Datsun Roadster: 2020 Challenge Build

Robbie said:

Lol, there are 10 inch DOT legal golf cart tires....

Maybe I just run on those.

10" DOT legal slicks, and you've got to lengthen the front of the kart chassis?

SVreX said:

I think I’m lost. 

Are you saying that because the car is an open top with non-DOT tires that it has to have a roll bar that’s 1 3/4”, even if it’s incorporated into a cage?

That sounds off. 

I've re read the rules again and I am more sure that is how the rules read. 

4:10 roll bars are mandatory in all open top cars running 13.49 or faster or non dot tires.

The rules also go on to say that in case of conflicts, the challenge rules override the nhra rules. So even if nhra says a cage is better than a bar, the challenge rules are technically saying the bar is still mandatory.

Again, I'm pretty sure I know what the spirit of this rule was. And I think you do too. But the spirit of the rule /= what is written. 

Oh well, I'm not building a cage and I'm not protesting anyone who has a cage instead of a bar. But if multiple competitors are allowed to run miatas with sm7 takeoffs and no 1 3/4 inch bar I'm going to be disappointed. This could also affect exocars.

Ok. Drawing from the teachings of three great people: Arnold Schwarzenegger, Mr money mustache, and Andrew Nelson.

I'm making a commitment starting today - each weekday morning I'm at home I will wake up early and work on the challenge car 1 hour.

Combining the following teachings:

1. Arnold - if you want something, wake up early and spend your first hour doing it.

2. Mmm - self improvement can start anytime, if you want something, make the change immediately and build a habit.

3. Andrew - do something on your challenge car every day.

This will not be easy as I'm not a morning person. But I did it today and felt great.

About 35 hours total so far. Today I spent just cleaning up the shop and organizing parts. Need to make a clean space for higher quality work.

I think I am going with the engine further back. 

And I also think I am cutting out the existing main hoop and replacing with a nhra roll bar (I may try to move the main hoop back a bit).

However, I think the first step is to get the engine mounted and running in the car. 

Robbie said:

SVreX said:

I think I’m lost. 

Are you saying that because the car is an open top with non-DOT tires that it has to have a roll bar that’s 1 3/4”, even if it’s incorporated into a cage?

That sounds off. 

I've re read the rules again and I am more sure that is how the rules read. 

4:10 roll bars are mandatory in all open top cars running 13.49 or faster or non dot tires.

The rules also go on to say that in case of conflicts, the challenge rules override the nhra rules. So even if nhra says a cage is better than a bar, the challenge rules are technically saying the bar is still mandatory.

Again, I'm pretty sure I know what the spirit of this rule was. And I think you do too. But the spirit of the rule /= what is written. 

Oh well, I'm not building a cage and I'm not protesting anyone who has a cage instead of a bar. But if multiple competitors are allowed to run miatas with sm7 takeoffs and no 1 3/4 inch bar I'm going to be disappointed. This could also affect exocars.

I’m not disagreeing with you that the GRM rules say that. I’m saying the rules are poorly written.

Consider a 10 second open top car.  If a roll bar was installed per your interpretation, it would violate the NHRA rules, the track tech inspection, and GRM’s own insurance company. I agree that’s what it says, it can’t be what it means. 

I thought you were trying to make the case FOR having a kart-style “cage”. 

This one deserves a little more input from GRM, and/or NHRA (regarding karts). 

The potential plus side to building to NHRA specs, is ERW tubing is allowed. MUCH cheaper than DOM. As noted in other threads, you can get pre-bent main hoops from JEGS/Amazon for cheap. Just look for one that has close enough dimensions. 

Now, if you're planning to use it for SCCA or similar stuff after the challenge, then maybe it's not a great option, but for challenge budget, it's nice. 

Time to give me a piece of your mind. What about these mounts is dumb, overbuilt, underbuilt, inefficient, hacky, etc?

Consider that I will be using angle iron and square tubing. Frame will be welded, but will bolt to the engine's factory mount holes, and the frame will bolt to the existing engine sliders on the chassis.

Realistically, how much does the engine need to move to tension the chain?  Could you do a pivoting mount instead?  Seems simpler.

¯\_(ツ)_/¯ said:

Realistically, how much does the engine need to move to tension the chain?  Could you do a pivoting mount instead?  Seems simpler.

That's a good thought, I was thinking of sliding mounts because that's what's already there. I'd just be bolting to the existing sliders.

In reply to Robbie :

I'm just envisioning every shift and launch slowly yanking that engine back along the "tracks" until the chain gets loose enough to do bad things.

Add a spring. 

If it’s a pivot mount, with a strong spring, it will self-adjust. 

You could also do a solid mount for the engine, and use an old sprocket on a bearing that can be adjusted as a tensioner. 

In reply to Robbie :

What if you just used steel or aluminum plates, instead of the tubing and angle?

Then you wouldn’t have to be concerned about the strength of each joint as the engine torqued.

In reply to SVreX :

Aluminum side plates on the engine would be my suggestion as well.

Keep the sliding tray. It's already there and the screw jacks won't allow the engine to walk around.

Spread the slider rails apart front to rear, then use some box or angle to fix them together and provide an attachment point for the side plates.

Threaded turnbuckle locks on the sliders would work as well. Lock it in place so it can't mobe over time, but is still adjustable. 

How about a repurposed serpentine belt tensioner?

Plates would be trick. Any ideas on where I can get a couple 20"x20" x 3/16 or 1/4"? aluminum plates on a challenge budget?

I'll have to try and swing by the scrapyard and have a look.

SVreX said:

Robbie said:

SVreX said:

I think I’m lost. 

Are you saying that because the car is an open top with non-DOT tires that it has to have a roll bar that’s 1 3/4”, even if it’s incorporated into a cage?

That sounds off. 

I've re read the rules again and I am more sure that is how the rules read. 

4:10 roll bars are mandatory in all open top cars running 13.49 or faster or non dot tires.

The rules also go on to say that in case of conflicts, the challenge rules override the nhra rules. So even if nhra says a cage is better than a bar, the challenge rules are technically saying the bar is still mandatory.

Again, I'm pretty sure I know what the spirit of this rule was. And I think you do too. But the spirit of the rule /= what is written. 

Oh well, I'm not building a cage and I'm not protesting anyone who has a cage instead of a bar. But if multiple competitors are allowed to run miatas with sm7 takeoffs and no 1 3/4 inch bar I'm going to be disappointed. This could also affect exocars.

I’m not disagreeing with you that the GRM rules say that. I’m saying the rules are poorly written.

Consider a 10 second open top car.  If a roll bar was installed per your interpretation, it would violate the NHRA rules, the track tech inspection, and GRM’s own insurance company. I agree that’s what it says, it can’t be what it means. 

I thought you were trying to make the case FOR having a kart-style “cage”. 

This one deserves a little more input from GRM, and/or NHRA (regarding karts). 

At the 2017 Challenge, I ran my Miata on SM7s and no roll bar. No one blinked an eye. Ran the drags on Mickey Thompson slicks, too.

In reply to DeadSkunk (Warren) :

Which, in my opinion, wasn't unsafe at all. Unfortunately with this new rule, it is no longer meeting the letter of the rules. I'm worried that this will cause issues.

In reply to Robbie :

The other place I have good luck with finding scrap is your local water jet or laser cut company. They end up with some odd pieces from internal cutouts and they are ussally willing to sell for scrap prices. I have a guys I use for parts and sometimes if I can wait he will cut parts nested in another project for a little over the mterial cost. Cant hurt to check and ask, all they can say is no.

Robbie said:

Ok. Drawing from the teachings of three great people: Arnold Schwarzenegger, Mr money mustache, and Andrew Nelson.

I'm making a commitment starting today - each weekday morning I'm at home I will wake up early and work on the challenge car 1 hour.

Combining the following teachings:

1. Arnold - if you want something, wake up early and spend your first hour doing it.

2. Mmm - self improvement can start anytime, if you want something, make the change immediately and build a habit.

3. Andrew - do something on your challenge car every day.

This will not be easy as I'm not a morning person. But I did it today and felt great.

Good advice, I need to follow it as well, with one ca rto put bak together and another to build. I should not be sitting around doing nothing.

Because if this, i took 10 from lunch to finish passengers mirror install and door maintenance on the duster

This is going to be amazing. Keep it up.

36 hours now after another hour cleaning and organizing. After taking apart the datsun, the f440, and also unloading a few boxes worth of motorcycle, I had parts everywhere. Now almost everything is boxed back up and organized.

Also, I pulled the engine again and turned the car on it's side:

This was a reasonable task for me by myself. It's really light!

I wanted to dump all the rocks and pebbles out (haha). No really I wanted to look at the bottom and I might zip out all these rivets so I can temporarily remove the bottom.

Note to self, left front bottom spherical bearing is a bit loose.