MOPAR AUTO STOP

[rekbender]

There isn't much information available on the MOPAR Auto Stop accessory hill holder offered in the early 1950's, so I thought I'd add a little more here. My Auto Stop was listed on Ebay a month ago and appeared complete. The seller accepted what I thought was a reasonable offer so I took a chance and bought it. It was all there, right down to the little envelope that included the installation pieces, missing only the driver instruction card. It even included an extra throttle switch for early V8 equipped cars and an extra gear shift lever switch. Think of it as a 6 volt line lock or roll control. It consists of a gear shift lever button (looks like a door bell button) with an armored cable, a control relay, a throttle linkage switch, and the 6 volt solenoid valve.

The gear shift lever switch monetarily completes the circuit through the rear wheel brake solenoid valve and activates the control relay on the fire wall at the same time. The solenoid valve then remains closed until the accelerator pedal is depressed. When brake fluid is the locked under pressure to the rear wheels, a parallel fluid circuit with a ball check in the solenoid valve allows more fluid to enter the circuit if more pressure is needed to hold the car on a steep hill, or if you simply want to activate the Auto Stop before stopping completely. Now you can take your foot off the brake pedal and prepare for the up hill start. An over the center type switch is placed in the throttle linkage and the pressure of the throttle return spring on the linkage keeps it closed. The control relay is grounded through this throttle switch so when the gas pedal is pushed, pressure on the linkage is decreased and the throttle switch opens. The control relay de-activates and you're on your way.  You, the driver, are required to have the clutch pedal out near the friction point, and bring the engine RPM up quickly to avoid rolling backward. I've been practicing this week and have just about mastered the technique. For some reason it feels counter-intuitive at first, but not for long. My biggest problem has been remembering to shift into low gear after I push the shift lever button to set the Auto Stop. It's hard for an old dog to master a new trick.

[knuckleharley]

I can see why new car owners in hilly snow country bought Dodge's instead of Plymouths.

[dpollo]

A most interesting accessory.   I installed one on a customer's  car that has yet to be completed so I am interested to know how it will work.

[Dodgeb4ya]

I have had one on my 1952 belvedere for nearly 40 years!... works great!

[medium_jon]

I saw that listing on eBay

Thanks for the details on how it works and what the installation looks like. 

[HotRodTractor]

Interesting widget. I think I might have to keep my eyes peeled for one.

[Worden18]

Very cool, thanks for sharing this 

[HotRodTractor]

I don't suppose you would share some nice high quality scans/pictures of the instructions that were included in the box?

[OLDMOPAR84]

who sold that cool item ? those are rare. i saw one on ebay a few years ago sell for about 700.00 

[rekbender]

Sorry it took me so long to respond. The instructions a pretty rumpled, but here are some pictures.

[rekbender]

I couldn't get the last two pictures to upload, so here's the last two. I tried to quote HotRodTractor but didd something wrong.

[rekbender]

OLDMOPAR84, an ebay seller called vintageamericanpartscompany listed the item as a buy it now for $385.00 with a make offer option.  I'm a pushover for accessories like this and was surprised when they accepted my low offer. I spent a bunch of time freeing the solenoid valve armature and had to buy 100 ball bearings to get the correct .281" steel ball for the check valve. I dis-assembled and cleaned the contacts in both the shift lever and throttle switch, as well as repairing the wiring. I decided not to use the ancient flexible brake hose included in the parts. It's really cool!

Edited July 16, 2017 by rekbender

[mightmo52]

i love those guys, i bought all my brake parts from vintage got my parts 1 day later . amazing price i just bought a new fuel pump from them for my p15 for 100.00 that is ethanol freindly. 

[OLDMOPAR84]

i agree they are great vendors 

[mightmo52]

i know the guy mike i met him many time at his shop he has a ton of nos parts and sells all the parts needed to get one of these old cars on the road .

he sells 588 fuel pumps also i just bought one from him . 

[mightmo52]

i just bought a new 1947 plymouth tank for my 47 plymouth sedan from mike best price i could find and super fit and quality. hes also a nice guy 

[rekbender]

One more bit of information to add here. While driving the car Friday, I had an "aha" moment concerning the operation of the Auto Stop. To make an uphill start with the Auto Stop engaged, I'd been letting the clutch out to near engagement and then pushing the accelerator to release the valve and go. There was still that brief period while the rpm came up the I'd roll backward a little. Then I realized that if I pushed and held the shift lever button down again before stepping on the gas, I could bring the rpm up without any roll backward as the button circuit keeps the valve activated by it's parallel ground circuit. Very clever on the part of the designers. Release the button when the engine takes up the load and voila - no rolling. I'll bet this procedure was included on the missing owner/operator card. This area of southern Ohio can be really hiily in places and now I'm wondering why this accessory wasn't more popular, or was it?

[rekbender]

I finally found pictures of the owner/operator card on ebay. Neil, from The Old Plymouth Cafe, was nice enough to send me a picture of the back of the card, as well as the front that he'd already posted. This fellow couldn't have been more helpful. Thanks, Neil.