sonic or progressive fork springs and what weight fork oil

[garyS-NJ]

well I have the carbs set pretty close and so now working on brakes and suspension.. I need new fork springs/

as I bought this bike, the front end was mush. I pulled the springs and saw the oem fork sping spacers were missing/.. so I made spacers which got me some preload ( almost 2 inches, just short of too hard to thread in the caps}. but is was still mushy with the stiff rear marzoochi shocks, the front end would porpoise on the highway// So then I cut the springs 1.5" shorter and added that length to the spacer.... better but not good enough... I used 15 wt fork oil.

Now I want to buy new fork springs with my 160 lb body and stiff rear shocks and an agressive riding style, should I go for the progressive springs or the Sonics???? And then what weight fork oil?

[mmattockx]

Sonic springs in the rate recommended by their calculator and 10W oil. Even better is to add RaceTech cartridge emulators along with the springs.


Mark

[Steve]

I have installed Progressive and Sonic springs on various bikes in my stable, so have experience with both. I prefer the Sonic springs.

Not sure what they suggest for viscosity, but I took advice from the suspension tuner of a major race team as my guidance. His advice was to use the lightest oil that keeps the wheel on the ground. If you use too 'heavy' a fork oil, the forks can't react quickly to bumps in the road. Since they don't compress to absorb the bump, the bike gets kicked up a bit. Since the fork oil still can't react for rebound damping, the wheel ends up in the air, not on the ground where traction is available. A lighter oil will keep the wheel on the ground.

Progressive recommends 15w oil on most of their installs. The previous owner of my Wing had Progressive fork springs installed and presumed that they put in the recommended 15w oil, but did not know for sure. All I know is that after a day-long ride, my wrists would hurt from the jarring over small bumps in the road. I changed the oil to 10w and the ride improved to all-day comfort with no loss of damping. I have installed 10w oil in all the fork upgrades that I have done and have been very pleased with the results.

For best results, check out the rate calculator on the Sonic site to see what spring rate you need for your bike, your gravitational attraction and your riding style. I think you will be pleased with the difference.

Oh, get rid of the stiff shocks and get something that works.

.

[garyS-NJ]

springs and oil

Thanks Both! Seems like Sonic linear rates.. Is that the choice in general from vintage jap street riders, or GS forum members, or track racers?? I'm wondering why you both like the sonics over the progressives..


Let me back up to explain my target better. I'd like to do something that gets me 90% there for high speed highway stability. I can tolerate city bumps if necessary, but not highway death wobble.. And over the winter, I'm looking to install a '97 katana front end and wheels on this '79 gs1000 which will necessitate me buying shorter shocks.. So I don't want to buy new rear shocks now or the race tech emulators..


Right now, with the stiff marzoochi rear shocks, on high speed humps, seems that rebound energy from the rear shocks is making it into the front forks so it feels like the bike is pitching, or porpoising (think of a slow speed bucking bronco). This is especially bad on high speed turns with humps/bumps which then tends to get the front end swimmy (think of death wobble.). So I'd like to go stiffer on the front to better match the rear shocks (I haven't been able to find softer springs for those marzoochis but definitely should tAKE THEM APART to see if they need rebuild to properly dampen..

Funny how sonic says progressive shocks are outdated technology and yet so many people put the progressives in their old front ends.. I did the race tech spring calculation and it tells me to select springs around 0.834kg/mm. I wouldn't buy the race tech springs but the stock is rate is 0.68 and the progressives are 0.63/.89. Progressive sound right, right? but then I did the calculation on the sonic sight and that comes out as 1.1kg/mm until I drop the bike and rider weight way down... (sonic sells 0.9, 1.0, and 1.1). And so seems that sonic springs are rated a little differently than the progressives (they are all higher)..

So why do you guys like the linear sonics again? Oh and I have 15W fork oil with a spash of hydraulic jack oil and I was thinking I should go even heavier to increase the rebound dampening.. ??? but you guys are saying go lighter on the oil.

Oh and steve, I also ride an '84 xvz12 (with progressives but needs for seals and install my superbrace) and have an '86 xvz13 parts bike.. LMK if you need anything for the venture.

S

[Steve]

So why do you guys like the linear sonics again? Oh and I have 15W fork oil with a spash of hydraulic jack oil and I was thinking I should go even heavier to increase the rebound dampening.. ??? but you guys are saying go lighter on the oil.

Oh and steve, I also ride an '84 xvz12 (with progressives but needs for seals and install my superbrace) and have an '86 xvz13 parts bike.. LMK if you need anything for the venture.

S

The idea behind progressively-wound springs is great, but a lot of the lighter-weight spring travel is taken up just as soon as you take the bike off the centerstand and get on it. That leaves you with the heavier windings and about 1/2 to 3/4 of your travel. Why not start with the proper rates?

As for the lighter oil, I explained that earlier, it simply allows the spring to do its job. Using heavier oil to control the rebound damping is also greatly affecting your compression damping. By using the proper spring rate to start with, you simply don't need to change oil viscosity to control movement.

My son's 1000G has Progressive fork springs and 10w oil, as well as a full Vetter setup with fairing, saddlebags and trunk. My 850G'K' has Sonic 1.1 springs, 10w oil and full touring setup with Pacifico fairing and GK luggage at the rear. The two bikes are probably within a few pounds of gravitational attraction, but I definitely prefer the ride on my 850 with Sonic springs. I am not a racer, by any stretch of the imagination, but I have not had any problems yet with the front-end suspension on my bike. RaceTech emulators are on the shelf, ready to go in, just trying to find the time to stop working on other 'stuff' and do some work on my own. Also need to rebuild my Koni shocks and install the heavier springs.

Thanks for the offer on the Venture stuff. The 13 is a project that has been on hold for too long. It is my son's bike. We took the carbs out to rebuild them, and also do a valve adjustment. While that was happening, he decided to do some repairs to the body work. Then he got a job on the road for a few years and the bike still sits in my garage, in pieces. One of these days, we'll get it pushed back to the shop and get going on it again.

.

[RichDesmond]

Thanks Both! Seems like Sonic linear rates.. Is that the choice in general from vintage jap street riders, or GS forum members, or track racers?? I'm wondering why you both like the sonics over the progressives..


Let me back up to explain my target better. I'd like to do something that gets me 90% there for high speed highway stability. I can tolerate city bumps if necessary, but not highway death wobble.. And over the winter, I'm looking to install a '97 katana front end and wheels on this '79 gs1000 which will necessitate me buying shorter shocks.. So I don't want to buy new rear shocks now or the race tech emulators..


Right now, with the stiff marzoochi rear shocks, on high speed humps, seems that rebound energy from the rear shocks is making it into the front forks so it feels like the bike is pitching, or porpoising (think of a slow speed bucking bronco). This is especially bad on high speed turns with humps/bumps which then tends to get the front end swimmy (think of death wobble.). So I'd like to go stiffer on the front to better match the rear shocks (I haven't been able to find softer springs for those marzoochis but definitely should tAKE THEM APART to see if they need rebuild to properly dampen..

Funny how sonic says progressive shocks are outdated technology and yet so many people put the progressives in their old front ends.. I did the race tech spring calculation and it tells me to select springs around 0.834kg/mm. I wouldn't buy the race tech springs but the stock is rate is 0.68 and the progressives are 0.63/.89. Progressive sound right, right? but then I did the calculation on the sonic sight and that comes out as 1.1kg/mm until I drop the bike and rider weight way down... (sonic sells 0.9, 1.0, and 1.1). And so seems that sonic springs are rated a little differently than the progressives (they are all higher)..

So why do you guys like the linear sonics again? Oh and I have 15W fork oil with a spash of hydraulic jack oil and I was thinking I should go even heavier to increase the rebound dampening.. ??? but you guys are saying go lighter on the oil.

Oh and steve, I also ride an '84 xvz12 (with progressives but needs for seals and install my superbrace) and have an '86 xvz13 parts bike.. LMK if you need anything for the venture.

S

Bottom line on linear vs. progressive is that the linear design makes better use of the available travel. A side benefit is that you need less preload, so fork action at the top of the stroke is smoother.

I would recommend the 0.95s, we have those for the GS1000.
Fork oil is partly down to individual preference, I use 15w in the GS1000, but I'm an ex-roadracer. Lots of people agree with Steve, and like the 10w better.
Holler at me if you have any questions.

PS, what part of Jersey are you from? I grew in central Monmouth County.

[garyS-NJ]

Hey Rich, I'm in Kearny NJ and grew up in the area.

thanks both again on advice on the sonics.. so rich with the .95's and Steve with the 1.1's I'm around 160lbs.. I assume rich you are a tad lighter and steve you are way heavier (haha, maybe I get the 1.0's I was leaning towards the sonics this am per your advice until I read that the factory springs guys like wes cooley raced with were progressive dampening... no doubt they had preload set just right and ass end matched to the front (which I don't)..

this article talks about my pogo-ing as if it is a common problem with older bikes.. http://www.motorcycleclassics.com/cl...1#PageContent1 I'm gonna guess that it is more a problem when you have mismatched front and rear suspension.. but also I guess with just crap ass old technology suspension.. Anyway the article does repeat what I knew about fork oil viscosity controlling mostly rebound dampening.. that's why heavy ass bikes with heavy springs use heavy oil. (but I agree the oil affects initial compression (mostly not the viscosity but rather the oil level which affects the air volume. The article does dog the progressive springs.

[glib]

Hey Rich, I'm in Kearny NJ and grew up in the area.

thanks both again on advice on the sonics.. so rich with the .95's and Steve with the 1.1's I'm around 160lbs.. I assume rich you are a tad lighter and steve you are way heavier (haha, maybe I get the 1.0's I was leaning towards the sonics this am per your advice until I read that the factory springs guys like wes cooley raced with were progressive dampening... no doubt they had preload set just right and ass end matched to the front (which I don't)..

this article talks about my pogo-ing as if it is a common problem with older bikes.. http://www.motorcycleclassics.com/cl...1#PageContent1 I'm gonna guess that it is more a problem when you have mismatched front and rear suspension.. but also I guess with just crap ass old technology suspension.. Anyway the article does repeat what I knew about fork oil viscosity controlling mostly rebound dampening.. that's why heavy ass bikes with heavy springs use heavy oil. (but I agree the oil affects initial compression (mostly not the viscosity but rather the oil level which affects the air volume. The article does dog the progressive springs.

Great article. I got some progressive springs as part of a trade and put them in my previously squishy 1100ES. Now it's so stiff I can't use my Corbin seat unless I know the roads will be glass smooth or my back and wrists will pay. I'd like to try emulators and viscosity reduction along with a switch to Sonic. Good info.

[Steve]

thanks both again on advice on the sonics.. so rich with the .95's and Steve with the 1.1's I'm around 160lbs.. I assume rich you are a tad lighter and steve you are way heavier ...

Not only is my gravitational attraction about half again as much (almost 16 stone), but I started with the heaviest GS that was available at the time, then added all the touring farkles. Yes, stronger springs were necessary.

.

[RichDesmond]

Hey Rich, I'm in Kearny NJ and grew up in the area.

thanks both again on advice on the sonics.. so rich with the .95's and Steve with the 1.1's I'm around 160lbs.. I assume rich you are a tad lighter and steve you are way heavier (haha, maybe I get the 1.0's I was leaning towards the sonics this am per your advice until I read that the factory springs guys like wes cooley raced with were progressive dampening... no doubt they had preload set just right and ass end matched to the front (which I don't)..

this article talks about my pogo-ing as if it is a common problem with older bikes.. http://www.motorcycleclassics.com/cl...1#PageContent1 I'm gonna guess that it is more a problem when you have mismatched front and rear suspension.. but also I guess with just crap ass old technology suspension.. Anyway the article does repeat what I knew about fork oil viscosity controlling mostly rebound dampening.. that's why heavy ass bikes with heavy springs use heavy oil. (but I agree the oil affects initial compression (mostly not the viscosity but rather the oil level which affects the air volume. The article does dog the progressive springs.

LOL, I used to live on Chestnut St. 1958-62. My parents grew up in North Arlington.

I said the 0.95s based on your weight, but I'm about the same and that's what I use in mine.

Back in the '70s and early '80s guys did race with progressive springs. No one does anymore.

[garyS-NJ]

Thanks Rich,

With something as basic as vintage front forks on vintage sport bikes and basically different as linear springs vs progressive springs, I figured there should be a concensus as to which springs were best. I poked around to see what other forums have to say and I think for a performance ride I'm seeing linear springs with the cartridge emulators. I'm not springing for the emulators and read I'd have to drill something inside my GS 1000 spring cap too (with race tech help but I'm not buying their springs.. So I'm going with the sonics and was going to get the 1.0 to get closer to my stiff ass rear end (just cant think right now about taking those marzoochis apart to check the shocks.. but maybe I'll rethink that..

Now I'm reading closely Rich desmond that you are a sponics employee and ride a gs1000 (gs1000, about same weight as mine?). so seeing as you are expert and experienced with the sonic springs on the GS, can you say if the 1.0 sonics will be entirely too stiff for my GS1000 with the hard ass marzoochi rear shocks (or the next set of shocks I might install (probably progressive 12 magnums). what kind of rear shocks do you have on your GS?

LOL, I used to live on Chestnut St. 1958-62. My parents grew up in North Arlington.

I said the 0.95s based on your weight, but I'm about the same and that's what I use in mine.

Back in the '70s and early '80s guys did race with progressive springs. No one does anymore.

[mmattockx]

I poked around to see what other forums have to say and I think for a performance ride I'm seeing linear springs with the cartridge emulators. I'm not springing for the emulators and read I'd have to drill something inside my GS 1000 spring cap too

The drilling is easy work and RT posts their instructions online for all to see: http://www.racetech.com/download/Ins...GV%20S3301.pdf

Emulators are worth every penny and much more. They get you maybe 85% of the way to cartridge fork performance, which is a huge improvement. Until you ride them you will not believe how much better your fork can be. I can't say whether that increase in performance is worth it to you, but I can assure you that no one has spent the ~$130 or so on emulators (deals are always around on fleabay) and felt cheated once they got to ride on them.


Mark

[RichDesmond]

Thanks Rich,

With something as basic as vintage front forks on vintage sport bikes and basically different as linear springs vs progressive springs, I figured there should be a concensus as to which springs were best. I poked around to see what other forums have to say and I think for a performance ride I'm seeing linear springs with the cartridge emulators. I'm not springing for the emulators and read I'd have to drill something inside my GS 1000 spring cap too (with race tech help but I'm not buying their springs.. So I'm going with the sonics and was going to get the 1.0 to get closer to my stiff ass rear end (just cant think right now about taking those marzoochis apart to check the shocks.. but maybe I'll rethink that..

Now I'm reading closely Rich desmond that you are a sponics employee and ride a gs1000 (gs1000, about same weight as mine?). so seeing as you are expert and experienced with the sonic springs on the GS, can you say if the 1.0 sonics will be entirely too stiff for my GS1000 with the hard ass marzoochi rear shocks (or the next set of shocks I might install (probably progressive 12 magnums). what kind of rear shocks do you have on your GS?

The 1.0s won't be crazy stiff at all, the difference between the 0.95s and 1.0s is very small, hard to feel actually. But I think the 0.95s will be a better rate for you.
I have an old set of S&W shocks on mine, they were on the bike when I bought it. Embarrassing enough, I've never measured the rate on them, but they are quite a bit stiffer than the stock ones (which I also have).

I'll disagree with Mark a bit on the emulators. They do help, but I've never found them to be a night and day difference over a setup of just the proper springs and oil. Can't hurt to try just springs and oil first, you can always add emulators later.

[garyS-NJ]

thanks again Rich and Mark. I'm going to order the sonic 1.0 and will consider the emulators if I go back to my stock front end after trying my '97 katana 600 front end swap. I'm sure even if the bike has good stability with the katana front end, I'm going to want to change the handlebars to get me back off the tank.. even my '95 katana 750 puts a lot of pressure on my wrists until I'm up to 100mph or if I'm just down and in it for a spirited ride (and then I'm not thninkin about my wrists).. again, thanks a bunch!

[garyS-NJ]

Mikes XS cartridge emulators

any of you heard of using Mike's XS fork cartridge emulators? much less expensive than the race tech emulators. will they work and are they functionally equivalent to the race tech parts?