74 450sl REBUILT auto slips in final drive
 

Hi! The technician rebuilt my 1974 450SL and it is
slipping in final drive [3rd]. He has adjusted modulator
pressure, line pressure etc. exchanged the valve body
with a used one I had as a spare. He has R&I the auto
AGAIN and replaced the 3rd gear clutch packs which
proved fruitless. He is competent but he must be missing
something? The slipping is substantial and I couldn't
live with it. The reason I had it rebuilt was because
it wouldn't go into 3rd [Before that it was SLIPPING
in 3rd]. Please, forum gurus and automatic enthusiasts help
us solve this seemingly impossible to solve problem.
Thanks! Stan M. Brisbane

WHAT modulator is in the trans..Metal OR white plastic..IS there a crush washer under the modulator? if there is a crush washer then THAT could be the problem.


Those transmission have an oil distribution tube & connector sleeve between the 2 clutch packs..if 3rd gear clutch pack doesn't fully lock-up or "burnt" previously then that oil distribution sleeve is a good possibility(slight crack).

Use the oil feed sleeve to Air test the drum for leaks around the welds and If your tech is not using the piston installation sleeve (tool) when installing the drum piston ,the odds of cutting the piston lip seal on this transmission, are very high.