chrishawley

I'm not sure I'm understanding that aspect of the description of the problem. Is that to say that the resting position of the indicator stalk is at 4 o'clock? If so, is it also the case that the column light stalk is at a 10 o'clock resting position? If so then the only way that can be the case is if the steering column cowl assembly (part 155177) is mounted about 30 degrees rotated from where it should be. Which is not so easy to achieve since when the wiring shroud (154833) is correctly affixed (and actually present!) it pretty much dictates the correct mounting (rotational) position of the cowl assembly. If the column cowl has been mis-fitted it is desirable to remedy this before attempting to adjust the self-cancelling. Tedious fulll disassembly should not be required and slackening the lower and upper clamps should allow the cowl to be rotated - but hoping that PO hasn't mullered the wiring shroud. No special tools required other than spanner, sockets and allen keys. For setting the self-cancelling on the indicators from a baseline unknown condition I'd suggest the following procedure: • Park up vehicle in a straight ahead position. Level not so important but straight is. • Remove steering wheel. No, this can't be avioded. • Slacken collapsible joint between upper and lower shafts. • Disconnect lower splined joint on steering UJ and slide lower shaft upward to allow free rotation. • Rotate the shaft untill the spring clip (140549) falls in the middle of the 'jaws' of the indictor switch unit (e.g. pointing 'eastward') • Lightly reattach steering wheel in a correct straight ahead position. Confirm that activation of the self cancelling is approx symetrical for left and right rurns of the wheel. Put s.wheel back to straight ahead. • Recouple lower UJ without accidicently rotating the column / moderate tighten pinch bolt. Moderate tighten of collapsible joint and moderately tighten steering wheel. • Carefully and at low speed perform road test (things only moderately tightened at this stage). If self-cancelling not symetrical then retrun to base and re-do lower steering UJ rotating by one spline in the requisite direction. Re-test and repeat as required. • Once self cancelling the best possible it can be then road test to determine whether steering wheel is straight ahead. If not, remove steering wheel and refit one or more splines rotated in the requisite direction. • When all is done tighten at all points to final tightness. In particular the grub screw/locking nut on the collapsible section which should be severely tight. One thing not to do is to try and adjust the position of the cancelling trafficator clip on the upper mast: Creates problems and avails nothing. Of course, the track rod end adjustment can be used to fine tune the centering of the self cancelling and steering wheel centering. But doing so affects both of these simultaneously - so it may correct one, but adversely affect the other. And if the tracking were aleady good it's oh-so-easy to lose one's datum points and end up having to retrack the whole thing. So I'd incline to getting the best adjustment 'on the splines' even if that means a few repeat efforts. If one does have to adjust the track rod ends for fine adjusment then proceed only by small increments/decrements e.g. half to whole turn and road test after each adjusmment.

I know you know this already but this cross section diagram is useful for keeping the front of one's mind the basic structure of sill. It occurs to me that there are other things to assess before removing anything else. In particular, right now, is the sill straight? To be more precise: it should be possible to put a very long straight edge on the lower lip of the sill and find it straight in both plan and elevation, from front to back. If there is marked deviation then that needs to be worked through before welding occurs. Don't rely on purely visual inspection for the sill accuracy, esp. if you wear glasses, as they can be terribly misleading. If you already have a replacement half floor pan is the outer, lip, edge of this straight in plan and elevation? So often repro panels are not terribly precise pressings and need 'working up' before being fitted. Serious bracing is going to beed need before the inner sill and stiffener come out. Outer sills on their own are very bendy. Really hard to say what is exactly right for your situation but in general 'crosses are stiffer than rectangles'. For example, hypothetically, one might brace with box section from top and bottom of B post to A post. But that's not all that stiff. But go top-bottom and bottom-top and join in the middle of the 'X' is very resistant to movement. Given that you aiming to preserve the outer sill that gets me thinking about a suitable method for fitting a replacement A-post lower panel giving that the upper spot welded seam for this is under the sill front upper face. i.e. it's only accessible without a sill in place. Hmm can't immediately see the answer to that. ,

Batteries v 240v drills. I've got something of an answer now. I borrowed a load of drills and did some bench tests and applied them to some practical tasks. I won't tediously go into all the details but it gist is this: Where 18v drills are concerned there is a direct correlation between price point and function. A £200 Hikoki outperforms a £100 Dewalt outperforms a £60 Bauer and so on. There are no bargains! But the best of the 18v drills was about comparable to a second hand Bosch CSB500 240v. This really showed up when drilling out some manifold studs on which the Bosch performed faultlessly - partially I suspect by virtue of having a decent Jacobs keyed chuck. No hard and fast conclusion here. But I'm sold on the idea that a proper branded 240v is a very good thing to have. But I've also learnt that you get exactly what you pay for. Economy products (Silverline, McAlister, unbranded Chinese, 18v or 240v) are simply a waste of money. Because I was testing things systematically I also got a more profound insight in what a GOOD THING cutting fluid is when drilling steel. But that's another story.

Now, I've only ever done two sills on Spitfires so I'm no expert. I know there are members who have vastly more experience and I would defer to their greater experience. The method of reattaching the outer lip of the floor you propose has some interesting aspects. To break it down a bit: Most of the sill length is triple skinned. Layer #1- the lower edge of the outer sill, Layer #2- the sill stffener, Layer #3- the downturn lip of the floor pan. Now, if #1, #2 and #3 were all pristine metal then attaching 'Layer #4' (replacement pan) could proceed well. But, if the spaces between #1 and #2 and between #2 and #3 (in the seams) are markedly infested with rust then when the welding torch is applied they may go to mush. In particular what one may see is like a worms head (do worms have heads?) poking out of the ground. As the weld cools it ejects a porous composite of steel, rust and dirt. Another aspect is some thought about the integrity of the sill stiffener. Most of it can't be seen because it's sandwiched between the outer sill and the inner sill. The inner and outer can look ok but the stiffener may have dissolved along its entire lower edge. Assuming none of us have boroscopes, a way to visualise the stiffener is to drill a few inspection holes in the inner sill and have a prod and poke. So, for the method you suggest much depends on a fine grain inspection the areas concerned. One ruse when assessing questionable metal is to simply put the MIG torch down to it and make a blob. If it 'blobs' nicely then that indicates good metal to weld to. If is flashes up and goes to mush then it was never going to weldable in the first place. Not sure I've expressed this very clearly. Canvas opinions widely!

Since you've got it all laid bare could you illuminate on a point? It's going to sound like a dumb question but hey ho. Where the outer edge of the floor pan sits under the inner sill, are there witnesses to show what the original method of welding was? For example; is the floor pan welded twice - once horizontally to the sill stiffener through the downturned lip of the pan and again 'upwardly' to the underside of the stiffener where it turns over. It'd be helpful to know. Thnx

As above, but to expand. GT6s only ever had Girling type 16 calipers: 16P up to mid Mk 2, then 16PB up to approx 1972 and then 16PB(metric) to end of run. This errant '15' really has to be a '16' and this could be corroborated by a visual comparison with the LH caliper of which it is most likely a mirror image. Slight wrinkle though: the '64326047' number is most likley to be associated with the 16P caliper rather than 16PB. Although 'P' and 'PB' will function just the same, the piston and rubber seal are different. 16P has a piston with a skinny rebate for the seal and no spring clip (see pic), whereas 16PB has a deep rebate for the seal and a wire clip as well. Bits for 16P are a bit harder to find. Refurb items: TD Fitchett (01952 620434) or Canley Classics are likely sources.

Current task is a Vitesse inlet manifold. So, where water flow through the manifold is concerned, that's the threaded banjo bolt on the rear and a threaded tail on the front. Have managed to extract both without terminal damage to the threads but they need a clean up with a suitable tap. What thread though? Any advice? Its 14tpi which would fit in with either 1/2 in. BSP or NP 1/2 in. Thw males threads that came out look to be parallel rather than taper. OPs manual just say '1/2 inch' so that leaves me in the dark. Can anyone give a definite on the females for BPST v BSPP v NPT v NPS? (Or anything else for that matter) Thnx

Glad to see you are making good progress. Your 'photos are excellent quality and it's possible to really see the nitty gritty of what's going on. I've just posted a item which might be relevant to you, see 'Replacing spot welded panels. Plug or Push tecnique?' Looking around the 'photos I can't say I have much confidence in PO's previous welded repairs. There are a lot of edges that simply aren't welded and patching over a rusty area is a no-no. I'd suspect that a lot of the previos will need to be excised and done again properly.

This starts a bit out of context but let’s suppose someone has posed this question: ‘When two panels were spot welded in construction how can one replacement panel be welded in, where spot welded repair is not possible? Number of possibilities but one could consider just two for now. One is the classic plug weld. One panel has its edge punched or drilled, then those holes are ‘plugged’ usually with MIG. There is an alternative but I don’t know a proper name for it so let’s call it a ‘push’ technique: Here, the two panels are set together then MIG is applied to the facing panel and melted through (‘pushed’) into the panel behind. Now I’m curious and wondering how those methods compare. For sure Plug will work on any thickness of metal but Push can only work on thin material (let’s say 1.0mm or less). To pics….. Pic 1: Two 1mm sheets in close contact. Setting ‘3’ on my MIG set (that’s pretty hot). Then 6 ‘push’ welds of 1,2 3, 4, 5, 6 seconds duration with the final 6 seconds burning straight through. Pic 2: Reverse of Pic 1 - it’s only a 4 seconds that there’s full penetration. That’s long! Pic 3: Destructive testing: Weld 1 and 2 yielded to light prising. Weld 3 gave with a sharp tap with a cold chisel. 4 and 5 rock solid. So, with the push technique the surface appearance on the facing side is not a great guide to weld integrity. Pic 4 repeats the same point. Pic 5 is a plug weld (2 x 1mm plate, 6mm hole). Torch at setting 1 to 2, about 2 seconds. A lot cooler and shorter than weld 4 as above. Pic 6 is reverse. Very happy level of penetration. Pic 7 is destructive testing. A fairly ferocious attack with chisel and hammer did not break the weld and if anything the parent metal will break before the weld does. And the point is??? Well, I’d sooner invite discussion than be dogmatic. But what strikes me is that ‘Push’ can achieve a full integrity weld but involves a lot of heat and that the surface appearance is not a good guide to what’s going on underneath. I'm more inclined to use plug as the default.

Just so I understand the scenario: Turn ignition to 'start' (position 4) , engine then fires and picks up, but on relaxing the ignition key to 'run (position 3) engine dies immediately. Hope that's correct. Could be simple: Let's take a pre KE20,000 as the easy example. There are two 12v feeds to the coil. A white comes off the back of the ignition switch and after a journey through the loom is eventually attached the one side of the ballast resistor. This provides the continuous current to the coil (via the resistor) in the running condition. The second wire, white and yellow, comes off the back of the starter solenoid and runs to the other side of the ballast resistor; this provides power to the coil in the cranking condition (and only in the cranking condition). Implication is that the 'white' circuit is open which could be the ignition switch, the wire itself, corroded connections anywhere, or indeed the ballast resistor itself (the coil of resistance wire on the reverse side can fracture after decades of service. On a post KE20,000 the same principle applies except that the ballast resistor was replaced with resistance wire hiden inside the loom. So now there is a white/yellow wire coming from the solenoid to feed the coil in the cranking condition but the wiring the 'run' condition is white from ignition switch to back of fuse box, then white into the loom where is joins with pink/white wire and the wire in joined to the white/yellow but the join is hidden inside the loom. Simple diagnostic tests for this would be either; a) with ignition switch in position 3 (run) check voltage present at +ve terminal of coil. Correct is any voltage 6v or greater. b) take a fly lead from battery +ve to coil +ve and start car. If runs ok the diagnosis is open circuit as above. But if car runs ok turn off engine pronto (few seconds max) so as to not possibly a fry a 6v coil with 12v continuous. All that's assuming that the system has not been modded for better or worse, but lets keep it simple for now.

Yup, Spit Mk4 glass channel is a very different arrangement from GT6mk3. In the event of non-availability of a replacement, how far gone is yours? If push came to shove is there enough left to effect a welded repair? (did so on mine) My method for seating glass in channel is: Get a strip of rubber of suitable thickness and width so that it will form a 'U' as per parts book 06-21. Smear lower edge of glass with suitable gloopy substance (dum dum, arbomast, gutter sealant) and attach U- strip. Put more gloopy stuff into channel. Invert glass and press channel onto glass (not pressing glass into channel - ends up on floor easily). May need just the lightest of taps with a rubber mallet to bed it down. Rubber strip needs to be thick enough to take up the width of the channel and suitable gloop provides enough adherence for it not to rattle loose. Don't use bonding adhesive like PU sealant - not needed and makes any subsequent removal/refitting very difficult. The plastic sheet under the door card can be cut to shape from any thick polythene sheet. I cut mine from the polythene that came with a tumble dryer. This does need to be firmly stuck around all the egdes. Here's the but! - don't fit it until you're 100% sure that the alignment/operation of the drop glass/q.light and door locks is correct and that the inner and outer weather strips are fitted because (obviously) once fitted there's no access to do anything.

Apologies in advance but I can't resist saying that I've always used an approximately 80% nitrogen, 20% oxygen mix in my tyres with satisfactory results.😃

Pettifordo>> Glad you are making progress on the welding. I think you mentioned a few posts back that you were sometimes getting very 'high' or 'knobbly' welds. Sometimes one sees welding where the result looks a bit like someone has glued petit pois onto the metal (or rabbit pellets). I'd never reallt thought about this much so I had a play ot see if I could understand it. #1 in the photo shows a strike where the heat was just a little on the low side and I deliberately kept the duration short. High build of wire on the working side of the work and only minimally adequate penetration of the reverse. #2 show same heat setting but now a deliberatley too long duration: Much less build on the working side but at the expense of excessive penetration on the reverse. #3: Now using a higher heat setting the with right (fairly short) duration. Close to ideal - quite flat on the work side, well melted in, and a nice penetration on the reverse. My deductuion is that 'petit pois' welds are an interaction of heat that is relatively low (in relation to the work in question) and a relatively short pulse. I experimented with altering the wire speed but that made no significant difference (the 'sizzle' range is pretty narrow anyway). If I recall, you're opting mainly for lap welds rather than butt welds. But a lap weld (for a given thickness of metal) requires more heat than a butt weld because one is, in effect, welding a piece that's twice the thickness. For a butt I usually use setting 1 on my machine for 0.8 - 1.0mm steel. But for a lap or a plug weld I'll step up to 2 or even 3. Hope you continue to make good progress.

This is a common problem, always solveable, but diagnosis and remedy is time consuming. On one I had, the final solution was to cut the pivots brackets off the tubes and reweld in a revised position. But that's jumping the gun. Based on past painful experience I would suggest that as a precursor to resolving the hinge pivot problem one needs to fit up bumper, q.valances, centre valances (or spolier) and the plastic over-riders. One can the look at the whole picture and not solve only problem only to make another. Examples of what can go wrong are i) bonnet in position, but fouls the bumper on lifting, ii) plastic over-riders won't line up with with nuts on hinge box and bumper, iii) impossible to adjust q.valances to acceptable position. So that's much the same as your question above about how the leading edge of the bonnet falls in relation to the upper lip on the hinge box. But I would encourage looking at the whole picture before further action. Oh, and what about the PO factor? Back in the day repairs/rewelds to the front chassis crossmember were commonplace and not necessarily accurate. When you say 'new' chassis does that mean NOS new or restored new?

I've never known a proper name for this technique. Of all the technical aspects of welding that have definitional standards I can't find one for this. Would be really helpful to have a proper name fo it if anyone knew.

Firstly, thanks for all the advice and opinions without the inspiration of which I'd have been well stuck. The end of the story is, yippee, I have a GT6 that can nip down the A600 at 72mph feeling as sound and as 'planted' as one can realistically expect. It's been an interesting pathway, though. I'd spent many hours tweaking various aspects of the geometry largely by driving feel untill it felt more or less right(ish). So I took it back to CVS (Shefford) to have it lasered. All credit to CVS who were supremely helpful and were happy for me to be hands on with them during the process. The main outcome was that although the shims were equal on both sides (L 2r 1f, R 2r 1f) caster was 4.0 degress left and 2.1. degrees right. And thats after I had added extra shims so the original caster after first laser alignment must have been about 3.0, 1.1. And that original alignment was done by selfsame CVS. So final shimming is (L 4r 1f, R 2r 1f). An caster is 4.0/4.1 Being on good terms with CVS I wouldn't want to criticise them for 'getting it wrong'. They are clearly knowledgable and proficient but the young operators just don't have the old skool feel, and trust the computer readout more than the evidence of one's own eyes. And as for conceptualising fractions of an inch - no chance. Trying to explain that 1/16th inch is about 1.6mm I could have been speaking Swahili. So that leaves me a bit ambivalent about laser alignment, but I got a happy result in the end. Thnx

It's a well made point that using a Dewalt DC725 (or its current equivalent) as a reference point is hardly setting a high standard. But for my purposes it would be a minimum standard. If typical 240v combis didn't even meet that level of capability then that would rule them out from further consideration. On the other hand my 'big' 230v Dewalt is a 218055 and is only 710w but has the capability/durability for everything I need - if only that level of performance were available in a physically smaller unit. A part of the equation is that I have to share my tools across hobby and work and the latter results in 'disappearance' and 'abusebyotherstodestruction' with depressing frequency which rather inhibits the wllingness to spend on the best. Looks like 'going 240v retro' is not that promising. Since I'm in for £££lots to rekit anyway I guess I just have to bite the bullet and buy some stuff and see what it's like in practice. But I remain open to suggestions before unpadlocking the wallet(!).

Most of my cordless combi drills (mostly Dewalt) have come to the end of their service and battery life pretty much simultaneously. Rekiiting with cordless is going to be £££lots. Meanwhile while my 240v Bosch combi is still going strong after 30 years. So, I'm thinking, why not have mainly 230/240v drills? And maybe just one cordless for 'on the move' jobs. But does anyone have advice on 230/240v drills? Paricularly the power, capabilities of the chuck and durability of the gear box. My tools get a hard life. I already have a 'big' 230v Dewalt for masory work and it's stood the test of time - but too big for car work. Any tips or experience wouldbe much appreciated. One option might be DeWalt DWD024K-GB if it operates up to the same level as, say, a DC725. (?????)

Courses are very few and far between. Locale HE colleges with often have an offering which includes body refinishing but they can be a dismal experience as you are likely to find your classmates are a bunch of apathetic juveniles. Most 'pros' have never been on a course - they learn it through trial and error. The whole refinishing job involves a lot more than just spraying but let's just stick with the spraying-of-paint bit for now: The minimal kit for spraying is: • a compressor • airline • PCL connectors • regulator and water trap unit • gun(s) Compressor: A pro level compressor is 200L tank, 4hp and ≥14 cubic feet/minute air flow. But most DIYers do not have space/readies to accommodate that. At the other end of the spectrum are micky mouse machines 25L/≤2hp/<10cfm. Utterly useless for any serious spraying. In the middle 100L/3hp/≥10cfm is a realistic minimum. Two ways to buy: Buy a cheap brand (e.g SGS, Machine Mart) or buy a respected brand (e.g. SIP, Sealey). Main difference (for the same spec) is cheapies have a shorter service life and sometimes not repairable and lacking any after sales support. Airline. Two lengths (compressor to regulator and regulator to gun). Need to be flexible not rigid. Sealey blue and red striped is a nice to use PCL connectors: snap connectors for air lines rather than the inconvenience of threaded BSP connectors. Regulator and water trap: Essential. At £30ish Sealey SESA4001FR is fine. Guns: As many men, so many opinions here. A respectable gun (FastMover, Sealey) can be had for about £30. There are Suction Feed guns and Gravity Feed guns - determined by operator preference. Cheap guns (with a wide needle, e.g. 1.6 - 1.8mm) are great for lashing on primer and there's no point in having anything better. But for colour coats (smaller needle e.g. 1.4mm) a pro-level gun (e.g. DeVIlbiss, Iwata) will be vastly superior. But a 'full spec' Devilbiss is £300 plus although they do some some budget options which represent a good compromise on cost and quality. I always keep two guns on the go - a cheapie for primer and keeping the 'good' gun pristine and for finishing only. As a first entry to putting on paint I'd suggest to buy a Fastmover MiniHVLP gun, 125ml pot, 0.8 or 1.0mm needle) - £20 ish. Not for serious spraying but is a very convenient way to get one's hand in before moving up to full size guns. Refinishing is a long learning curve but the amateur who has dedication and persistence can often produce a result better than yer' average body shop working under constraints of time and budget. (in fact there's one 'pro' outfit near us who are soooo bad they've become referred to as 'Peter's and Lee'.

As promised here's a few illustrative photos'. But with a strong caveat opinions vary about optimal techniques for different circumstances. Specimen #1: upper weld made with impaired vision. Evident wander. Lower weld made wit exactly same machine settings but with clear sight and the shroud firmly held and close up (nearly touching) the work. Acceptable 'caldera' like appearance. Speciemn #1R: Is the reverse side of #1 showing minimal if any penetration of the 'bad' weld. The good weld shows full penetration (= good) Specimen #2: Much the same result as #1 but this time a weak single handed grip on the torch. You can see where the electrode has struck and bounced off and then restruck a few mm to the left. Specimen #3: Show 9 single pulses of weld (top and bottom rows) and then what it's like (middle) if one makes the pulses contiguous. That's now a continuous weld without any pinholes or burnback. Specimen #3R: Is the reverse and illustrates full penetration weld and continuous on the reverse (ok, pehaps a little over penetrated but it is 0.8 steel). Specimen #4: Is an actual join along a 1mm gap. Acceptable calderas each one merging into the foot of the next. Getting the pulses to be contiguous is really hard to describe, but roughly: Lay in the first pulse. The operator then has 2 - 3 seconds while the initial weld is still glowing bright red to plant ( by sight) the electrode tip in foot of the first caldera and make the second strike, then 2 -3 seconds again and so forth. But as heat builds up in the material the duration of the each pulse has to be diminished as the line of welds develops. I'm not sure I've explained any of this very well so do post back if I've been obscure.

Second thoughts. Can't see from you photos but are the torsion springs present and correctly fitted?

Here's some pictures of what HS4s are supposed to look like (on a Spit 1500). There should be two linkages between F and R carbs. Does that give a clue?

I've contemplated you photos and have some suggestions. But I know how dispiriting it can be to have others picking holes in one's efforts during the learning process. Within the limits of the resolution of the photos I can see a) burn back, b) lack of penetration and c) severe porosity in places. For c (porosity): assuming that the gas flow is good (say 8 - 10 lpm) a common cause is detritus on the reverse of the work area (rust, paint, underseal, wax). Ideally the reverse of the work needs to be pristine clean as the facing side. Not always achievable, but should be aimed for. Also, fresh mild steel (or CR4 say) may be coated in various ways for atmospheric protection which means it does not accept the 'strike' of the weld well. Linish everything. Regarding a and b. Critical is having good sight of the weld bead as it is in action. One should be able to see the fine detail of the tip of the MIG wire as it goes about its job. I wear varifocals day to day but need special 6 dioptre specs so I can weld up close at about 9 inches. This means I can see the minutiae of the hot spot rather than 'point and hope'. And not having the auto dimming on the mask too dark so that one can't see. The lowest setting ('9') is often correct for lightweight work. Next is torch control. The natural tendency is to try and control the torch position with a firm grip of the right hand (for the right handed). But this leads to intentional tremor and poor control (wander) of the hot spot. The torch should be lightly balanced in the right hand and position control provide by gripping the shroud of the torch with the left hand. Much the same as a snooker cue. The left hand needs to be firmly planted to give a decisive position. Related to this is 'kick back'. As the MIG wire hits the work it tends to push to torch backwards toward the operator if the torch isn't firmly controlled - and this may result is getting a superficial tack of weld which doesn't penetrate. Sometimes one needs to mentally push the torch into weld to counteract this tendency. Also wire speed to consider. If the wire speed is too slow the weld will be silent (and result is tabs of poor penetration weld). Too fast and the torch will kick back sharply and tend to put a great blob of ineffective weld on the surface of the work. The correct in between is where the weld makes a distinct 'bacon and eggs' sizzle - exactly that. Frequently I will attach a dummy piece of metal adjacent to the work area (of similar thickness to the work) to check good sizzle before starting the work in earnest. Trouble is that many MIG sets have appalling calibration on the wire speed control and minute adjustment of the knob is required to get on the sizzle spot. On my SIF '5' is much too little (for power = 1) and '6' way over the top and correct is a gnats worth of adjustment in the middle. Onwards and upwards! It comes with patience and rehearsal. If I get a chance later this week I see if I can find some photos to illustrate some of my suggestions above.

Ok. i'll try dropping the rears. I'm on standard 4.5Js. But my spitfire is best at 24f22r so I can see the logic. Nope, no spoiler. GT6 is a really early Mk3 and I'm rather reluctant to do anything which subtracts from the authentic appearance (outwardly at least). But I would consider an undertray if there were some sort of tried and tested design.

Yup, adjusted front toe in when changing the caster. Tyre pressures approx 26f 28r (but none of my TGPs agree with each other!). Tried pushing the pressures up but that led to marked skittishness. So, one more round of measurement and then perhaps leave it alone for a few hundred miles; the car is still pretty fresh on it wheels and definitely settling/softening as miles accumulate. On the first few test drives it was absolutely appalling - boneshaker would be an understatement. And I still have a very thick lowering block on the rear spring which was required to get the ride height down to something normalish. But I suppose that with the passage of miles that will need to be changed for a skinny block or none at all. And thanks for all the comments and advice without which it would have been creeks and no paddles.