Track forum general chit chat.

[elim11]

Anyone going to bimmerfest this year? Will be tracking on Sat. Look forwaring to seeing you guys out there!

[dogbone]

Originally Posted by OG Shark

I'm curious has anyone ever gotten to the point on our specific platform where they have had to dial the downforce down on the front? Where they have had too to run too much AOA on the rear to compensate and introduced too much drag & lost pace?

I have the hood & fender vents - not installed but leaning towards putting them on when the rest of the aero goes on. I'm planning to run through a few plywood designs as test runs. 5" and not having to be chassis mounted sounds pretty nice - is that why you run the panel latches? Is the splitter pulling on the bumper too much without them?

I doubt many people have achieved too much aero downforce on this platform. On a pro-level build, I have heard someone claim that they had so much front mechanical grip that they felt the need to reduce it.

Ah---the fender latches. I forgot about those. On the OEM setup, there is a thin, flat metal hangar that sits between the bumper and the fender and connects them. The front aero was pulling the bumper down enough that the hangar was being bent. The tip of the hangar is sharp and was being pulled down so much that, at Auto Club Speedway, the metal hangar was grinding the edge of my tire. Yuck. So, Racewerkz Engineering found these latches and installed them. They've been GREAT. Problem solved 100%.

[roastbeef]

dogbone, i'd like to see you with a chassis mounted time attack front splitter...

[slicer]

Originally Posted by roastbeef

dogbone, i'd like to see you with a chassis mounted time attack front splitter...

Me too - considering everything that was done to bandaid the OE bumper to accommodate the lip it would have taken similar effort to fabricate a chassis mount.

[dogbone]

Originally Posted by roastbeef

dogbone, i'd like to see you with a chassis mounted time attack front splitter...

hehe you're talking about one of those Unlimited Class dining room table-sized splitters that could sit a family of 4 for dinner? Yeah that would be pretty awesome.

In all seriousness though, you have to start with a light car. All the aero in the world can only do so much good if the car is heavy, and we just have a heavy platform. The M3 just isn't a true time attack platform. But that doesn't stop it from being fun!!

[roastbeef]

Originally Posted by dogbone

hehe you're talking about one of those Unlimited Class dining room table-sized splitters that could sit a family of 4 for dinner? Yeah that would be pretty awesome.

In all seriousness though, you have to start with a light car. All the aero in the world can only do so much good if the car is heavy, and we just have a heavy platform. The M3 just isn't a true time attack platform. But that doesn't stop it from being fun!!

i just think you can do better, and i'd like to see more effort is all.


(i have to live vicariously through you guys temporarily)

[slicer]

Originally Posted by dogbone

hehe you're talking about one of those Unlimited Class dining room table-sized splitters that could sit a family of 4 for dinner? Yeah that would be pretty awesome.

In all seriousness though, you have to start with a light car. All the aero in the world can only do so much good if the car is heavy, and we just have a heavy platform. The M3 just isn't a true time attack platform. But that doesn't stop it from being fun!!

I would settle for the same size splitter (that you currently have) chassis mounted

[dogbone]

Originally Posted by slicer

I would settle for the same size splitter (that you currently have) chassis mounted

A few years ago, I recall Racewerkz Engineering saying that chassis mounting a splitter on a DCT was challenging. I'm not aware that they ever came up with a solution for chassis mounting a splitter to a DCT. By comparison, I believe a 6MT was much easier to install a chassis mounted splitter.

Regardless, the bumper mounted splitter is very effective. Remember, the downforce is not just caused by the splitter itself pressing down. A splitter encourages air to go over the car, instead of under it. As the air goes over the hood, that is creating force. And, by allowing less air under the car, there's less lift underneath the car. So, the splitter itself doesn't need to stand up to the weight of 4 fat dudes just to be useful.

Again, I'll preach a bit of practicality-----several of the chassis mounted splitters that I have seen that ripped off the car destroyed a TON of shit underneath the car. They're potentially hard-connected to so many things underneath the car, that when they rip off.....they take a ton of stuff with them......We saw one guy with a chassis mounted splitter on an E9x M3 rip that thing off and it took a bunch of fluid lines with it.....the car was oozing all kinds of liquids everywhere.......nasty.....

So, while chassis mounting would be nice, and it's an impressive party trick to have someone stand on your splitter.......I don't think it's necessary for the track day enthusiast given what I've experienced. Again----let's be practical here people!!! (yeah like any of this is practical.....)

[OG Shark]

Originally Posted by dogbone

A few years ago, I recall Racewerkz Engineering saying that chassis mounting a splitter on a DCT was challenging. I'm not aware that they ever came up with a solution for chassis mounting a splitter to a DCT. By comparison, I believe a 6MT was much easier to install a chassis mounted splitter.

Regardless, the bumper mounted splitter is very effective. Remember, the downforce is not just caused by the splitter itself pressing down. A splitter encourages air to go over the car, instead of under it. As the air goes over the hood, that is creating force. And, by allowing less air under the car, there's less lift underneath the car. So, the splitter itself doesn't need to stand up to the weight of 4 fat dudes just to be useful.

Again, I'll preach a bit of practicality-----several of the chassis mounted splitters that I have seen that ripped off the car destroyed a TON of shit underneath the car. They're potentially hard-connected to so many things underneath the car, that when they rip off.....they take a ton of stuff with them......We saw one guy with a chassis mounted splitter on an E9x M3 rip that thing off and it took a bunch of fluid lines with it.....the car was oozing all kinds of liquids everywhere.......nasty.....

So, while chassis mounting would be nice, and it's an impressive party trick to have someone stand on your splitter.......I don't think it's necessary for the track day enthusiast given what I've experienced. Again----let's be practical here people!!! (yeah like any of this is practical.....)

Again with the practicality! Next thing you know you're going to be preaching things like responsibility & self-discipline when it comes to building our cars! This is the track forum good sir - there is no room for concepts such as those!

[roastbeef]

here's a thought- what about cables or wire that are chassis mounted that have a combined break away limit? that way, when shock weight is introduced, they give up and the splitter just falls off? how many you would use would depend on how many connections you have.

[OG Shark]

Originally Posted by slicer

I would settle for the same size splitter (that you currently have) chassis mounted

If he hasn't had any issues previously what would be the advantage? Not being sarcastic (if it comes across that way) - serious question. Thanks.

[dogbone]

Originally Posted by OG Shark

Again with the practicality! Next thing you know you're going to be preaching things like responsibility & self-discipline when it comes to building our cars! This is the track forum good sir - there is no room for concepts such as those!

I know I know......I'm probably the last person that should be on this forum preaching practicality, but in my head, I FEEL like I'm a practical guy!!

I mean, c'mon----I could have told you that without a carbon flat bottom, your car has no chance at being a real track car. There. Is that better?

[OG Shark]

Originally Posted by roastbeef

here's a thought- what about cables or wire that are chassis mounted that have a combined break away limit? that way, when shock weight is introduced, they give up and the splitter just falls off? how many you would use would depend on how many connections you have.

What is the benefit of stanchions vs cables anyways?

[OG Shark]

Originally Posted by dogbone

I know I know......I'm probably the last person that should be on this forum preaching practicality, but in my head, I FEEL like I'm a practical guy!!

I mean, c'mon----I could have told you that without a carbon flat bottom, your car has no chance at being a real track car. There. Is that better?

I thought the carbon full flat bottom was a given

[roastbeef]

Originally Posted by OG Shark

What is the benefit of stanchions vs cables anyways?

all i have are theories, since i haven't experimented at this level yet. i would argue that cables aren't as rigid as stanchions.
now, i'm not sure how much someone could tell the difference, but its my first thought.

dogbone has pics of his car on the roval at autoclub speedway, which is the fastest track out here in terms of miles per hour. you can clearly see the front splitter flexing down between the stanchions.
my theory (continuing with the same theory i poised above), is there is lost downforce in that flex. the splitter is absorbing it to an extent. the splitter is attached to the bumper and the bumper is moving/flexing a little bit. i feel like cables would add a third moving/flexing component.
here is another thing- flexing or not, its still creating downforce. i'm not 100% confident that it isn't creating the same amount of downforce that it would if it was much more rigid and chassis mounted. but- does it have a different effect by being more constant? so maybe being flexible doesn't directly help with downforce, but it helps with how the chassis behaves/responds when the downforce is applied.

i'm just thinking and typing, i'm not trying to present this as fact.

[Bartledoo]

Originally Posted by roastbeef

all i have are theories, since i haven't experimented at this level yet. i would argue that cables as rigid as stanchions.
now, i'm not sure how much someone could tell the difference, but its my first thought.

dogbone has pics of his car on the roval at autoclub speedway, which is the fastest track out here in terms of miles per hour. you can clearly see the front splitter flexing down between the stanchions.
my theory (continuing with the same theory i poised above), is there is lost downforce in that flex. the splitter is absorbing it to an extent. the splitter is attached to the bumper and the bumper is moving/flexing a little bit. i feel like cables would add a third moving/flexing component.
here is another thing- flexing or not, its still creating downforce. i'm not 100% confident that it isn't creating the same amount of downforce that it would if it was much more rigid and chassis mounted. but- does it have a different effect by being more constant? so maybe being flexible doesn't directly help with downforce, but it helps with how the chassis behaves/responds when the downforce is applied.

i'm just thinking and typing, i'm not trying to present this as fact.

It could actually be giving him more steady-state downforce if the splitter is getting pulled closer to the ground because of the deflection. He basically has active aero haha. The transient downforce (while the whole assembly is in the process of increasing deflection) would probably be very slightly less, but his setup must not be too loose.

[roastbeef]

yea, i'm not sure. think about it backwards like this- if f1 teams had the ability to make the front aero 100% rigid with no deflection, would they do it? durability and weight aside, i would guess yes.

i forget exactly how the story goes for the canards that dogbone has, but there was a reason why they constructed the metal bands to tighten them up and increase rigidity.

[slicer]

Originally Posted by OG Shark

If he hasn't had any issues previously what would be the advantage? Not being sarcastic (if it comes across that way) - serious question. Thanks.

I think he has had some issues with the bumper pulling away from the fender which has resulted in him installing the clips. Have you ever removed your front bumper? It's not a rigidly mounted structure. Plus the bumper itself is flexible plastic - a noodle. DB is a fast driver and obviously his setup is working for him but that certainly doesn't mean that there isn't room for improvement. This is all part of the fun... And please don't think I'm claiming to be the ultimate authority of this topic.

As a general rule you want your splitter to be rigidly mounted (along with your wing) as you want the downforce to get transmitted to the chassis to push the car down - not to the bumper to flex it to the point of pulling out of the mounts.... then to the chassis.

[SAMM3Y]

I dunno if you track guys run aluminum under trays but the Turner aluminum tray is chassis mounted, what about attaching an APR splitter to one of those?

[slicer]

Originally Posted by dogbone

A few years ago, I recall Racewerkz Engineering saying that chassis mounting a splitter on a DCT was challenging. I'm not aware that they ever came up with a solution for chassis mounting a splitter to a DCT. By comparison, I believe a 6MT was much easier to install a chassis mounted splitter.

I'm not sure why that would be the case. There isn't really any difference on the front end of the car that I know of.

Originally Posted by dogbone

Regardless, the bumper mounted splitter is very effective. Remember, the downforce is not just caused by the splitter itself pressing down. A splitter encourages air to go over the car, instead of under it. As the air goes over the hood, that is creating force. And, by allowing less air under the car, there's less lift underneath the car. So, the splitter itself doesn't need to stand up to the weight of 4 fat dudes just to be useful.

Good point but it could do more if it's mounted rigidly.

Originally Posted by dogbone

Again, I'll preach a bit of practicality-----several of the chassis mounted splitters that I have seen that ripped off the car destroyed a TON of shit underneath the car. They're potentially hard-connected to so many things underneath the car, that when they rip off.....they take a ton of stuff with them......We saw one guy with a chassis mounted splitter on an E9x M3 rip that thing off and it took a bunch of fluid lines with it.....the car was oozing all kinds of liquids everywhere.......nasty.....


So, while chassis mounting would be nice, and it's an impressive party trick to have someone stand on your splitter.......I don't think it's necessary for the track day enthusiast given what I've experienced. Again----let's be practical here people!!! (yeah like any of this is practical.....)

I really don't think a bumper mounted splitter is any more practical than a chassis mounted version. I suppose this all depends on how the splitter is mounted and the rigidity of the splitter itself. The same damage you described could occur with a bumper mounted splitter that gets wedged up and into the fluid lines. I have had multiple GT4 splitters get hung up and rip away from my bumper causing damage to the bumper itself (not to any fluid lines). While a splitter that is not mounted to the bumper in any way would not cause any damage to it. For example the GTS splitter (too small I know) is mounted to a bar that is mounted to the chassis. It doesn't have any contact with the bumper. I think this would actually be a better scenario if it rips away. A very rigid splitter has the potential to do some damage when it get's ripped off - no matter how it's mounted. Now, if the chassis mounts are done in a way that they are near fluid lines, then I can see your point. I would like to think there is a safe way to execute. For Example - an easy way to take some of the load off your bumper would be to change the splitter rods. The splitter rods running to your splitter could be mounted to the bumper support (instead of the flimsy bumper). Maybe you have already done that but it looks like it's mounted to the bumper.

Not meaning to claim to be the ultimate authority here - just partaking in some thoughtful discussion.

[slicer]

Originally Posted by SAMM3Y

I dunno if you track guys run aluminum under trays but the Turner aluminum tray is chassis mounted, what about attaching an APR splitter to one of those?

It's only chassis mounted to on the back end where it meets the Reinforcement plate under the front sub frame. Towards the front it's mounted to the bumper - which is not rigid at that point.

[roastbeef]

Originally Posted by SAMM3Y

I dunno if you track guys run aluminum under trays but the Turner aluminum tray is chassis mounted, what about attaching an APR splitter to one of those?

i'm not sure how to feel about it. i'm not sure how much of the undertray i would incorporate in mounting a chassis mount splitter- i wouldn't want something to rip away all of the 8mm mounting bolt parts of the undertray and fender liners.
i'd want to have something that comes through the felt near the "frame" and some stanchions that extend from the composite bumper rail behind the bumper to the splitter.