Cheshire based rear diff specialist

I had to fit a new one a 40k miles. All i did was try the launch control just once and while being totally underwhelmed with the whole launch thing it developed a whine at about 50mph. Cost was £3600 new, i did try and get the old one fixed but they couldn't guarantee the fix and i would have to re mount the thing and try it to se if had actually been fixed so i just bought another.................its now done another 90k miles with no problem and crucially..no launch controls either