Controlling overdrive transmission
I have finally found the time to set up the control gear for my 42RH transmission replacing 727.
I used pressure switches for both overdrive and lockup with vacuum switch to drop out of lockup on relatively light throttle opening and throttle position switch based on a WOT switch to drop out of overdrive at about half throttle.
I started off with the PATC pressure switches but then found some neater ones from RS Components and used PTFE / Stainless braided hose with AN fittings to extend to the engine compartment to make adjustment easier.
I made a mistake not using the PATC vacuum switch. Almost all the other adjustable vacuum switches I could find are differential switches. The operating vacuum is adjustable but then a small difference will operate the switch. I started off with a 50kpa rating which operates with a change of pressure of 0.7PSI which is way too sensitive. The 80kpa operates on a difference of about 2PSI which might be ok. If not I will have to order one from PATC but shipping to the UK will be a killer.
I have finally found the time to set up the control gear for my 42RH transmission replacing 727.
I used pressure switches for both overdrive and lockup with vacuum switch to drop out of lockup on relatively light throttle opening and throttle position switch based on a WOT switch to drop out of overdrive at about half throttle.
I started off with the PATC pressure switches but then found some neater ones from RS Components and used PTFE / Stainless braided hose with AN fittings to extend to the engine compartment to make adjustment easier.
I made a mistake not using the PATC vacuum switch. Almost all the other adjustable vacuum switches I could find are differential switches. The operating vacuum is adjustable but then a small difference will operate the switch. I started off with a 50kpa rating which operates with a change of pressure of 0.7PSI which is way too sensitive. The 80kpa operates on a difference of about 2PSI which might be ok. If not I will have to order one from PATC but shipping to the UK will be a killer.