the forks. I put I'm the correct amount of oil for the stock forks not counting for the extra displacement of the larger springs.

I took 30ml out of each fork and the bike runs really well now with no bottoming out. I've gotten an '08 FZ6 since then and I wouldn't say the GS corners as well but with Sport Demons on it the bike does pretty well, flicks great with the smaller profile tires, and I have more confidence at speed

[bombsquad83]

I made the same mistake the first time with my forks.  I kept blowing fork seals and finally realized I was overfilling the forks.  130mm from the top with the springs out and forks compressed feels good to me now.  I have a ~3/4 in spacer.  My springs and spacer came with the bike.  I think if I would have been doing it myself, I probably would have more preload, but it's good the way it is.

[RichDesmond]

I forgot to update this but it was just too much oil in the forks. I put I'm the correct amount of oil for the stock forks not counting for the extra displacement of the larger springs...

I made the same mistake the first time with my forks.  I kept blowing fork seals and finally realized I was overfilling the forks...

Thanks guys for posting those, probably help a lot of people. 
The two most common mistakes people make when installing aftermarket spring are either too much oil or too much preload.

With the oil, they either use the stock amount, which is generally too much with the better springs, or measure with the fork fully extended instead of compressed.
On preload, they'll cut the spacer so that the total spring/spacer length is the same as stock, which is too much preload with good springs.

[gsJack]

[burning1]

120-130mm with after-market springs is probably about the same as 99mm with the stockers. 99mm with after-market springs is right about the point of hydro-lock and seal blow-out. I was able to run 100mm with .85s. That might be too much with thicker coils.