Monthly Archives: July 2011

Snetterton Prep

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With the IVA booked for the week after Snetterton the first thing I had to do was bolt back on the bits I’d take off – fire extinguisher, brake bias adjuster, ARB adjuster, video camera etc. I also uploaded the ‘normal’ map to the Power Commander and fitted it onto a new bracket in the engine bay – it kept falling off the velcro fixing I had previously. It’s new position also keeps it in cooler air.

Since Donington I’ve given much thought to the car’s handling and after discussion with Ian and Brian decided to shift the car’s aero balance rearward by means of adjusting the rake. When I originally set the car up I set the ride height at just over 80mm all round so my plan now was to introduce a bit of rake with the rear slightly lower than the front. On Saturday afternoon I stuck the bags of sand in the cockpit, stuck some fuel in the tank and set about measuring it again. To make this easier I made myself a simple ride height gauge. Demon Tweeks sell one for £227 plus VAT but mine comprises a block of aluminium with a hole tapped through it for an 8mm bolt. Slide the thing under the corner, unscrew the bolt till the head butts against the underside of the car, pull it out and read the height using a vernier caliper. Simple but effective. It also shed some light on why the rear of the car’s a bit lively – both front corners were 73mm with the rears at 85mm and 82mm, giving about a 10mm rake. Clearly the front springs have settled quite a bit. So my plan now was to reset the suspension with zero rake and see how it feels at Snetterton.

The suspension is adjusted using the turnbuckle pullrods so it didn’t take long to get it to 80mm all round then I got the car onto the weighing platforms to look at the corner weights. It was a little out with the diagonal at 52.9%. So I adjusted the suspension again till I had the diagonals at 50% then got her off the scales to check the heights again. Miles out with the left front at 97mm and left rear 78.5mm. I ran out of time and resumed Sunday morning with a few more cycles of adjusting ride heights followed by adjusting corner weights. Eventually I got it back to 50% across the diagonal with all 4 corners within less than 2mm of each other.

With the car now pretty much ready for Snetterton next weekend I headed back to the IVA to do list. One of the time consuming things to do was to make a new passenger seat. I’d made a start on this on Saturday afternoon by blanking off the handbrake mechanism and the rails at the sides with cardboard and sitting in the first bag of foam. After a couple more mixes of foam the seat was ready to carve to shape – trimming the edges, smoothing off some of the ripples and doing the cutouts for the harnesses. I ended up sticking it back in a bag and adding a bit more foam to fill out the area around the handbrake to make sure it enclosed all the non rounded edges of the bracketry.

Attention then turned to headrests. So far I’ve been using some of the foam roll cage padding wrapped around the vertical strut Brian has welded into the chassis for a headrest. This has been OK for racing but I need proper headrests for IVA including one for the passenger side. I decided to make some from MDF to start with with some foam padding and covered in vinyl. Following a quick telephone conflab with Brian to discuss options I made a start on the driver’s headrest. There are various IVA regs specifying maximum gap from the seat, minimum height and minimum width etc. and once I thought I’d got my head round those I cut out a blank and machined a pair of 6mm bolts so I could countersink them and glue them in as captive bolts. Once this was done I glued some foam on there and covered it with vinyl backed cloth. The result isn’t perfect but will do the job, although it looks far worse in this dimly lit shot than in real life!

The passenger side is a bit more tricky so I opted for a much taller headrest so I could bracket it off the top of the roll cage as well as the diagonal. With captive bolts glued in and some aluminium brackets made I then got that padded up and covered. I’m pretty happy with the headrests and once I’m confident they are in the right place (and don’t need to be adjusted forward at all) I may well take them somewhere to get them upholstered a bit more neatly. In this shot the passenger one isn’t actually bolted on, the roll cage will get some foam tape trim before it gets fixed on there.

Then it was time to get all the tools etc. packed up ready for the trek to Snetterton on Thursday evening. With testing booked for Friday and a double header weekend I should get plenty of seat time. and of course it’s the RGB Marshals’ BBQ on Saturday night :)

IVA prep

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Before getting going on the IVA prep I needed to fit the revised engine mounts. The BDN uses a sort of modular system to allow any engine to be fitted using the same basic mount sbut with different machined adapter bobbins to accommodate the different engine widths. Ian and Brian think the bobbins allow too much flex once the engine’s under full power causing the reverse gear to impinge on the starter motor so Ian’s redesigned them with pair of beefy machined parts. The lower part braces the mount back to the rear bulkhead and unfortunately needed a bit of modification as it didn’t quite fit – probably because I’d needed to move the mounting hole when I originally fitted the engine. Here it is fitted to the engine mount plate ready for refitting.

The upper part looked like it was going to be a drop in fit but needed a couple of extra 10mm holes drilling in the mount plates. Once I’d done that I had to file quite a bit off it as the engine mounting lugs slope backwards rather than being vertical. Here it is once I’d sorted that and got it bolted in. It certainly looks like it should keep the mount plates nice and square.

 

I had limited time at the weekend but did make a start on getting the car ready for IVA. The initial stages of this mostly comprised taking things off it. I started with the rain light and the video camera then took the fire extinguisher out. I left the plumbing for this in, I’ll make sure the extinguisher end is secured and taped up and I removed the cockpit nozzle which was on a little ali bracket under the dash. I then removed the brake bias adjuster and it’s bracket then moved onto the cockpit adjustable ARB – I suspect this would actually be OK but I don’t want to leave anything on that might cause an issue especially when it’s not a terribly difficult job to take it off. I tapped a long 6mm screw to replace it so I still have an adjustable ARB, just not from the driver’s seat.

On Monday the nice man from VOSA rang me to get my credit card details to charge me the £450 for the IVA. I later had an email asking me for receipts and photos to confirm that it was an amateur build by myself. It didn’t take too long to produce copies of receipts for all the major bits and I printed off a selection of my vast collection of photos. Since the VOSA main office is only about half a mile from the surgery I dropped them in at lunchtime on Tuesday.

While working on the car on Sunday I realised the garage had reached the point where it was a hazard! I was having to step over stuff wherever I went so I decided before I carried on I needed to have a tidy up. I hadn’t actually seen the bench for a good couple of months for all the clutter on it so that was the first focus of attention.

After some email correspondence with Dan Bromilow, a fellow RGB racer who SVA’d his race Fury, I decided to stick with my plan A on the harness front which was to use the cheap ‘E’ marked harnesses I got from Car builder Solutions. These need normal bolts rather than eyebolts and our local emporium didn’t stock tensile 7/16″ UNF bolts so I ordered some from Namrick. Having cleared the bench I also turned a set of 10mm spacers as the harness eyes are cranked and need spacing out from the mounting points.

The handbrake was next on the list. It works great but at present there’s no compensator mechanism to balance the two sides and the IVA manual states “The parking brake mechanism must incorporate a means of compensation between all brake assemblies operated by the parking brake control, and a means of adjustment to compensate for wear.”. On ‘normal’ cables this is usually done by using a single cable with a semicircular part that allows the cable to slide around it. Having given it some thought over the months I did have a cunning plan involving a pivoting bar connected to the lever via a rod and a small rose joint.

I’d posted the original reverse gear back to Brian on Saturday and the shiny new one arrived back on Wednesday. Brian’s pretty busy at the moment getting his son Rob’s car sorted and I know Rob’s over from Australia at the moment so I wasn’t expecting such a quick turnaround. This didn’t take long to fit then I refitted the rear sprocket and got the chain tensioned.

Friday’s goal was to get the handbrake sorted out along with anything else I could fit into the day. As these things usually pan out it took far longer than I’d anticipated but by late afternoon I’d fabricated new bracketry and got it painted and hung up to dry. Once fitted I was very happy with it, the previous bracketry had a bit of give in it while this is braced much better and is more effective. Lots of folks have trouble getting Wilwood handbrakes through IVA, at least I have the advantage that the pads/disks are well bedded in.

The VOSA inspector rang me around lunchtime to book my test appointment. Unfortunately he was booked up for the following week and was off on hols the week after so it’s booked in the first week of August. I initially booked the Wednesday but rang him back and changed to the Friday – we’re racing at Snetterton the weekend before and I probably won’t be home till late Sunday night which wouldn’t leave much time to prep the car. Also if anything were to happen to the car and I had to cancel you lose the fee if it’s less than 3 days notice.

So this means I’ll need to refit some of the bits I took off. There are still plenty of things I can sort though.

On Saturday I got the headlight adjustment sorted. With them just bolted on they’re pointing just a tad lower than they need to be so I needed some way of being able to adjust them upwards. I came up with a plan involving sticking a couple of rivnuts just below the mounting holes with 5mm screws through them from the back so that when screwed in they push the bottom of the light unit up. This worked nicely and will allow adjustment with the covers still on. You can see the lower adjusting screws with their locknuts in this photo.

I didn’t get much done on Sunday as management had other plans for me. I made a start on refitting the stuff for Snetterton and got the rain light and camera refitted. I’ll concentrate this week on getting the car ready for Snett then try to get some of the other IVA stuff done that won’t need to come off for racing like wiring pup the hazards, making a new passenger seat etc.

Next steps

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The plan all along has been to try to get the BDN through IVA. I originally wanted to do this as soon as I built the car and well before the race season but there wasn’t time and it hasn’t been possible since. I put my Westfield and the Ultima through SVA so have a good idea of the process and what’s required. The only thing I could think of that might be a show stopper is the emissions, so I decided that I’d see if I could get it to an acceptable level before forking out the £500 fee to actually apply for the test. The problem is that it might require reinstatement of the PAIR valve system and I really don’t want to be bothered with that.

I rang VOSA this week to check on the waiting list and was informed it’s currently about 5 days at the Cardiff centre so if I could get the emissions sorted I can get a form in and make a start on all the modifications I’ll need to make.

On Friday morning I took the car round the corner to our local garage with the laptop and stuck the gas analyser up its exhaust pipe. As expected it was miles out, CO level was high, lambda was out and hydrocarbons were through the roof at 800-900 with a limit of 200 for the test. With the laptop connected to the Power Commander I started leaning off the part of the map that was relevant and pretty soon had the engine running so badly it wouldn’t idle! By the time I’d spent about half an hour on it the numbers were still nowhere near. Some of the changes I was making didn’t seem to be doing much and eventually I realised that although it was at idle the Power Commander thought it was about 2% throttle so I started modifying the fuelling for the 0%, 2% and 5% columns together. And we started getting somewhere with all three numbers getting somewhat closer. Eventually at -25% fuelling all 3 were within the parameters.

By now the engine was getting a bit hot – oil temp was fine but the water was at 105° so we left her to cool down for a while before we did the fast idle test. This didn’t actually take long at all and was fairly easy to get the CO to <0.2%, hydrocarbons <200ppm and the lambda around 1.0.

I was a bit worried about the degree of difficult meeting the requirements for the idle but when I checked the limits again you only need to hit all 3 for the fast idle at 2500-3000 rpm,
the only requirement for the 1000rpm idle was CO <=0.3% which had been easy to get.

We also had a quick look at the headlight alignment which only needs minor adjustment and I have a couple of ideas about how I can achieve that.

This was pretty pleasing and meant I could now commit myself to actually submitting the car for IVA. So on Friday afternoon after a quick call to VOSA to check that I could concoct my own VIN (and you can so long as it's unique and contains 17 digits) I filled in the form and popped it in the post.

I then set about dismantling the reverse gear and the engine mounts so I can fit the modified mounts and send the mangled reverse gear back to Brian for him to make a new one.

I do now have a whole new to do list which includes:

  • Sort out handbrake compensator
  • Headrests
  • Brake fluid warning light
  • Adjust headlight alignment
  • Remove extinguisher and cable pulls
  • Remove Rain light
  • Add ignition lock
  • Add immobiliser
  • Remove tow loops
  • Remove splitter
  • Remove external master switch
  • Fit passenger seat/harness and make new seat
  • Trim edges around cockpit
  • Sort out 19mm radius underside dash
  • Trim edges of spoiler brackets
  • Trim edges of cooling ducts

So not much to do then!

Donington Park

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After slapping a bit of black paint on the new splitter spacer I got the motorhome loaded up and the BDN on the trailer and headed off to Donington. At 190 miles it’s not the most distant track but on a Friday afternoon the M5 and M42 meant it took over 4 hours. The paddock was pretty sparse, having had a grid of 28 at Snetterton we were down to around 20 this time, possibly due to it being a single header.

The weather on Saturday was lovely, blue skies and warm sunshine. It was all a bit of a rush with scrutineering at 7.20 and of course you have to sign on before you scrutineer. Since I’d never raced at Donington before I also had to fit a ‘first time racing at circuit’ briefing in. I had a very pleasant scrutineer who made complimentary noises about the car and found nothing apart from commenting that the harness QR clasps should have split pins through them to stop them coming off the eyebolts. He did also then add that that wasn’t in the Blue Book and was only a recommendation and not a requirement. By 8.15 I was all set.

The Allcomers qualy session was pretty busy with some pretty significant speed differentials. I got up to some sort of speed fairly quickly since I knew my way round reasonably well. Then I had a little ‘moment’ round Craner – I’d eased off round Hollywood to let Derek through, I was going pretty slowly and wasn’t really off line or anything but the rear of the car was moving around and felt pretty unstable. This didn’t do a lot for confidence levels of course, I was already worried that the lowering of the splitter would give me more front end at the expense of rear end stability although the car seemed fine everywhere else. I suspected it was me being a bit clumsy at Craner. My fastest lap was a fraction slower than I’d managed on the trackday 4 weeks earlier. I was 10th on the grid of 32 for the Allcomers race.

Here’s a short clip showing the hatch in front of me getting out of shape on the outlap in the Allcomers qualy followed by my wobble at Craner – I knew Derek was behind me so I backed off round Hollywood till he was past.

Poor old Austen didn’t get out at all in the Allcomers qualy – he’d developed a terrible exhaust noise on the way to the assembly area. This was because the lambda bung had fallen out of his manifold. He eventually found it in the sidepod but it was too late to get out.

I had a chat with Derek and we had a look at the video. Apart from deciding I needed to go faster round all the corners (no surprise there!) he suggested a couple of adjustments so I softened the rear dampers off by a couple of clicks and raised the rear spoiler to its top adjustment prior to going out for RGB qualy.

The car did seem to be a bit better round Craner so I started to go a bit faster. After a few laps I had Austen about to go past me but exiting McLeans the rear end started to slide and I didn’t catch it. I spun across the track and exited backwards onto the grass in the infield. I frantically stabbed at the clutch and was relieved to find the engine was running when I came to a halt. I got her into first gear and eased my way back onto the track. The car seemed fine so after a few corners I tried to press on again. I had another little moment between Schwantz and McLeans where I ran a bit wide and dropped a wheel onto the grass, ended up bailing out of the turn and ended up with all 4 wheels on the grass. The positives were that I’d gone 2 seconds quicker, I had clearly started to get closer to the car’s limits and I’d coped with a spin without trashing an engine. The negatives were that my confidence levels were pretty low and I was near the back of the RGB grid – 16th out of 20.

The Allcomers race wasn’t terribly inspiring. I was alongside a Focus and behind 2 MR2s and my lap times from the RGB qualy suggested that I should be able to keep up with them. Then I bogged down at the start and they all got away from me. Even worse was that a very nice looking Lotus Europa got past me and proved very difficult to get past. He was a lot slower than me round all the fast corners but I just didn’t have the confidence to make an aggressive move up the inside. In fairness he was a very experienced driver and clearly didn’t want to make it easy. I did get past him on the run from McLeans to Coppice on one lap but then since my entry to Coppice was compromised he got a better run out and went past me on the straight. He was also consistent and every time I made any kind of minor mistake the gap would open up again. there was also the not so minor distraction of occasionally coming out of the chicane onto the main straight and seeing a huge pall of blue smoke over Redgate, this happened a couple of times, also down at the Old Hairpin a couple of times. It turned out to be Eddie Ives who is running a Global with a ZX10 engine and he was having problems with it spitting its oil out. The last I’d heard he’s routed his breather into the airbox but clearly something was going badly wrong as it was apparently his car producing the huge amounts of smoke. He ended up retiring and getting his car back on the back of the recovery truck :-( Anyway, I started 10th and finished 8th but was pretty disappointed with myself.

Come the RGB race and the weather was still fine. I was determined to concentrate better at the start and duly did manage this with a flyer. I made up quite a few places on the run up to Redgate but then a combination of being too timid on my cold tyres along with being in the wrong gear meant that a stream of cars went back past me by the time we got to the Old Hairpin. It’s a bit of a problem really, I tend to get a good start but then end up in front of drivers who are anything up to 2-3 seconds a lap quicker than me. I don’t want to get in their way but don’t see the point in deliberately starting slower than I can.

I ended up behind Ben Butler in his Westy and David Watson in his MNR. After about 2 laps there was a bit of a melee involving Paul Rickers and Duncan Marshall at the chicane and I ended up getting past both Ben and David. the 3 of us were together for the rest of the race, both were quicker than me round large parts of the circuit but I had good straight line speed and once I got to the Old Hairpin I was usually able to open up a gap on the run through Schwanz and McLeans. David got alongside me on the run from Coppice a couple of times but couldn’t make an attempt on the brakes into the chicane as there were yellow flags due to Tim Pell’s Genesis parked in the gravel trap there. He eventually got past me at Redgate but I managed to hold Ben off till the end of the race. In the heat of our battle I didn’t see Paul Rogers come up behind us to lap us and he decided to go past me on my left on the way down towards the Old Hairpin. Unfortunately I was heading over to the left ready to turn into the Old Hairpin so we had a very gentle coming together. The 2 cars were pretty much parallel to each other with minimal speed differential so there was no real harm done, I’ve just got a minor scratch on my front wheel arch.

Here’s what video I’ve got. Sadly I had camera problems, the night before going to Donington the charger for the Li ion battery went pop and the hard wired power supply was intermittent due to a crappy connection on the recorder so halfway through the race the battery died.

I did manage to improve on my lap time by about half a second which I was pleased about as you tend not to do your fastest laps when you’re embroiled in a race with someone. But my overall feeling is of being pretty disappointed with myself. Towards the end of last season I was putting in better lap times and racing with the likes of Austen, Colin and Al and at present I’m miles behind them. I guess it will come with time but at the moment it’s pretty embarrassing being in what is potentially a fast car and being near the back all the time. The trouble is the tentativeness is infectious, once the confidence isn’t there I start making all my other mistakes like getting off the throttle before the braking point, braking too early, getting back on the gas too late etc.

When I decided to build the BDN it wasn’t because I thought it would make me much faster, I have always been realistic about that. It was really because of the frustration of turning up to race weekends and always having to battle to overcome problems with the car. So far we’ve had race meetings at Mallory, Brands, Snetterton and now Donington and it’s all been pretty much plain sailing. I’ve had problems with the gear change (which still is far from perfect) and there was the issue with the noisy PAIR reed valve cover at Brands but apart from that the car has been great and in particular I’ve not had problems with bits dropping off it. At Donington all I needed to do apart from the suspension and spoiler adjustments was refuel her. I need to get the setup sorted. And my head.

Donington Preparation

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Only a couple of minor issues to look at prior to Donington. Neil Constable-Berry (he of the orange BDN that was driving away from me down the straights at Snett) had a test day at Snett with Derek to help him which apparently didn’t go well. I gather Derek was using terms like ‘undriveable’. Brian suggested that one of the things Neil looked at was the splitter angle and suggested I look at mine. The splitter has a strip of marine ply as a spacer at the front and Ian’s instructions suggested “Thickness of spacer to be used to adjust aerodynamic performance recommended starting point 12mm thick”. Checking mine revealed that mine was about 18mm higher at the front than at the back, you’d expect maximum downforce with it level so I contemplated adding another strip of ply to lower the front of the splitter.

I had a chat with both Brian and Ian first though, and while having more front downforce sounds like a no brainer it isn’t and Ian had deliberately recommended the setup I’ve got as a slightly understeery mid-engined car is of course much safer in the hands of a non-driving god like myself than a very pointy but oversteery mid-engined car! I think the car is actually set up pretty neutrally and that I haven’t been pushing it hard enough yet. So I’ll make up an additional spacer that can easily be added in but what I need to do is go out and try a bit harder in the first qualy session on Saturday.

I also ticked off a couple more things off my to do list, the first being the addition of an additional throttle return spring. Since replacing the throttle cable I’ve had no problem and the throttle snaps shut just fine but I decided I wanted an additional spring anyway. I’d had a look at Tony Gaunt’s setup when we were in Brands and decided to partially copy that. After pondering how to fix a spring to the hole on the cam used by the closing cable on the bike for a while I decided to use a spare nipple with a very short length of cable inner through it to retain it. I then stuck a 6mm screw through the side of the airbox to hold the other end of the spring and the job was done.

During the week I got a few more little jobs done. I relocated the microphone for the video recorder, it was on the chassis rail just inside the passenger compartment but was getting a lot of wind noise so I moved it to the engine bay. I also made an additional spacer for the splitter, I reckon it will take no more than 15 minutes or so to add it in if I think the car definitely is understeering. I adjusted the clutch shortening the master cylinder pushrod to reduce the risk of the clutch dragging, it will also reduce the risk of the actuator pushing it too far which isn’t a good thing.

I also downloaded the logs from the Donington trackday. While they confirm that I do of course need to go faster (my fastest lap would have put me about 2/3 of the way down the grid the last time RGB were there in 2008) in fairness it was a trackday with traffic and I didn’t really get any quick solo dry laps in in the afternoon, my fastest lap was at 11am. It looks like I managed to peak at about 110mph down Craner with plenty to go as the lateral G there was just under 1.2 which is definitely well into ‘could do better’ territory! For reference I did manage 1.3 G around Redgate, 1.25 round the Old Hairpin and 1.45 at McLeans. 1.5 is probably about as good as we can expect on our tyres. I’ve also watched a bit of YouTube footage which has given me a few ideas for a couple of the corners although I don’t think watching Ayrton overtake round the outside at Craner in the wet helped me out a lot! I suspect the engine remap is probably worth a couple of seconds too.

Following an exchange of emails with Austen and Derek I decided to change my plan on the splitter front. Both felt that I should get the splitter flat because that’s the way it’s supposed to be and because it’s generating both drag and lift at present. Derek also had some very constructive suggestions for managing any potential oversteer if it should happen. So on Thursday evening the spacer got fitted which brought the splitter within 3mm of being level. It’ll be interesting to see if I can feel the difference in the front end, I will of course need to be a little more careful on the gas coming out of corners although that doesn’t worry me too much as my experience has been that the car’s really good at letting me know what its doing and and rear end slides have been very easy to control.