Subject: [TR] Type A overdrive question

From: ron landis <[email-masked]>
Date: Sun, 20 Jul 2014 08:08:23 -0700

List.  I have a type A OD on my TR250.  It is from an Austin Healy.  On
occasion the OD will not "kick in", when I hit the switch.  I t appears the
solenoid is not working.  Then by magic it starts working.  I have replaced
the solenoid, relay under the hood, and the 3/4 th gear switch on the
transmission, also checked the spacers, and checked the Ground wire.  

Any
Ideas??

Thanks
Ron

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From: "Randall" <[email-masked]>
Date: Sun, 20 Jul 2014 10:19:07 -0700

> It appears the solenoid is not working.  Then by magic it starts working.  
> 
> Any Ideas??

Get a meter, hook it up, take a test drive.  If there is power getting to the solenoid when it fails to engage, then you have
divided the problem in half (it's not in the control switches, relay, etc.)

Then do it again with the cover off, so you can do a visual on the solenoid.  If it is getting power but not moving, your new
solenoid is bad.

Did you check the solenoid adjustment after changing it?  If you just used the "pin in the hole" method as given in the book, I
would suggest trying the "ball lift" method given in the Buckeye Triumphs articles.  Sometimes the internal components wear enough
to make the hole method inaccurate; and erratic engagement can be a symptom of incorrect adjustment.  The ball gets harder to lift
when there is full pressure against it, so the linkage flexes more and doesn't get the ball off the seat.

Also check how far the solenoid plunger can fall.  Some ODs have an adjustable stop there (which can fall out), some just use a
rubber button (which can also be missing).  If the plunger falls too far, the solenoid may not be able to pick it up.  But usually
the solenoid burns up soon after, so that probably isn't the problem.

In my most recent round of A-type problems, it was the pull-in contacts inside the solenoid that were intermittent.  Since it had
already been changed about 15 years ago, I decided to try adding a snubber diode to protect those contacts.  Dunno if it will
actually help, but it should.

Randall