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SCOR Round 6 : Plurenden Farm - Race Report

 

Before the Race

The first job following round 5 was cleaning. Lots and lots of cleaning. I hand picked a lot of mud out of the wheel arches, a good couple of buckets worth. Reinstating the stock wheel arch liners was definitely the right choice as it limited what could collect in difficult to get places. The mud flap extensions broadly worked and reduced the mud build up around the front suspension and prevented the area above the belly plate filling with mud. Once this was all scraped out and cleaned up it was time for the jet wash and the remaining 75 or so litres of rain water in the waterbutt (we currently have a hosepipe ban) collected from the workshop roof to clean the car as best I could.

 

The first mechanical job I tackled was the one job I didn't do before the car returned to racing - to replace power steering fluid. This was relatively straight forward to do but of course I spilt the old oil and made a bit of a mess that took longer to clear up than changing the fluid.

 

The next major job was to investigate the unrequested automatic tracking adjustment, which as I said in the previous post was due to the bend in the near side front shock. This and the rattle were addressed with the build of 'version 2' of the front suspension (post to follow). This was completed and installed the week before the race, the car was tracked up with the trusty Gunson Trakrite and given a road and very quick off road test, it felt good.  On the way back to the workshop, near disaster struck.

 

Driving along a straight country road with national speed limit, suddenly, the bonnet opened and smashed back against the windscreen and roof. After being momentarily terrified I realized that amazingly the screen had not broken, and that I could still see where I was going by looking in the crescent under the bonnet. I checked the mirrors and quickly stopped.

 

The bonnet was a mess, but I managed to get it mostly closed and one of the bonnet pins through and drove slowly to the workshop. Once there I set about trying to get it back into something like the right shape. The bonnet was already damaged from previous accidents 'back in the day', and I was planning to replace the bonnet in the coming months (I already have a good used one in the workshop) but not in the next few days.... I straightened it as best I could, and put it down to experience. It would be OK for the race. All I can think is in my coming and going in the workshop I'd opened the bonnet at some point and not clipped it close with the pins properly.

 

Another little job was to replace the missing indicator. I managed to get a replacement from Silverlake that had a Rav in for 'pick a part'. When I came to refit I used the modification I had spotted on the old bumper had a mod replacing the retaining screws with cable ties. 

 

Finally, I wanted to sort the 12v 'cigarette lighter' socket. This wasn't working, but I wanted to use it to power the camera during the day so we could record more video. After some messing around it just turned out that the socket was dirty. Once the dirt and corrosion was removed it worked fine!

Thursday evening I decided to check the tyre pressures and start to collect tools and spares together to load up on Saturday. As the 12v outlet was now working I started the car to run the pump and went round the car checking the tyres. The last one I came to was the near side front. As I was watching the gauge I noticed a drip of coolant hit the floor. I started poking around and found the top of the radiator was damp. It looked like it was either leaking from the top hose or from the joint between the radiator metal fins and the plastic top 'capping' structure. It could have only been the hose, but i didn't want to risk a worsening leak during the race. Fortunately I has an almost new rad 'in stock'

courtesy of the breaker at Silverlake, so Friday afternoon was taken up draining the coolant and replacing it.

 

Race Day

Again a 05:45 start saw us on site by just after 8 for scrutineering. I was surprised that is was 16 degrees when I set out. It was going to be a beautiful day! As we unloaded it was warm and windy with barely a cloud in the sky.  Despite only being 7 miles as the crow flies from Bilsington Priory (where round 5 was held), the terrain was much flatter at Plurenden. One minor issue was noted to be sorted in scrutineering, and then it was the driver briefing and then of for the 'look, see' lap around the 3.5 mile course.

 

 

Run 1

Around the field margins the grass was still wet from overnight dew and fairly slippery in places. As we transitioned into the woods, the sun beaming through the trees looked beautiful but it made it fairly hard to see the terrain and spot the bigger bumps and ruts. We hit a couple pretty hard, harder than the front shocks were happy with!

 

At about 1.5 miles at the end of a fairly fast straight there was a large mud hole. It seemed like an odd place for water to collect, even though the terrain was fairly flat, it felt like we were at a high point on the course. Even at the start of the event it was pretty deep, and very smelly...

 

 

Run 2

From the end of run 1 we looped straight back into the queue and out for our second run. A few corners after the entrance to the woods there was a diagonal cross rut in the track.I hit this far too fast and it threw the car from side to side, hard enough for my HANS check straps to pull tight and my head to hit the side protection on my seat. 

 

At 1.8 miles the course turned right from the field margins and dropped into a large wooded ditch with a narrow (and slightly sketchy looking) wooden bridge over a stream. Approaching the tight 90 degree corner I totally misjudged the grip level on the grass and overshot the turning, needing to back up to take the corner. As the lap went on a knocking became apparent from the nearside front suspension.

 

At the end of the lap I headed back to the pit area. On opening the bonnet we found the upper part of the top mount had cracked and the bearing was moving in the mount. It looked like our day might be over already.

 

 

Run 3 & 4

After some discussion and a lot of staring at the mount it did not repair itself. We decided I should go back out, reduce the pace a bit and see how the mount would hold up. The car still felt good in the fields but in the woods the noise was increasingly unpleasant, but the car drove OK so I pushed on, taking is slowly over the ruts and bumps.

 

On lap 4, not long after entering the trees a group or deer ran across the track a couple of seconds ahead of us. You can just about see them on the in car YouTube video here...

 

Run 5

I took run 5 on my own as the rattle was getting much worse, and then part way around it weirdly stopped. At the end of the lap I headed back to base to have a look at the situation and on opening the bonnet I was greeted by this view: 

 

 

The top mount was now completely destroyed and the shock was 'missing'. As the car runs McPherson struts I was pretty surprised that the front suspension has not completely disassembled as a result. I think due to the length of the spring and the geometry of the strut top the shock (although it was detached) has stayed wedged in the corner of the strut tower and has continued to do its job. We obviously couldn't continue like this so we needed a plan to patch the car up. 

 

After a lot of head scratching (and some lunch) we decided we needed to get the strut back in its hole and use a large thick washer to give us something to clamp the shock  in place with against the remains of the strut top. We chatted to a couple of the other teams and eventually found a large washer (that looked like it was probably a washer from a land rover radius arm) that looked like it would do the job. 

 

With the car reassembled I headed back out on my own for a tentative 6th & 7th run. I slowed right down for the ditches and deep ruts, and the laps passed without issue. We were back in the race!

 

Runs 8 to 12

With the car now repaired well enough to allow us to continue, my co-driver jumped back in for the remain runs.

Time was now getting short and the last 5 runs had to be driven back to back to make the last run time of 15:00. Each time we returned to the start finish line it was a quick torque check on the front struts and back round again. Despite the noise from the suspension it held together well, and even though the front shocks were now so hot they seemed to be providing now damping whatsoever, the car was driving OK. 

 

One lap merges into another on one of the runs at about 2 miles I clipped a tree with the near side door mirror. This spat out the mirror glass that landed in the co-drivers lap completely intact!

 

We arrived back at the end of run 11 moments after 15:00. All the other teams had finished so the timing caravan waved me round for the final run... At the end of lap 2 I really did think we were done for the day, but somehow we had made it to the end. A bit of ingenious 'engineering' and nursing the car on the rough parts to protect the front suspension had got us to the end of the event.  So, eventually... we arrived home a solid last. (Technically I think it was actually second to last as there was 1 DNF, but we were the last 'finisher'.)

 

 

After the Race

Lets start with the 'elephant in the room'. The Version 2 front shocks were a major disappointment. Firstly, the new top mounts began to fail after only 2 laps, eventually failing catastrophically, punching the bearing through the aluminum top machining. Strengthening the bodies to prevent the bending seen in round 5 ran the risk of finding the next failure point, but in their current form the strut tops are just not fit for purpose.

 

Next thing is the shocks themselves. Even on the slow speed 'look see' lap it was apparent how little rebound damping there was in the 'uprated' Bilstein strut inserts, and the situation only got worse as they heated up. Following the event I pulled the struts out and stripped them down and it seems the loss of damping is permanent, rendering the inserts useless. I reached out to Bilstein by phone, they said sent an email detailing the issues. 2 weeks on they have yet to reply.

 

The video camera running off the power supply was able to record all day but when I went to edit the footage captured I found that it hadn't recorded any audio! Luckily the co-driver was wearing a camera for a couple of the laps so we were able to capture some video with audio ... audio filled with the sound of rattling suspension! 

 

At this point, I'm really not sure if I can have a suspension solution ready for the final round at Manston at the end of October....