Progressive springs? Worth it?

[adelii]

I have a leak on my forks so i am going to get the seals replaced. I figure for $80 it be worth putting in some progressive springs. I mean my fork internals are almost 40 years old. I really would like to get that dive out of my braking.

suggestions?

[motoman]

Without replacing springs, I'd suggest completely take apart, clean everything spotless and replacement fork oil needs to be 15w variety.

[DiverRay]

The springs ARE nice. I've put them in two of my XS11's, and been happy with the results. You'll still get some dive, but not as much.

[adelii]

I definitely want to clean up everything and get the "good" oil and right viscosity. I just wonder if the springs would be a worth it upgrade for $80. I already have the brace.

[motoman]

I suggested the 15w fork oil just for the reason that the dampening orfices get slightly enlarged over years of compressing of the forks. The bit heavier weight rating of the fork oil compensate for that. This IS common practice for those that understand how oil itself does create friction. Oil friction from passing through those orfices is also the reason forks get warm, and even hot on moto-x bikes....even too hot to touch after a moto-x race....BTDT many a time in past years. That friction is what tends to enlarge the orfices. The progressive springs, as Diver Ray suggested, and done himself to his bikes does compensate for, and used instead of factory reccomendations . Any advantage my bike may or may not have, other than using 15w fork oil, is the factory full dressed, 81 Venturer I bought new, which also was the only model XS1100 that came stock from factory with progressive fork springs.Hope that was of some help as to your option choices.

[adelii]

That was great help. thanks guys. ill be trying to do it all.

[MaximPhil]

That was great help. thanks guys. ill be trying to do it all.

Hi Adelii,
Be aware that Progressive is also a brand name which I presume wind all their springs to be progressive.
It is certainly an economical way to improve/restore some front end suspension. The change to 15W oil is more dependent on your weight and mileage rather than age of the forks. If the orifices have not been opened as explained by Motoman the damping will be slowed. ( how much ??)

Jetmechmarty changed to emulators which require straight rate springs which is a much more $$ upgrade to the front suspension.
Having ridden his Special I can say it is a vast improvement but whether worth the expense would have to be a personal decision.
It does require some expertise so best to send the forks out to be done.

Phil

[adelii]

Yes thank you. there is no way im doing any of this. I just want to get the right stuff to make that front end feel better.

[motoman]

To add, a third option by some is to add a heavy duty fender type washer atop the spring and THEN add a thickwall heavy duty piece of PVC a couple inches long topside of that. This makes the spring compress a bit slower and you do loose a bit of overall travel, along with a bit stiffer compression overall.

[TopCatGr58]

Hey Adelli,

To add to what Motoman stated in his last reply, adding a little bit more of a shim inside the forks can help set the preload tension a little higher, will provide a bit less SAG affect when you sit on the bike, as well as reduce some of the dive because the springs will already be under a little more compression tension than stock.

The Specials...which is what you have uses a longer upper fork tube, and therefore a longer OEM spring. However, Progressive only makes 1 size/length spring for the XS11....to fit the Standards, and then just use a spacer when placed in a special. IIRC, the spacer will be about 4" long, but I'm not totally sure of this, so don't hold me to it, just be aware that you will/should receive a spacer with the springs when specifying for a special.

SO...you can then use the PVC, or what I used which was some black iron pipe that I cut to fit, and I was able to make the spacer ~ 1/2 " longer than it would normally be and that will give you a little better preload tension. YMMV as to the final length of the spacer, best to start a little longer, and then you can adjust/trim back a little if you find it a little too stiff.

T.C.

[Jerry]

Years ago I wrote a piece about upgrading the XS suspension, front and back. from memory, here are a couple observations.
Progressive vs straight-wound fork springs. On one hand, the progressive-wound springs give a better street ride. The theory is that minor bumps are absorbed better as the forks will move with less load. Larger bumps take more effort to compress the spring further. I had progressive brand springs installed in my XJ some years ago; most of my riding is interstate and the extra comfort was higher on my priority list.

Progressive springs generally have a dual-rating such as 80/120; the first number indicates the force needed to move the suspension (generally per inch) though the first part of the spring travel, the 2nd number indicates the force needed to compress the spring (again, per inch) through the remainder of the spring travel.

On the other hand, you have only so much suspension travel and straight-wound springs offer very predictable handling. It takes the same amount of force to compress the springs the first couple of inches as it does the last couple of inches. If handling is a high priority then straight-would springs would be a better choice.

It is true that fork springs are not custom-tailored to every bike. A common trick is to use short lengths of PVC pipe at the top of the forks to set a preload. PVC is inexpensive and you can play with different lengths to get the feel you want. In my case, the installers used about a 3.75 inch (IIRC) length based on the fact that I had a full fairing mounted and am a heavy guy at 240 pounds. After the install I never used the air preload function of the XJ's front forks.

Another tip the installers gave me (springs were installed at an Americade rally by Progressive techs) was to fill the forks by level and not by amount. Most fork specs include a fluid level setting (as measured by from the top of the fork) and this value is what the Progressive techs use when installing new springs. IIRC this value is present in the XJ's fork spring specifications and probably is in the XS specs as well.

Front and rear suspensions should take into account suspension sag. This is the amount of suspension travel taken up when you sit on the bike; the suspension "sags" when you get on the seat and move the suspension from the resting position into the working position. Most suspension gurus recommend this value be around 1/3 of the total suspension travel. This can help you pick a starting point for your PVC spacers; to little sag and the suspension will hit the top stops and damage your suspension and to much sag robs you of suspension travel and leads to bottoming out, also not good for your bike's parts and pieces.

Please note: PVC spacers (or air pressure in the XJ's front and rear suspension) will not change the spring rate; it only affects the preload, or the force needed to get the suspension to begin to move. Spring rates do not change when preload changes.

And just one more reminder: get the correct fork seals if you are going to change them. Many catalogs and vendors have the wrong parts listed; Yamaha used at least 2 different size fork tubes in different models. The XJ took 37x50x11 seals and I think the Specials did as well but the Standards took a 37x49x8? (Others can confirm this.) In short, make sure the seals you get are the correct ones for your bike.

A suspension upgrade will help your handling considerably, and adding a fork brace will help as well. Then you need to look at the rear suspension...

[skids]

Good overview Jerry.

[mcmotohistory]

BIG YES , I have them in my Venturer. Big improvement.

[motoman]

BIG YES , I have them in my Venturer. Big improvement.

The Venturer model came new from factory with progressive fork springs, along with schrader valves to add air to forks.

[jetmechmarty]

I am not a fan of progressive springs. It's old school, like the bike. My Special had progressive springs that I assume were original. I have custom wound springs in there now and as Phil pointed out, Race Tech Gold Valve Emulators.

Going up to 15W oil will slow high speed damping. You may not want to do that. When you're done cleaning up the fork internals, ignore the recommended oil quantity in the service manual. Collapse the fork with the spring out and fill the oil until it is 130 mm from the top. Oil level controls bottoming and fork stiffness in the last 30% of travel.

Raising the oil level may be the only thing you need to do to make you happy and it won't cost anything. The oil needs to be changed periodically anyway. I'd probably stick with 10W as 15W will only slow the forks down.