So if I have a brand new iron and there bottoming out, what should I do?

 

Go the Progressive route.

Just got the front forks perfect on my 2011 Iron. They too bottomed out when new so I did the Progressive 11-1527 spring upgrade. Like everything, it's in the details and you still need to adjust the spacer, oil level and oil viscosity properly for rider weight.

First, there are many discussions here over oil viscosity and it's hard to compare brands as fork oil is NOT rated like an SAE engine oil. Progressive recommends the stock viscosity "Type E" oil so I went with Honda SS-8 10W after I found it is engineered for Showa forks and a very close match to Type E viscosity in cPs at 40 and 100 deg.

Next is oil level and I again followed Progressive recommendation of 5.5" from the top when fully collapsed without the springs inserted. I put the tight winding in first that displaces more oil leaving a smaller air spring on top.

Finally, I found the Progressive 3" spacer gave too much preload (stiff) and went with a 2.5" spacer that sits 0.25" above the fork top when fully extended. The springs then get about 1.25" preload when the fork caps are screwed back in. I didn't like the chintzy PVC spacer so got a Craftsman 21mm socket that was a much better fit all round with a 29mm diameter stainless fender washer underneath.

Now the front forks are very compliant following every ripple in the road and neither bottom nor top out on big bumps with my 195 rider weight. This setup cruelly exposes any weakness in the rear shocks and you need to balance both ends for the best ride consistent with the limited suspension travel.

Chers, RR

 

- Ah, someone that did their homework and got it right the first time.
I thought the same thing about the PVC spacers but used them anyway. I guess Progressive knows what they're doing, because with 70,000 miles on them, the PVC spacers are doing just fine.

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PVC is lighter. As a former racer I feel bad for every gram I add to my bike.

 

Do you notice it mostly in traffic? When it's hot out, I can feel water droplets getting thrown back into my face from cars that are running air conditioning.

 

Thanks, I'm going to try a 2 1/2 spacer now. I used the same shock oil you used.

Spacers tried
1 1/2 too short - not ride-able
3 1/4 too long - not ride-able
Emailed Progressive recommend 1/2(2 3/4) to 5/8 protruding from top of cap.
2 3/4 almost right but still a little stiff. - no bottom out, but dips are a good hard jolt.
2 1/2 is perhaps the soft/sweet spot.

 

I tried (2 1/4) now after (2 1/2) on the spacer. I'm leaning towards going back to the (2 1/2) spacer. All together I find them to be way stiff no matter. I might also change to a lighter weight oil to see if that helps.

Better than stock I'd agree, but might be better options if you're shopping for new front springs for a low model.

 

Replace the fork oil to the tech. manual amount give it a few days worth of rides befor you spend big bucks. Had the same probem on my 98 fatboy changed the oil and no difference. As I wondered what to do it dissapeared, must have taken awhile to get all around. better than replceing until solved.