134 replies to this topic

[EunUCh]

 watts.jpg   52.54K   1 downloads

 

Nice work !..are the outer ends of the control arms supposed to be where they are or are they meant to be connected to the chassis rails ?

[Bigfella237]

G'day EunUCh, yep there are two ways you can set up a Watts Link, you can either have the pivot attached to the centre of the diff with the arms attached to the chassis (like the factory Fraud setup), OR you can do it the way I have above where the pivot & mount attaches to the chassis and the outer ends of the arms attach to the diff.

 

If I may borrow a couple of eyepeeler's photos, this is what it looks like on an actual car...

 

 

The advantage in doing it this way is less unsprung weight, that is to say, less bulk attached to the actual diff itself.

 

Sprung weight is anything supported by the car's springs (plus a percentage of the springs themselves and anything else like shocks, control arms, etc. connecting 'sprung' to 'unsprung'), sprung weight can be controlled and therefore tuned.

 

Unsprung weight is connected directly to the road and therein lies the problem, more mass equals more inertia, more inertia means the unsprung weight resists changes in the road surface.

 

"Objects in motion tend to stay in motion" - Newton's First Law of Physics

 

Think of hitting a speed bump at speed, a lighter diff will tend to change vertical direction easier and so follow the contour of the bump, a heavier diff would tend to be thrown into the air by the inertia of its own mass, the aim is to keep the tyre in contact with the road as much as possible.

 

[76lxhatch]

What I'm trying to do is design the strength into the structure rather than the material, if I can use 3mm plate instead of 5mm I've saved 40% of the weight

Have you watched Project Binky on Youtube? Celica GT-Four suspension and running gear into a Mini, the guy does a lot of bracketry etc using folded sheet metal (much like factory stuff) rather than simple thicker plate steel like many would. He has less choice with such a small car otherwise its going to kill the weight but he does a good job of it. The videos are reasonably entertaining too.

[Bigfella237]

Wow, those guys on Project Binky do some nice work, I can't believe I just watched all 9 episodes from start to finish.

 

How's his discipline making everything from scratch, pretty sure I (and most other people) would just be cutting brackets and strut towers out of the Celica shell to graft into the Mini, but kudos to them, can't wait to see the finished product now!

[Bigfella237]

It's actually not too hard to do rims in CAD either as it turns out, this was literally just five minutes work (ignore the pattern, I just threw something in there to break up the boredom)...

 

 test rim 17x12.5.JPG   71.27K   1 downloads

 

Hmm, this could get interesting...

 

(It's probably lucky I don't have a CNC machine )

 

[Heath]

[Bigfella237]

A little side project...

 

 SS Grille Emblem_sml.JPG   50.11K   0 downloads

 

 SS Sticker_sml.JPG   43.08K   1 downloads

 

I actually did this for wheel caps but couldn't resist doing an emblem and sticker version!

[Bigfella237]

Pulled an all-nighter on this dual-purpose mechanical/hydraulic handbrake design, damn this thing is taxing my brain power!

 

I've only done the lever so far but that's where most of the magic happens, this is the lever in the straight (cable) position (obviously it won't be see-through IRL)...

 

 Handbrake Lever in Cable Position.JPG   29.56K   1 downloads

 

To change to hydraulic mode you trip the latch underneath and the handle then pivots upward to a 45° angle like this...

 

 Handbrake Lever in Hydraulic Position.JPG   34.72K   1 downloads

 

As the handle pivots in the centre, two opposing "S" cams cut into the back of the primary lever on each side of the pivot alternately push one of the spring-loaded large pins back through the secondary lever.

 

In the straight position, the left pin will engage the mechanical cable pull. Also note the two halves of the ratchet release pins line up in this position too.

 

Changing to hydraulic mode allows the cable pin to retract into the secondary lever and extends the hydraulic pin. Also note the ratchet mechanism is now locked out.

 

Now I know what you're thinking but there is no 'neutral position', if you somehow managed to pull up the handle somewhere between the two detents you would get both cable and hydraulic braking at the same time. And you physically can't change over unless the handbrake is in the off position because that's the only time both holes line up for the pins to alternate.

 

To get an idea of the scale, the whole thing is 350mm long, the primary (front) lever is 35mm OD, the secondary lever is 40mm OD and the two large pins are 10mm OD, the clearances will all be tight so I can't see a 10mm solid pin shearing off in a hurry?

 

The best thing is, for the most part this will look (and act) like an ordinary handbrake lever once it has a boot around it. I may yet redesign that little catch underneath to be a little more discreet, maybe have it covered by the leather boot altogether?

 

I'd love to keep going and finish the back part but I need to check my eyelids for holes.

 

[Bigfella237]

This is not getting any less complicated I can assure you...

 

 Handbrake Assy 04.JPG   47K   0 downloads

 

 Handbrake Assy 05.JPG   40.1K   0 downloads

 

...but I think it's mostly done, although there's still a couple of little things I need to finish.

 

The cable lever is the blue, the hydraulic lever the red. The handbrake can operate through 45° which is full stroke on the hydraulic cylinder (1.400"), not sure how far cables normally pull but I set them up for the same travel too, I can change that fairly easily later if it's wrong anyway.

 

The top of the box sits 150mm off the floor, I could get that down to 100mm if I angle the cylinder but being "in line" (no reservoir, no bleeder) it has to be somewhat self-bleeding, so it would take up a bit of room under the armrest part of a centre console but I doubt that would be any different to any other hydraulic handbrake available?

 

I still have an adjustable proportioning valve to fit somewhere too, I hope to get it under the inner handle facing forward so just the knob is visible, well still not easily visible, but hopefully easily adjustable?

 

[Heath]

Holy shit.

Hate to be a wet blanket, but that's why we have mechanical foot-operated parking brakes in Toranas! hahahah

I hope you actually make this.

[Bigfella237]

I forgot to mention, you may have noticed that I intend to run my handbrake cables through the car as I'll need a full-length console with the top mount of the 3-link rear suspension between the rear seats anyway so I hope to have them follow the upper trailing arm out then run along the axle tubes to the wheels.

 

I guess the design could be modified to run the cables (or a single cable) through the floor but it would take some thought? And I'm just about all thunk out right now!

 

P.S. This is the proportioning valve I downloaded...

 

 Wilwood Prop Valve.JPG   18.57K   0 downloads

 

...pretty sure it should fit where I want to put it?

 

I should give a big shout out to Wilwood too, their website has been absolutely invaluable when designing all these floater kits etc., the amount of technical info they make available is unreal.

 

Everybody bags their product, but if it's even half as good as their tech support I reckon I'd give their gear a go.

 

EDIT:

 

Dammit, note to self, I need to (somehow) add a microswitch for the handbrake light on the dash. And I suppose it should only come on when the cable mode is activated too... hmm

Edited by Bigfella237, 26 July 2015 - 08:55 AM.

[Heath]

Very interesting about the console...

[Bigfella237]

Yeah the console is just another thing on the list of 'things to design'. I want it full length front to back; it'll need arm rests front 'n back to clear the handbrake and rear suspension mount; I want to duplicate the touchscreen controls for the stereo (carputer) front & back; I want to separately duct floor and face/air con vents to the rear seats; and the list goes on (and on).

 

But it's getting to the point where I REALLY need a CAD model of a Torana floor and chassis rails to design stuff off of. I'm more than happy to do the CAD work but I need about a thousand measurements off a body on a rotisserie?

[Rockoz]

Should be near enough detail for the chassis in the plan thats floating around on here to at least get you started.

Would give you base points for the chassis rails.

May be able to get started with it

[Bigfella237]

If you mean this one...

 

 90704_Torrie_Body_Spec_s_122_495lo.jpg   210.86K   1 downloads

 

...I already tried, but there's just not enough detail.

 

I could guess a lot of the angles and probably make it "look" okay but I want to design suspension mounting points and exhaust headers and gearbox cross-members and a truck-load of other stuff so it needs to be a little more accurate.

[Rockoz]

Have you tried a scan to cad application?

[Bigfella237]

Thanks Daz, I'll just have Jeeves warm up the Learjet...
 

Have you tried a scan to cad application?

 

Thanks Rob, is that the thing where you take like a thousand photos from every different angle and upload them all to a cloud server, which then generates a 3D model?

 

Would that work on something so big?

[Heath]

Yeah you can do a bloody cruise liner with the same technique lol. But nobody is going to want to process & clean up the data unless someone's paying them decent coin for it

[Rockoz]

Was thinking more along the lines of taking a scaled drawing and scanning it into a CAD program.

The alignment drawing would give the basics. The program then works out the lengths and angles etc.

Other drawings could then be scanned and overlaid.

Not perfect but may work well enough to give the basis of what you are after

[Sven]

Before I was made redundant a few weeks ago, I got to play with some cool toys.

For dimension acquisition, I used a hand held 3D scanner/camera by Creaform.

The scanner was called Maxscan.

(Image from Wikipedia)
https://en.wikipedia...orm_REVscan.png

First, you place positioning targets all over what you want to scan.
These targets are 10mm diameter stickers, with a black matt black band around the outside, and a 6mm diameter reflective centre.
The first scan you do, picks up the location of these targets, and turns them into xyz coordinates on the computer screen.
The second scan uses the laser to map the surface between the targets.
Looking at the computer screen while scanning, it looks like reverse spray painting, with the object appearing as you sweep over it.

Once you have finished with the scan, you are left with a "skin" of your object.
You export this "skin" (STL) into your CAD program, but you then have to build your model out to the skin.
It's the building of this model that gives you your CAD data.

There is a youtube video of the process.
This video is of the next generation scanner to the one I used.




The CAD program I was using, was UniGraghics.



The next cool toy I spend a couple of years using was FDM machines.

Stratasys, two 900 machines and one 400 machine. (Also a wax printer to make investment casting prototypes, but I hated that printer)

http://www.stratasys...es/fortus-900mc

These use a calibrated tube between heater plates, to extrude ABS plastic, while the head of the printer moved around to build your part.

There where two sizes of calibrated tubes that I mainly used.
The larger one is called a T20 tip, and the smaller one is called a T12 tip.

The T20 extrudes a ribbon of plastic 0.7mm wide, for the xy axis of the build, with the table dropping 0.33mm for the z axis.
The T12 extrudes a ribbon of plastic 0.45mm wide, for the xy axis of the build, with the table dropping 0.178mm for the z axis.

There are a couple if interior build styles.
Solid or honeycomb, depending on what you want you part to do.

I was doing a lot of pattern masters, that would then be turned into production patterns for the foundry, so a lot of the prints I did was with the honeycomb.



Okay, if you've stayed with me this far, how would I use this on our cars.

Reproduction parts baby.

Example?

Flares, and I'll just talk rear wheel flare for a hatchback for this example.

Choose a car with the best example of the wheel flare fitted.
Place the positioning targets on the flare and some of the body panel, WHILE STILL ON THE CAR.
Scan the flare and some of the body panel and save three version of the same file, but with different file names (this will hopefully make sense soon).
Take the flare off the car, and with the second copy of the scan, scan the back of the flare.
With the third copy of you original scan, scan the rest of the body work of the car.

You will now have three scans, all aligned to each other.
One with the flare on the car. (So you know what it's supposed to look like on the car)
One of the complete flare. (So you know what the back looks like)
One with the surface of the area of the car, the flare fits to. (So you can make the flare you want to make, actually fit the car, by following the cars profile)

Import the scans into you CAD program, and start modelling.
Remember that your building your model out to the scan.
The scan is just a skin to guide you.

Once you have your model, send it to your 3D printer.

Trial fit your flare to the car.
This is to make sure that you got it right before starting on production equipment.

By using this method, you don't run the risk of damaging the part.

And just for a reality check...
The scanner costs US$45000
The large 900 printer costs US$500000.

I spent 5 years using this stuff thinking, "There has to be a better use for this, besides my actual job."

:-)

[Heath]

Bradken?