lightweight pedal box design and build.
Turbo Mini Forums

Good evening,

Well morning. Currently burning the wick at both ends.

If anyone has any a bit of spare time and a standard pedal box in the spare parts store you wouldnt mind dragging them out and chucking them on the scales would you?

Any help would be much appreciated!

Thanks

Samuealle.

Edited by Sam on 22nd Apr, 2011.

Ive got mine out at the minute, Ill try and weigh it later

pedals and all of you could please bud, everything bar the master cylinders pretty much. Ill owe you a drink at one of the show.

Guess 2 measurements are better than 1 though;

2.505kg for a servo-type pedal box, inc. linkage between brake pedal and servo, but one edge from both the brake and clutch pedals trimmed off (due to having pedal extensions on). No brake switch fitted either (the plastic thingy).

Dave

Ah thats good to know, my one should come in at 1.38kg (What solid works says) Cheers for that Pottsy. Its usefull information to have on here!

Ideally though im after a non servo. Both pedals, the box. pin and nut. owt else.

Standard is 2.298kg, your target weight is 1.356kg

I seriously doubt it!

Seems an appropriate time to suggest a Mini version of the cycling Weight Weenies website (http://weightweenies.starbike.com/listings.php).

Clearly requires a lot of input to set up though me thinks - and someone that knows how to build websites of course!

Well, wouldnt think it would be that hard to setup. Wouldnt take too long to chuck together i wouldnt have thought...But yeh, thats on a bit of a tangent....A thread wouldnt be such a bad idea on here to be fair.

Cheers for that paul. still got a little way to go then, given i have to factor in my mountings........Still think i could remove a little weight. Till, i work out the solidworks stress testing malarky.

Im guessing it has one. I cant see where i can remove anything yet....

1137g now. Plus 148g for tube for mounting. 1285g in total. Ill see what the program kicks off in testing.

I think testing with a force of 120kg on the pedal is sensible. Id say thats about twice what i would ever realistically achieve

Good going, any pictures to show us?

I seriously doubt it!

Sounds good, i'd like to see the finished product too.

A static load test of a pedal, ill do a fatigue test some point soon.



3kN static load. Pivot on pin location and static fixture on "cable hole"

In the worse case scenario im only ever likely to tickle 1kN of force. But a safety factor is required in something so critial.

Obviosly the clutch pedal can go lighter then the one shown. The one shown is 434 grammes so quite a chunky item.

Paul, do you think you could move this to the show us yours section and ill use this thread as a project log rather then clutter up the forum.

Also for my benefit as im an aspiring engineer and all this is a learning curve for myself. It would be fantastic for input from some of the very accomplished members of this forum.

:)

Edited by Sam on 22nd Apr, 2011.

What material is it?
How thick is it?
What size holes are they?

The stress test looks good, have you tried pushing it to the limit?

I seriously doubt it!

Its mild steel. I can only presume a medium carbon grade. So when the time comes, ill see what i can get hold of, input the data as such and re run the tests. I dont think itll be too far off to be honest.

The holes are 20mm dia into 5mm thick material.

Limits wise, ill lighten untill i get close results at 2kN.

Cheers for popping this over by the way.

You can lose a lttle more by replacing the foot pad with alloy and drilling/tapping a couple of M4s into the main upright

I seriously doubt it!

http://turbominis.co.uk/forums/index.php?p=vt&tid=170151

nice work sam, what software are you using?

600 MPa @ 1000N for steel is a little high !!!!!

I use Strand 7 at work, need any help give me a shout

Edited by longy on 22nd Apr, 2011.

1972 998 TURBO SLEEPER

Just thought, does that take into account the opposite force of the master cylinder pushing the on the other end?

I seriously doubt it!

Well. I did a little bit of make shift testing.

76kg is all ive got in my right foot. Thats properly going for it. Under normall breaking pressure. 50kg max.

So by this logic, im going to test at double that the most i could give. 70kg. Multiply that by two. So near enough 1.4kN. I Ran a test at this.....



Using Solid Works for this. Been using it for perhaps two days now. Infact. first time ive used anything like this. So still getting used to things!

360MPA with steel yield around 450MPA, well probably for what ill be using anyhow.

Edited by Sam on 23rd Apr, 2011.

Just done a pedal again, so ill construct the pedal again. Bit lopped off the top. Holes into slots and 4mm steel.

Down 152g per pedal. So. 833g + 150g. So 983g all steel contruction.



All steel construction. With alloy pedals another 42g per pedal can be saved.

So. 749g + fixings. I think i could probably get away with much shorter fixings thinking about how i want everything set out. So 200mm of tube perhaps. 94g. So 749g + 94 = 843g


But again, subject to overall stess test!

Over all weight with master cylinders and fluid in the reservoirs.

843g
286g x 2 (master cylinders)
113g x 2 (Fluid. 4.0 oz)

1641g overall if i use pauls idea for the pedal pad, thats as light as the pedals are gunna get.

Edited by Sam on 23rd Apr, 2011.

I admire the work you are doing, but regardless of what solid works says I think you are mad to be looking to save this amount of weight from the brake pedal. I am certain there are other areas of the car not as safety critical that will yield the same weight saving.
For instance, there is no way you will load the brake pedal when used in anger perfectly square as the model suggests. So now take into account bending loads. And bending loads into a 4mm pedal sound a particularly BAD idea to me.

As Tom says but worse....

Assuming you are fitting this to a standard pedal box, the existing design has a very large offset at the lower end to keep the two pedal footpads apart.

That offset isn't in your model.

Because of the offset, even if you allways pressed square (which you won't because the driving position is not in line with the pedals) there will be both a significant bending moment and a torsional load applied to the main run.

Not trying to be negative but if you use CAD modelling you have to factor everything in no matter how trivial it might seem.

EDIT - modern designs tend to use an inverted "U" channel which is far stronger in bending and torsion than a rectangular bar and hence can be made of much thinner section.

Edited by Rod S on 23rd Apr, 2011.

Schrödinger's cat - so which one am I ???

Cheers Tom and Rod. Cheers for the input. You know, that never crossed my mind. VERY valid points.

Im going to look into that Rod S

Time for a bit of market research

http://www.cardwells.co.nz/images/Brands/Tilton/3ped.jpg

Perhaps copy the style of that pedal?

Edited by Sam on 23rd Apr, 2011.

more for your market research, this is one for a mini

http://turbominis.co.uk/forums/index.php?p=vt&tid=170151