and one thing that keeps popping up but which i can not find any information about is the mbt-90 program, aperintly Germany figured 3ed times a charm (after mbt-70 with the US and mbt-80 with the uk) and teamed up with the french for a new main battle tank
The MBT 80 was a pure British project; you are probably thinking of the FMBT (Future Main Battle Tank program) known as the Kampfpanzer 3 program in West-Germany.
And the only things I have been able to find about it is that it was short lived (1980-1983) and it was the predecessor to both the lacerc and the leopard 2.
It was not the predecessor of the Leopard 2. The Leopard 2 already entered service in 1979.
Anybody here have more information?
First talks between France, the UK and West-Germany were held in 1977, directly after the end of the FMBT project. The UK participated in these talks, but already had started work on the MBT 80 program and decided to not join a cooperative development effort. In January 1979 and Feburary 1980 two MoUs were signed by the French and the West-German governments for the first phase of the Char 90/Kampfpanzer 90 project.
This first phase was limited to requirement analysis and concept work. It was discovered that ther ewere major disagreements in the requirements of both sides. France insisted on a weight limit of 50 tonnes, which according to a joint-study was insufficient to reach the protection level both partners had agreed on. West-Germany wanted all concepts to be based on the Leopard 2 hull mainly to reduce costs, but also argued that automotive technology wouldn't evolve enough within the decade to make any difference.
In the end an MoU for a second development phase was signed, which did include the option for France to demand a lighter hull at the end of the second phase.
It was agreed that the new tank should have the same firepower and mobility as the Leopard 2, while reaching a higher level of protection by using an autoloader (allowing to reduce the height of the turret and re-invest "freed weight" into armor). The Heer also demanded low complexity and higher reliability (which is why the Leopard 2 hull was proposed).
France reduced its defence budget in 1981, making a sustainment of the project unlikely. Also there was a five year difference between the projected date of introduction of the new tank for France (1991) and West-Germany (1996) resulting in the cancellation of further work.