Overview
When Mark McCann bought a Mansory Veyron in two halves, plenty of people said it would never drive again. Six months later it drove out of our workshop, forwards and, crucially, backwards.
If you’ve followed Mark’s YouTube series, you’ll know the story. A 2006 Veyron 16.4, reworked by Mansory in 2008 with a Pur Sang-style finish, showing under 8,000 miles and never crashed. The catch: a failed gearbox that had left the car split in two for years, passed between garages with no one able to fix it.
Mark paid £900,000 for it. Bugatti wouldn’t sell him a gearbox or even quote for one. So he built a team: Pascal at KMP Powertrains rebuilt the gearbox and reverse-engineered the clutch, Revotec built a test rig, and Rob Barnes and Andrew, the ex-Ricardo engineers who wrote the Veyron’s original gearbox software, lent their knowledge.
When it came time to put the car back together and make it run, Mark brought it to us. Here’s what that involved.
Mark McCann’s Mansory Veyron as it arrived in two halves.
Getting the hydraulics spotless
The Veyron’s dual-clutch gearbox runs on hydraulic oil through galleries so fine that dirt invisible to the eye can block them. Swarf and fibre debris in that system is what burned out the original clutch. So before anything went back together, contamination was the enemy.
Chris started with the gearbox oil tank and cooler system, cleaning out every trace of swarf and fibre before refitting it with the accumulators and pump. Every bolt was torque-marked as it went in.
While rebuilding the oil tank system, Chris spotted a small weep from one of the cooler lines. The culprit was a single O-ring with a nick in it from a previous assembly. It’s a part that can only be reached with the car split in two. Left alone, it could have meant separating the car all over again. We replaced the O-ring rather than the whole pipe, which is the kind of fix-don’t-replace approach Mark pointed out a main dealer probably wouldn’t have taken.
The rear differential shares the same hydraulic oil as the gearbox, so Chris disconnected and blew through every one of its lines with clean compressed air. What came out proved the point: visible particles of dirt, any one of which could have ended up in the wrong place.
We then filled the gearbox tank with fresh fluid through a fine filter while everything was still exposed. With the back of the car open, we could see and touch every joint and pipe and check for leaks before they became impossible to reach.
Fitting a reconditioned gearbox oil and cooler tank to Mark McCann’s Veyron. – FIXING THE £900,000 BUGATTI VEYRON I BOUGHT WITH A HUGE PROBLEM – Mark McCann
Furlonger finds leak in hydraulic in a gearbox cooler line. – FIXING THE £900,000 BUGATTI VEYRON I BOUGHT WITH A HUGE PROBLEM – Mark McCann
Finding dirt in hydraulic fluid lines for the gearbox. – FIXING THE £900,000 BUGATTI VEYRON I BOUGHT WITH A HUGE PROBLEM – Mark McCann
Joining the two halves
Refitting a Veyron’s gearbox means marrying the front and rear halves of the car with millimetre precision. Bugatti uses a dedicated alignment trolley for this. We built our own simpler version, then levelled both halves with a spirit level and measured each side to get them parallel.
Chris manually turned the gearbox to align the master spline and the gearbox went home onto the engine for the first time in around two years. With fuel lines, coolant hoses, hydraulic lines and the titanium joining bolts to connect, the whole team helped persuade the two halves together. Mark said it best:
“I can’t believe how well Chris has done.”
Reassembly turned up a few legacy problems we fixed along the way:
- A crushed hydraulic line had been bodged at some point in the past. We welded on a new end, fitted a temporary braided line, then made a proper crimped replacement.
- Two missing titanium fasteners, a spline nut and an engine mount bolt, needed sourcing.
- The transmission control unit, irreplaceable and loose in the footwell for years, was reconnected with great care to protect its pins.
Before the first start, we checked down towards the turbos with an inspection camera for anything dropped during years of storage. All clear. Then the moment of truth: the pressure pump ran, the accumulators held, there were no fuel leaks, and the car went into forward gear, then reverse.
Furlonger team pushing 2 halves of Mark McCann’s Veyron back together. – FIXING THE £900,000 BUGATTI VEYRON I BOUGHT WITH A HUGE PROBLEM – Mark McCann
Mark McCann’s Bugatti Veyron being put back together – FIXING THE £900,000 BUGATTI VEYRON I BOUGHT WITH A HUGE PROBLEM – Mark McCann
Teaching the clutch to bite
The car moved, but the new clutch slipped on pull-away. Because Bugatti wouldn’t supply original plates, the replacement used a modern material without the original’s oil-channel pattern, and the gearbox software was still calibrated to the old clutch.
The alternative was splitting the car again. Instead, working with Rob Barnes, we used the self-learning routine he wrote into the Veyron’s gearbox back in 2006. First the car learned a new kiss point while sitting still at temperature. Then it needed steady driving: about 30 seconds at constant revs in each gear, across the rev range, so it could adapt one point at a time.
Daytime traffic kept interrupting the process, so Matt took the car out at midnight on a Sunday and ran a quiet loop over and over. After around 110 km of adaptation driving, the verdict from the team was clear: shifting was dramatically better and the slip was all but gone. No second split, no second gearbox removal.
Veyron clutch developer Rob Davis heading out on a test drive with Chris. – ATTEMPTING TO DRIVE MY BUGATTI VEYRON FOR THE FIRST TIME – Mark McCann
Matt setting the clutch adaption on Mark McCann’s Bugatti Veyron. – ATTEMPTING TO DRIVE MY BUGATTI VEYRON FOR THE FIRST TIME – Mark McCann
Clutches from a Bugatti Veyron. – ATTEMPTING TO DRIVE MY BUGATTI VEYRON FOR THE FIRST TIME – Mark McCann
Fixing, not just replacing
With the drivetrain sorted, three faults stood between Mark and a finished car. Each shows how we approach a Veyron: understand why something has failed before reaching for an expensive part.
- Locked doors. After the first drive the car locked itself, with key, remote and handles all doing nothing. We stripped the mechanism to see how it worked, found it ran fine off the car, and traced the fault to tension in the cable linking the handle to the lock. A small adjustment fixed it with no parts bought.
- Drooping rear wing. The wing had lost communication with the car and sat at an awkward angle. Nylon bushes now hold it at the correct height while a permanent fix for the sensors is completed.
- Limp mode with no warning light. The engine was down to roughly 200–300 hp but logged no fault code. Chris compared airflow sensor readings bank to bank, found one side reading well apart from the other, and fitted genuine Bosch OEM sensors through the carbon-fibre wheel arch liners rather than dismantling more of the car.
Then Mark finally got behind the wheel of his own Veyron for the first time, and drove it home.
Fixing the drooping rear wing. – ATTEMPTING TO DRIVE MY BUGATTI VEYRON FOR THE FIRST TIME – Mark McCann
Fixing the broken door handle. – ATTEMPTING TO DRIVE MY BUGATTI VEYRON FOR THE FIRST TIME – Mark McCann
Your Veyron, in specialist hands
The finished car was valued at between £1.75 million and £2 million by three specialists, including our own Matt. Mark has no plans to sell. He took it to TRAX at Silverstone in August, and it’s now enjoying life on the road again.
Mark’s Veyron is an extreme example, but the lessons apply to every one of these cars. Contamination has to be taken seriously, parts should be repaired where repair is the better engineering answer, and faults should be understood before money is spent. Veyron ownership doesn’t have to be the expense its reputation suggests.
We look after Veyrons from across the UK, from routine servicing to complex mechanical work, alongside our restoration of cars like the Ferrari F40 and 288 GTO. If you own a Veyron, or are thinking about buying one, get in touch with our workshop team.
Mark McCann’s Mansory Bugatti Veyron completed by Furlonger. – ATTEMPTING TO DRIVE MY BUGATTI VEYRON FOR THE FIRST TIME – Mark McCann
Watch the full series
Videos and footage courtesy of Mark McCann.
