Datsun Roadster Forum-311s.org

Purpose of this thread

Im hoping we can share ideas that you have either adopted from other racecars, or things you've developed on your own. I dont think anyone here is going to be racing head-to-head against each other and will really want to keep their ideas to themselves. If you do, thats fine. My hope is that we can share ideas and help all of the Roadsters get out and kick butt.

I think the biggest thing Ive seen is in regards to airflow and managing that airflow in and around the car.

Airflow into the engine bay

Heres some pics from Solvang of the beautiful #33 car. Direct routing of air into the oversized radiator


The Rock Vest car has a nice heatshield that runs forward to the front, as well as using the headlight opening to route air to the carbs



a few more views of it





Aerodynamics/ Downforce

Removing the windshield seems to be a #1 item for a full-bore racer, so that reduces drag.

I know the BRE air dam is a purely functional setup, anyone care to share close up pics or mods they did to improve its functionality. Has anyone done anything like a rear wing/ spoiler. I dont think this is remotely legal, but has anyone actually tested to see if there is any value to one?

I also have been reading about the airflow into the wheel wells and the lift they can cause. Saw this on a race-car 510 and was wondering if youone has adopted something similar?





Weight Reduction

Obviously anything that doesnt belong should be removed, but are there some often-overlooked items that help trim the fat? Im at the point that the heatercore is about to come out, but not really sure what else there is to do other than lightweight body parts (which Im not sure how legal they are for Vintage racing)

Thank you for the photo of my Roadster and the radiator shroud that said, I am happy to share. Keep in mind that sanctioning bodies will allow some modifications but not others, keep in mind that rules are there for a reason, to make the playing field as even as possible. Note that My 67.5 and Mikes 68 (the Rock Vest Car) raced in different eras with different rules. So for instance my car due to the rules I race with which are C Production rules from 1972 do not allow a cold air intake through the headlight, although it was legal in E Production in the 80's and 90's along with a lower weight and suspension pickup point modifications. With this tips and tricks section you might want to segregate this by classification. That said we can address a few problems that Roadsters have: 1) Roadsters trap heat in the engine compartment, anything you can do to clean up the air going into the engine compartment or to get it out will help with performance, the BRE airdam across the bottom of the car helps clean up the flow and pull some heat out of the motor for instance. 2) comp springs are not a benefit on a roadster, they lower the back of the car too much and don't provide the softer compliance needed in the back of the car. We run the front of the car as tight as possible and the back as loose as possible. We run a Panhard rod to dial in the rear suspension and to adjust the roll center.

Thanks Ron!

I think in general any tips/ tricks should be with the caveat of verifying that it will work in the racers choice of group and their own rules.

But I agree, there are general things that could and should be addressed and should be legal, universally.

Thanks for sharing!

What sanctioning body will you be racing under? I agree with Ron (soft rear suspension with panhard). How light is the car now? In addition to safety, a lot of folks added roll cages strategically to stiffen up the car as well.

cole455 wrote: ↑Wed Jul 25, 2018 7:45 am What sanctioning body will you be racing under? I agree with Ron (soft rear suspension with panhard). How light is the car now? In addition to safety, a lot of folks added roll cages strategically to stiffen up the car as well.

VARA D-production is the goal.

The car should be pretty light right now as there is not much of an interior beyond the dash and single bucket seat, though the heater core still needs to come out. All the glass is still in place for now, as I wont be full-race for a while. Roll bar will also be a two phase project with a proper, welded to the frame roll-bar with harness bar as 'phase one' followed by the full cage when I am all out race car. As far as the roll-bar/ cage is concerned I am going to wait until after the Historics so that I can inspect every single Roadster race car and see what their setups look like.

Thinking out loud, I would assume that the rear bars should go to that crossbar that the rear shocks mount to, but id like to see where others have done before I start cutting holes and welding stuff to my car

The ones I’ve seen, the uprights go directly to the frame rails and the 45 supports go through the trunk and directly to the frame as well.

cole455 wrote: ↑Wed Jul 25, 2018 11:00 am The ones I’ve seen, the uprights go directly to the frame rails and the 45 supports go through the trunk and directly to the frame as well.

Yea looking at where my current roll bar mounts to the body it would need to be a little further back to be as wide and go straight down to the frame rail. The 45* bars seem to vary from cage to cage. I believe the main hoop needs to have the diagonal bar and a harness bar on it.

I am bringing over Alvins pics from the Rollbar thread and trimming it down to show the 45* bar, and also what looks like either a harness bar, or simply a chassis stiffening bar, which Im not sure how legal that would be

Alvin wrote: ↑Thu Jun 29, 2017 12:13 am Other VARA racing roadster roll bar setups

DP-prepped roadsters:

The last pic also shows the bar that goes across from the main hoop to the pass side a-pillar floor. I forgot what Ron called this bar, but he said it was a very helpful bar to have. Id like to have this, but it would need to be either removable in phase one, or something that simply waits to phase two. It certainly looks like something that will really stiffen up the chassis and also aid in safety. win-win

A pic of the the changes that made the Rock Vest car a winner. There is a lot of subtle and not so subtle changes. The more you look, the more you'll see

[quote=2mAn post_id=280570 time=1533250220 user_id=4843]
A pic of the the changes that made the Rock Vest car a winner. There is a lot of subtle and not so subtle changes. The more you look, the more you'll see

bottom_of_the_vest.jpg
[/quote]

Not familiar with this one, looks pretty stock to me!

cole455 wrote: ↑Thu Aug 02, 2018 8:10 pmNot familiar with this one, looks pretty stock to me!

Look at that, I am seeing leaf springs and an axle.. Stock as can be..lol

2mAn wrote: ↑Wed Jul 25, 2018 10:45 amThinking out loud, I would assume that the rear bars should go to that crossbar that the rear shocks mount to, but id like to see where others have done before I start cutting holes and welding stuff to my car

You want to go much farther back. Almost all I have looked at seriously go to the same spot. Back in the back of the trunk, to the frame rails. The forward cross bar is called a Petty bar.. The point of the long diagonals is to keep the hoop standing "just in case"... You don't want to main hoop folding either forward or back..


This one shows the rear bar coming down through the trunk floor to the frame rail. This is a one piece bar going to the main hoop.
.

We are trying to figure out if there is a way for my dad to ride in the car in the parade to the Quail, so you get a shot of the petty bar. My car actually has 2, one from the main hoop, one from the hoop the coil overs attach to. We think it will work for parade duty.. I can sit there comfortably, and my dad is significantly smaller than I am.. There will be some temp roll bar padding going in, and the seat will be removable. Anyway, the Petty bar is a straight bar from the main hoop to the floor (in this car to the post that comes thru the floor), thru the floor to the frame rail.
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When we were working in the fab shop bringing things back to straight, we saw examples of cages built to survive top level off road racing. We feel like we do not need to go this far. But it was pretty stunning to be able to see the thought processes that create these things, and to consider how it would apply to what we are doing.. Like this.. This is the back wall of the passenger compartment. The seat backs are on either side of this. ALL of the forces of the entire truck end here, and keep the energy out of the compartment. It really was awesome to study..
.

Anyway, stay safe. lol

[quote=RCMike post_id=280589 time=1533283191 user_id=2861]
[quote=cole455 post_id=280573 time=1533258652 user_id=1462]Not familiar with this one, looks pretty stock to me!
[/quote]

Look at that, I am seeing leaf springs and an axle.. Stock as can be..lol
[/quote]

Haha, exactly! It's about one of THE most modded one's out there!

I want to have a discussion about roll bars, cages, etc but because it varies from group to group I thought we could focus on the one issue that affects every Roadster everywhere. I had a chance to ask Peter Brock a question at the Historics this past weekend and I asked him what is the best tip for prepping a Roadster for serious racing and he basically said that heat in the engine bay is the biggest killer...

so with that, what ideas do you guys have for heat extraction? I have already started working on something that Greg (greg672000) told me about a heat insulator on the headers, but Im wondering about things like shimming the hood in the back to allow heat to escape?... or other means of venting the engine bay of heat, or possibly routing of the radiator heat out before it cooks the engine bay?... Ive seen some heat shields separating the intake from the exhaust but what extremes have you guys gone to?

You need to give the air that has gone through the radiator somewhere to go. Trans is a tight fit in the tunnel, so where are you going to make low pressure to get the air to go? Choices are up to you.. In my race car, I think the low pressure was created by the air dam, and the heat is sucked out the bottom..

RCMike wrote: ↑Wed Aug 29, 2018 2:10 am You need to give the air that has gone through the radiator somewhere to go. Trans is a tight fit in the tunnel, so where are you going to make low pressure to get the air to go? Choices are up to you.. In my race car, I think the low pressure was created by the air dam, and the heat is sucked out the bottom..

The airdam works wonders for this. This was one of the first things BRE found after installing the first one. Suddenly, the car ran cooler. Create an air dam and you will decrease drag, and increase cooling.

Will