Progressive Fork springs

[jetmechmarty]

Yes, Jerry. What makes mine bad is that I have progressive on back and I did not want to give up that bit of travel. I had what Progressive said was heavy duty for the XS11. I couldn't avoid dragging hard parts when two-up. I replaced the springs with 140/200 rate. Now, I have the performance I wanted, but the ride is very harsh. Straight rate would have been a much better choice for me. I'm better educated now.

For the record, my forks are equiped with RaceTech Gold Valve Emulators.

[jwhughes3]

Marty you should try the XJ air shocks. Much better ride and range of settings.

John

[madmax-im]

I like the Progressive springs up front...I was surprised they improved the ride quality on the hwy. At the S.E. rally i didnt notice any ill effects from the new springs with all the twisites we did over 3 days of riding as opposed to straight rate springs which i have yet to experience...I suspect that if I ever do try the straight rate springs I would better understand Marty's POV.
However Jerry makes some good points about wanting to be more coddled in our old age. Thas certainly true for me...comfort but yet still have enough performance to keep it interesting. After I installed the Shinko rear tire I honestly can say i never gave my suspension another thought(at the SE rally) it was just twisty...touring fun...

[Crusty Snippets]

Pov

Modern suspension will absorb small pumps and keep the tyres on the road before during and after the bump. For the moment lets consider we are going in a straight line. They're to die for to quote a TV add.
That is fairly easy to attain with modern gear and bikes that weigh around 400 pounds or less. A reasonable facsimile would be satisfactory for these 550 pound bikes.
The interesting stuff happens when we go around a corner. These bikes are long wheel base. The more dampening we have the more the wheel base changes, and that changes the arc of the corner, which in turn changes the direction of the bike. So us older guys, especially ones like me who have been to the track, would prefer to have very little dampening, to maintain the wheel base length. Now little dampening may cause the bike to bounce over a bump, but as long as the bike is still pointing where we want it when it lands, who cares. If the bump causes the frame to flex or the rubber bushings to flex then there can be a problem. The last two are the 69 Kawasaki 500 and a Norton Commando.

I have stiffened the suspension on Yami, maximum spring tension on the new shocks, and heavier oil with 20 psi of air in the front. It will now get some air over a bump but as above that is the way I like it.
On the SV1000S Suzuki I have switched to tyres with a harder center section. The front forks are untouched and we have turned the rear dampening ( anti squiggle device I call it ) two positions.

The old track bikes weighed so little that a lot of dampening was not required. We ran everything stiff. On the Norton that weighed about 315 pounds, I used Koni shocks and 60 / 90 springs. What we now call progressive. The front was adjusted be the oil weight and the hole sizes. But still stiff to take care of severe braking.

Unkle Crusty

[Bonz]

This good discussion begs to pose this into the equation, if the air forks are in working order, I'd rather have an air spring to set up with pressure vs. either a new progressive spring or a straight rate spring.

I've put new sonic springs in my V Strom 1000 and in my ZRX 1200, both yielded much better fork action and less brake dive with great ride quality and bump compliance vs. stock springs, as I got the rate that was correct for my weight and riding tendencies. But those aren't air forks, and I can tune the air on my 80SG and 80G to give any ride I want.

I vote for the stock air forks (with springs) as a very favorable combination that is without the level of compromise of either spring option.

Thoughts?

[jetmechmarty]

I vote for the stock air forks (with springs) as a very favorable combination that is without the level of compromise of either spring option.

Thoughts?

It's great...for 35 years ago. The straight rate spring/emulator option is a big improvement. I'm happy with it, though it took a good bit of futzing. Another option, though obviously more expensive is to let somebody build the forks for you. Somebody like RaceTech or Traxxion Dynamics. It's a whole new ball game.

[Crusty Snippets]

Pov

I've put new sonic springs in my V Strom 1000 and in my ZRX 1200, Quote from BONZ

Your V Strom and my SV1000 are very similar.
These newer bikes can be a joy to ride. It took a while, but finally Made in Japan bikes handle well enough. My SV is more than satisfactory for the public roads.
And my XS11 is more than comfortable enough as a cruiser. The engine is also smoother than my SV. Mrs Snippets prefers Yami, but it will be the SV I will use to make her one of the fastest seniors about. Gonna take her to 120mph next year.

Unkle Crusty

[b.walker5]

It took a while, but finally Made in Japan bikes handle well enough.

Unkle Crusty

Umm... as compared to what??

[Crusty Snippets]

Handling

Umm... as compared to what??

There was a time when other countries made motorcycles.
The early British bikes handled quite well. The engines were ancient.
Some of the Italian and German bikes had okay engines and reasonable handling.
The early Japanese bikes had good engines but lousy handling, compared to all other bikes at that time. The time being 60s and 70s and 80s.
I mentioned a 69 Kawasaki 500 further up the page. There were many others.
Then in the 80s and on the Japanese bikes got better in the handling department. Some like my SV1000 Suzuki are a joy to ride. There are many others.

As an aside, some of the race bikes like the TD2 Yamaha handled very well, but not quite as good as a 250 Bultaco

HTH, Unkle Crusty

[motoman]

There was a time when other countries made motorcycles.
The early British bikes handled quite well. The engines were ancient.
Some of the Italian and German bikes had okay engines and reasonable handling.
The early Japanese bikes had good engines but lousy handling, compared to all other bikes at that time. The time being 60s and 70s and 80s.
I mentioned a 69 Kawasaki 500 further up the page. There were many others.
Then in the 80s and on the Japanese bikes got better in the handling department. Some like my SV1000 Suzuki are a joy to ride. There are many others.

As an aside, some of the race bikes like the TD2 Yamaha handled very well, but not quite as good as a 250 Bultaco

HTH, Unkle Crusty

.........specially if it were a Pursang!.......didn't get much better than that.

[Jerry]

The XS 1100 series was never known for it's handling. Even road tests of the day suggested the Yamahas did not handle as well as other large-displacment bikes of the era. (Suzuki GS1000 in particular handled better.)

Air forks let you set the initial pre-load, the amount of force it will take to get the fork to move in response to a road imperfection, but air forks do nothing to change the spring rate, damping, or other fork characteristics.

When I had the progressive springs installed I was advised to fine-tune the preload with spacers put in above the springs, under the fork caps. I ran no pressure in the XJ's air forks. I had Progressive install the springs at an Americade rally and they looked over the bike, took my wieght, and came up with a spacer they though would be a best fit. I've never changed it. I think the spacer was around 3.25 inches but can't really confirm that. They used Progressive 10 weight fork oil when they did the installation and measured the fluid level, not volume, in the forks.

Anyway, while there are things you can do to improve the handling of an XS or XJ you are still dealing with a design that was not optimized for handling. Engine mounts, in particular, have been identified as a detriment to better handling. Combined with drive shaft torque reaction and a twin-shock rear suspension you have a design that will not compete with modern mono-shock systems. My Connie handles much better than my XJ, for example, and the 1000cc Concours deisgn goes back to 1986.

So there are limits to what can be done up to a point of diminishing returns to make an XS - XJ handle better. New fork springs, new rear shocks, ss brake lines, fork brace, custom-built engine mounts all will help. By the way, a fork brace works because it forces two independent fork tubes to act as a monoshock system, limiting the flexing and independent movement of each fork. Front tire stays more 'planted' with a fork brace installed.

Fork springs selection is one of several factors in creating the ride you want. Fork oil weight, pre-load, spring selection, fork brace, and even the choice of tire will all affect your ride. While this thread has concentrated on the choice of springs, progressive or straight-rate, that is only one factor in building a fork that will suit your riding style.

I put over 80,000 miles on the XJ after Progressive worked over my forks (work was done in 2000) and that was the best $120.00 I ever spent. (Show special. Buy the springs and Progressive did the install, including new fork oil.) Again I stress: You work toward getting the ride you want. I added the fork brace, SS brake lines, and progressive springs over a two-year period. Started with the springs as the OEM units were sagging pretty bad.

No one change is going to get you all you want, in most cases, and you can go further if you wish. I would like a set of Progressive 412 series rear shocks on the XJ when I get it on the road again as well as replacment motor mounts. There is always something you could do, it is just a matter of time, money, and energy.

[Bonz]

"Air forks let you set the initial pre-load, the amount of force it will take to get the fork to move in response to a road imperfection, but air forks do nothing to change the spring rate, damping, or other fork characteristics."


I am under the understanding that air in a fork is a great way to adjust ride, not just preload but fork action overall as air is compressible by nature, just like a spring. My mountain bike has an air fork up front and air shock out back, absolutely they control spring rate. Even in combination with springs in an XS fork, air pressure/fork fluid level (thus tuning the air space in the fork tube) very much helps control spring rate of the air, per se, for lack of a better way to term it.

[jetmechmarty]

There is always something you could do, it is just a matter of time, money, and energy.

You got that right! I spent a bunch of time, energy, and money on mine. Some of it was do-overs. Ultimately, I'm happy with the result. Another member here took his forks to Traxxion Dynamics. I saw what they did. They installed custom wound straight rate springs, RaceTech Gold Valve emulators, on fork got 10W fork oil and the other got 15W. The emulators have different settings on each. One fork is set up for compression damping and the other for rebound. I thought mine was as good as it could possibly be, until I rode this one.

[b.walker5]

By the way, a fork brace works because it forces two independent fork tubes to act as a monoshock system, limiting the flexing and independent movement of each fork. Front tire stays more 'planted' with a fork brace installed.

Would have thought that the front axle, and the triple tree would take care of the "independent movement of each fork". If every thing is clamped up properly, it should be quite impossible for forks to move independently of each other.
The only thing a brace can do is reduce flexing.

[Jerry]

would take care of the "independent movement of each fork

Several years ago I had a talk with Tkat about his fork brace and why it improves handling. His opinion is that the fork brace makes the forks into more of a solid beam than two independent tubes. Tires deflect when they hit something. The force resulting from the deflection is transmitted into the fork tubes. The "solid beam" concept limits the effect of this force by equalizing it between both tubes. The tripple-T is to far away from the end of the forks to effectively act the same way as a fork brace does. Just as you can't stop a musician's tuning fork from vibrating by holding onto it's handle, the tripple-T does not stop the fork flexing as it is effectively the handle at the end of the forks. A fork brace acts on the forks the same way putting your fingers on the legs of the tuning fork; the vibration is canceled much closer to the source.

air in a fork is a great way to adjust ride, not just preload but fork action overall as air is compressible by nature

Here is a comment I found on another board:

Coil forks/shocks have a linear spring rate which makes for good control throughout the range of travel. Air forks/shocks are non-linear in that they start out soft and then get stiffer as you compress them more. This can make them more resistant to bottoming, but they tend to "blow through" their travel easier.

The XS - XJ forks have minimal air in them. Adding pressure to a coil/oil fork does not change the spring rate, damping, or other characteristics of the fork other than preload. It does change these parameters on a genuine air fork design, one of the pros of that design. (One other is weight savings.) It is easier to fine-tune an air fork - just change air pressure - than a coil/oil system. Downside, but getting better, is air forks tend to leak air and have to be re-adjusted with a small air pump. You can't really compare air spings to coil/oil; air springs operate differently and have different characteristics. I stand by my statement.