Colin Mill

My earlier post was only partly joking - sawdust in the oil was (is?) an old dodge to shut a noisy back axle up long enough to get the car sold so the basic idea probably works! My only experience of wide range multigrade gear oil (Esso 85w140 if I recall correctly) was in a VW gearbox that became very notchy and hard to change when hot. The multigrade worked very well indeed, solving the change problems completely. Why this oil almost completely disappeared from the market some years afterwards I don't know. Is this Redline one very expensive?

I was thinking of getting them to make me a special swirl pot with a stant cap - I would be interested to know how you get on.

Sawdust? 😬

Hi Jason - sorry I didn't spot the thread in time to save you the expense! Unfortunately, I am unable to deny it 😬

Nick - perhaps you needed to look at the water valve on the heater to make sure it went to the fully off position! I bought the heater specifically because it would blow cool air into the footwells and use it for that far more than as a heater.

Hi Jason How much do you need and what diameter? - we stock the stuff as a way of tidying up the wiring in model helicopters. I used it on my headlamp wiring etc of the 7 and it looks good.

The AGM battery I bought has flush M5 tapped terminals the wrong way around so I had to make up an adaption here. It would be fairly easy to do something similar for the Bosch.

Yes, that is the odd thing - the Banner has the positive terminal on the left with the terminals towards you. Is it that the Banner numbering is non-standard?

Hi Elie - Have you fitted one of those Bosch ones? I got the local motor factors to get a Bosch one (and I think that was the number as it matched up with the number on the Banner I had) and it was perfect dimensionally but the terminals were swapped over.

Yawn it may be but one it would be politic to make large of to counter the cardboard sandal wearers 😬

AFAIK there is no exact replacement from other sources - I had a Varta one that was close but because of proud filler caps (as opposed to the flush ones on the Banner) the hold-down strap had to be replaced. I have given up and adapted to a AGM sealed battery as I felt the Banner was rather too short lived.

LiPos are rather more fun than the all-too-safe modern vented electrolytics. We set up an old LiPo flight pack in the yard on a long lead to a 20 amp PSU to give it a little overcharge and it did the full Chinese firecracker bit. However, this experiment leaves you with a slightly uncomfortable feeling when holding one (inside a phone) next to your ear 😬

The old wisdom was that dopant migration set in above 150C and the standard sum for bipolar transistors was to calculate heat sinks for a worst case junction temperature not exceeding 150C. Of things I have looked at recently the LM35 temperature sensor ICs are rated up to 150C. Although I wouldn't advocate pushing things (I'm a rather conservative designer by inclination) I suspect there is quite a bit of leeway as a pal of mine, on discovering that a 1N914 signal diode would carry 1 amp, set one up on a bench supply to see how long it lasted. He got bored after about 6 months!

Well, compared to a 1kW linear its not so expensive - and with that example you are probably paying a 50% premium for the flashy case 😬

From a recent thread (here) about minilites its possible they are genuine (or K&N which is associated with minilite) and it sounds as if they are extremely helpful. Might be worth contacting them. Having said that the wheel is probably stressed for a much heavier car with a good safety factor on top so I doubt it would break up on a 7.

Semiconductors can withstand prolonged operation at up to 150C so some cheap bits of kit make use of this! However, switch mode technology is so cheap these days that they might well use it (PC supplies are switchmode and are all dirt cheap)

You could do it with a switch mode buck regulator. This would be much more efficient than the linear regulator I guess you have tried. There are a lot of ICs designed to do the job that will require a suitable inductor and some caps to complete the circuit. (Here is an example - the MIC4576BT complete with data sheet here) The alternative would be to use a linear regulator (LM317T for example) and arrange a suitable heat sink. With 12v in and 3.6v out you would be looking to get rid of about 8 watts of heat with a 1Amp load. So a 5 degC/watt heatsink would do the job. Edited by - Colin Mill on 15 Jun 2008 18:17:11

If you don't have a heater there would be room for the header bottle above the scuttle. It would probably be an improvement on the standard scheme if you connected the lower port on the bottle to a T on the bypass line instead of running a hose from the submarine section. This would promote the outflow from the head into the header before the thermostat opens.

One of the many electronic jobs I want to do is to beef up the MFRU as I suspect it is implicated in a lot of the dreaded clunk issues. I thing replacing the relays with say 50Amp fully protected mosfets would be a move in the right direction. Are there different MFRU for EU2 and EU3 cars? and does anyone know where I can buy them? (I don't want to butcher the existing unit till I have a working replacement!)

Does that mean the wheels that came with my Classic are real Minilites? I always assumed they were Far Eastern Minilite ripoffs (Minirites 😶‍🌫️ 😬)

I fitted a bleed T from the word go and have never had any trouble bleeding the system. You can make one up out of bits from the local plumbers merchant using a 15mm 'Yorkshire' T and a bleed valve (that simply solders into the leg of the T). I then slightly extended the arms of the T with stubs of 15mm copper tube. I think I also cut a 15mm Yorkshire straight joiner in half and soldered the halves over the stubs to increase the diameter. When filling I have taken the screw completely out of the bleed valve and put a short length (about 9 inches) of 16mm pipe and a funnel onto the leg of the T to aid pouring coolant into the T. You can see the bleed T on mine in this picture here

The "hot and running" thing drives me up the wall. I had a Jag with an auto box that required this method to check the ATF level and you could get any reading you liked. In the end I was told about the two handed technique of having someone turn off the engine and you plunge the dip stick in very briefly just as the engine comes to a stop.

Hi Paul Sorry, I was adding a bit more to the above when you posted. As you can see, you are right - if the exhaust dimensions confine the flow then, for a given mass flow (dictated by the intake conditions etc of the engine) then the flow speed increases and thus the pressure at the cylinder end of the exhaust. While one can get increases in resonant exhaust performance by playing around with increasing the pressure (because the resonant exhaust reflects back pressure waves as rarefaction pulses that help empty the cylinder) this is usually only of benefit where the engine is run virtually at a single speed such is the narrow rpm range over which such exhausts work. (this is OK for us model helicopter fanatics as we run the engines governed to a fixed speed so the exhaust can be incredibly peaky so long as the resonance and the running speed are matched)

The velocity of sound in a gas increases as the square root of the absolute temperature. So, if you have a resonant exhaust such as the classic twin cone 2-stroke exhaust the rpm at which resonance is reached increases as the temperature of the gasses in the exhaust increase and this increases slightly as the wall temperature of the exhaust increases. However, the residence time of the gasses in the exhaust is usually short enough that the gasses do not get anywhere near equilibrium with the walls and the gas temperature is significantly higher than the exhaust walls. This rather complicates matters when it comes to designing the exhaust. As for changes in the speed of flow of the gasses from the exhaust there are two other factors:- The volume of gas increases linearly with the absolute temperature. This rises more rapidly than the velocity of sound so, all other things being equal, the higher the gas temperature the longer it will take to expel the charge. Although of much less importance in the flow regime (Reynolds number) in an exhaust, the viscosity of gasses increases with temperature - quite the reverse of the behaviour of liquids! - and this will very slightly inhibit the exhaust. Another way of looking at the problem is via Bernoulli's equation which is appropriate for subsonic flow. Pressure = 0.5 density x speed squared. Now if we increase the temperature of the gasses flowing down a given pipe we reduce the density (inversely as the absolute temperature). However, if the mass of gas flowing per second is kept constant the speed must increase to keep density x speed the same. If we plug this back into Bernoulli's equation we see that the pressure needed to drive this flow has increased linearly with speed. Edited by - Colin Mill on 10 Jun 2008 08:58:56

If you do find that it needs water check the output voltage of your alternator (and if you use one, your charger) Most modern batteries are intended to be maintenance-free but will gas if the charge voltage is too high. 14.4v is generally considered OK for cyclic use and is a reasonable upper limit for the alternator. Any charger you use as a long-term maintenance charge should not be above 13.8v.