E30 Build Progress

#1

Started removing the interior to prep for roll cage install. Will also pull transmission for rebuild/refresh. Will keep you posted. I am excited to help get the class going in TX.

#2

Perfect is the enemy of good enough. Keep in mind that every thing you do to the car delays it’s ultimate completion. I would guess that most folks that decide to build themselves a race car never complete it. I’d suggest that you create 3 categories of tasks…1) Must do before racing, and 2) Maybe do it after I start racing.

Maybe the tranny rebuild is cat 2.

#3

Mine was supposed to be a dirt cheap 5k build but ended up being 13 and took two years to finish. It is impossible to build a car for less than you will find a logbooked one sold for. I’m sure you won’t listen to reason because I knew better twice. The first was an H-prod x-19 that I wasted a bunch of money on and then scrapped.

#4

[quote=“Ranger” post=65888]Perfect is the enemy of good enough. Keep in mind that every thing you do to the car delays it’s ultimate completion. I would guess that most folks that decide to build themselves a race car never complete it. I’d suggest that you create 3 categories of tasks…1) Must do before racing, and 2) Maybe do it after I start racing.

Maybe the tranny rebuild is cat 2.[/quote]

I’ll second that. I’m going to my third track weekend tomorrow (at CMP), two years after my first one. Mind you, the car has been almost completely rebuilt, so I’ll probably end up sticking it in the wall.

Andy

#5

I hear both of you…but for me it’s all part of the journey. I bought the car knowing the tranny was hard to shift into third gear. I’m not going to re-paint yet…the car is presentable. So the cage, suspension, fire bottle, cut-off switch… and safety gear shouldn’t take too long. I do plan on removing the door glass and putting in NASCAR door bars…any thoughts on this…?

#6

I don’t know whether it is accurate or not, but a very reputable cage builder I know says that X-bars are actually safer than nascar bars, to the point in the car that he built for his brother and him to share he put in X-bars. I’m sure he could give you all the details behind the engineering involved…

I built an IP/GTS-3 M3 many years ago. As much fun as that was, the build kept me from racing. I’m now in the process of buying an already-ready car that I can race (and replace parts on) as soon as it arrives. Also, Great to hear some interest in Texas. My goal is to race at Eagles Canyon in October…

#7

Yes do nascar bars and remove the windows. Your either one of the people who want to keep the car street legal or your not. People who want a streetable race car are a little crazy if you ask me. I’ve never wrecked so I can’t give you a testimonial about why everyone needs nascar bars. You only live once though.

#8

First, a big round of applause for what looks to be the Texas region finally coming online. Super excited to have some folks to race with, I was getting tired of trash talking 944 drivers.

Second, couldn’t agree more on the buying the car ready to race - it is part of the journey, and mine went from daily driver to track only. But others have said this is time not spent racing, and I can honestly say now that I’ve done my first race I wish I’d skipped the journey. You’re already into it so by all means get all ya can out of the experience, but if it helps any making a sure must have list and being aggressive about it will help. I stalled for a few years having paying for my cage, then after getting into r-comps, and then again before buying suit and safety gear. in hindsight wish I’d signed up for comp school as soon as I was close. It’s a great motivator - plus your seats and belts won’t be going out of date a measly year after your first race (like me). And, all the things you preemptively replaced when you bought the car won’t be going bad and cutting your race weekends short (also like me).

Finally, on door bars - I got gusseted x’s based on a lot of research and conversation with bmw folks. The cage shop (who did mostly spec miata’s) were ok with either but recommended nascar style that were “stacked” on top and bottom of the existing crash bar. I went with the X’s based on the research and previous conversations. I don’t regret it, but based on how close the bars are to my leg I do wonder if it would be better to have a little more breathing room in case of a love tap, or t-bone. Well, that and the drivers-ed style crash films they showed in comp school.

Two other things with the cage - allow plenty of time at pick up to look at every weld and make sure you’re happy with it ad that you feel good it will pass tech. I had a couple places that I had to go back because they stitched them but didn’t go back and get them all the way around. Also, don’t think you’ll save money by painting it yourself, just let the cage shop do it so it’s done. Numerous rattle cans, rollers jobs and limboing my tired body through a maze of bars I’ve finally got the thing covered in paint. Almost.

-mark

#9

I am interested in more evidence supporting this:

#10

Thanks for all the feedback. I do all my own welding, for the very reasons stated above. So the next question is 1.5in .120 wall or 1.75 .095 wall for the cage. I’m using the options for the 2501-3000 pound requirements. The car will not be street legal. The reason I asked was because I wasn’t sure if anyone else was gutting the door.(with the exception of the stock crash bar.)

#11

X-bars being stronger than nascar bars doesn’t make much sense to me. I’ll see if I can do that kind of simulation with solidworks this summer if I find the time.

#12

I can believe that they’re stronger as far as overall cage stiffness, especially in a frontal impact. However, when getting side swiped or t-boned, I believe NASCAR bars will do a better job of distributing the impact load to the cage, and this happens at a safer distance from the driver.

#13

Sure, NASCAR bars, because of their bends, might not provide quite as much longitudinal stiffness for a frontal crash as X bars, but keep in mind that they are only 2 of 4 bars in that role. There is also the bar down at the rocker panel and the longitudinal halo bar up above your left shoulder.

In contrast, should you get tboned the NASCAR bars are the big enchilada. So if indeed NASCAR bars aren’t quite as stiff logitudinally, you’d be sacrificing a small amount of passenger cell protection for a frontal crash and gaining a large amount of protection against the tbone intrusion.

A frontal crash, IMO, is a relatively safe scenario because there’s a nice crumple zone in front of you and your harness and HNR are designed for just that scenario. We’re pretty vulnerable to a bad tbone tho. The harness and window net won’t help much, the HNR maybe a little, and a halo seat some.

Not only are are Xbars too close to you, but also the middle of the X tends to be kind of low. That allows for a scenario where a car piles into you such that it’s front bumper is for some reason a couple inches higher than normal and therefore manages to come in just over the center of your Xbar.

The tbone scenario is a dangerous scenario.

#14

[quote=“silence” post=65898]I am interested in more evidence supporting this:

I posed the question to an email list of racers and got this response from one of them, which was then confirmed by a cage builder/race-prep guy that is the only person in California that NASA allows to tech his own cages. He’s arguably the best club race cage builder on the west coast…

It may not answer the “which is safer” argument directly, but it does shed some light on the subject.

[quote]The way I understand it, is the X-bars allow some room for the door structure to crush and dissipate some of the impact before the cage comes into play. With the NASCAR bars, the full energy of the impact is immediately transferred to the very stiff cage structure, resulting in more G’s being experienced by the driver.

I think the ideal setup would be a deformable “crash structure” contained between the X-bars and the door skin. I saw something like this in Racecar Engineering, and I think Tony was talking about it at one point as well…[/quote]

#15

Good day today I got alot done. Everything the needs to be removed for the roll cage install in now removed.

#16

[quote=“ffej” post=65937][quote=“silence” post=65898]I am interested in more evidence supporting this:

I posed the question to an email list of racers and got this response from one of them, which was then confirmed by a cage builder/race-prep guy that is the only person in California that NASA allows to tech his own cages. He’s arguably the best club race cage builder on the west coast…

It may not answer the “which is safer” argument directly, but it does shed some light on the subject.

[quote]The way I understand it, is the X-bars allow some room for the door structure to crush and dissipate some of the impact before the cage comes into play. With the NASCAR bars, the full energy of the impact is immediately transferred to the very stiff cage structure, resulting in more G’s being experienced by the driver.

I think the ideal setup would be a deformable “crash structure” contained between the X-bars and the door skin. I saw something like this in Racecar Engineering, and I think Tony was talking about it at one point as well…[/quote][/quote]
Hmm. I guess it’s a little scenario dependent. NASCAR bars stop intrusion. Stopping intrusion means higher g-loads, that’s inescapable. But if I had to choose between the two, I choose g-loads. There’s no surviving a car in your lap.

Obviously we don’t have much in the way of crush zone on the side, but the other guy does in a tbone and his crush zone absorbs g’s not just for him but for you too. The energy dissapating effects of the crush zone is shared.

Also, consider this. The straight section of the NASCAR bars is what, 2’ long? The bent part of the NASCAR bars fore and aft, would tend to move the impacting car fore and aft. Moving the car means less g’s transfered then stopping the car. Also, those bent bars gain the same advantage of door crush zone that was described for the x-bars. So what we’re really talking about is a 2’ long “hard zone” right beside the driver that doesn’t tolerate much crush, flanked by softer zones that will happily crush. Anything that hits the hard zone pretty much dead on will tend to deflect to either side.

Imagine the scenario where something 6’ wide of uniform hardness tbones you. You have a very hard 2’ section flanked by softer sections. Your 2’ section penetrates the “tboner”, so to speak, and also deflects him a bit fore or aft into your softer structures.

All science and engineering are specialized areas and I’m no specialist. I took my BSME and joined the infantry and it didn’t get much use there. Ok, there’s a couple good stories like when the two tank retreivers were using cables to try to pull a fueler out of a rice paddy. Any idiot could see from the angles of the cables that the fueler was going to flip and spill it’s bezillion gallons of diesel… I dunno, other guys will have to chime in and do their own armchair analysis of scenarios and door bar types.

#17

So far I have gotten the seats, exhaust, and ordered the shocks and springs today. I have the rear subframe removed, for painting and bushing replacements. I also got my tube bender floor mounts completed so will order the DOM for the cage.

#18

Sweet - glad to hear things are comin along, a full podium of e30’s here in Tejas would be a great sight.

#19

[quote=“ffej” post=65937][quote=“silence” post=65898]I am interested in more evidence supporting this:

I posed the question to an email list of racers and got this response from one of them, which was then confirmed by a cage builder/race-prep guy that is the only person in California that NASA allows to tech his own cages. He’s arguably the best club race cage builder on the west coast…

It may not answer the “which is safer” argument directly, but it does shed some light on the subject.

[quote]The way I understand it, is the X-bars allow some room for the door structure to crush and dissipate some of the impact before the cage comes into play. With the NASCAR bars, the full energy of the impact is immediately transferred to the very stiff cage structure, resulting in more G’s being experienced by the driver.

I think the ideal setup would be a deformable “crash structure” contained between the X-bars and the door skin. I saw something like this in Racecar Engineering, and I think Tony was talking about it at one point as well…[/quote][/quote]

Maybe this will tricke-down to the club racing level at some point:

Impaxx foam, side impact protection:
http://www.coastal-automotive.com/solutions/motorsports-safety

The notion that an x-bar and skinned door will work together to dissippate energy in a side impact does not hold water for me. A 2500lb car will move through that sheet metal like it wasn’t there.

#20

Not if you leave the impact bars in the door. I am not advocating, nor did I, a simple door skin with an X bar. The full door structure is what is there. Plus, I trust the cage builder that told me this. He knows far more about it than most do, he is often asked by rules-makers about such things.

As for the impact foam…that is something that would make a considerable difference and would be nice to see some version of it become financially and fitment accessible to those of us that don’t have NASCAR budgets :slight_smile: