Advice required: Making complicated brake duct out of aluminium sheet

[Hyperblade]

I need to go from this hole at a 45" angle up, right and inward towards engine bay and then adapt shape to to a 2.5" or 3" outlet to attach the hose on to, space is very tight.

Orange plate will be 2mm ali, currently thinking of having it laser cut instead of doing it by hand.

What options are there for achieving this relatively quickly and potentially at home? 

One I option i had thought of was to 3d print the inner and just hammer the aluminium around it, then get the seam welded (or try to do it in one piece), either way I would probably use a separate ali ring for the hose to clamp to. would end up being welded to the plate

2nd option might be the same inner but get someone to lay up carbon fibre around it (don't know anyone who does carbon fibre, or what that would cost me), but high temp area and not sure how specialised that is.

I can't see fibreglass withstanding temperature?

Any other thoughts on how to solve the problem?

 

 

 

 

 

[Unclejake]

With respect: I think you're on the wrong track as a rigid assembly connected to the sprung chassis (even with flexible air conditioning duct) but then attached to an un-sprung rotating strut will fail in alloy.

There doesn't look like much strength around the aperture  of the orange template and if I'm looking at it correctly it isn't designed to force air onto the rotor??? Perhaps I'm interpreting it incorrectly and you're trying to suck air out?

Is this a street legal car? If so I have no idea of the legalities.. but if it's a track only car air conditioning flexi-pipe and cable ties works pretty well for blowing air onto the rotors.

[RXFORD]

Might help to make a wireframe buck/template first. Can do it with tig wire or gas welding 'panel' wire.

Bend the wire to the shape you want, tape/tack weld them togethor, then you can lay paper over in sections to transfer onto Ali sheet. 

 

[Hyperblade]

11 hours ago, Unclejake said:

With respect: I think you're on the wrong track as a rigid assembly connected to the sprung chassis (even with flexible air conditioning duct) but then attached to an un-sprung rotating strut will fail in alloy.

There doesn't look like much strength around the aperture  of the orange template and if I'm looking at it correctly it isn't designed to force air onto the rotor??? Perhaps I'm interpreting it incorrectly and you're trying to suck air out?

Is this a street legal car? If so I have no idea of the legalities.. but if it's a track only car air conditioning flexi-pipe and cable ties works pretty well for blowing air onto the rotors.

Always open to feedback.

Old one seemed to be ok for 5 + years? It's AE86 front struts so hose goes straight to chassis mount, so hose is taking all the flex. There so some pressure on the plate, but there is a tiny bit of flex in it? I am considering bracing the inlet against the strut to take any movement out of it.

Yeah the aperture is one concern i have, but i really need the biggest hole i can get. (Guess one option is to get the whole thing made out of carbon)

Air is coming in from the strut side from high pressure zone on the front spoiler through the orange pipe.

Race car only, rotors are seeing sustained 600c +, this is a 267mm x 25mm disk all under a 13" rim with a 12 lap race where i'm often in traffic, so getting rid of heat is a big problem, so it needs more than your typical race car.

 

 

5 hours ago, RXFORD said:

Might help to make a wireframe buck/template first. Can do it with tig wire or gas welding 'panel' wire.

Bend the wire to the shape you want, tape/tack weld them togethor, then you can lay paper over in sections to transfer onto Ali sheet. 

 

Good idea! hadn't considered that approach.

[HumberSS]

Youve got two radiused ends on the plate, I would start with two split tubes at each end of the curved slot then curve some flat to stitch in between then duct from there. 3D printing something would be a good way to get a feel for the shape but analog is sometimes easier to figure out on the fly to start with. 

[ajg193]

Just use your brakes less you hoon

[Hyperblade]

3 minutes ago, HumberSS said:

Youve got two radiused ends on the plate, I would start with two split tubes at each end of the curved slot then curve some flat to stitch in between then duct from there. 3D printing something would be a good way to get a feel for the shape but analog is sometimes easier to figure out on the fly to start with. 

Very true, good idea on an approach.

 

1 minute ago, ajg193 said:

Just use your brakes less you hoon

Sometimes when you racing cars with 500hp the braking zone is the only time you will ever get close to feeling like you can pass them

[GARDRB]

Two questions,

One, does the larger aperture on the plate help if you're still only using the same-sized tube to get the air there? Could you achieve the same with a hole the size of the pipe and then vanes coming off the orange plate to distribute the air around the inside of the area? 

Two, have you considered/can you go to a thicker disk to give yourself more material to dissipate the heat

[Hyperblade]

3 minutes ago, GARDRB said:

Two questions,

One, does the larger aperture on the plate help if you're still only using the same-sized tube to get the air there? Could you achieve the same with a hole the size of the pipe and then vanes coming off the orange plate to distribute the air around the inside of the area? 

Two, have you considered/can you go to a thicker disk to give yourself more material to dissipate the heat

Current hole size is 1500mm2, tube is 2.5" (3100mm2) however the inlet on spoiler is 2" (2000m2)

New hole size is 4000m2, I'll be upgrading the tube to 3" (4500mm2) and the inlet to match. If i was 3d printing in metal or maybe doing it carbon fibre it's possible to get the hole on the plate to 4500mm2 but it's a more complicated shape.

So i really do need to increase the hole size, no room internally in the rotor for vanes, only have less than 20mm to play with and there is bolt heads in there as well. also don't think it would help, i need to get air into the center of the rotor and let the rotor vanes then pull it out.

I'm already running maximum disk size you can in a 13" wheel. there is 2mm of clearance between caliper and rim, to go thicker would require new calipers and going to larger rim.

Background: I'm warping rotors as the hats have not been designed large enough and so the air is going straight through and up the outside face of the rotor, I have a solution for that, but that means any air will escape where this plate sit, and that means there will be cool air flowing over one face of the rotor, creating a temperature differential which will cause them to warp again.

At $600 per rotor I can't afford to warp another set (If i can get temperatures into the correct zone they will last many years), so I have to make sure the air goes out the vanes evenly, hence the tight fit, but then I need to ensure enough air gets in, and larger is better in every way as you can always blank off the inlet.
 

I also only want to do this once, so prepared to spend time/money getting it right.

[NickJ]

I've designed and had made exactly this from carbon, it can be done and CF is no dearer than the other options, its the tooling, time and consumables that add up...

Fiberglass would probably be fine, its the resin system that generally defines service temps, no real structural reason to use carbon over glass either.

I love sheetmetal, cheap easy and fast, thats where i'd be leaning as a first off, a diffuser cone to go from the 3d print to feed duct desn't look too hard? Not too hard to CAD, print A3 and then cut out.

[nzstato]

Choice of materials just depends on your comfort in fabricating them as such?

I think making it out of alloy sheet from a basic wireform is ideal.  Once you have the pattern you can flip your sheet to mirror the same on the other side. 

Keep the alloy section is small as your can get away from otherwise could cause some local cracking. 

[Hyperblade]

1 hour ago, NickJ said:

I've designed and had made exactly this from carbon, it can be done and CF is no dearer than the other options, its the tooling, time and consumables that add up...

Fiberglass would probably be fine, its the resin system that generally defines service temps, no real structural reason to use carbon over glass either.

I love sheetmetal, cheap easy and fast, thats where i'd be leaning as a first off, a diffuser cone to go from the 3d print to feed duct desn't look too hard? Not too hard to CAD, print A3 and then cut out.

Do you think it would be possible to do the duct and the plate as one piece in carbon/fibreglass? Does it have to be machined afterwards to give the tolerances required? Can you use PLA as the one time mold or does the resin eat it?

Anyone you recommend in Chch for the carbon/fibreglass work?

1 hour ago, nzstato said:

Choice of materials just depends on your comfort in fabricating them as such?

I think making it out of alloy sheet from a basic wireform is ideal.  Once you have the pattern you can flip your sheet to mirror the same on the other side. 

Keep the alloy section is small as your can get away from otherwise could cause some local cracking. 

Correct, was planning to do this myself (i have limited experience), but running out of time before race day and current thinking is to take a step back do a proper job on this.

[ajg193]

Is there a particular reason to stick with 13" wheels? (Cheap supply of tyres?)

 

Going up a size or two would remove a lot of bottlenecks 

[Hyperblade]

6 minutes ago, ajg193 said:

Is there a particular reason to stick with 13" wheels? (Cheap supply of tyres?)

 

Going up a size or two would remove a lot of bottlenecks 

I run the ex TRS Michelin slicks which are 13" and have amazing performance and cost me bugger all (new are $450 a tyre).

I have a fairly large stock pile of them and the car looks and handles better on them.

Yes, my life would be a whole lot easier if i ran 15" but it's worth the pain for the performance.

[NickJ]

23 minutes ago, Hyperblade said:

Do you think it would be possible to do the duct and the plate as one piece in carbon/fibreglass? Does it have to be machined afterwards to give the tolerances required? Can you use PLA as the one time mold or does the resin eat it?

Anyone you recommend in Chch for the carbon/fibreglass work?

Correct, was planning to do this myself (i have limited experience), but running out of time before race day and current thinking is to take a step back do a proper job on this.

Yeah/Nah/Maybe

Not really an easy short answer cos the variables are huge in composite design, more shape complexity just means more nasty tooling design!

With CF, rule of thumb, anything under 2mm precision needs post machining, of course with specific part experience and process/tooling/layup development that can be shrunk but this is a safe start for a one-off.

If I was making this for you, I would be going for a sheetmetal solution first to get further clarity on air flow requirements, its a dicky subject so before investing in tooling and materials, getting a good idea the plan works (just heavier) is a good start, Aluminium also gives great track day modification options when things don't work out as planned! In one day I could CAD and manufacture both left and right from 0.8mm Al sheet. In one day of design for carbon i'd be lucky to be unloading the first tool from the mill.

As for manufacture, not currently sure who would take this on sorry, most of the suppliers I have worked with would want to be making 100s. Technically I have all the gear here to do it, (mould making, vacuum pumps, ovens etc) but the cost might be prohibitive? 

 

Are you still WFH? i've got plenty of free time, happy to discuss in depth over a coffee/beer

[Hyperblade]

17 minutes ago, NickJ said:

Yeah/Nah/Maybe

Not really an easy short answer cos the variables are huge in composite design, more shape complexity just means more nasty tooling design!

With CF, rule of thumb, anything under 2mm precision needs post machining, of course with specific part experience and process/tooling/layup development that can be shrunk but this is a safe start for a one-off.

If I was making this for you, I would be going for a sheetmetal solution first to get further clarity on air flow requirements, its a dicky subject so before investing in tooling and materials, getting a good idea the plan works (just heavier) is a good start, Aluminium also gives great track day modification options when things don't work out as planned! In one day I could CAD and manufacture both left and right from 0.8mm Al sheet. In one day of design for carbon i'd be lucky to be unloading the first tool from the mill.

As for manufacture, not currently sure who would take this on sorry, most of the suppliers I have worked with would want to be making 100s. Technically I have all the gear here to do it, (mould making, vacuum pumps, ovens etc) but the cost might be prohibitive? 

 

Are you still WFH? i've got plenty of free time, happy to discuss in depth over a coffee/beer

Yeah was figuring all of that would be the case and was wishfully thinking it might have got easier, nothing is ever cheap being 1 off.

Sounds like I'm going the aluminium route, i've take the time pressure off myself as i want this done right, so I can spend some time mucking around and see how far i get.

Yep still WFH most days, thanks for the offer, but i'm probably ok to proceed at this point (but if you ever want to pop round and check it out just sing out), if not will give you a yell

 

Thanks everyone for the thoughts/advice appreciate it!

[mjrstar]

could you maybe make 2 halves from some MDF, then use that to press the shape into aluminium and then weld together, if you get some O state alumimium its very workable...

[Unclejake]

3 hours ago, Hyperblade said:

Warped rotors

One small thing we used to do when I was racing was to move the car (hand push a few hundrend mm) in the pits a few times after each race. 

Our thinking was the hot calliper reduced heat dissipation from the hoy rotor so if we pushed the car further back into the tent every few minutes after the race the rotor would cool more evenly. 

I have no idea if that really helped or not though.  Ha.

[Hyperblade]

1 hour ago, mjrstar said:

could you maybe make 2 halves from some MDF, then use that to press the shape into aluminium and then weld together, if you get some O state alumimium its very workable...

Good idea, I have seen something similar done with 3d printed molds.

38 minutes ago, Unclejake said:

One small thing we used to do when I was racing was to move the car (hand push a few hundrend mm) in the pits a few times after each race. 

Our thinking was the hot calliper reduced heat dissipation from the hoy rotor so if we pushed the car further back into the tent every few minutes after the race the rotor would cool more evenly. 

I have no idea if that really helped or not though.  Ha.

This is actually a thing, pads create a hot spot, or so I've been told. Have been moving it after racing, but believe warping occured during race.

[GARDRB]

1 hour ago, Hyperblade said:

Good idea, I have seen something similar done with 3d printed molds.

I've done a 3d printed dimple die. We pressed panel steel with just a nut and bolt through the die. Alloy should be much easier than panel steel to work too.

It would be a fun CNC project to make up MDF forms