It's been a while!
We've been a bit slow on the updates to the thread but lots of things have been happening in the background. We took the car to Germany in April for a full track day at the Nürburgring, it was the first of the season and we were lucky to have great weather and great company... but more on that in a moment.
Leading up to the ring trip things were getting pretty busy in the workshop developing and fitting some new parts to the car. Our new catch can, in vented form, was installed along with an active gearbox cooler developed specifically for the MX5's 6 speed box.
Anyone who's spoken to us (or read back through this thread) will know that gearboxes have been an issue for us for a while now. It's a known weak point in the mx5's drivetrain, once you're over a certain torque figure gearboxes, even the 6 speed variety, become a disposable item. Fun as it is to drive a car back from a track day with most of the teeth rattling around in the casing (it's not fun) the novelty of changing gearboxes had well and truly worn off for us.
There are many theories why the gearboxes don't last and the reason we find most believable is high torque causing excess friction, leading to high temperatures. We believe the high temperatures introduce two problems.
1. The fluid starts to break down and loose its integrity. The film strength of good quality gearbox fluid is such that there is no metal to metal contact when the gears mesh, as soon as the fluid breaks down the teeth touch, friction and therefore temperature increases and a vicious circle begins.
2. The second problem is the casing itself. As the temperatures increase the alloy casing beings to expand and flex, this would only be by a tiny amount but it is possible that it's enough to allow the gear mesh contact patch to change or to effect a bearing or two. It's telling that it's generally 4th gear that lets go, as this is the gerear canoet furthest from the supporting bearings.
Anyway - the outcome of all of this theorising was that we decided reducing gearbox fluid temperatures wouldn't be a bad thing. Keep the fluid within its operating temperature and it will retain its properties, the housing keeps its tolerances and all should be well.
With the kit designed and high quality components sourced we fitted it ready for Germany. A dedicated oil pump draws the fluid from the drain plug on the 'box through a super fine filter before sending it on to the cooler core. It then re-enters the gearbox via the fill point. We designed a special bracket so the core can be installed out of the way of stones and speedbumps. A second bracket secures a Spal fan to the core, this means it doesn't need to be positioned directly in airflow - giving even more mounting options. Both the pump and the fan are triggered by a temperature switch, so it's a real set and forget system, exactly what you want on track.
The parts are back from powdercoating today and we haven't had a chance to photograph them, it will look a lot like this though...
With the gearbox cooler fitted we moved onto suspension, choosing in the end a set of GAZ Gold Pro's and Whiteline front and rear adjustable anti roll bars. We were after compliance in the suspension with excellent damping so that we could take the car over curbs without unsettling it while retaining good body control.
For tyres we figured more rubber on the road would be a good thing, with Federal 595's in 205/50R15 we could still have them spin up in third (in the dry), while exciting this did make it challenging to make use of the power available. For this trip we thought we'd try Nangkang AR1's in their relatively new 225/45R15 profile. They're now available in 245 for a 15" wheel, next time maybe. The AR1's are a serious looking tyre, have very little actual tread basically a slick, and nice solid sidewalls. They look the business and we're told are an equivalent to Toyo R888r's, with a tread wear of 80 we'd believe it!
After making the long drive we found ourselves at the 'ring and collected all the bits and piece from the drivers briefing ready for the next day’s track time. Starting with an hour of sighting laps we had a really good chance to get our eye in. The car felt great, once the tyres were up to temperature the mechanical grip was incredible and as we'd hoped you could confidently hit curbs and the suspension just soaked it all up. A proper open pit lane meant you could do flying laps and use the full length of the main straight. We did around 35 laps in total sharing the driving around between ourselves and a few friends - it was awesome.
Once the track day was complete the track reopened to the general public for a touristenfahrten session. At this point we gave the keys to Serxio, a One Laps Heroes guru, who's local to the Nürburgring and has a day job at RSR Nürburg.
He's well known for some super quick laps in his lightly modified 90hp mk1. This video says it all...
Never has the saying been more true, drive a slow car fast not a fast car slow - we love it how he goes round the outside of the Porsche!
We'd been talking to Serxio quite a bit before we got to Germany, he's in the process of rebuilding his mk1 with a K20 swap - it's going to be very cool. Fellow One Lap Heroes legend Kostas is also rebuilding his once turboed mk2 with a LFX v6 swap, again very cool. These guys know MX5's inside out and know the Nürburgring better than we ever will, who better to properly test the car and see what it's capable of...
Serxio took the car out and did 5 laps, back to back. He really went for it (exactly like we asked him to) and was on track to getting a really, really awesome lap time (not that we were timing
). But, unfortunately as is generally the way, it was the last lap of the day that did it. A slight misfire had developed, impossible to hear with helmets on and cylinder temperatures were too high. On lap 40 for the day, with both needles pretty much off the clocks a piston melted through and the lap was over.
You can see it all on the video here...
Luckily for everyone Serxio knew what he was doing and parked the car in a safe place behind the barrier. A trip on the Bongard truck and the car was back at RSR to assess the damage. Satisfied that we weren't going to be driving it back to the UK we all went to the pub to make a plan.
This is where Age ter Veen comes into the story. A dutch guy with an amazing mk2.5 - so clean that if you didn't know better you'd be forgiven for thinking it was a show car that doesn't get driven to the shops let alone on track! Looking closer you start to notice little details that give it away, thermal strips on each caliper to monitor brake temperatures, R888r tyres, custom Alcantara wheel (made by Tobias) and the big giveaway, a nitrous bottle in the boot! Age is a seriously good driver and his car is set up to perfection. He’s also smart enough to come to the ring with a trailer and generously offered to drive us and the car back to his parents workshop in The Netherlands. Not one to turn down an adventure we jumped at the opportunity. A few phone calls later and we had a new engine ready and waiting for us at an MX5 specialist, we'd collect it on the way to the workshop, install it the next day then drive home very gently.
As usual things didn't quite go to plan! The new engine turned out to be a short block so the decision was quickly made to pull out the rods from the damaged engine and reuse them. With a mixture bits we were able to build something half decent. Friday's challenge had suddenly become; take old engine out, strip it down, rebuild new block with all salvageable parts, get it back in the car, test drive, drive back to the UK - and what a day it was. In the end it was only possible with the help and hospitality of Age, his fiancé Desiree, Tobias, Age's parents and their amazing workshop. We can't thank them all enough. This video gives a bit more insight into the trip and the rebuild for the return journey....
If an effort to summarise all of these words we think the key points are;
1. The catch can works. The horrible oily mixture we poured out of it once the piston had let go could have ended up all over the track. Had that happened and someone had had an accident as a result we'd probably still be in some German jail.
2. The gearbox cooler works. Never have we had a gearbox in the car that can go more than 15 minutes on track without starting to feel notchy. With the cooler we comfortably drove to the ring, did 40 laps, then drove home and the shift still feels great.
3. The combination of 225 section AR1's, Whiteline anti-roll bars, and Gaz Gold Pro's was epic. The car felt balanced, pointy and had immense levels of grip.
4. The cooling system worked, it was in the mid 20's for the track day and inlet and coolant temperatures were all kept in check for both track use and cruising through the streets
5. The mx5 community is amazing we couldn’t have done this without the help we received. We will be back to the ring, we've got some more plans for the car (dual chamber inlet manifold!!) and that lap needs to be completed.
). But, unfortunately as is generally the way, it was the last lap of the day that did it. A slight misfire had developed, impossible to hear with helmets on and cylinder temperatures were too high. On lap 40 for the day, with both needles pretty much off the clocks a piston melted through and the lap was over. 
