Datsun Roadster: 2020 Challenge Build

In reply to sleepyhead the buffalo :

Yes, that's it. I didn't realize he made a video. I was talking to him about it at the Challenge. 

Yesterday was final fitting on the harness crossbar, and getting some initial welds to hold it in.

Today was working on the upper seat support. 137 hours.

I pondered quite a few designs for the seat back support, using scraps from my quickly growing pile of scraps from just this build.

In the end, I decided to go with simple and light. Just need to drill a hole in the seat and weld this up! Not pictured yet but I did clean all the old paint off.

Since the seat is not on a slider it makes this considerably easier. The pedals and wheel (and probably shifter) will have a bit of adjustment instead to fit drivers of different sizes.

I like that... using scrap from itself!

Full day of work today. First I finished the seat mount.

Next I finished removing all the Velcro and associated adhesive from the inside of the seat.

Then I grabbed the harness that came with the car. Anyone hip to harness rules? This one doesn't seem to have dates on it anywhere. Nor sfi badging. It is 3 inch wide straps on the hips and shoulders, and seems to be in good condition with no fraying or anything.

Is it good to use? Also, what would a harness void of any identification tag be used for? Is that a carting thing?

Next up I had to make a longer clutch cable. The f440 came with a sheath the right length, but one end was cut. Also, very oddly, there are two different threads here.

So I cut off the end, and the ground a bevel on the outside so the 2nd thread was useable. I also used a large drill bit in the hole to deburr the inside to prevent cable catching on a sharp edge.

I tried to emulate the stock gsxr cable ends as closely as possible. I had this green coated cable handy so I thought why not?

It came out pretty good, and it works perfectly. Adjustment works at both ends, exactly like a stock cable. Just longer. And green.

Next I turned to the shifter. I spent way too long trying to make fetch happen with one setup. Then I gave up and fell into a much better setup. Happy accidents!

and then I prepared a bracket so the shifter can be attached.

145 hours. 

You'll need a new harness; from the rules: "Racing harnesses must have a minimum of five points, and may be no more than two years old. Older harnesses that have been professionally re-webbed, inspected and re-certified within the previous two years are acceptable." Without the tag they can't verify if it's 2 years old or newer. Strangely FIA certification usually expire after 5 years so I don't know why the rules are more strict on that front. So cheap belts (usully SFI certified) would be fine since you can't use them more than 2 years anyway.

That cable ferrule has been cross threaded; that's not two different threads it's just damaged thread.

In reply to dculberson :

Thanks! Any idea what the 6 point non-tagged harness would be used for in the first place? I'm confused where a no tag harness would be legal.

The cable ferrule wasn't damaged like that originally. I thought it was two pieces since the threads were different, and I grabbed the end with a vice grips and really damaged it. Then I took the pic.

What was odd was that the end was a NF thread and the base was a metric thread. They had a very similar diameter, ao I thought it maybe was a spacer piece that slip fit into the other. I imagine that if you tried to tap one onto the other you would end up with more missing threads. There was a nut on the NF portion that spun off by hand, and after I cut that section off, the nut on the metric thread spun off by hand too. If someone managed to make that happen by simply cross threading it, I'm not even mad, I'm impressed.

SCCA solo does not require certified belts.

Challenge rules follow NHRA which call out SFI and 2yr replacement.

A little drilling, a little tapping, a bolt from the "old bolt bucket", and we're here. It would work fine, it's got a bit more play side to side than I'd like, but I may be able to fix that with just a skinny washer. I did cut the bolt down to length after I took the pic. 146 hours.

147 hours. I started on the bracket for the transmission end of the shifter cable. I thought some of the pre-existing holes could be used, but it turns out probably not. Extra speed holes now.

148 hours. It's getting there. I don't love the angle on this so I'm going to make some modifications, but forward is forward!

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I probably should have started with CAD on this one. I transferred the important stuff to new metal.

Unhappy bracket is unhappy to see you!

But, now that it's back on the motor and cleaned up, I'M much happier. 

Any concern over the green sheathing on that cable causing sticktion when things are at temps?

In reply to bluej :

Good question! I hadnt considered that possiblity, but I think there's quite a bit of space in the sheath the cable would have to expand to fill. I'll keep an eye out for that for sure.

I only got about 30 minutes in Friday morning, but then I did about 90 minutes Sunday night and another hour this morning. So I'm now at 152 hours total.

Let's let this be the 150 hour photo:

In other news, the shifter is working!

Here's what I did for the front cable bracket.

Here it as a complete system, before final welding and cleaning up the brackets. It shifts great.

Here is it mocked up on the car, all the cables fit. Even though the shift cable is longer than the clutch cable (and perfect would be the other way around), everything fits and works and moves as it should.

And tacked into place.

Next up, the gas tank. I spent about 30 minutes this morning just basically looking and thinking and trying a couple different things.

I think for now I'll be going with the stock tank in the stock location. As few wiring splices and fuel line extensions as possible feels key to me to hopefully eliminate as many potential issues as possible.

The next issue is should I mount the tank to the engine or the frame. Remember the engine slides forward and back in the frame for chain tensioning.

Mounting the front of the tank is WAaaY easier to the frame. Mounting the rear of the tank is probably slightly easier to the engine. In either case I want the mounts to be strong strong strong. Tank is a 3.2 gal tank iirc and weights 10-15 lbs empty, so it's potentially a 40ish lb fire bomb and I don't want it flopping around.

help my memory....  is the engine unsprung?  I recall that it moves with the rear suspension....

either way, I would lean towards mounting to the frame with long hoses to allow plenty of room for adjustment and suspension movement. 

Rear frame.

And can you do the passenger side instead? Gas tank above a chain....

Ive seen chains break and come off. Wouldn't want that E36 M3 hitting a gas tank behind my head.

Another frame vote, don't want that moving around.

And chain gaurdperhaps as well?

Engine is unsprung, but I predict only about a 1/4 inch of movement at the engine throughout a full suspension travel swing. That would represent maybe 1/2 inch of suspension travel at the wheel.

And yes, there will be a beefy chainguard. I don't want a chain flying anywhere if it goes rouge.

If I mount the gas tank to the side or down by the rear axle, I would still be splicing harness wires and making long fuel lines. In that case I might as well use the small aluminum tank. Eventually I might do that anyway, but for now I'm trying to get to a running driving car in as few steps as possible.

In reply to Robbie (Forum Supporter) :

looking at your seat back support, is there a minimum area spec for the plate that contacts the seat back?  i'd like to see that a good bit larger, in the off chance that you spin it and back into a lamp post, looks like the current size could punch through the seat and put you in a wheelchair.

AngryCorvair said:

In reply to Robbie (Forum Supporter) :

looking at your seat back support, is there a minimum area spec for the plate that contacts the seat back?  i'd like to see that a good bit larger, in the off chance that you spin it and back into a lamp post, looks like the current size could punch through the seat and put you in a wheelchair.

I don't think the NHRA has one, and judging by what is for sale I'm not sure the size is commonly considered. https://www.ebay.com/itm/Roll-Bar-and-Cage-Seat-Brace-for-1-5-8-Harness-Bar-NHRA-Legal-/323093438023 for example.The seat also seems pretty thick for fiberglass, and I would imagine it is much better than a thin piece of flat aluminum in terms of punch through.

I will say that was part of the reason I liked the angled design however, as it would have a propensity to bend in a crash. It also wouldn't be hard to stick a bit more plate back there. I can measure it and get a total sq inch number if you're curious.

In reply to Robbie (Forum Supporter) :

i also like the angled support. it's quite possible that the current configuration is acceptable, but it jumped out at me as something that might warrant more analysis.  you do good work.  carry on.

In reply to Robbie (Forum Supporter) :

Hard to tell from that angle but could you run a tube between your rear down bars and then come up to the bracket on the back of the tank?  I with everyone else in that I think a frame mount is much better than engine,

Gotta say great work so far, looking forward to seeing the finished car in October.

In reply to Fladiver64 (Forum Supporter) :

Thanks! I can't quite do that as the rear bars are next to the engine not above. But I do have a plan to come up from them at an angle. I have to be careful sinceweldijg something in that area could make it hard or impossible to remove the engine as a unit. So the rear fuel tank mount will have to be bolted in.

154 hours now.

I took apart the fuel pump assembly to just do a last quick gut check to see if I really wanted to use the big tank. I do think that I could easily just plop this pump into the small tank and extend the lines and wires a bit. I'm still not going that route right now, but I'm glad I took the pump apart.

The ring terminal for the level sender was broken, so I fixed that. Also, the pump does pull from the bottom of this bell. There is a sock down there and everything. And there was a bit of junk I'm glad I cleaned out.

155 hours, and 550 posts!

Today I'm still being romanced by the idea of using the small tank. It just fits better, and is 10lbs lighter (25 lbs lighter if both are full of gas). I could do it without cutting any holes in the aluminum tank. Basically just drop the pump into the aluminum tank, trim the foam inside to hold the pump in position, run a new vinyl fuel line from the quick connect on the pump inside the tank out through on of the AN fitting holes and up to the fuel rail. Could extend wires out the same AN hole and plug the rest with a silicone or epoxy or similar.

But I did at least start on the brackets: