Ultramatic gearbox problem slipping direct drive clutch

Posted by gbuchner On 2024/7/6 7:48:50

Hello,
I'm George from Austria and have the following problem with my Ultramatic gearbox.

After I got my 1951 250 convertible with Ultramatic gearbox out of the winter garage, I noticed that the direct drive clutch in the gearbox was slipping.

I have now checked the oil level and the setting of the throttle valve lever and found no fault.
According to Ultramatic drive trouble shooting and corrective measures, I have carried out the following hydraulic tests:
- Front pump regulated pressure test, OK
- Hydraulic governor pressure test, OK
- Direct drive clutch pressure test, OK

During the converter inlet pressure test, I noticed that the pressure in the converter does not drop to max. 22 psi in direct gear and with the clutch engaged, as described in point 30b on page 46 of the Ultramatic workshop manual, but only drops from 70 to 55 psi (see attached photos).
It says to check the converter inlet valve and clean the converter outlet valve.

Now I have the following questions:
where is the converter outlet valve located, I can find it on the sequence of hydraulics operations, but I can't find it on my transmission?
Where exactly is the converter inlet valve located and what could be the fault?
Is it possible to remove the hydraulic unit when the transmission is installed or is that not possible?

I'm in a hurry as I'm starting next weekend at the Ennstal Classic, a very demanding classic car rally in the Alps!

I hope you can help me here!

Many thanks and best regards from Austria

George


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  car driving in H direct drive clutch disengaged, left clutch pressure right converter inlet pressure.jpg (869.64 KB)

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