Hello all.

You may know me from various DIY threads I've shared with the forum in the past.

I wanted to share some observations I've made over the last few weeks as I've played around with my front and rear suspension.

This isn't a DIY thread really, more like a collection of thoughts/tips on the process of changing out the rear shocks, and putting new springs and/or fluid in the front shocks.


Observation 1 - Rear shocks: Taller rides way way better, even if the taller shocks suck.

My first change on the bike was to see if cranking up the preload on the factory shocks would help the abysmal performance. LOL, no. As expected, it just got rid of the sag, but didn't change the fact that there wasn't enough travel with the rider on the bike, and the spring just couldn't work under those conditions.

My first mod was to throw on some 13" sportster shocks I had lying around. These came off of a 2003 XL model of some forgotten variety, and they were arguably worse shocks than the ones that came on my 2012 iron. However, even being 9 years older with tens of thousands of miles on them, they still made the bike WAY BETTER TO RIDE. Preload turned up, the extra travel gave the bike enough range in the rear to actually start soaking up bumps (instead of beating the hell out of the rider)

I noted that the cornering of the bike got better, partly due to the extra lean angle, and partly due to the fact that these shocks simply worked better.

This convinced me to get a set of 13" Progressive 412s.

I installed those about a week later, and they are just perfect. All of the advantages of the previous 13" shocks, but with way better damping and better spring characteristics when compressed hard.

I wanted 444s but the price is double of the 412s. I don't regret my decision, but if your budget isn't as tight as mine, get the 444s for sure.

NOTE: Your bike will lean further on the kickstand. It freaked me out at first, but now I think its fine. Time will tell.

Thoughts on replacing the rear shocks:

0. Optional: Measure the current fender height, sag and static sag. Write this down.
1. Jack up the bike until the rear wheel just comes off the ground.
2. Break all four shock bolts loose with a socket by hand (no impact), you will need a spanner for the lower bolts that have a nut.
3. Carefully tweak the height of the jack until the rear wheel is unloaded, where there is no pressure on the shock bolts.
4. Remove the lower bolts, remove the upper bolts. Keep the bolts, washers, and the top shrouds.
5. Install the top bolts of the new shocks with the correct spacers so there is NO lateral pressure on either top or bottom of the shock.
6. Tweak the jack height again, as the new shocks will probably not perfectly line up with the old shocks.
7. Install the lower bolts. Use a torque wrench to set the top and bottom bolts to the factory spec (45-50ft*lbs for a 2012 iron).
8. Lower the bike, check the static sag, sag, etc... and set the preload to your preferences. Compare with the optional data from step 0 above.


Front shocks:

I was torn on the front, wanting to make a change in both the oil and the springs. As an engineer though, I prefer to make single changes at a time, so I can know the individual effects of each change.

I talked to a guy at Progressive suspension about what fork oil to use, and he said that most guys with my bike seem to report that they prefer the factory fork oil at the factory oil height. I have read a lot of guys who love the Belray 10wt also, claiming that the OEM harley fluid is 7wt. Seems right to me.

So, I figured I would swap in the new springs and leave the fluid as it was.

Comparing the factory setup with the progressive setup: Harley spring is shorter and way softer, with a MUCH larger preload insert. The Harley preload insert comes up out of the fork tube (when the cap is off) more then 2". The Progressive spring is longer, firmer, and has a smaller preload insert.

The Harley spring looked like it was running almost 2.75" of preload, I wish I had measured it (remember to add 13/16" for the depth of the fork cap to your preload measurement).

The progressive setup says that most riders will do best with 3/4"-1" of preload if I recall correctly.

I cut the PVC spacers they give you, such that the spacer+washer was coming up 2mm above the height of the fork tube, which should mean my total preload is 13/16" + 2mm, whatever the hell that is. Its just under an inch, is the short version.

Front results: Amazing. Way less sag, way firmer ride, but also, the entire bike really has a feel much more like a sportbike now. It turns in way easier, stays leaned over way easier. It soaks up bumps really well, and it feels like the tires are really stuck to the road like velcro.

On hard braking there is basically no front dive, maybe 1/4-1/2" tops but its hard to eyeball.

On hard accel, the rear sticks way better because the bike doesn't sag backward like it used to.


Overall thoughts on going to 13" in the rear and making an upgrade to 412s and springs:

This is how the bike should be. Low bikes turn like ****. If I had clipons and proper sport tires, I could drag my knee now.

This is really what I wanted this bike to be. Total cost was about $290, purchasing everything on Amazon.

These mods are easy and you should do them if you have tools and the skill.

 

I would love links to the parts your purchased. I'm looking to upgrade the suspension this winter so the wife will WANT to ride with me but doing so on a one income bases. I have been trying to hunt down some SG 12" shocks for cheap but they all go so fast it's hard to get a set.

 

thanks for the install instructions man. definitely thinking about taking my stock street bob shocks up to 13.5" even more now. Planning on the 412s as well

 

I've been wanting to do this to my Nightster for awhile. I even bought the 14" Progressive 412s but I am yet to install them. My main concern is I was told from a couple shops that I need entirely new fork tubes as well as the springs. That is what has kept me from doing this mod. I don't have the confidence to change my front end or the $ to have a shop do it. Are the 14" shocks too long for the Nightster? I appreciate the info and hopefully this will inspire me to get'er done.

 

If you want to take your front end to the next level then this is the recipe:

racetech "single rate" springs made for your weight.
Ricor intimidators and amzoil 5wt shock therapy fork oil.
Set sag for 1/3rd of the travel (by measuring and cutting or adding the spacer.

Once you got it set...it is as awesome as you can get for a HD

 

Para, I went a similar route, I used 13.5" Progressive 440 standards in the rear and I installed Progressive Fork Springs in the front and used the 3" spacers as is. I run BelRay 7w fork oil in the front. I wouldn't change a thing, it's Perfect.

 

Links:

Rear shocks (NOTE: For two up riding you probably want the Heavy Duty version, which is a different part number. Go to Progressive Suspension's website and use their part lookup for the "HD" version of the rear shock which is probably what you want for two up riding):



Front fork springs:



Most affordable fork cap socket you can buy (half the price of the HD tool and actually very high quality):



Good replacement fork oil that is not very different from the weight of the OEM oil:

 

Great write-up, thanks for posting. I have followed your path in a manner of speaking, swapping the stock shocks on my SuperLow for longer Hagons and using single-rate Race Tech springs up front. In both cases, with sag at better levels the bike is now a Super-not-so-Low, but with more suspension travel at both ends and improved cornering clearance.

I also have Emulators in the front forks, but frankly they were a waste of money - I can't tell they are there and the instructions for 'adjusting' them are meaningless. I recommend using single-rate springs, matched to your riding weight. Progressive-rate springs are a poor substitute for properly matched ones.

I have spent a lot of effort and cash improving the suspension of my Glide, which now has custom-built rear shocks with single-rate springs and tuned damping to match my weight and bike. The quality of ride is way superior to my Sporty and I regret not buying better quality shocks for it. Up front on the Glide I have custom-tuned Intiminators and single rate springs, although have yet to ride it.

There is plenty of mileage to be had improving Harley suspension, regardless of model (except my FXDXT!).

 

You say after the longer shocks it cornered better. What is "better"? By raising the rear (or lowering the front) the bike will lean or go into corners quicker but will be less stable in straight line highway speeds. Conversely if you lower the rear (or raise the front) the bike will feel more sluggish or slower in corners but will be more stable in straight line highway speeds. Over the different versions of my bike Ive noticed the cornering aspect of raising/lowering the front/rear is VERY noticeable when cornering, they straight line highway stability change is not so noticeable.

 

I think what he means by better is the lean angle/clearance. Stock the bike will be a little lower in the rear once the rider is on the bike. By using longer shocks on the rear, and most importantly setting the sag correctly, this will at minimum level the bike or slightly raise the rear compared the the stock front thus slightly quickening the steering but not making the bike unstable. Once the front springs are changed, and again the sag set correctly, this will even things out because the front is not dropping as it will with the stock set up.

Hey parabellum....if you want even more lean angle install a pair of Oberon "Racing" foot pegs. They are a bit shorter than the OEM pegs.

Linky: http://www.oberon-performance.com/ac...Foot_Pegs.html