Lotus fully adjustable hubs – prototype for mine?

So, a while ago, ceebmoj from the project cyan blog asked me about some fully adjustable hubs my friend Simon (from Cornering Force – chassis dynamists) made some fully adjustable hubs for his Lotus Esprit race car, and I said I’d get some photos. It’s total car pron.






This is what the blank looks like – made from a piece of billet aluminium about 50mm thick. You can’t laser cut this that thick, so it is water-cut under-size by about 5mm all the way around. This is because the jet is less accurate on the far side of the cut. However, the facing side of the cut is accurate. So, you then start on the facing side and machine it all the way through accurately. Then you have both sides accurate.




This is the hub with the bearing bolted on. Simon found a bolt-on bearing that was the right size for the Lotus. Then, of course, the hub was designed to take the bolt pattern.







IMG_1854.JPGNow we have it from the other side with the caliper and disk attached so you get an idea of just how it is fully mounted. The piece at the bottom allows fully adjustable bottom wishbone height by varying the shims.






IMG_1855.JPGHere is the shiny lovliness going up the back.






I hope you pleasured yourself over this, and normal service will result soon.



Handbrakes – I’m taking a different approach

I’ve been thinking and have two major thoughts about handbrake arrangements.

  • the current option doesn’t work well – My fury has cosworth brakes on the back, with a sierra handbrake cable and escort handbrake – all very standard and familiar to most fury and Se7en builders. Similarly (I expect) to most on here, I’ve always struggled to get the handbrake to bind well – I think the handbrake cable has too many corners to go around.
  • my composite tunnel will need hard-points – in order to mount the original handbrake, my tunnel will need some major hard-points fitting in for both the lever mount and the cable pass-through.

So, I got to thinking, rather than run a hydraulic handbrake which will not pass MOT, are there any other options. I have a few ideas, two of which assume an IRS and one doesn’t:

  • solid mechanical lock – This one is inspired by a rallying mate of mine with a hydraulic handbrake, who would stick a screwdriver through the transmission tunnel into the propshaft UJ to prove to the scrutineers that he had a way of mechanically locking it. So, taking this idea to its logical extreme, one could mount a pair of solenoids on the transmission tunnel, pointing into the UJ. Hit a button, have the solenoids go out, plunger locks the prop. If you use a laser and a photoreceptor shining through the UJ, you accurately know where the prop is, you can guarantee the solenoids will go in. Advantages – simple, but the ally panelling in the transmission tunnel we all tend to go for isn’t strong enough to support the brackets. A weld-in cradle on the other hand would do it. Disadvantages – no use if you’re drifting . Also, if you applied it at any speed above about zero, it would probably eat itself for lunch.
  • swap calipers – use a pair of electric handbrake calipers, as per many modern cars. It seems simple to make a bracket, bolt them on and give it 12v when it wants it. There are advantages to throwing away the handbrake cable and routing, bracketing, handbrake, etc. and the disadvantage is that you’re adding to the unsprung weight. I think the overall weight would be quite similar. However, these things would open up a can(bus) of horrors in control
  • Linear Actuator – use a linear actuator instead of a handbrake lever. These guys come in many pull/push forces (easily upto 400kg) and various throw lengths, from 50mm upwards. 50mm is all I’d need. They’re simple to control, basically being a DC motor and lots of quality gearing – +ve voltage sends them one-way, negative the other. What’s more, they can be adjusted for start and stop positions, and can be specced with a potentiometer for position management. Add the whole lot to a micro-controller and you have a solution.

So, after much pondering and chin-stroking, I went for this e-stop kit from Speedway Motors in the states. The cost of a roll-your-own solution in the UK would be about £250, and the cost of theirs including shipping taking advantage of the strong pound, is about £350. Neither option includes cables, which I’ll need custom making at about £40. The cables will be Ford disk to m6 thread. Using their kit does mean I’ll save days of engineering a solution (much as I would enjoy doing it).


I’ve been meaning to make this post for a while – this is the collection of books from my car based technical library. They get opened and used (well, some of them do) but it’s a good book list to share.

What Author Why I like It
Porche 956/962 The Enduring Champtions Peter Morgan A great book that goes into long term racing strategy at the same time as having a great photo archive. The archive has some great pictures on how problems are solved as well as covering the history and evolution of the cars.
Automotive Handbook Bosch It’s a well indexed reference book. I don’t really read it much; it’s like learning C++ from the reference guide.
Race and Rally Car Source Book Allan Staniforth It’s a detailed book, covering Allan’s speciality (suspension and chassis) as well as having lots to say about aerodynamics.
Competition Car Suspension Allan Staniforth It’s the bible. It has all the hard sums in, but lots of pictures of how they’re applied to cars. All hail Allan.
Drive to Win Carroll Smith One of the three of his essential books I own. Studies show that 80% of learning is experential, and 20% is from training. This is the 20% you need to know if you want to improve your technique and have groundwork over and above instinct to get you started.
Nuts, Bolts, Fasteners and Plumbing Carroll Smith A brilliant book that covers everything from ensuring your holes don’t have a sharp edge, metallurgy, how to arrange rivets so they don’t fail, how to radius a transfer, etc. If you’re building a high performance car, this book shows you just how not to cock it up and squish yourself for the sake of a bad bolt choice.
engineer to win Carroll Smith How to build your car so it survives the race, and you survive it. Way more of the same above. Don’t forget Carroll Smith has build many championship winning racing cars and seen many drivers come and go.
Competition Car Composites Simon McBeath This is a great book that takes you through simple moulding techniques all the way through to carbon fibre. However, that’s not the good bit. The good bit is that it’s aimed at us, making this stuff in our sheds, enjoying too much solvent and seeing the devil erupt from our kneecaps.
Race Car Chassis Design and Construction Forbes Arid Terrific amounts of design information from first principles. It’s backed up with lots of excellent photographs from paddock that clearly show just what to do. I loved this book and often refer to it.
Fibreglass Composite Materials Forbes Arid Another great book on the subject. This one includes techniques we can use, and also takes you into some of the professional tooling and techniques. A great read in a day.
Race Car Aerodynamics Joseph Katz If you want to know how it’s done and how the pros do it, this is the book. It’s a good primer if you intend to design anything based on what the composite books above may have to offer.
How to Make Your Car Handle Fred Puhn There’s a lot of what’s in this book in the books above, but Fred shows how to do it with two bits of hairy string and a dangly weight.
Automotive Fuel Injection – A technical guide Jan P Norbye This book is potentially dated now, bearing in mind on the kit car community this is now considered a commodity where before it was considered witchcraft. However, it’s a great book to get you up to speed with the principles and gives a great summary of the evolution of fuel injection.

Narrowing my OBP Pedal box – or “is my warranty OK?”

So, as expected, my lovely OBP Pedal Box doesn’t fit the admittedly narrow fury footwell. There’s nothing wrong with this per-se. It’s a lovely made piece of equipment and I knew when ordering that it wouldn’t fit. This previous post shows the modifications I’ve needed to make in the footwell to prepare the shape to accommodate the OBP box, but after careful consideration, I decided there wasn’t enough room to make it all fit with any degree of clearance so decided to slit it like a cheap whore and make it thinner.

So, what you can see here is the pedal box in the 360 degree vice, scored and cross-hatched ready for cutting. I’ve been sure to leave enough room for the brake and clutch cylinders to have plenty of clearance, and the slit also takes into account the cross-bracing gusset. The only place it should be narrowed is between brake and clutch, not between brake cylinders – the clevises need to be straight when they go onto the cylinders. Moreso, it wouldn’t really be feasible narrow it here, what with the pedal wanting to be in the way.

Also worth note is the fact that I bought a 360 degree vice for the clean half of my garage. This means I can mount and mark and weld things without having to take them over to the dirty grinding cutting side of the garage. What you may be able to see on the right there is the corner cut off and grinded ready for welding.

It’s not all that clear in this photo, but I’ve got the whole thing cut now (0.8mm slitting disk for maximum accuracy). The steel used the the pedal box is only 1.2 or 1.5mm thick (hard to tell with the powder coat) so the disk went through it like a e.coli in an OAP home. I was pleased with the results though – the fact that it’s difficult to see the gap in this photo is because I’ve got very clean mating edges – essential when tig welding something so thin. One cock-up and you blow straight through.

This is what the extracted section looks like. There are a couple of stitches on each edge of the gusset that need removing. Up close, you can see where the stitches have penetrated the back plate (a good thing) and this meant I had easy guidelines to mark and cut against. The gusset came out quite unscathed, but in hindsight I wish I hadn’t ground it quite so thin at the base to remove the stitching – it made it very thin to weld. I would have rather left a little metal around it and used that as filler. Live and learn.

Next is lots and lots of spots at about 1″ distance. They’re done at 40A and with very little filler. Bearing in mind I am seam-welding this, and the metal is so thin it would just warp away from me (in the vertical plane) if I attempted to weld in a seam. Patience now means a better result later. At this point I was also glad I have so many different welding clamps.


When it came to completing the seam welds I stitched an inch and let it cool completely first. I also drilled mounting holes in it and bolted it down to my big heavy 1cm thick welding plate. Even then I ended up with a very small amount of warping, but so little that it pulls flat when bolted down. I initially kicked off at 40A but found that to be too hot when putting the seam in and had to back off to 35A. That gave me a great weld, full penetration and very little filler needed on the 1mm dia rod.

Here’s the end result. I’ve ground the seams flat (little effort) because I want to get the ‘not been touched or modified’ look when I get it back from the powder-coaters. You can’t see the gusset in this shot. I did struggle a little with this blowing through (where i’d ground it a little thin). I compensated by going up to a thicker filler rod and chucking a lot of metal in (it ended up looking like tidy mig). Then I got my pointy ended tungsten carbide burr and dug around in there like a demented dentist until it was all nice and smooth again. As long as the powder coat goes on reasonably thick, no-one will be any the wiser. The strength is all there though.

Following is the final result. Note the greater amount of room on left now – plenty of space to rework the foot well. I feel fairly chuffed with this result.

Pedal boxes


There are a few things I don’t like about the original pedal box, or there are ways in which it isn’t suitable for me any more. Don’t get me wrong, it’s not a bad pedal box at all but I have some reservations:

  • The original clutch pedal was specced for cable clutch, and I now need hydraulic with the new engine. I could modify it but it wouldn’t be that simple and would take a lot of time.
  • the the brake pedal (whilst with bias) wasn’t adjustable from the cockpit, and I couldn’t get the central bearing to not fall out without blocking it with washers. Blocking it with washers wasn’t such a bad idea though because it passed SVA with that, cross-drilled shaft and locking r-clips. It also rattled a little.
  • The pedal pivot mechanism was a bolt in a sleeve, and I want somethin g a little more sophisticated, like bearings
  • The throttle pedal went up through the top of the footwell, was roof mounted (if you  like) and left a big hole where it protruded into the engine bay. this fails scrutineering because you cant have a point where fluid (hot, burning fluid I assume) can get from the engine bay into the footwell

So, rather than re-engineer it or make one myself, I just went and bought an
Optimum Balance Products race pedal box, with dual accelerator cable adapter block and cockpit balance adjuster.

So, I’ve gone from the old to the new.

Fury Handbrake Cable – ooooOOO preparation, that’s what you need

Meh – it’s all about preparation. I’ve removed the rear diff carriers to powder coat them and get them ready, and then it dawned on me – handbrake cable. Bugger.


The handbrake cable (dunno what flavour it is anymore) was cable-tied to the diff carrier in a couple of places to make it route. I didn’t p-clip it because the car was built as a rolling chassis at the time I bought it and I converted it from drums to disks, so a different cable was needed to the original. This is made more difficult because you can’t easily get to the weird sides of the carriers when they are in situ to screw p-clips. When the body is also on, and the entire rear suspension is in place, it’s even harder. Hence it was put in place with cable ties.

Like a pair of nylon pants, the cables have chaffed now.

So, last night was to put the diff carrier back in place, work out where the brackets needed to go, mark up and weld up. Then drill the brackets to take M4 bolts for p-clips. Two brackets in, four to go: two brackets on each carrier, and one each side of the chassis.  The end result will be that the handbrake cables now are properly suspended in mid air, and routed sensibly.

Speedo Sensor Mount

In a similar manner, I’ve also moved the speedo sensor mounting bracket from the top of the diff carrier down to the floor. The main reason was to create space in the top of the transmission tunnel for the fuel-tank to go in there. I’d hate to have to make a recess in the tank to accommodate the sensor otherwise – just isn’t worth it. It also game me an opportunity to put the whole unit on the bench to position it to get the maximum amount of the face of the Hall-effect sensor facing the diff/propshaft mating bolt head. I’ve struggled a bit in the past with this and have had to bend the bracket now and again. Hopefully this is a done deal.

It’s all about preparation – taking time now to put a few brackets in place will mean the handbrake cable should fit and route in a few minutes when the chassis is back from the powder-coaters. Mental note to self, fit the handbrake cable when the diff-carrier is going back in, not afterwards – it’s a pig. Worse if the body is on.

It’s a right pain to do now, but I’ll feel very smug when it all goes back together quickly later.