'78 109 200tdi conv brakes

got My 109 back today after having the stearing box, transmission and transfer case replaced. ( the steering box was just bad, the tranmission and transfer case came with water in them. . . it wasn't pretty.)

Steering is still a little dodgey but way better than it was. Probably need to look into the steering relay and tire alignment next. It's the brakes that worry me now. Feels like the vacuum pump isn't working. . leak or something since the higher the revs the more resistance the brake pedal has. At low rpms the pedal goes dow to a point then i have to smash it to get any braking. Also some wheel cylinders needs replacing as do the shoes but really what drum brake truck doesn't have that. . .

Sounds like you should be taking a good look at the entire brake system.
Is it petrol or diesel ? Diesel with a vacuum butterfly in the manifold takes very careful setting up. I have binned the butterfly arrangement on my 2.25 88" diesel in favour of an electric vacuum pump.

Just re read your post as you have 200 tdi ignore my comments re butterfly

have you checked pump producing a vac

just got it back today, haven't had much chance to look into it but vac pump and lines are my first guess. will know more tomorrow.