KW and Toyo upgrades work out – Debden 28-Sep-14

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Build

As regular readers of my blog will know, at each of the last three visits to Debden, the Mustang has had a very bad spin at the “dustbin” chicane. This has been caused by the rear end being very lightly loaded as the nose dived under heavy braking, then been bounced into the air as the car reached the crest of a hill just before the chicane. The result is always the same – the car flicks round instantly and uncontrollably. Working with engineers at KW suspension in the UK and Germany, they studied the videos and designed new valves for the dampers and provided new stiffer springs (800lbs / inch at the front).

Performance

The updated KW competition dampers were a great success – although the rear end went light, it was controllable. Similarly the new Toyo R888 tyres provided by our latest sponsor, Toyo, worked fantastically – mechanical grip on the very uneven surface at Debden was not an issue.

A lap of the Debden track…

I launch up the straight with a fairly conservative granny start due to the broken track surface, otherwise it takes a long time to get the wheelspin under control. First gear, wheel spin stops, second, third…. I then keep the car to the right to avoid tramlining on grooves in the track and align myself for the gap in the barrier. As I get the position exactly right, a last moment twist of the wheel flicks the car through the gap without having to lift off the throttle. Keeping the power on I drift to the left to align myself with the cones on the entry to the bus stop. Judging the braking to the last moment and hoping that trail braking will give me more steering control as I weave through the bus stop chicane, I hear the grinding sound which at the time I through was contact with the wheel arches, but later transpired to be the Whipple Supercharge pulley eating its way through the bonnet.

I drop into second under braking and then put the power on coming out of the bus stop, but the rear end lights up and the thought of the potential body contact means that I am less committed than I should be. I feather the throttle a couple of times until the wheel grip, but by then I am already into the hairpin. On previous events I have always had massive understeer on this corner, with the nose of the car snowploughing on and running wide before the apex. However, this time the changes made by the Steeda engine mounts and strut brace, combined with the modified KW competition suspension and the grippy Toyo R888 tyres mean that the cars goes exactly where I ask it to, so that I can balance the power around the corner, although the grinding noise again prevents me from fully committing to push the car as hard as it could go.

Coming out of the hairpin I am still a little hesitant and wind gently around the complex series of obstacles around the next left hander, placed there to avoid holes in the track. Once I am past this I ease the power down around the long curving right hand bend and brake really hard coming to the wall of cones marking the next left, to the point where all four wheels lock and the ABS kicks in momentarily. I am pleased that I have completed this last section about as fast as it is possible to go.

Going round the left hand bend I feed the power on and then drift to the right of the track to line up for the dustbin chicane. In the back of my mind I remember the last there events at Debden where each time the car has spun off the track. This has been down to the nose of the car being heavily depressed under braking so that the rear end goes light. As I reach the crest of the small hill just before the chicane on previous occasions, the rear shocks would extend slightly and lift the rear of the car off the track, the angular momentum of the car going round the bend on the approach being sufficient to spin the car back to front and slide it off the track backwards up a service road, narrowly missing the banks and ditches that are all round this track.

However, this time I put my faith in the KW suspension engineers who had change the valves on the rear shocks to provide additional damping specifically to deal with the problem on this corner on this track. It worked ! I concentrated on keeping the car as straight as the approach to the chicane would allow and braked hard, I then weaved right on the exit of the chicane as I put the power down and breathed a sigh of relief – thanks to KW !

I rev the engine as I pass the exit of the chicane and then put the power down on the next short right hander, taking care not to over do it, having learned the car and track limits during practice when I nearly ran too wide into the bushes under a power slide at this point. Coming round the next 90 degree right hander into the go kart track I keep in second gear and stamp on the power to take advantage of the short straight into the first chicane. Right – left – right I feather the throttle to keep the supercharger on the boil whilst twisting through the very narrow go-kart chicanes which no ordinary Mustang could hope to negotiate. Finally I put the power down as I line up for the final finishing straight. I change up to third just before the finish line, which has been shortened due to a massive skip that has been parked there by the army. I tried staying in second in practice but found I was faster sacrificing the time for another gear change rather than bouncing off the rev limiter in second.

Results

Debden is a very tricky circuit with extremely rough and broken surfaces that don’t allow the application of power as well as extremely tight bends, particularly the go-kart section, so it has always been a challenge for the Mustang where it has performed poorly. This coupled with concerns over the noise coming from the car on bends (which I had supposed to be the wheel arch rubbing problem that I had previously experienced), but turned out to be a supercharger problem had really dented my confidence and so I was unable to push the car.

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Unfortunately I didn’t do very well as I had to retire after the first timed run as the noise turned out to be my supercharger pulley eating its way through my bonnet. This was caused by the body diving relative to the wheels end engine mounts, causing the bonnet to come into contact with the supercharger pulley. The clearance issue had been noted when the supercharger was installed and a cut was made in the inner skin of the bonnet. However, the issue with the body movement relative to the engine was not forseen.

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After the event Redline American Muscle and Steeda were able to make modifications to the car that would transform performance and handling beyond belief – it would become a whole new car.

I did at least manage to beat the time of Frank Trueman in his Porsche 944 turbo, who has always beaten me in the past. I would like to think if I hadn’t had problems I might have been able to beat my old nemesis of Brian Winstone in his Porsche 911 GT3 who was only two seconds faster.


1st 25 Howard Dawson HCAAC
Porsche Cayman 64.97 secs

2nd 725 Graham Scarborough HCA&AC
Porsche Cayman 66.38 secs

3rd 28 Bill McKenna B19
Porsche 996 66.87 secs

4th 34 Andrew Innocent B19
Nissan 350Z 68.52 secs

5th 33 Paul Braddock WSMC
BMW Mini Cooper S Works 68.60 secs

6th 35 Jonathan Dawson HCA&AC
Ford Focus 69.17 secs

7th 30 Anthony Prickler HCA&AC
BMW Z4 M 69.80 secs

8th 31 Jim Giddings SDMC
Triumph TR8 69.91 secs

9th 27 Brian Winstone B19
Porsche GT3 RS 70.87 secs

10th 32 Alex Peters 7Oaks
Ford Mustang GT 72.54 secs

11th 26 Frank Trueman GBMC
Porsche 944 Turbo 73.96 secs
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