I set off at just after 6am Saturday morning, heading over to Andy Bates at AB Performance. Andy was confident he had a lobro/CV joint that would fit. I avoided the M4/M25 route and went via the Midlands and after an uneventful journey got there just before 11.
We fairly rapidly established that the splines on the inboard end of my drive shaft weren’t standard Sierra. Andy had a few lobros that were the right size but wrong splines. Andy didn’t seem fazed and was adamant we’d sort it. As our series sponsor he’s pretty much worth his weight in gold. After loads of fiddling round trying different things we took Andy’s lobro to bits and rebuilt mine using the cage from Andy’s and the inner/outer parts and ball bearings from mine and it seemed to work OK. So I got the car back together.
Andy also had a few diffs lying around so I ‘borrowed’ the viscous LSD unit from one of them – I had a half-formed plan involving a partial rebuild of the 3.38 diff followed by a diff swap between qualifying and racing. Tim and Derek had both been doing over 130mph at the end of the Revett straight last time here so the 3.62 diff giving a vMax of 120mph was going to be woefully short, even the 3.38 would only give me 129mph. I’d spoken to Austen yesterday and his Dad is going to rebuild my 3.14 diff, the crown wheel and pinion are intact, it just needs rebuilding with new bearings and seals. Apparently the crush spacer had disintegrated causing the input shaft bearing to fail.
I left Andy’s at 3pm and got to Snetterton at 4. Tony Gaunt was there and I collected the 3.38 diff off him and got on with prepping it by tapping and helicoiling the mounts for M12 bolts. The rest of the gang arrived in dribs and drabs and I was reminded why I go to all this trouble – it’s a great atmosphere in the race paddock, they’re a great bunch of people and there’s a great sense of anticipation for the following day’s racing. Tim had helpfully booked the restaurant just by the circuit so a crowd of us walked there for a meal, the food wasn’t bad at all and I had a good chat with Brian and Ian Baldwin, creators of Derek’s BDN S3. Some people like being big fish in small ponds but I’m quite happy in the company of people who know vastly more than I do, it’s part of the attraction of RGB really.
So I started the day full of anticipation. It was an early start with scrutineering at 8am which was uneventful. After a bit of preparation we headed to the assembly area at 8.45 for the Bikesports qualy session. I had new front brake pads that I wanted to try to bed in as well as getting to grips with the new gearing. The brakes seemed fine, the car was noticeably shorter geared but all seemed fine. I didn’t really get any quick laps in, Andy and Rob Grant’s mechanic Mark was out in what used to be Colin Duce’s Fury and was having a bit of a torrid time with a clutch that didn’t want to work (probably because the engine had been standing for a long time) and first of all he parked up on the racing line on the exit of the Bomb Hole with white flags being shown then a bit later just before the Russell Chicane resulting in a red flag. After the restart I got a couple of quicker laps in getting down more or less to my fastest lap from March. I wasn’t too unhappy as I knew I could go much faster. I was hitting the limiter just before the 300m board before the Esses with the braking point being around the 100m mark so I wasn’t losing too much time there. My main problem in the session was awful clutch slip meaning I could never get on the power hard out of any of the corners. It seemed worse that it had ever been before I managed a 1:23.63 in the end, 0.3 seconds slower than March.
After the session I decided to run the RGB qualy session with the car as it was and leave the diff change till after it giving me around 3 hours for the swap. Andy Bates had fitted the LSD unit into the 3.38 diff and had the diff ready to swap my drive flanges into it. Brian Baldwin came over and we were talking about my clutch slip. We agreed it seemed unlikely to be anything to do with the actuating mechanism and he asked what oil I was using. Since the winter I’ve been using Silkolene Race 15w50 which seemed to give slightly improved oil pressure when it was hot. Brian reckoned that was the cause of the clutch slip – they’d tried it in Derek’s car a couple of years ago and gave up on it straight away because of clutch slip. Andy Bates came over and at the first mention of Silkolene agreed that was the likely cause, he’d also stopped using it some years ago. So I grabbed 8 litres of the Maxima 15w50 that he supplies. I’m aware that Andy supplies Maxima and is therefore biased, but the reason he supplies it is that he back to back tested it against the Castrol he used to use and got a bit more power but more importantly better oil pressure. Changing the oil actually took quite a long time by the time I’d drained the engine, the dry sump tank and taken the filter off to get the oil out of there and I was still grubbing round under the car when they called us to the assembly area so it was a bit of a rush getting changed and getting over there.
This session was much better – of course my clutch plates were still soaked in the Silkolene but there was an immediate difference and it got better with a couple of laps. I was quickly seeing low 1:23′s and the diff ratio was becoming a much bigger problem, I was now hitting the limiter by the marshals post halfway down the straight and hitting it consistently on the much shorter Senna Straight. I did see a 1:22 on the lap timer so knew I was going faster but the diff must have been losing me an additional second or so as I was sitting at 118mph for a good 600m or so when I should have been hard on the gas.
As I came round towards the finish for the chequered flag I was aware of some vibration that felt drivetrain related. I suspected the rebuilt lobro so took a very slow in lap. I tried wobbling the driveshaft about and indeed there was a bit of play so I thought the lobro was on its way out, but Andy Bates noticed the diff drive flange was moving and thought it more likely the diff was causing the problem. So I got changed and set to getting the diff out which meant draining and removing the fuel tank, all the tunnel panels etc. It took just over an hour to get it out then I took it over to Batesey’s truck and he removed the drive flanges and stuck them in the other diff, we stuck some new oil in and replaced the cover.
Getting the diff back in is a bit of a pain but it was all going OK and I was on track to have it done in time till they announced over the tannoy that our race was brought forward from 2.30 to 1.45! By now it was just gone 1pm and I was sticking the diff bolts in. Andy Cunningham came over and gave me a hand as we refitted the prop, tunnel panels, drive shaft bolts, fuel tank etc. Time was really running out so more hands arrived – Brian Baldwin, Paul Rogers and his mate Andy all mucked in. Derek helpfully pointed out that even if I missed the race start I was allowed out into the race from the pit lane.
I did miss the race start but went round to the assembly area where the marshals held me while they checked on the radio that it was OK to let me out. Meanwhile I reprogrammed the dash for the new diff ratio. As soon as I got out of pit lane I could feel a vibration. This really wasn’t what I wanted! I tried to keep off the racing line as the leaders came round as I was on cold tyres and going slowly. As I went up the Revett straight I was more aware of the vibration which became bad enough to blur my vision slightly so I backed right off at the Esses and decided to pull into the pits. I raised my hand and moved over to the extreme right edge of the track and slowed right down. As I came out of Coram and on the short straight to the chicane something let go and there was a clattering in the tunnel so I pulled straight off onto the grass shut down and hopped out and watched the race with the marshals.
There was a trail of oil from the spot where the big bang had happened and I had a horrible feeling that perhaps the failure this time was the prop but that it had then lunched the front of the diff
I suggested to the marshals that because I thought the problem was prop or diff related it was best not to tow me back so they winched the car, with me in it, onto the back of the flatbed recovery truck. I was told to stick my helmet on and keep my foot on the brakes. I was waiting for the driver to tie the car down but realisation dawned that that was why the instructions regarding helmet and brakes – no tie downs! It’s funny but I never really worry about the brakes failing when out on track but while bouncing along going backwards on the back of this flatbed I did!
Back in the paddock we looked under the back of the car and saw no oil, suggesting it wasn’t diff oil. Lifting the bonnet immediately revealed the problem – the front UJ of the prop had failed, the prop had then done the customary flailing about and had broken the spigot off the dry sump scavenge pump resulting in the pump then enthusiastically scavenging the oil out of the sump pan and onto the track
There was no obvious damage to the engine casings but to be honest I had pretty much lost the will to live and couldn’t be bothered having a proper look. It could of course have been much more serious but telling yourself that never really helps much. All my tools were still out from the frantic diff swap and there was 7 or 8 litres of Silkolene still sloshing round in my drain tray so I got rid of all the oil, cleaned everything up, tidied the tools away and stuck the Fury back onto the trailer.
I had a chat with Andy and we’d both reached the same conclusion – that the original primary problem was actually unknown but the diff failure at Oulton, the lobro failure at PDQ and this were all related. I suspect the prop might actually have been the primary problem setting up some vibration which then damaged the diff at Oulton. He suggested getting a new prop from Bailey Morris as he’s given up getting them elsewhere due to failures like this. He says he always specs heavy duty UJs and a TRT tube (which gives a bit of cushioning in the system). What I actually plan to do is go back to BAR who fixed it last time (and indeed commented that the prop had originally been made using cheap inferior UJs) and talk to them about what they can do to produce me a bomb proof prop. I’ll also replace the lobros and get a couple of spares (and find out exactly what vehicle they’re originally off to make sourcing replacements easier).
I will of course be back, I’ve gone to far too much trouble to bail out now. Also I feel like my driving’s getting better and the car’s just so good to drive when it actually is working OK with the engine working really well and the handling feeling reasonably balanced. Indeed my fastest lap in the RGB qualy was 1:22.35, a second quicker than in March and I suspect I was losing at least a second from being undergeared. At least I discovered (and solved) the clutch slip problem although a lot of the nice new oil I got from Andy was deposited on the track. Whether I’ll be at Mallory in just under 3 weeks time I’m not sure but I’ll do pretty much whatever it takes to be at Silverstone for the Birkett on October 24th.
Monday lunchtime I took the airbox off and had a better look. I think to say I’ve been lucky would be overstating it but the damage appears minimal.
- The scavenge pump appears to be unmarked – what appears to have happened is that the prop has hit the spigot and ripped it off by stripping the aluminium threads out of the housing, the 2 screws are still there attached to the spigot and the O ring is even still there. The spigot and hose are badly marked but look to be serviceable.
- The gear shift lever is a bit bent but looks intact although I’ll need to have a more careful look to make sure the shaft isn’t bent.
- There’s a bit of damage to the loom where the prop’s hit it but all the wires are intact with just one of them having a bit of bare copper visible.
- There are no marks anywhere on the engine casings so that appears unscathed.
- The sump tank is still at 2/3 of the normal volume so firstly there’s no risk the engine suffered oil starvation and secondly I didn’t lose all my new oil!