We are changing the standard fork springs on my other halfs 09 Fatbob for a set of Ikon springs and I'm not sure what grade of fork oil to use. The new springs are stiffer I believe, to stop some of the dive under brakes and to get a better ride and I thought maybe a 10w oil would be right?? Has anyone done this before?

Hi mate

Progressive springs in my Fatbob with 10W.  I weigh 90kg and it rides fine.  Would not stick heavy weight in if your other half weighs less than that.... mine soaks up the bumps and the front brake dive is reduced.  I dont punish the bike in the bends mate,  too much brain damage to think fast LMOA

Make sure you cut spacers (Not sure if IKON supply spacers with the springs) and set your preload.  You would be looking for about 11/4 inch with rider on the bike. 

Easiest way to get ithe spacer close first up:

1.Put new spring in fully extended fork

2. Measure from top of the thread with the end cap out, to the top of the spring in the tube (It will be about 100mm)

3. Measure the thread on the end cap (about 20mm) and deduct that from your measurement in 2.

4. Add 38mm to that number and you have the length of spacer you need to cut.

Make the spacer from PVC tubing or cut the original stainless spacers to size.  Make sure they are square both ends.

Stix and the boys would recommend Race Tech Springs (Sold to match your weight) and Gold Valve Emulators if you want to part with the cash but I think you will find a nice little improvement with the IKON springs.

Your instruction sheet with the springs will most likely have this.  If not follw this and click on the Street Bike Fork Springs PDF

 

http://www.progressivesuspension.com/literature.html

 

Hope this helps you..

Jam

 

 Thanks Jam....I forgot that I'd have to cut a couple of preload spacers. Hopefully that size of spacer will be ok for Sue.(she is just under 50kgs!)

Hi, just after a little help re fork oil on my 2009 Fat Bob. I have just put progressive 812's on the rear and stock length progressive springs on the front. Not much of a mechanic but had ago myself anyway. My confusion is in regard to the spring oil level. When i took the old springs out the oil level was about 300mm down the tubes from the top but the progressive instruction was that it should be about 140. At 140 the oil just overflows when trying to push the spacer down and screw in the cap. I had about 3/4 - 1" of supplied spacer sticking out the top of the tube so it was a bit of an effort to screw the cap back in. Anyway I settled for oil level at about 160 from top without spring in tube, then put it all back together. Just can't help but feeling that I have probably got this wrong and would really appreciate any solid advice. I put in 10w oil and I weight about 90kgs. set the rear shocks 1 up from softest setting ( I think)

Thanks in advance.

Thanks Hilly, maybe I can't see for looking but I cannot locate the quantity in the book that came with the bike. I guess it is not a proper service manual. Do you have any idea what level is supposed to be in a 2009 Fat Bob? Thanks a heap.

Hilly, do you mean compress the fork or make sure it is extended all the way out? At the moment I am about 160 down from the top of the tubes where the cap screws into. It all seems pretty strange, with the progressive instruction sheet recommending a maximum of 140mm to the oil level from the top of the tube but the existing level which I measured following removal of the springs and spacers was something like 300mm from the top.

Thanks Hilly, your a champ. I'm at the sunshine coast at the moment ( daughter had 1st baby, yeh I'm old!) but will stuck straight back into it when home. I must be dumb, just couldn't connect the dots.... did not think to compress the forks and measure!
Will let you know how it fairs ins a week or so.

Hi Hilly,

Been out of action for some time obviously.  Well I got itall together thanks to your advice. standard length progresssive springs in my fat bob with 10 weight oil. Also progressive 812's on rear. At first I thought it wasll pretty good but now after doing around 1k the front does feel a bit hard. Same old story, getting there fun and fast, returning home a bit of hard work with our country road being rough.

Should I change the weight of the oil do you think? or maybe a small set of apes instead of the drag bars would help. I must say the bike does not feela whole lot better than when standard, perhaps i wasecting to much. I perhaps feel closer to the road with the rear progressive 812's package and new fork springs but strangely not as confident in my riding.

regards,

 

Alfun

I used 15wt in my 08 street bob and upped the amount slightly to 800mls.

I haven't got the standard amount data right in front of me but it was around 780mls (26.something oz)

2010 FXDF

G'day Hilly,

I am not sure what preload I did, I cut the plastic tubes as per the instruction sheet. The end result was that the plastic spacers stick out the top of the fork tubes (before capping) only just slightly lower than the pre-existing metal tunes. I was guessing this was in order?

The progressive springs that I installed were 812's fully covered like the existing harley shocks. Again I assumed that the '12' in '812' meant that they were 12" but having said that I guess I don't really know the length of the standard fat bob shock. I will check it out on the net in a minute

I weigh about 85Kls and ride one up most of the time. I am guessing a setting of 2 would be okay for the shocks.

I mean it all works okay but just does'nt feel to turn in or to be able to throw it about quite as flippantly.

Regards,

 

alfun

All the 08 Dynas (apart from the wide glide) are as follows:

page 2.55 in manual

level is 110mm from top

26.6 oz (787cc) per Fork

Type "E" oil - HD-99884-80


So you might want to check what the 09 manual says.

Thanks Hilly & Daggs,

 

Will checkout tyre pressure. It;s in for service and Dyno tune on friday. Got about 3k on it since 103 kit. I will ponder whether to change the oil changed in the forks. The oil in there at the moment is honda 10 weight, could this non-harley oil also make a diffrence? I know I should have put harley oil in it but I don't have a harley dealer close by and patient i'm not, stupid maybe!

 

Regards,

alfun

I wouldn't be concerned about only using HD oil.

We don't have a Harley dearlership with in about 300k's and the three other bike shops I went to had sweet fuck all so I grabed some castrol 15wt from a local agent.

This is why I usually get everything I need online, local or OS.

The recommended oil is 5W (FORK OIL not a petroleum based oil which disintegrates over time as changes occur in its molecular structure in your rubber parts) which is the equivalent of the HD type (Type "E" oil - HD-99884-80).  When you use thicker oil than your metering is than different to what the engineers who designed this piece of equipment.  You are going to have a bit of a problem figuring out the sag due to the progressively wound springs you are using.  My job is suspension.  You may change the metering holes by welding and re-drilling or use the inexpensive Race Tech Cartridge emulators where you can change by a screw driver and a 5/16" wrench.  The compression is adjusted by the oil height as is the last bit of the stroke prior to bottom out.  Raise the oil level and the result is increased resistance  as the forks moves through the last part of the stroke.  This is known as increasing your air spring.  Each line is representing 10 mm increase.  The shock dyno is used on a single 30 mm Öhlins cartridge mounted inside of a fork.  This is for a visual example only.  This is used inside of one of my Fat Bob forks.  There you have it.