Desperately Seeking Wisdom - I have a 1966 Ford C550 Cab-over-engine Flatbed. It has a 330 c.i. MD engine and manual shift transmission - Appears someone has changed the **** on the shifter arm and I cant tell what I have now. Through trial and error I have figured the gearing and it appears to be a 5 speed with 1st gear as a bull low. Reverse and 1st are all the way over to the right while the rest are a standard "H" configuration - My dilemma is, there is a large **** on the dash that doesn't move. I think it's too caked with rust and old dried grease to function. It may be an overdrive as the cable leading from it goes to a large arm on the side of the tranny. While driving the vehicle, top speed appears to be about 100 kph and the engine is screaming at that speed, which leads me to believe it has an overdrive somewhere and I just cant locate it. This is an old petrocan truck and was used on the highway so must be capable of highway speeds. Anyone that can help or knows anything about this engine-transmission combination would really be appreciated. Thanks.

 

That would be a power take off control.

No transmission would have an extra cable controlled lever for OD. It will either be the top gear or gears as with some newer transmissions, or a separate unit on the tail or mounted aft of the trans.

You should be able to see a PTO near that lever. Similar to:

https://www.google.com/search?q=chel...w=1920&bih=976

100kph or 62 mph sounds about right. You do not have a two speed axle, right?

You can post the warranty plate info and get a decode on axle ratio if you'd like.

 

I cant see any PTO on the engine or tranny but I will take pics and post as I have never seen a PTO before - The only numbers I can see are cast into the tranny (A-U-EK 219016) Maybe the pictures will help identify it - The **** in the cab leads to a large arm that is at the rear side of the tranny. Again, pictures are worth a thousand words so hopefully it will say what I cant - I don't know what a two speed axle looks like but this one looks the same as any light truck except its dual wheels - Many thanks.

 

A two speed would look like:

https://i.imgur.com/GgfaG.jpg

In your year model, they are electric shift. They used a red switch on the shifter to shift the axle. Up for high, down for low. You'd see it if it's there.

The lever would be on a PTO bolted to the case of the trans. Does this lever simply go into the main case of the trans? Or does it go into another assembly bolted to the main case of the trans?

 

Here are pictures of Tranny and Rear Axle:

1966 Ford C550 Cabover


Left Front side of Tranny


Lower Left Rear Tranny


Lower Right Rear with lever leading to large **** on Cab Dashboard


Lower Left Rear Tranny


Lower Rear view Tranny


Upper Rear view Tranny


Front of Rear Axle


Back of Rear Axle


Top Right side of Tranny showing linkage to gear shifter in Cab


Top Right side of Tranny showing linkage to gear shifter in Cab


Top Left side of Tranny

 

Look at your "lower right" view of the trans. The lever does not lead into the transmission. The connection on the transmission is merely a pivot point. (note the castle nut and cotter pin) Follow the linkage further back and you will see that this is the parking brake linkage and cable.

My dad had a C600 but it was never operable, so I do not remember the parking brake being on the dash with a cable. It makes sense though, as with the tilt cab, you have a tough time with linkages. Cables make it a lot easier.

If you post your warranty info, your trans code can be checked.

I've tried to find images to match up to your trans, no luck. Could be a NP541, but that's a WAG.

Also, no PTO on that trans. Again, looking at the above picture, note the cover on the lower part of the trans, held by 6 bolts. That's where a PTO bolts up. Your trans has two such ports.

You have a single speed axle.

 

Ok, problem resolved. the lever in the "Lower Right Rear" photo actually leads to the parking brake lever in the cab - sorry for the confusion - It's a bit hard tracing these lines. the lever itself has an arm above the rear output of the tranny. I suspect it engages brake shoes directly onto the output shaft and the large drum behind the rear axle has a hose that leads under the housing for this brake. I was told by a heavy duty mechanic this drum is the reservoir for the parking brake so it all starts to make sense now. The **** in the cab is on a cable that leads to the left side (seen in the "lower left rear tranny" photo) - it is fixed to a plate covering the hole intended for a pto - I suspect the pto was removed and the plate installed to cover the hole and also secure the cable that operated the pto - many many thanks to 85e150six4mtod for explaining the pto and parking brake system on my little relic.

 

I missed that cable attached to the PTO port just hanging there....

As for the drum behind the axle, it looks like a hydrovac brake booster.

The parking brake should be strictly mechanical, with no connection to the booster system for the service brakes.

Check your hose routings. You should have a small master up under the dash. (two, one brake, one clutch) A line from the brake master should go back to that hydrovac. Lines from the boosted side of the hydrovac should go to each wheel. In addition, a fairly large line (tube) should go to the engine manifold as a source of vacuum for the booster. Another tube might route up into the cab or other higher point as a vent point for the system.

Might be some variation there.

There are hydraulic parking brakes on some automatic transmissions, but this one should be just the lever/cable/linkage set up.

Good luck with your truck. Please do sort out the brakes first, as another member just posted about his braking misadventure.

 

Thanks again, I will go over the braking system carefully before I attempt anything - I am about to remove the transmission to replace the worn clutch, pressure plate and throwout - I'll have to remove the cables and linkage attached to it first so it's best I understand the systems before removing their cables, hoses and such from the tranny.

 

Continuing to have issues with this transmission - the linkage from the gearshift in the cab to the transmission has an interesting array of u-joints and tie rod adjusters that I cant seem to get apart. Do you know how these u-joints come apart as the tie rod adjuster is impossible to move. Linkage appears above in "Top Right Side of Tranny" photos. I cleaned the area to get a better view: