After that, I had to figure out how (and if) the stock console would fit.

There are two types of 5-gallon tank out there, and they differ in the bracket that the console attaches to. Almost all the bikes use the same method as the Fat Boy, which is the flat triangular shaped bracket.


That's the tank I got, and that's the one that I made work.

The other style tank is the one used on the Low Rider. That has a very different mounting bracket.



That was never gonna work. If you want to use the stock instrument panel, it can be made to work on the Fat Boy/Heritage style tank, but if you wanted to use a Low Rider tank you'd have to cut off the mounting bracket and weld your own on.

As far as fitting the instrument panel, there are three holes in the triangular mounting bracket. And it just so happens that there are two pegs in the rear of the Fat Bob's console that just perfectly fit into two of those holes. Those pegs are used to hold the rubber trim/gasket/whatever in place, but I cut those bits off the pegs so that they'd fit in the holes.




I cut the webbing away from the posts, and then glued the rubber trim back in place using some silicon sealant.



With that done, the console would now lay on the tank. Not perfectly, there's a gap, which you will never see from any reasonable angle but there's about 1/4" gap that you can see if you get down and peer directly where the console hits the tank. For perfectionists, it may be an issue (you can sort of see it in that test-fit pic up above). From the position of the rider you'll never see it. And I have plans in the future to address it anyway. Just letting you know, it's there.

So the console can be made to fit, I then had to make a bracket that attaches to the third hole in the tank mount, and provides two screw-holes for the console to attach to the tank. That was a simple strip of about 3/4" wide steel, I hacksawed it into the right width and length and bent it in the right shape with pliers, drilled a couple of holes where the screwholes lined up, and JB-Welded some nuts on the back. With that made, the Fat Bob's original console bolts right up.


In the above pic you can see that the left side cap isn't in place yet. But this pic also shows the Sundowner seat, and it pretty much covers the gap. I think the stock seat might too, but I don't know, I got rid of my stock seat long ago, but again -- if the seat overlaps the tank by about an inch or so, it should cover the gap.

Last step was some bling. I love, love, love, love the badges off the 115th Anniversary bikes. So I got some.

Here's the 5-gallon tank in (almost) all its glory.

 

Note, if you want to use the Heritage/Fat Boy/Deluxe instruments and console, the trim piece that runs from the instruments down to the base of the tank will cover up the gap nicely. I am plagued with the gap because I didn't want my bike to look like a Heritage or Fat Boy, I wanted it to still look like a Fat Bob, so I didn't want that big ol' trim piece. Hence the gap. And, yeah, if Corbin will insure that the front of the seat overlaps by an inch, you should make that gap disappear...

Also note that the reason the other bikes have that big trim piece running down the center is to hide the seam. There's a seam right in the middle of the tank. It's not painfully obvious, but it's there if you look for it. If you go the way I did, with all that bare tank exposed, you'll see the seam; if you opt for the Heritage/Fat Boy type of instruments and console, those will cover the seam.

 

About the fuel pump -- could you get by with the 3.6 gallon pump you already have? Maybe. It does appear to be the same pump as the 5-gallon, but the 5-gallon pump has a second pickup and a different sending unit. If you could find a donor pump to get the flexible tube off of, in exactly the right shape and size, and then you could drill out the blocked pickup hole in the 3.6 gallon pump, and then you bought the $70 sender from the 5-gallon pump, then maybe you could get it to work and spend a little less.

To me, that was all false economy. The whole reason to do this mod was to travel farther and eliminate range anxiety. Do I really want to be risking being stranded on the side of the road with a homebrew modified fuel pump, all to save $100? ($310 for the new pump, minus the $70 you have to spend on the sender, plus however you get ahold of the flex tube, plus drilling, etc, and losing the $100 you'd probably get from re-selling the old pump on ebay, leaves a NET cost of a new fuel pump of about $100). To me that was well worth it, to get the proper fuel pump.

 

Okay, last thing -- instruments -- does the Fat Bob's instrument panel work with the 5-gallon tank? It's too early to say exactly, as I've only put 100 miles on the bike so far in this new configuration, but it does seem to work, or it seems like it's adapting itself to work.

Data points: there are three things the instrument panel tells you: a) the overall fuel level, in terms of the 8 dashes; b) the low fuel warning light at 1 gallon, and c) the miles to empty.

First thing I did is put in a bit over a gallon of gas in the tank, and rode around; after 10 miles the low fuel light came on. That's a good sign! Filled the tank up, and the low fuel light went away. So I believe that's probably a digital on/off signal coming from the fuel level sender, telling the system when there's less than a gallon left. It appeared to work, and that's the most important indicator.

Second test is on the dashes. Disappointingly, even when I filled it to the brim, I only got 7 dashes on the gauge, not 8. I wanted to see all 8, but it didn't show them all. Now, I've read in the Heritage thread that others have had a similar issue, so I suspect it's a fuel pump issue and not a fuel gauge issue, but for whatever reason, it didn't show all 8 bars. However, the bars it does show, do appear to be working. It seems each bar represents about 30 miles of range, as the bars started disappearing after about each 30 miles. I ran 100 miles, and there are four bars showing, so it's showing half a tank. That's about right; 5 gallons at 47 miles per gallon should give a theoretical range of 235 miles, so it should be showing about a half a tank. And if the bars do truly end up matching to about 30 miles of travel, then that's about perfect; 8 bars would measure 240 miles, and the theoretical range is 235, so ... it appears to me that the gauge is working appropriately.

Finally, the range to empty -- the jury's still out on that one, as it's going to take a tank or two for the computer to adjust, but so far it appears like it will work out just fine. When I first filled up, the tank went to 162 miles remaining, and it stayed there. I drove for 20 miles and it still said 162 miles remaining. Eventually the miles started coming down, but very slowly. As of now I've driven 100 miles and it says I still have 106 miles to go before empty. I believe that by the time I get to the end of the tank, the numbers will probably be about right, and when I fill it up it'll probably tell me I have 235 (or so) miles of range til empty.

 

So that's it, the conversion is very simple, and can be done affordably, and oh HELL YES it's worth it. I can't tell you how nice it is to be forever done with range anxiety! Normally after driving 100 miles, I am on the lookout for the next gas station; now I haven't even crossed the halfway mark. The underlying stress of range anxiety is gone.

The tank's bigger, yes. Wider. It does push your leg out a little further. I'm wondering if a Heavy Breather would fit now, without causing knee interference like it would on the stock tank... I might look into that.

In the meantime, if you're thinking about doing the 5-gallon tank, and can swing $600 or so, and can find a tank on ebay or in the HDForums classifieds, man... it's probably the best upgrade I've done. It's right up there with the Stage II.

 

This is very awesome. Thank you for sharing and giving such details on the fitment of the instruments. I too may have to follow your example and get this done.

The only thing for me is that it may be hard to find a used black denim tank that's not scratched to hell. I could always just use vinyl wrap on any tank as a cheap way to make it look good and match my bike.

Edit: Just noticed that you too have the denim tins. Or at least it looks like it. If so it doesn't look all that bad with the gloss tank.

 

You are the man! Excellent mod and superb write up. Another option to cover the seam and the gap between the seat and tank would be to use a leather tank bib with the stock fat bob gauges. I have the stock leather tank bib from my 13 slim sitting in the shop, I loved the cat eye console and leather tank bib set up, do not care for the huge tank length console myself. You have me seriously considering this. Probably mock it up with that stock tank bib and then get a custom one made if I like it. Thank you for the write up!

 

Tell me about it! In fact, what pushed me over the edge was finding that my black denim tank was already scratched up a lot due to my tank bag.

The only black denim 5-gallon tank out there is from the Softail Slim. You can buy a new one for about $1100 painted and with tank badges, or you can get the primed tank for $600 and get it painted for around $200.

Yep, I faced the dilemma. I was originally going to get this Fat Boy tank painted flat black, but the more I worked with it the more I realized that almost everything on the Fat Bob is gloss black -- the instrument console, the headlight housing, the side covers, the forks, pretty much everything. So the gloss tank looks fine. The Bob is a mishmash of flat and gloss, so it works.

I may someday get the tank painted, or I may get a custom leather tank protector. But truthfully the gloss looks fine on it.

 

You're welcome, and we are on the same page. I have been thinking about some custom leather for the tank, I want to tie the leather of the seat in with it, and that would also cover the gap. So that is something I have thought about for a long time, and the gap is what is going to push me into looking into it seriously.

 

Oh, Bowhunter, FYI there's a denim Softail Slim tank on eBay right now. Guy wants $750 for it, and it has a dent, so it wasn't worth it to me when I could get an undented, primed tank from Surdyke for $500 or so and get it painted flat black for $200.

But, that tank has been up there for several weeks, and it does say "make offer". Who knows if he would take a realistic offer?

Again, the only 5-gallon denim black tank they make is the Softail Slim.