Looking for proper beam grouping

[Maarten Deen]

I have a piece of music in 3/4 which has bars like { d4. c8 b8. a16 }
Lilypond groups the last three notes together, making it look like a 6/8 
measure, but I want the c8 to be separate and only the b8. a16 to be grouped 
(like a proper 3/4 would look like).

I've tried some settings, like #(override-auto-beam-setting '(end * * * *) 1 4) 
or \set beatGrouping = #'(4 4 4) but to no avail.

How can I accomplish this?

Regards,
Maarten