Have I finally gone over the edge with weight saving?

[Bob Simon]

Here's the current development in lightweight handbrake technology. Note the use of space age lightweight organic composite structure.

 

edited to add; Weight of entire brake assembly is only about 240 grams!

 

-Bob

94 HPC VX Evo III

 

 

Edited by - Bob Simon on 22 Dec 2007 15:48:02

[Julian Thompson]

That's perfect Bob.

 

I would like one of those. Any chance of a bulk buy?

 

Also, would it be possible to mill some slots in it to reduce weight further?

 

😬

[Bob Simon]

I understand that the composite material is now readily available at Home Base for reasonable cost. Don't club members already get a discount for Home Base purchases?

 

I suppose further lightening may be possible. A structure of lateral ribs with diagonal bracing comes to mind. I'll have the design team run it through finite element analysis to make sure structural integrity would not be compromised.

 

-Bob

94 HPC VX Evo III

 

[Alaskossie]

Bob,

 

Having applied your own organic handbrake on occasion (and having kicked it around in the victim's footwell on more occasions), I can also attest to its earth-friendly, carbon-neutral attributes (and I know you intend to recycle it by composting, instead of incineration).

 

I understand that you see this mod as your own small contribution to mitigate the world's inconvenient truths....

 

Alaskossie

[Bob Simon]

and I know you intend to recycle it by composting

 

Absolutely!

I also plan to celebrate Earth Day by burning my old Dunlops in the garden, thereby mitigating some of the worlds inconvenient tyres as well

 

 

-Bob

94 HPC VX Evo III

 

[edmandsd]

My Hart420R powered Caterham was 415kgs in its lightest form. The new owner's put a Hayabusa in it so it will be interesting to see who's got the lightest Caterham in the World

 

Home of BDR700

[Julian Thompson]

Yes Dave, it will !

 

I've sold a few of my bits to your man from my car actually - he's a nice chap

 

My money is on my car being lighter though because I'm doing the detail build myself wheras he has had someone else do it. I guess (though may be wrong!) that to achieve strict weight targets you have to be thinking about it every time you bolt a part on...

 

We shall see!

[edmandsd]

I agree Julian, as it was only by taking this approach that I manged to build the lightest non bike engine Caterham.

 

The lightest BEC will never be de-dion

 

Home of BDR700

[Julian Thompson]

Yes, I am sure that's right, too.

 

One thing that Keith has that I have not got (yet 😬) is your gun-drilled halfshafts...

 

...I just can't find anyone mad enough to do it for me! Did HTR do yours Dave, and if so, do you mind me asking how much it cost? Did you have to do new shafts from "unobtainium" or something or did you just use the standard plasticine ones and drill those? (Presumably they had to be hardened after?)

 

 

We will see about the weights - Keith is so excited to just get it on the road that I don't think he's really that bothered YET....but if he spends much more time talking to me on the phone I'll get him converted and drilling holes in everything pretty quick, I guess 😬

[edmandsd]

Hi Julian,

 

My gundrilled half shafts came from Elite - they'll organise this for you if you wish. I never had a problem with them and they improved on the standard Quaife design at the same time.

 

They didn't make the l'weight alloy rear hubs though which the bike discs are fitted to. Aaron at HT arranged that although he didn't do the work himself.

 

Note that my axle was converted to Group 4 half shafts which are much stronger and lighter than a de dion. I recall Mike Chitty running a 400bhp Escort Thundersaloon with this axle arrangement years ago without any problems so it would be virtually indestructible in a 7.

 

Elite also made me a l'weight steel spool which saved a huge chunk of weight over the standard Tran x diff.....just in case you run out of ideas just to get it under 350kgs ❗ Yoiu can also get magnesium diff noses which would be fine with bike torque.

 

Home of BDR700

 

Edited by - edmandsd on 23 Dec 2007 17:05:40

[Alaskossie]

edmandsd,

 

What was your power to weight ratio, with the Hart 420R and 415 kg total weight?

 

 

 

Alaskossie

[C7 BAD]

 

Julian/Dave

 

I think the damage is done re my attitude to weight saving because of you two

 

I am going to get the car up and running and then work my way back through it once i have my building works on the house complete,(i am going to drive you both nuts with queries!)this will give me a double garage and workshop,the car is 140 miles away being built so a bit of a pain.

 

As it was not road registered and Dave removed everything that was surplus to requirements we are having a couple of slight problems which are delaying things,we need to put a handbrake into the car but the chassis rails under the dash in the passenger footwell have been removed so there are no fixing points,can a hydraulic handbrake legally be fitted for SVA purposes?

 

Oh,i will have a S1 Lotus Exige running a 300 bhp Honda VTEC Rotrex Supercharged engine for sale soon if anyone is interested,it's in Laser blue,low mileage etc

 

Keith

[edmandsd]

A genuine 675bhp per tonne Alaskossie........enough to run 10.13 @ 136 mph in the quarter mile.

 

Hi Keith - we won't let these minor problems stop our quest

 

Home of BDR700

[C7 BAD]

 

Dave,your enthusiasm and advice make it do able mate

 

I can't wait to get this car up and running,i am quite sure it will become an an enjoyable obsession,i predict a worthwhile weight loss once i'm back on my bike post christmas

 

Keith.

 

 

[Julian Thompson]

Hi Keith!! Want to borrow a hole saw kit ? 😬

 

Cheers for that Dave!

 

I already have the lightweight diff nose - you're right that saves nearly 7kg!!

 

Will perhaps speak to Elite about the halfshafts.

 

[Julian Thompson]

Keith

 

No - the hydraulic brake won't cut it for SVA.

 

I was thinking about this.

 

Have a look at Hayes Cable mountain bike brake discs... Could you clamp a disk on the propshaft and use a MTB caliper (cable not hydraulic) to create a handbrake?

 

[k80rum]

I'd been pondering this too Julian

 

I've seen someone do this succesfully with a wilwood/airheart spot caliper. Not sure whether an MTB rig would have as much friction but I wouldn't have thought it's much different - the spot calipers have never been hugely efficient have they?

 

I've just upgraded to hydraulic titanium Hope 6-pots on my bike and have a couple of disks and cable-operated calipers left over. I'll happily send one half off to you in the New Year if you want to play with it. I think the disk would be okay, but reckon a better caliper would be needed to get a bigger surface area. Alternatively I guess 2 calipers could be used if space permits (not ideal from your weight saving POV tho.. )

 

Darren E

 

K80RUM Website and Emerald maps library

 

Superlight R #54

 

 

[Sheds Moderator]

Good idea Julian. I don't think you would get enough oomph from one MTB mechanical disc though. Maybe as you say you would need 2 calipers. Stupid light though, and that's before you start making the discs out of ally. Hey - nobody says they have to wear well!

[Bob Simon]

A caliper on the propshaft would only see 1/3 or so of the holding torque that wheel mounted calipers because of the CWP ratio.

 

Wasn't it BRM P48 that ran the entire rear braking system with a single caliper on the pinion shaft hanging off the back of the transaxle? The caliper was quite small for service brakes. I imagine the disk would have to be structurally substantial enough to withstand centripetal force generated by high RPM at Vmax.

[CanAm]

As Eric is busy with his self-assessment returns, I can confirm that the BRM P48 had a single transmission brake with the disc mounted externally on the rear of the gearbox. I think one or more ran at the end of the 1960 season with conventional rear disc brakes.

 

Alan

_{Machines were mice and men were lions, once upon a time.}

[Irrelevant]

busy with his self-assessment returns

*eek*Got to do mine ☹️

Ta for reminder

[k80rum]

Looks as though the BRM P48 affair was quite substantial (understandable really, given it's the rear braking system rather than an occasional handbrake )

 

There's a fantastic pic of it tho here

 

I did find a web-page that shows one of the airheart / willwood calipers being used to provide a handbrake function, using a propshaft-mounted rotor for a bike-engined Locost. There's a piccie on Bob Carter's very interesting web page here

 

Edited to add: ...and there's a nice pic of a billet mechanical kart handbrake here which looks light and effective: here and can be picked up in the UK here for around £43 inc.

 

I'll be looking into this as a project myself later in '08

Darren E

 

K80RUM Website and Emerald maps library

 

Superlight R #54

 

Edited by - k80rum on 30 Dec 2007 18:31:31

[Bob Simon]

The caliper on Bob Carter's car looks suspiciously like the Mico units that CC supplied with the AP rear race brake upgrade. Put a post in the wanted section for one. Most of them are probably just taking up space on garage shelf, having never been installed. 😬

 

 

 

-Bob

94 HPC VX Evo III

 

 

Edited by - Bob Simon on 30 Dec 2007 18:49:38

[k80rum]

It is indeed Bob 😶‍🌫️ It's the same Airheart/Wilwood/Mico unit that CC used. In fact, I've got a couple adorning my garage shelf too!

 

The pad size is fairly small and to be honest in order to work properly and centre itself , it needs to sit in a sliding bracket, rather than be mounted on thin ali ear as CC devised (the 'proper' sliding hanger would foul the inside of a 13" wheel). End result is that to pass an MOT, the rig needs adjusting such that the pad is dragging to start with - unsuitable for use day-to-day so they usually get removed/disconnected until MOT time.

 

I think a mech MTB caliper is going to use an pretty small pad size and reckon the best approach to get a decent friction size to easily pass an MOT, whilst keeping the solution as light as possible, would be the kart caliper acting on a propshaft-mounted disk. Keeping the rotor diameter as small as possible would need help to reduce any rotational mass and hopefully being used as a handbrake only would mean no heat is really going to be generated and a light, thin rotor could be used. There's still the safty aspect of spinning such a disk at propshaft speeds but assuming Bob Carter's still alive, that seems achievable

 

I will most likely have an unused and spare Wilwood caliper if other options don't fit the confines of the tunnel Julian 😬

 

Darren E

 

K80RUM Website and Emerald maps library

 

Superlight R #54

 

 

 

Edited by - k80rum on 30 Dec 2007 19:06:22

[Bob Simon]

I only wish the Airheart caliper was lighter. As I recall they were made of cast iron. Quite lardy. Most of the lightweight alloy karting calipers are hydraulic these days. The full floating alloy caliper you found is made by Biesse Karting Products. It looks promising.

 

-Bob

94 HPC VX Evo III