The Stovebolt Site Forums The Shop Area Engine Shop Overdrive Problems

Well, I installed a tach in my truck and it confirmed my suspicions. My overdrive isn't engaging. It does go into the "free wheeling" mode, but the RPMs don't drop at all.

It is a 55 2nd with the 3 speed column shift. After reading the shop manual, it appears to me the likely cause in either the soleniod, the relay, or the governor switch.

I am about to start down the trouble shooting of the electircal components as outlined in the manual.

Does anyone have some insight regarding what is the most likely cause, or something I am not seeing?

Hi Newbie, there's also a speed element involved. Below lockup speed (something like 35 mph or so?) the o.d. acts just as you described. Make sure you're above that speed for your test.

I think that is where the "governor switch" come into play. That will probably be the last thing I check. I'll start easy, like the relay fuse and work my way up the chain.

Welcome to the site Newbie. That’s the way to do it one thing at a time. Good luck.

When you get up to around 28 mph are you letting off the gas a little then giving more gas (on the peddle) to engage the OD?

Just a thought.

One thing it could be is the blocker plate is worn. Mine did that, with the exact same drivability problem. The only whay to tell for sure is to take it apart, though. Could be somewhat difficult to get a new blocker, they're not being made. The manual says you can squeeze it together if the tension is weak to restore operation, mine was beond that. Got lucky enogh to find another trans to rob parts from (the main box was trash, od ok). I had a few other issues, to. A peice of the blocker broke of and damaged the housing, but that was secondary t the actual problem.
Check out all of the electrical and external controls first. If they check out, most likely the blocker is the culprit.

First thing I would do is pull the solenoid and energize it. Should be a strong/definate pull on the arm. My father in-laws' 55 Ford had a bad one on it,
Scott

OK, first thing I checked was the fuse. It was blown. I replaced it and tried the OD and it blew the fuse again. I can't seem to find the fuse amps listed anywhere. Does anyone know what the amps should be? It had a 15A, so that's what I put back in.

That's about all I can do tonight, were leaving for a Mom's day weekend. Monday I start the investigation process of testing all of the electrical components.

Thanks for the input everyone.

One of the main causes of blown fuses is that oil gets in the solenoid and drowns it out. There is a seal in the trans and also one in the solenoid. The trans seal number is 3060 CR, available from Napa. I dissassemble and wash out with paint thinner and hang it up to dry out. Clean up the contacts with 400 sand paper. To test, ground the case and apply 12 volts to the #4 terminal, if it clicks in and stays in it's good to go.
A 15 to 20 amp fuse should be fine.
Fred

OK, I need some more advice. I unhooked all of the wires (except battery) from the relay to test the relay without any potential load. I used my test light to see if the relay was passing current to the kick down/governor post. As soon as I touch the kd post, I pop the fuse. I assume that means the relay is shot. Correct assumption?

Part 2, where should I look for a relay. Is this something my NAPA store may have, or do I need to look at specialty restoration parts stores?

Any heavy duty relay will work. You should check the wire from the battery to the relay for a short also. You can get the relay from any flaps.
Tom

55,
You may have multiple problems, but try this first. With everything hooked up -
Connect a jumper wire to the KD terminal of the relay to ground, if the solenoid clicks, relay and solenoid circuits are OK. No click or blows fuse usually means a solenoid problem.
Fred

Well it works now. What a difference! It turns about 2100 rmp at 60 mph. It was a bad relay. I'm looking for a "period" replacement now. I haven't been able to find one yet.

For now I hooked up a generic relay (from Radio Shack). It's one of those small black plastic cubes. It looks terrible.

Thanks to everyone for the input. I feel I understand the overdrive system now.