Gator's 818R

[Mitch Wright]

I will take a shot of the front of the door's along with a measurement on both sides. I would bet you can still get them in there using 2.5" tubing.

[Sgt.Gator]

Tom has finished tacking up the 818R Halo Cage for Tall Boys!
It's inspired by the Lotus 2-Eleven FIA GT4 design.



Tom's done a good job replicating it to the 818R frame.
The tubes triangulate with downtubes in the frame:

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Closeup of where the front hoop triangulates with the existing front low hoop, crossbar, and downtube:



I should be able to get in and out thru the top as the normal exit/entry, or possibly thru the "window", I'll have to practice on both. And thru the "window" if the car is upside down sitting on the roof.

This should end any questions about the broomstick test.

Please let me know if you see any issues before we finish weld it!

[Hindsight]

VERY cool!!! It will be so much safer. I want to do something similar.... Even with my S, at the speeds I hit on the track, I really feel nervous without this kind of protection.

[Mitch Wright]

Looking good

[Rob T]

It looks really good. I can't tell from the picture, but is the rear tube the same (standard) height that came with the car?

[Sgt.Gator]

Thanks Mitch and Hindsight.

It would be cool to do an FEI analysis to determine if this makes the car stiffer or flimsier. My layman's eye says it probably stiffer.

[Sgt.Gator]

It looks really good. I can't tell from the picture, but is the rear tube the same (standard) height that came with the car?

Yes. The Main hoop (Rear) is unchanged. The same rear braces too.

[Zach34]

That's awesome. Good to see more frame improvements. All that tube coping had to be time-consuming. Very interested to see how looks with the body on.

What's going on with the panel with the 4 large circular holes close to the steering wheel?

[DanielsDM]

I like it.
I would add some gussets where the smaller diagonal bar meets the front hoop.

[C.Plavan]

Now that is the correct way to make a cage for the 818R. Very nice.

[Sgt.Gator]

That's awesome. Good to see more frame improvements. All that tube coping had to be time-consuming. Very interested to see how looks with the body on.

What's going on with the panel with the 4 large circular holes close to the steering wheel?

Gusset. If we roll the car and force is coming down on the front hoop it should strengthen it. It's a bit left over from a previous version where we didn't have the brace all the way back and above the downtube. Once we moved the brace back and directly above that tube it's not as important. But we'll leave it in.

I like it.
I would add some gussets where the smaller diagonal bar meets the front hoop.

That's in the plan. Probably a couple more here and there too.

Now that is the correct way to make a cage for the 818R. Very nice.

Thanks!

[Rob T]

Gator: When you get it worked out, are you going to sell "kits" for the rest of us? Or is there too much custom for each car to make that work?

[Sgt.Gator]

Gator: When you get it worked out, are you going to sell "kits" for the rest of us? Or is there too much custom for each car to make that work?

I hadn't thought of that, but I think it could be done. I'll talk to Tom about it.

[phil1734]

It would be cool to do an FEI analysis to determine if this makes the car stiffer or flimsier. My layman's eye says it probably stiffer.

Unless this "Tom" is the worlds worst welder it's impossible to make it flimsier by adding supports. It's more of just a question of how much you added. I really wish I had done an R chassis for my S. The thing has the torsional rigidity of an over-cooked lasagna noodle. Wouldn't surprise me in the least if it's somewhere in the 5,000 ft-lbs/degree range.

[DodgyTim]

Unless this "Tom" is the worlds worst welder it's impossible to make it flimsier by adding supports. It's more of just a question of how much you added. I really wish I had done an R chassis for my S. The thing has the torsional rigidity of an over-cooked lasagna noodle. Wouldn't surprise me in the least if it's somewhere in the 5,000 ft-lbs/degree range.

We tested the R on a torsion rig at over 17,000 Nm per degree

[Mitch Wright]

That's 12538.60 Ft-lb per degree.
I just jacked up the front of my R over the weekend and with the jack under a front corner of the chassis I raise both sides. So the R is a bit stiffer than a over cooked Lasagna noodle. Not saying it can't be better but the chassis is not bad, which also attributes to the car being sensitive to chassis changes. At least that has been the experience I have.

[turbomacncheese]

Reads to me like he thinks the S is the lasagna noodle, hence wishing he'd built an R?

[phil1734]

Correct, I wish I had done an R chassis for the street as a few others have done. Even my girlfriend generally prefers to step over the doors rather than bother with them so for me there's no reason to have them and the gaping hole they leave in the chassis. I don't have a problem with roll-bar clearance, but that would be an added benefit as well for some. The problem with the S is the doors are completely non-structural without any side-impact bracing, and there is no load bearing center tunnel to help like an OEM vehicle would have, which means all the front-rear interaction goes through a very small, short area.
818s-suspension.jpg
It's pretty much just a skateboard and it's very obvious the chassis flexes a ton both by sound and a simple finger-feel test around the doors pulling up inclined surfaces at an angle.

My arm-chair engineering would have pegged the R right around where you tested it, but it's awesome to see someone has done it. Thanks for sharing Mitch. For comparison, I've tested quite a few convertible OEM performance cars, (Corvette, Mustang, Miata, SLR type deals,) and they generally range from 8,000ft-lbs/degree to 14,000. GT3/GT4 cars typically come in 35-45,000 and open cockpit carbon tub prototypes 55,000. (Pardon my cryptic nature, I do this sort of measurement for a living and I don't feel it appropriate to share the exact numbers/models that someone else paid big bucks for.) I never have done an open tube frame sports-racer/818 type though so I'll add that to my mental database.

[Mitch Wright]

Jim at FFR in one of our conversations that FFR has done structural analysis and mentioned what the number was with and without the diagonal crossbar in the passenger area. I just don't recall the number.

[UnhipPopano]

" I wish I had done an R chassis for the street as a few others have done."

If my memory serves me correctly, there was a discussion concerning the safety of driving the "R" version without a helmet. If you use the R chassis for mostly street, would you modify it, drive around with a possible safety issue, or drive around town with a helmet?

[flynntuna]

I too considered getting a R for the street. And modifying the rollbar by moving the front down bar to have it run along the top of the door and fully gusset the rear down bars behind the seats.

Not sure if that would be effective as far as maintaining the safety aspects of the rollbar or not though,
And really haven't thought about it since I got my car from a second party.

[phil1734]

" I wish I had done an R chassis for the street as a few others have done."

If my memory serves me correctly, there was a discussion concerning the safety of driving the "R" version without a helmet. If you use the R chassis for mostly street, would you modify it, drive around with a possible safety issue, or drive around town with a helmet?

The only issue I see from behind my computer would be the roll hoop brace that runs forward. That tube would need removed/lowered or if it's far enough away at least some serious padding. Obviously nothing about driving these cars on the road is really safe by modern standards. You're realistically only slightly better off than a motorcyclist. I personally am always far more concerned with people driving on the street with 4/5 point harnesses that they leave loose so they can actually turn their head and body to look for traffic/park.

[DodgyTim]

" I wish I had done an R chassis for the street as a few others have done."

If my memory serves me correctly, there was a discussion concerning the safety of driving the "R" version without a helmet. If you use the R chassis for mostly street, would you modify it, drive around with a possible safety issue, or drive around town with a helmet?

I used a drift style seat for my registered "R", not perfect, but it does give a feeling of protection from the sidebar
They also had the advantage of being one of a very limited number of road legal aftermarket seats where I live
autotechnica.jpg

[Sgt.Gator]

The halo is finished but not yet painted. I'm considering going with another color than the typical black for the halo. Maybe Subaru World Rally Blue, Subaru Metallic Silver, or Red to go with my CRR Logo. Tom put smaller tubes in the corners instead of traditional gussets. They should work as well or better, I think he was showing off his coping & fitting skills. Looking at it up close i can see how this is going to make the chassis super stiff, probably the stiffest 818 chassis on the planet today. :


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A few shots with body parts just laid up there for a better visualization:


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So here's where I start to think "Doors..What do I need doors on a R for? I don't need no stickin doors! Then it keeps going...I don't need either of the two rear engine covers...and the rear bumper, to heck with that, it's just a parachute slowing me down....and heck I probably don't need the rear quarter panel/side rails either!

[Hindsight]

Looking good. You had better get one of Josh's digital dashes for that thing!

[Mulry]

That's looking very good, Gator. I'd be interested in a kit if Tom wants to sell them too -- at least the circular pieces at the top. I can bend and form everything else myself.

One design question on the forward-going front hoop triangular brace. Why not take that to the node at the top of the roll hoop to intersect that horizontal bar? Was it a concern that would be more restrictive on ingress/egress? Three-way nodes are definitely more difficult from a fitment standpoint, but they are stronger too, so I'm curious about that decision. Cheers!

[aquillen]

STOUT. I like it.

[RetroRacing]

WOW!! Well done!!

[Sgt.Gator]

Looking good. You had better get one of Josh's digital dashes for that thing!

I'm guessing you know he just installed one in my Palatov D4? Here he is setting up the Gear Indicator.

https://drive.google.com/file/d/1_pl...ew?ts=5a77ebd3

That's looking very good, Gator. I'd be interested in a kit if Tom wants to sell them too -- at least the circular pieces at the top. I can bend and form everything else myself.

One design question on the forward-going front hoop triangular brace. Why not take that to the node at the top of the roll hoop to intersect that horizontal bar? Was it a concern that would be more restrictive on ingress/egress? Three-way nodes are definitely more difficult from a fitment standpoint, but they are stronger too, so I'm curious about that decision. Cheers!

Yes, there was a learning curve to the semi-circular bars. He had a few that didn't bend correctly.

There's two possibilities for making kits:
1) We make a jig and hand cut, cope, and bend the tubes.

2) We use the FF CAD design to include these tubes and have a pro shop that cuts, bends and copes tubes on a CNC system make them for us. I know a shop that does that for the pro teams.
Either way it won't be cheap by the time they are shipped.

And if S builders want a verson too we'd have to borrow an S and do it all again.

Or FF could incorporate a full cage design as an option on future Gen II revisions to the 818.

On the brace question: I don't think that idea came up! It would have either had to angle inwards, or the top bar would have had to come further down the front hoop. Maybe next time! LOL...

STOUT. I like it.

WOW!! Well done!!

Thanks we think so too. I'm pretty confidant that a roll over will be no problem and even a couple of Grand National GT1 cars stacked on top will be survivable!

[Sgt.Gator]

I put it up on scales tonight to see how the weight had changed. The following weights are sort of Go Kart mode, seats in but not bolted down, the only fiberglass body panels are the front fenders. Besides all the extra tubing adding weight I subtracted some weight out: Deleted the parking brake system, the AWIC is now a FMIC (but no IC pipes yet), the crazy heavy rear trunk oem hinges are tossed out; the 15 lb PC 680 battery replaced with 4 lb EarthX ( I'm a dealer!) .
Added: Fire Bottle.

Brando had taken the dry sump out and sold it, so that weight will be going back in.



No Driver.

Total Weight: 1763 lbs
LF: 345 - RF: 391
LR: 541 - RR: 486

Front: 42%
Rear: 58%

I'll put this in the Post your weight s thread too.

[Mitch Wright]

I will start a pool on the completed weight with DS, FMIC and body work 1956#
The guess that is the closest will win a NCM Tee. NCM Tee.jpg The shirt will go to the runner-up if I happen to be the closest.

[Sgt.Gator]

I will start a pool on the completed weight with DS, FMIC and body work 1956#
The guess that is the closest will win a NCM Tee. NCM Tee.jpg The shirt will go to the runner-up if I happen to be the closest.

You're on, I want one of those tee shirts!


Oh wait, I might have an Unfair Advantage...hmm, but Mark Donahue would say go for it!

[Hobby Racer]

2084 lbs for the win!

[Mitch Wright]

Gator put your number in now, you're good plus I guess I could give more than one shirt.

[Sgt.Gator]

Gator put your number in now, you're good plus I guess I could give more than one shirt.

Guess I better weigh this pile of body panels!

That's the 818R's little sister "Pearl" in the foreground. She gained a bit of weight too when we made her Wookie capable. The normal weight was around 950 lbs, when I get the 818R off the lift today I'll get a final ready to race weight. If you ever come to the PacNW Pearl will be at Oregon Raceway Park, ready to rent by the Lap, Hour, or Day.



For the Tee shirt contest: Race Weight No Driver, no pass seat, wet: 1,950lbs.

[Sgt.Gator]

Is anyone aware of a build thread that has this solution?:
Side panels were riveted to the frame. Re-install with some type of quick release fastener like a Dzus, Sparco Hood Pins, Aerocatchs? The doors are bolted on, replace bolts with quick releases? Front and Rear Bumper quick releases?
Overall I want to make it easy to remove as many body panels as fast as possible at the track in minutes.
Thanks!

[Wayne Presley]

I'll say 2015 lbs

[Mitch Wright]

So far entries for the Gator 818R weight pool are:
Mitch 1956#
Hobby Racer 2084#
Gator 1950#
Wayne 2015#
Retro 1990#
DanielsDM. 1972#
Weights has to be in 24 hours before Gator post the assembled weight to win the NCM Tee shirt.

[RetroRacing]

INstall pins sticking down through the bottom door sill, then lean it in at the top to dzus tabs installed at the top for the doors. Super easy to take on and off.
Side panels, install dzus tabs sticking out even with the bottom rail and install wires at the top mounts for the dzus buttons. three at the bottom, two at the top and maybe one on or two on the flat part of the door panel. Just two bolts on each side hold the rear on, so that's easy. The front is more complicated.

Ill see if I can draw something up

[Sgt.Gator]

INstall pins sticking down through the bottom door sill, then lean it in at the top to dzus tabs installed at the top for the doors. Super easy to take on and off.
Side panels, install dzus tabs sticking out even with the bottom rail and install wires at the top mounts for the dzus buttons. three at the bottom, two at the top and maybe one on or two on the flat part of the door panel. Just two bolts on each side hold the rear on, so that's easy. The front is more complicated.

Ill see if I can draw something up

Great info. A drawing would be awesome.