Re: Converter Lock-up

Posted by Peter Packard On 2012/1/4 2:07:08

G'day all, There are very few adjustments to the Ultramatic and Twin -Ultra ( same as the ultra but with an optional shift from Low range band to High range clutch)
The Ultramatic is a very good box but has a few problems when bush and shaft fitments enlarge, particularly in the high range clutch area. Packard used these bushes as seals and it was in my opinion a good move at the time, but prone to abuse if the fluids were not changed very regularly. This wear/pressure problem occurs where the front and rear pump pressures enter the gearbox output shaft to pressurise the High Range Clutch and the Direct Drive Clutch.
Essentially in High Range the initial take off is using the Front pump and converter. The Governer kicks in when it flings around enough to energise the converter valve which awaits a signal that the rear pump pressure has overcome the throttle pressure, at which time the Direct Drive Clutch will engage and the Front pump will go to idle. This smaller rear pump now pressurises the direct Drive Clutch and High range clutch packs, therby allowing the oil to cool
I note that many contributors to this topic have mentioned over-revving in high range and I would suggest that in many cases this is slippage in the Direct Drive or High Range Clutch packs.
I would strongly suggest that if you are at light throttle at 40 MPH, back off and then put a reasonable amount of throttle (say 30%)and try to pick when it starts to slip or the road speed to engine revs increase does not respond like a manual vehicle. then you have a problem which can easily toast your box. Linkage adjustments are confined to throttle pressure and would have no effect after 50 mph anyway. Best regards Peter Toet

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