Datsun Roadster: 2020 Challenge Build

Ah, the zoomed out view puts it back in perspective for me. Clean it up and moving on...

Looking great.

104 hours.

I was thinking about my fuel tank and pump situation. I had a gsxr pump that came with one of my parts engines, a bent up gsxr gas tank I bought on eBay for $35 or so, and this tiny aluminum tank that came with the formula car. 

Best budget solution is to use the gsxr pump and the aluminum tank. Second best solution is to use the gsxr pump and tank for the additional $35 or so. So - can I put these together?

That photo was after I removed the fill cap. This aluminum tank is setup for gravity feed to an inline pump. I want to convert to intank pump, and the gsxr pump mounts to the bottom of the tank.

Two big chunks of what I assume is anti slosh foam.

Ewwwwwwwwww.

Unfortunately the hole is just too big. I think I'll leave the fill cap here and try to put the pump in the bottom. Is there a specific gasket rubber or maybe a silicone type sealant made just for gas tanks? There has to be. Then I should be able to just cap the bottom hose, leave the top as a vent, and good to go.

Should I keep the foam?

Also, I started cutting roll bar support tubes but no pics of that process yet.

In reply to Robbie :

Since you have AN hardware on the bottom hose, just use a metal AN cap, or an appropriately sized steel ball under the present fitting. What about an adapter ring and 2 gaskets on top to mount the pump? McMaster sells neoprene rubber sheet with a nylon fabric core that I have made mechanical fuel pump diaphragms from. That would certainly work, but is not cheap.

Robbie said:

Two big chunks of what I assume is anti slosh foam.

 

Should I keep the foam?

off-hand... I say "keep the foam"... especially if it's not degrading.   But... you could get around not using it, if you always keep the tank over 1/2full-ish.

Yes, autocross will mean violently changing direction, so fuel slosh is more of a concern.  only, you'll have time to top it up between a few runs... if you can get in the habit to fill it after every other run, so it's automatic, then you're fine.  If something starts acting up, though, and you're chasing rabbits... then you might forget to do that, and it's something that could compound... especially if stress is ramping up.

ymmv.

With the GSX-R pump mounted in the bottom of the tank as designed, and the size of that aluminum cell, I would probably be comfortable ditching the foam.

Where does the pump actually pick-up fuel?

In reply to sleepyhead the buffalo :

Ha! Ian and I are pretty scarred from the fuel filter issue with the AMC this year. (We wasted 4/6 autox runs at the challenge chasing a fuel issue.) I'm pretty sure fuel level is now high on our internal list of troubleshooting steps. But it's a fair point. 

However, even the stock bike only holds like 3 gallons of fuel, so I'll be interested to find out how much fuel is actually used during a few autox runs.

Gumby, I actually think the pump pulls fuel from the bell (below the bottom of the tank). If you think about people riding wheelies for miles and doing big stoppies, I think the stock pumps are pretty well designed for not running dry.

Three hours of cutting tube and grinding and checking and grinding and checking and grinding, etc. I made the left tube just a hair shorter than I wanted to and that made me mad but I think it'll be ok.

Starting to really take shape here! 107 hours.

Rear stays look good!

I agree on fuel starve with the bottom mount pump. That well around the pump will be 100% below the tank, and serve much better than any sumped cell. The only concern I would have is sealing it up. I see what looks like a Viton o-ring in one pic, was there a receiver groove on the bottom side of the MC tank for that?

I recall the bottom surface of that aluminum cell is angled toward the feed fitting as well. If you can seal the MC pump assembly to the bottom, I would mount the cell in the car with the bottom surface level, so the pump well remains the lowest point, and ship it.

In reply to Robbie :

Are you hand grinding the tubes or using a hole was tubing notcher. I have an extra tubing notcher that I loan out or sell if interested. 

In reply to Robbie :

I would just use the GSXR tank/pump for a few reasons.

1. It is guaranteed to work with this powertrain, injectors, fuel rail, pressure, flow rate, etc.  Its literally perfectly engineered for this application...
   1. You will be trading reliability and man hours for what, a few lbs of fuel?  Hard pass for me.
   2. If it leaks or doesn't work perfectly, you've lost time and possibly the event?
   3. Why introduce these possible grevious variables?
2. It seals by default since its an OEM application (Suzuki).
   1. Parts/seals/orings are readily available off the shelf, next day delivery
3. You won't have to fill it near as often as the little aluminum tank.
   1. Retrofit the aluminum tank at a later date when you are streamlining/enhancing the build?
4. It's only $35 to the budget, that's like free/no brainer?

Best of luck in your decision tree!

Looking really good!  Love how well the rear stay tubes fit!  Just like we planned (well YOU planned, I merely nodded my head in agreement).

$35 is almost 2% of the budget! It does sound like efficient use of that budget based on your other reasons, though.

The motorcycle tank is also physically large and annoying to mount. But all the points are valid.

I got in 3 more hours Sunday on the front tube notching. I'm pretty happy with it now. I might tweak them some more but I think they'd be fine. I'll try to draw up and explain my method a bit since I don't have a tubing notcher.

I used my tape assisted design to mark out this bottom angle (marked the tape, and then used the tape to transfer the angle to the bar). That worked really well!

This morning I started the arduous task of taking the old frame apart to harvest some tubes. 111 hours.

Fladiver64 said:

In reply to Robbie :

Are you hand grinding the tubes or using a hole was tubing notcher. I have an extra tubing notcher that I loan out or sell if interested. 

Thanks for the offer! For now I think I'm almost done doing it by hand (famous last words maybe).

Fladiver64 said:

In reply to Robbie :

Are you hand grinding the tubes or using a hole was tubing notcher. I have an extra tubing notcher that I loan out or sell if interested. 

I might be interested in it. 

Another hour deconstructing. Almost done with this task. Gah. Cutting weld takes way longer than cutting metal.

Reduced to a pile of parts. 

Next I ground off all the remaining weld and also de-painted one of the tubes. I love 3m sand and strip disks!

Placed sort of in its final position.

113 hours.

The cage is looking fantastic!

In reply to 03Panther :

Thanks! When all said and done it will be more roll bar and less cage, but either way I like how it's coming along too.

Today I finished grinding and depainting the other forward bar. I got in and made racecar noises.

I started looking at the front hoop. There are 4 large brackets here that are going to be a pain to cut off but I think they need to go. The top two for sure, I might leave the bottom ones for a bit. 114 hours.

I don't have anything constructive to add but I'm really enjoying watching this come together. 

These brackets were solid. Holy moly! I mean not actually solid but built very solidly. You know what I mean.

Cutting them off was not quick!

I finished one side, still need to finish cutting and grinding the other. 115 hours.

Ok, let's talk tubes for a moment here. First, here's some detail on my general method for notching tubes.

And next, a general question. Which of the below is a better joint method?

I'm pretty sure the top is better but let me know if I'm being daft.

Top is better than bottom, but I would aim to split the difference.

Wow. Those brackets were stronger than the frame their attached to

In reply to 03Panther :

No kidding!

Today's work was finishing the removal of second bracket, prepping and welding in bars, and then fitting the second to last "structural" bar. 117 hours.

The shape strongly reminds me of the bones in a bat wing.