J.R.

Gary Ideally wanted to change it before the end of August for a hillclimb where I will be using my tall road tyres. Ironically my car is a Blackbird with a 3.14 diff which was built for the Nurburgring but is a tad overgeared for most circuits on 20" slicks, hence wanting to change to a 3.38. If nothing comes up before then, October will be OK, - stay in touch - my mobile is 07768 695599

Wanted (in order of preference hence price) Crown wheel & pinion Or complete diff Or complete LSD W.H.Y.?

Fatcat. The TNI is a great price but abit limited on temp range, I have a laser targeted (Raychem or Racal?) one bought on special from screwfix for £49 inc feel free to try it next time at Lydden. Agred it is perhaps not so accurate as my probe one but that takes a lot longer to register the correct temp for each tyre, by which time the others will have cooled significantly. I am not too worried about absolute tyre temps and use it as a comparator to measure the gradient across the tyre and also sneaking measurements of the competitions tyres; - they would not be quite so happy if I poked a probe in them!

The paint will fall off easily with Nitromors but usually leaves behind the etch primer, or more probably the coloured etched surface, this has to be removed with a DA sander or similar before polishing so quite a lot of work. If you are lucky and the paint job is as bad as you say then it might not have been etch primed but then again it could well be covering up filler 7 dents etc. Sounds like you have not much too lose by giving it a try.

They are made by Grayston products of Chessington but they only supply to the trade and in volume. Rally Design at Faversham buy from them and sell retail in small quantitys but have a limited range usually in the longer lengths for wider wheels/spacers etc, you may have to cut down one longer than you need. I have some spare studs (standard and longer) if you are stuck, let me know what size you require i.e length of thread measured from shoulder and thread size (usually M12 * 1.5)

With a bike engined car you have to downchange through each of the 6 gears when braking to a standstill, this must also be done whilst still moving. It can be a problem when doing an emergency stop or when you just plain forget! whereupon you hurriedly have to snick in 5 downchanges in the last couple of yards whilst counting down the numbers in your head!

Use R4 superbike synthetic oil as it does not have the friction modifiers that "car" synthetic oils have that wreak havok with the bike wet clutches. That said I fitted Bailey Kevlar plates to my other blackbird which has yet to slip the clutch whereas I have experienced slight slip on full power changes on the car using R4. I removed & checked the plates and they were within limits and only worn by about 2 thou each!, refitting another second hand set (with another 1 thou each) has cured the problem for now. For peace of mind I will always use R4 and as & when the plates need changing use Kevlar ones, - but be warned the very last plate is different to the other 9 or 10, the bailey clutch plate set I bought werte all the same so I couldnt replace the last one; which is a real fiddle anyway!

Assuming that it is a 7, - what type?

Oil pressure relief valve is set to 65psi, on a cold or moderately hot engine it will reach this pressure by about 6k revs. During race conditions at max revs and high oil temps this can drop as low as 49psi momentarily without problems. Definitely check the sender as above, make sure that it is remotely mounted using a flexible pipe. The pressure relief valve (which is normally inside the engine) is relocated to the end of one of the upper return pipes to the dry sump tank so is easy to inspect.

Redline components sell them, they are cheap but not free!

Rick Make sure that you have aligned the cut -outs in the rear caliper pistons with the lugs on the pads, it is possible to get this wrong because of the thinner discs that are used compared to the standard set up. When I made this mistake it took many thousands of miles to bed the pads into a tapered "cheese" shape 😬

Arnie Engage the pair of suspect dogs in your hand and try driving one against the other in both directions, (you may also need to engage in the second position dependant on number of dogs). You will probably find in one direction the dogs "cam out" and in the other direction still grip, this will give you a good indication of how much wear is permissable before problems.

I disc cut a rectangular aperture on the bottom unseen part of the can for almost the whole length. It was then covered with a 16g ali sheet rolled to the correct radius and riveted in place using exhaust sealant. Please note that fibreglass or rockwool insulation may burn or be blown away within 1 long evening blat unless the aforementioned mesh or similar is used. I also once experimented with expanded foam (introduced through a small drilled hole) with disastrous results to the environment and other motorists unfortunate enough to follow. It looked, smelt ad tasted like a chemical weapons attack when it caught fire!!

The bespoke machined bits i.e sump, timing case etc are made by Nova Racing Transmissions. I dont have their number to hand but you can E-mail me if you need it. They also make these and other parts for the Whiting Fireblades. If they cant help you then I have two sets of bare castings that were originally used before the billet CNC machined ones from Nova. One set I had intended to machine for my original (non dry sumped car) you can have the other one if you need it, I havnt yet had the time (or money) to arrange the machining but the cost would halve if both sets were done. About 6 months ago when Caterham discreetly "forgot" all about the Blackbird they had many sets of all the bespoke items in stock for the next production batch. Despite knowing they would not be producing any more cars they would not sell them at a discount, guess they have now had to throw them away! but it might be worth some diplomatic enquiries.

I have successfully reduced the noise output (and appetite for stuffing) of two seven silencers over the last decade. The first was on my steel X/flow westfield, the second on my Caterham Blackbird. In both cases what I did was to tightly wrap the perforated core with what I think is Berrylium copper filter mesh material (similar but lighter to the type used in some dry sump scavenge filters). The silencers were then packed with a fibre glass and /or rockwool roof insulation - whatever was to hand. Before using the filter mesh the can would be quiet initially but soon consume the stuffing and get very loud, this has not happened since using the mesh. On the Westfield with 254 and 264 cams I had a particularly bad 4 into 1 resonant period where the engine would not pull under load through 2500=2800 rpm. Inoticed that while the stuffing was burning out of an "unmeshed" can the problem went for the first time ever! the subsequent exhaust used the first 8" of the can as an expansion chamber 9 the volume of which was derived by calculation and fine tuned by experiment) this allowed the engine to run properly and did not significantly affect the silencing. My other interesting finding was on the new caterham silencer fitted to the Blackbird, it had got progressively louder and i was convinced that the stuffing had burned away. When I opened the can it was still stuffed full of unburnt wire wool apart from some condensation corrosion all looked OK but the car was registering 116Db at less than the required 3/4 revs. After the fine mesh treatment and stuffing with the asssorted contents of my garage and loft it is not only at 100DB but also considerably lighter. Have since done a 1/2 hour race, the Cadwell track day and 500 road miles and all seems well, only time will tell. My other Blackbird uses the original Honda 4 into 1 section which has some composite acoustic padding, sort of a steel mesh enclosing wire braid, this car has always been embarrassingly quiet and never eaten any of the exhaust stuffing from the original unmodded Caterham silencer. I dont know the science or many of the answers but remain convinced that how the exhaust gases are handled before the sound waves are exposed to the resonant material has a great bearing on sound reduction and silencer life.

Chris I stand corrected. Thankfully being self employed my boss is as ignorant as I am. No I dont repair aircraft but if you are worried perhaps you might want test the aircraft mechanic on ohms law before you fly. Just goes to show that you are never too old to learn the basics of electrical theory, mathematics or politeness

Totally wrong and talking out of my 🙆🏻?? Makes you wonder how I have earned a living in this field for the last 12 years doesnt it? I suppose my algebra must be equally bad because I cant see how you can turn a linear equation - "power = voltage * current" and "current = voltage resistance" into the exponential "power = voltage squared * resistance. But then what would I know

I really would like to see someone drilling a tapping hole then taper reaming then tapping a tapered thread that would really make my day 😬 😬 When tapered threads are referred to as in BSPT it is the male thread that is tapered, this can be screwcut on a lathe. The corresponding female thread is a standard parallel thread, it is not possible (nor desirable) to generate a tapered thread with a tap. The confusion may be from the 3 types of tap for each thread. Taper tap - used for first tapping of drilled hole. Can be used alone for through threads on thin material. Second cut tap - used to finish threads after the taper tap on blind holes. Plug tap - used after the above if the thread is required to go to the bottom of a blind hole. Edited by - J.R. on 2 May 2003 11:19:13

Chris W. If the cable resistance was 1/10 ohm to the switch and 1/10 ohm back then the total resistance would be 1/5 of an ohm not 1/20th. Current draw on main beam circuit is 5 amps per light (each light has seperate feed cable, but even using your figures of 20 amps and a resistance of 1/20 ohm would only result in a voltage drop of 1 volt. Electrical power (watts) is directly proportional to voltage, not squared. Watts = amps * volts. So using your figures the reduction in power would only be 8.33%. If you check you will see that the resistance of the lighting cable is lower by several orders of magnitude than 1/20th of an ohm, more likely to be less than 100th of an ohm per metre. Also the current flow does not go to "the switch and back" the return is via the nearby earthtag to the chassis return & to the battery via the earth strap. Your calculations would hold true (excepting the voltage drop squared) for a bad earth or switch connection. The easiest way to measure volt drop if you are worried is to use an accurate multi-meter set to the lowest range with the lights switched on, one probe at the switch connection the other at the headlight connection. The fractional voltage displayed will be the voltage drop, this divided by the battery voltage and multiplying by 100 will give the percentage reduction in power from the voltage drop in the circuit.

Did the upgrade to my 1987 De-dion car. Caterham do a boxed kit of all the parts required including brake pipes, handbrake cables, calipers, pads, de-dion ears, discs, hubs, etc etc. It cost about £300 in 1998. As this is one of the "kits" listed in their price list for componet assembly it is sold at a better price than the sum of the parts and their dealers make a much smaller margin on it. for best price (in this instance) buy direct from Caterham.

You will need more than a "friendly MOT garage" if you "catless" car is post 98 and does not have the V5 endorsed with "lower SVA testing limits". Good luck

Hi steve. So changing the diff was the only thing you did "apart from the puncture repair" then? 😬 😬 😬

both old and new uprights are machined from the same forging , the difference being the new ones have a plain shaft without the thread or the grease hole through the middle. The bearing diameter is smaller but as it doesnt have the grease hole in the centre or the stress raisers at the thread roots they are considerably stronger. I modified my 1987 chassis to the new set up and remachined the old uprights to the new pattern, these are now "weaker" as a consequence because of the grease hole. They have however held up through 3 race seasons without incident. My lower wishbone front mounting had a protruding stub with internal 5/16 unf thread. A bit of mucking around with Y9 and Y16 bushes soon solved the problem. the upper link was a standard upgrade part which is bolted to the rear of the anti-roll bar mounting with longer bolts and necessitates a carefully cut hole one each side panel.

Easiest & cheapest way to test the pressure is to run a length of clear tubing vertically from the pump outlet. If it were pumping water then 1 psi would raise the the fluid by 2.307 feet or 27.6" this is ok if you pump water for testing, if you pump fuel then the relative density is lower and it will go proportionately higher. Dont know the relative density of petrol but someone will probably soon post it. This method is also very usefull for testing the ram air intake pressure. Why are you using flat slide carbs? have you been having difficulties with fuelling, jetting, fuel pressuer etc using ram air set up on standard carbs? - if so I have been there myself may be able to help.

Hope that you get more life from these than the rallycross boys. The last one that I saw being replaced between runs after failing appeared to have the yoke ends fixed with a couple of pop rivets perhaps that was to locate the assembly whilst the glue went off. In any case the glue or whatever else was backing up the rivets had failed.