simonr

Why is it then that in a LR, it never directs me anywhere unsuitable for an ordinary car when it seems that if you are on a scateboard, every second turn is the lane from hell? I guess it's the same reason it never snows here! Si

Graham - you read my mind! I'll be coming up with the rest of the Horsham possie on Sat afternoon - so will miss the road book (sorry), but it does give me an extra day to weld broken bits on my Landy! See you in the pub! Si

In that case - Yes! Si

Yup - that's what I did. There was some part or other that nice Mr Ashcroft supplied - but I may not be remembering right. One way or another, the most difficult bit was coming up with the right hi/low/diff-lock lever as the BW box only has hi/low - but again Mr Ashcroft came to the rescue! Si

I bent a tube once by filling it with sand, welding end caps on and using the LR to tow one end round a steel bollard in the street. It worked remarkably well. The next one was made from scaffold using a hired tube bender. My friend & I made two cages in two days - fairly basic hoops rather than full externals. Worth having a chat with Chris above though - you will save yourself a lot of time, money, angst and blisters and end up with something that doesn't look like it belongs in a childrens play park or the Tate Modern! Si

I like the idea of bashing the pliars with a hammer - that will probably grip better than one squashed in a vice. I used to just squash the connectors a bit then solder them - which works pretty well. Contrary to popular belief, solder is not that good a conductor so you need the crimp for the conductivity and the solder just to keep it there. Now I have a tool from VWP - which was relatively inexpensive and is fantastic! Si

Sorry chaps, all gone now - with a couple of people in reserve in case the first three do not come through. Thanks for all your help. Si

We now have a series version - or at least a version for field trialing. I would like to find three people who would be interested in fitting one of these to their vehicle. You will get the brake at cost (so pretty cheap) and in return, we need feedback and where appropriate, photographs. We want these to be the best they can possibly be when they are launched and the best way to achieve that is to have real people using it in real situations. I know loads of you have PM'd me or emailed regarding this already, but I can't remember who asked when etc, so I'm starting with a clean slate. The first three PM's received after this message goes live who have suitable vehicles will be given first refusal. It should fit Series II & III and possibly Series I, bit I don't really know enough about them to say if the transfer box is the same (the zip on my kagool is jammed today). Si

"Yeh...it's an improved version.....it turns in to an 80 inch on hill climbs" Si

I would have a chat with Big 'Bathtub' Pete - about using expanded foam. He's an expert in sound-proofing (his head at least ) with the stuff! Si

Very clever! Si

Almost right. The chopping is much faster than the motor can speed up and slow down - generally between 10 and 20 thousand times a second. It is not relying on the momentum of the motor so much as the magnetic hysteresis in the electromagnets that make up the motor. If you were running on 24v, you would get twice the speed, but 4 x the torque. If you chop the motor supply with a 50% duty cycle, you get half the speed and torque. However, that still gives you the same speed as on 12v, but with double the torque (1/2 x 4 = 2). The power is a square relationship. If you double the voltage - you quadruple the power. If the motor is only running half the time, you get half of that i.e. 2 x the power. Nev, There are problems with Thyristors. You still need a chopper (or an AC supply) in order to make them switch off (when you switch one on, it will stay on until the current flowing drops to zero). There are ways around this like using 'gate switch-off thyristors' (expensive and low current) or a thing which generates a negative going transient spike on the supply lines sifficient to instantaneously stop the current flow (good for zapping other bits of equipment). A DC motor with a commutator you might think interrupts the current as the commutator switches from one set of poles to the next. This is true some of the time, but with big multi-pole motors, there are always several sets of coils in use and the current never drops to zero. This is the way to do it without Mosfets! Something I tinkered with in the past! Mechanical Speed Controller Si

Cost is certainly an issue - a full H-bridge, four quadrant design is likely to be £200 to £300 to make (look at 4QD Speed controllers if in doubt - these are exceptionally good value). A bigger issue is likely to be bomb-proof-ness. I have personally destroyed over a grand worth of MOSFET speed controllers through things like lack of motor surpression causing spikes or connecting the battery the wrong way round. Sometimes they just let the smoke out for no apparent reason - particularly when they are running close to the maximum load. It is possible to make a fairly bomb-proof controller (4QD Uni series are a good example), but they have to use a relay to protect the controller - so arguably since you have one relay in circuit, why not just keep the original solenoids? These problems are all possible to overcome - but at too high a cost I suspect for the likes of us! (Sorry Will, even you ) Si

Thought it best not to mention that! Simon & I were talking about this in the pub - how to make a controller which would safely run a 12v motor on 24v The best answer so far is effectively a switch which switches the motor on and off very fast with a 50% duty cycle. This would give you the same top speed as running on 12v, but twice the torque - so the same gain as running a pair of 12v motors. Additionally, it would be easy to make it act as a speed controller so you could vary the speed from zero to 50% - might be useful? The down side of this is likely to be cost. I reckon you'd need a PIC controller, high side driver, opto-isolator and a bank of 20 mosfets on a heatsink to give you 500A continuous rating. That would probably cost best part of £100 to build. Then we went on to talk about adding a second motor - no, not copying Jim - a two stroke petrol engine. Only connect the spark plug when the electric motor is running. The electric motor will start it (in either direction) and it will provide additional torque while the eleccy motor is running. It would probably need to be geared down a bit to be useful though. Four stroke would develop more torque - and best of all would be a little two stroke diesel! Food for thought! Si

I seem to remember explaining this a few days ago on another thread on here! Have a look at: Paul Hills Motor Explanation It gives you a lot of useful info to calculate what your motor will do if you double the voltage. In short, if you double the voltage, for a given torque, you will double the speed. The torque is proportional to the square of the current, so if you double the voltage, you double the current (by ohms law), but you quadruple the stall torque. For a given load, the current will be the same in both 12v and 24v (since torque is not related to voltage). Since the line speed has doubled for this torque, you should only have to run the motor for half as long. It thus, for a given recovery will generate half the heat (same wattage for half the time) - this is where the potential efficiency gain comes from. The problem comes from the fact that you have 2 x speed & 4 x torque available and you will probably use it! If you do, without reducing the duty cycle, you will cook the motor. Silver soldering the joints inside the motor only increases it's life a little as the enamel on the wire will melt around the same temperature normal solder melts. A lot of decent motors use welded contacts anyway. If you over-volt a motor and treat it properly, it will last every bit as long as one not over-volted - and you will still get the higher performance. If you move outside it's performance envelope, you will however cook it far quicker than the non overvolted motor. Si

Cheers Dave - cheque in the post Si

Very nice looking - and low profile! I like a lot! Well done Jez! Si

I have ordered a GSM card machine - but it's not turned up yet (there is always tomorrow). If not, give me a call next week - I'll sort you out! Si

I did have a mail address for him - but he doesn't read it much. I'd PM him. A big plus of his main shaft is that the disk brake assembly is better held in place. Remember the Slindon Challenge where Jon Staff's (Chelsea Tractor) disk pretty much exploded on the first punch? It was because the circlip came off - and we lost most of the bits in the mud. The day didn't get better after that! All-in, although it's expensive, It's a good bit of engineering. I'd certainly buy one if I broke or damaged the original. Si

That is just so cool - wonder if they'd like a UK agent! Si You coming to the pub later Graham?

Will, it's not too difficult. Most of the ones supplied have the lip around the outside partially folded so you only have to beat it round over the frame. One bit of advice however - get some thick insulating tape and use it to electrically isolate the skin from the frame. a lot of the corrosion in the both the frame and skin are electrolytic in origin. The insulation stops most of this dead! Si

Si

Interesting post! WTH have they still got photos of mine on their site if it's that cr**. The comment "Just bust 1 at the weekend bracket isn`t very strong . Bassically the bracket holding the calliper twists under load " is good. It is designed to twist in order to reduce the potential shock loading on the speedo housing. There have been 5 'Failures' to date - but without exception they have been due to the caliper being adjusted too tight. There is a plastic spacer behind the pad which melts if it gets too hot. The boiling plastic can force the pad against the disk and cause it to lock. However, if you follow the instructions on how to adjust it in the first place - there won't be a problem! I suspect that the one in question was supplied by SR, who in their wisdom are supplying their own instructions which do not have the adjustment info in. I guess that's why it was not fed back to me. I figured that making the back plate flexible would absorb some of the shock loading if you put the brake on in motion. I figured that a twisted back plate, although inconvenient, is better than the back of the transfer box being torn off. If you do twist the back plate, we will replace it free of charge. We have even replaced the over-heated calipers as a gesture of good will, even though the manufacturer will not entertain a warranty claim as they have been over-tightened and the failure was the fault of the fitter. Time will tell if this was a good or a bad call! I had heard that SR's response was going to be to start a 'whispering camaign' via a number of trusted individuals - so this wasn't entirely unexpected. Si

I expect I'll be shackled to my stand most of the day - although I would like to go and shop for a couple of bits. Come & enjoy a free can of coke and a keyring! Si

Sorry to hear that! If you PM me your address (I don't keep forum names in the database), I'll send you another free of charge. There seem to have been a few of them that have been opened by the post office (security perhaps?) and not re-sealed very well. I did look at making wing-bars - but the problem is that unless you are attaching it to a cage, the bulkhead is not strong enough. Imagine what would happen in a head-on collision. The pointy bit is going to be heading straight for you and will just poke a hole in the bulkhead. Although the A post hoop is in pretty much the same place on most 90/110s, it is not exactly the same enough to make a strong enough 'universal' mounting. Si