Depends on transmission/make/model (using general known examples here for RWD
transmissions). The vacuum modulator (especially the adjustable ones) allow
you to tailor the shift points with engine vacuum (very helpful with high stall
converters and big cams on the older vehicles).
Remember, shift points are also referenced via load and TPS.
Chrysler (No vacuum modulator - even on the older models)
45 Series is electronically controlled
42/44/46 RE Series is partial electronic (PCM does watch line pressure)
42/44/46 RH Series is hydraulic
GM
TH200,350,400,700R4 use a Vacuum Modulator
Ford
C4,C6 also use a vacuum modulator
>
> Bernd,
>
> Let's pretend that I know nothing about chrysler transmissions and
> everything else that I know about transmissions is based on the ford AOD.
> Anyway, here's my take on what you're saying... I think you're saying that
> my trans is definately electronically shifted, right? What's this vacuum
> modulator that I keep hearing about and what does it do in regards to
> shifting? does it work like a TV cable? I've never seen a trans with
> vacuum lines attached to it before. I've done some transwork (on the AOD -
> i'm a former fox body owner) and didn't come across anything like that. I
> thought that all transmission function (besides gear select lever) were
> based on line pressure and how it was routed through the valve body to open
> specific pistons that cause the clutch packs to engage.
>
> --
> - Josh
> Lowered 2000 Dakota CC 3.9L
>
This archive was generated by hypermail 2b29 : Fri Feb 06 2004 - 11:46:19 EST