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robhume

Building my Eleven

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Simon Marks - North Oxfordshire AO

Hi, Rob,

The bonnet should be secured to the round tube with cable ties (i bolted on a couple of angle brackets to assist with this) and my favoured solution for limiting travel is an offcut of 3"x3" timber which I place underneath the radiator opening prior to lifting the bonnet!  I posted a couple of pictures of a car with a bonnet stay on Stephen's thread (a couple of pages ago).  i believe that Stephen is going down the line of having such an item made.

The scars that are visible on the picture of my extra Dzus fasteners on my bonnet are as a result of the bonnet being caught by a gust when I had returned from the rolling road tune of the car and hadn't replaced the cable ties.  Adding those cable ties is a quick job worth promoting to the top of your "to do" list for this weekend!

I have not vented the top of my bonnet because I'd rather smell the countryside than engine fumes whilst driving.  I also recall reading in a book about Frank Costin that he was horrified by some impromptu vent holes in an Eleven in period and that was a man that certainly knew what he was up to.

Simon

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stephenh

I think you have to be wary of using just cable ties to limit the extent of opening the bonnet, but equally don't just rely on having something for the outside of the front of the bonnet to rest on in the open position (such as a short piece of 3x3"!). What you need is both. Even then, if the bonnet was caught in a strong gust when in the fully open position it will put a big strain on the front of the fibreglass clamshell, around the grill opening, because there isn't much fibreglass around there (because of the position of the grill opening) and the brackets are supporting quite a heavy bonnet/clamshell. That is why I am going down the route of having a suitable bonnet stay made in stainless steel rod. That way most of the strain is taken by the stay and its fittings either end, and saving quite a lot of the forces which otherwise pass through the front of the clamshell.  

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Simon Marks - North Oxfordshire AO

Hi, Rob,

Just in from work and dived under the bonnet of the Eleven.  Fitting a wheel sensor to an MG Midget front upright is an absolute breeze as very few folk fit stone guards to the backs of the front brake discs.

Tripmeter Wheel Sensor1.JPG

All I did was to drill a hole suitable to receive the sensor in some 2mm steel.  I then shaped that to fit snugly against the upright and, after drilling another, smaller hole, bolted the plate into the threaded hole that previously accepted the securing screw for the stone guard.

The sensor reads from the Allen headed cap screws that hold the disc onto the hub (four "pulses" are created per wheel revolution in this case.  Dependent on which proximity sensor you use, you will need to set a clearance from the screw heads.  The one I have used is a Monit sensor which has a handy LED that shines as the screw head comes within range.

Tripmeter Wheel Sensor2.JPG

I believe that the Brantz sensor also has this useful feature which makes it easy to see when you have the distance in the working range as you set up the sensor.  Once set and the securing nuts nipped up either side of the plate, my experience is that they will stay in place for ever.

These sensors are available from Demon Tweeks (other motor sport suppliers are available) but your choice of speedometer may well define the type of sensor that you need to use.

It would also be possible to fit a proximity sensor to read propshaft bolts (as I once did with a LandRover) or on the nose of the diff.  Taking readings off the driven (rear) wheels can be problematical due to wheelspin and is advised against by the tripmeter manufacturers.  If you lock a front wheel, you are generally too busy dealing with the issue to notice that the speedo. reading has dipped!

Simon

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robhume

Simon,

 

Great information and photographs, very helpful.

I wonder if you or Stephen or anyone can tell me what width the Plays Kool  narrow roll bar is.

To be more specific, the information needed is;  width, centre of mounting plate to centre of mounting plate,

Height from bottom of mounting plate to top of roll bar and the length of the backstays.

This would be for a narrow chassis.

 

Edited by robhume
more detail

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Mark (smokey mow)

Rob, narrow roll bars are in the region of 850mm measured to the tube centres; this compares to 905mm for a wide body. 

Backstays length, position and angle will vary slightly depending on whether the rollbar is for a live axle or independant narrow as there are variations in the shape of the chassis and the rear.  Looking at the shape of the chassis at the rear of the XI it looks quite different to a narrow.

 

I'm not sure what your plan is for the ROPS but I can reccomend someone resonably local who has fabricated one for my Westfield in the past and also for the JW4.

 

XI%20Chassis%20002_zpsuh7xjycl.jpg

DSC_0420.jpg

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stephenh

Breach of copyright alert! 

That is my car, Smokey, and my photo, so you owe me oooh....................lets say half a pint of bitter next time we meet.:d;):d

To be serious, Rob, are you sure you want a rear antirollbar? As I understand it, most people with live axle cars find that an antirollbar is only required on the front, to achieve reasonable balance. Although I must admit that I don't have much experience of setting up suspension on live axle cars. I'm just going by what others who do have (or have had) track cars with live axles have said.

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Simon Marks - North Oxfordshire AO

Hi, Stephen,

I took this as a request for sizes for a rollover hoop / bar, not an anti-roll bar to further control axle movement. 

I am mocking up a rollover hoop myself this weekend but, as this will fit within the rear hump, it does not comply with MSA regulations for competition.  Trackdays here I come (shortly)!

Simon

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robhume

Come on Stephen, what bar have you been at, one that stops you rolling, aka antirollbar, Ha, ha.

Having looked at the world famous blue book, which now only has a small amount of blue, it would

appear that my plan to try and make a narrow body roll over hoop fit, ( ROPS) but I don't think it would be

accepted as I think the eleven will fall into sports racing car and has to have a 48.3mm diam x 2.6mm wall thickness.

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stephenh

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Mark (smokey mow)

 

1 hour ago, robhume said:

Come on Stephen, what bar have you been at, one that stops you rolling, aka antirollbar, Ha, ha.

Having looked at the world famous blue book, which now only has a small amount of blue, it would

appear that my plan to try and make a narrow body roll over hoop fit, ( ROPS) but I don't think it would be

accepted as I think the eleven will fall into sports racing car and has to have a 48.3mm diam x 2.6mm wall thickness.

Rob, the defintion of a Sports Racing Car was debated on uphillracers at great length in the Rollbar thread.  The MSA defines a Sports Racing Car as a "Two-seater open or closed racing car, built for the sole purpose of taking part in races on closed circuits."

Given that your car will not be competing in circuit racing, and nor was the Westfield XI designed and bult for that sole purpose, it is not by the MSA's definition a Sports Racing Car. Your Van Diemen would however be a Sports Racing Car.

 

Going back to last year I thought it had been determined that the XI would be a Specialist Production Car? "A car of which at least 20 identical examples are manufactured within a twelve consecutive month period and fitted with a series production car engine."

On ‎11‎/‎10‎/‎2016 at 13:19, robhume said:

Westfield have confirmed that they have indeed produced in excess of 20 elevens in a year, so all good.

 

 

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robhume

Oh Mark if only life was that simple.

The central, southern and south eastern associations will exclude Modified Specialist Production classes and put them into Sports Libre. this year.

However the WSCC does have a suitable class structure, so will be, eventually, competing that way.

I take your point about the ROPS, so will contact Plays Kool regarding the dimensions of the narrow ROPS they sell.

If the width is 850mm or close, then I can make it fit without mods.

Bit more progress today, fuel tank, still got strap to fit and vent hose and fuel filler fitted and no scratches!

 

DSC_0080.JPG

DSC_0081.JPG

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Mark (smokey mow)
1 hour ago, robhume said:

Oh Mark if only life was that simple.

The central, southern and south eastern associations will exclude Modified Specialist Production classes and put them into Sports Libre. this year.

The MSA define the safety regulations though, the clubs only define the classes.

Regardless of whether a club decides to put Modified Kit Cars in the same class as sports Libre cars for their events these cars would still only have to comply with the MSA Regulations for Modified Specialist Production.

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robhume

I understand all of that Mark and will eventually compete under the WSCC regs but it is bl...y annoying that they just change regs.Section of hethel regs.PNG

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Simon Marks - North Oxfordshire AO

Hi, Rob,

Just breaking off from scheming my roll hoop and having had a look at the Blue Book Regulations myself, I concur that you are going to be working as a Modified Specialist Production car.

  • As such, you need rollover protection to S10.1.3 (which refers you to K1.6.2) for a sports car
  • K1.6.2. refers you to two drawings, K.60(i) and K31
    • as well as specifying the material (CDS 350 N/mm2), tube size (48.3mm dia) and wall thickness (2.6mm)
  • K60(i) shows a full width hoop with two back stays and an optional diagonal to the main hoop.
    • as well as guiding you to a minimum height - a straight line from the the top of the roll hoop to a strong point at the front of the car (take the front of the cam cover for this) so I reckon that the hoop will need to be about 450mm above the seat belt fixing rail.
    • The back stays could come right down to the joint between the floor, rear round cross tube and the sloping square tube from the rear susension tops should be doable with a suitable welded bracket welded in this corner.  Stays cannot be fixed with Rose Joints any more as they will act as hinges, rather than give a rigid structure for the driver to hide beneath.
  • K31 shows a front view of the hoop and, I think, here is where the problems lie with an Eleven
    • The centre of the seat line to the inside of the roll hoop (horizontally) sets a minimum dimension of 20cm.  Having measured my car, this is 5cm outside the chassis structure behind the seat.  This will mean that any mounting would have to be cantilevered out from the strong point at the top of the shock absorber, over the wheel (and possibly forward a few mm as well to allow to tie this in to the square / round tubes coming up from the floor / rear pontoon.
    • The drawing shows the hoop going down minimum 60cm from the driver's chin.  This is not possible as, described above, the hoop is going to come down over the rear wheel.  This would need discussion with the MSA.  Michael Duncan  in the Technical Department is very knowledgeable and knows Westfield Elevens and his boss, John Ryan (the Technical Director) is also very helpful.  I would have thought that you would be looking to formalise a design outside of the regulations for which a waiver could, hopefully, be granted.
    • Achieving a maximum distance of 250mm from the hoop forward to the driver's helmet should not be an issue.

Sorting out the rear bodywork would then require a bit of thought - I would go for a roughly horizontal steel strip/ unequal angle connecting the roll hoop and back stays and allowing the rear deck to be cut around / between and  then Dzus fastened to this piece of metal.

The hoop I am about to build would have been acceptable last year for my roadgoing Eleven, but roll over protection in line with the regulations above is now mandatory for this class (rather than recommended) so I would have to do the same as I have described - which would be a real headache with my preferred hump-backed car.

Simon

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Mark (smokey mow)
12 minutes ago, Sunbeam Lotus said:

 

    • The drawing shows the hoop going down minimum 60cm from the driver's chin.  This is not possible as, described above, the hoop is going to come down over the rear wheel.  This would need discussion with the MSA.  Michael Duncan  in the Technical Department is very knowledgeable and knows Westfield Elevens and his boss, John Ryan (the Technical Director) is also very helpful.  I would have thought that you would be looking to formalise a design outside of the regulations for which a waiver could, hopefully, be granted.

Simon, I'm not quite sure you're interpreting this correctly.

The 60cm dimension is a measurement vertically from the base of the seat.  At this point the the width to the inside of the rollbar measured from the centreline of the drivers seat should be a minimum of 20cm. Its just coincidence that in the diagram this happens to coincide with the position of the drivers chin, but it is not of relevance.  

This is much the same as the regulation for single seaters that requires the width inside the rollbar to be 38cm measured 60cm above the seat.

The roll bar simply has to be fixed to a substantial structure, this can be either at the top of the chassis (such as above the wheels) or the base of the chassis.

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