1976 Eldorado Speedometer Troubleshooting and what is this?

[toukow]

Hello: The speedometer stopped working on my 1976 Eldorado. I found the following thread, which has many of the forum veterans weighing in, and will follow it for further troubleshooting. So far we have simply verified that the cable from the transducer to the speedometer turns freely, with the speedometer responding accordingly.

http://forums.cadillaclasalleclub.org/index.php?topic=150480.0

I do have a few questions though, and did not see the information in the factory service manual, but may be looking in the wrong area.

1.   Is this a reservoir of some sort associated with the transmission speedometer gear? If so, does it require fluid check, or? I was trying to pull the cover, but decided to post first after the following……

2.   After removing both speedometer cables from the cruise control transducer, I happen to look down and found the copper washer shown in the photo directly underneath the transducer. I am not sure if it happened upon removal of the cables, or came from somewhere else. It will fit the cable connection which goes to the speedometer, but not positive where it belongs. Does it ring a bell with anyone?

I figured the next step was to disconnect the cable from the transducer to the transmission, and attempt to drive the transducer  as 76 cadillac bob did.

Your comments appreciated. Hopefully I've attached my photos correctly.  Thanks, Toukow

[cadillactim]

Check the cable from the transmission to the transducer. The transmission cable drives a gear in the transducer that is connected to another gear that drives the speedometer. It's possible, but rare for the one gear to not drive the other gear. The most common problems are the transmission driven gear assembly gets gunked up or worn causing the speedometer needle to be irratic and jump. If the needle does not move at all then it is likely a damaged cable. You said the speedometer cable was okay, so check the transmission cable or drive assembly at transmission.

Tim

[toukow]

Thanks Tim. I went ahead an pulled the lower cable, and it's the culprit.

What's the deal on ordering these? So far everything I'm seeing is lengths of 38", but this measures 27". Does anyone have any advice is this regard?

Thanks, Toukow

[TJ Hopland]

Unless you are going for show quality correctness the longer cable should not be a big deal.  Longer would usually be better than short.   There should be plenty of room to route the cable so the bends are gentle and it doesn't get in the way of anything especially the hot exhaust.

That thing above where the cable goes in in the transmission is the governor and its housing.  It doesn't have fluid in it.  Its a set of spring loaded weights that tell the transmission internals how fast the car is moving.  The RWD cars have them too but in those its more built into the case so its not as obvious.   

[cadillactim]

Just make sure the ends and caps are the same where it attaches to the transducer from the transmission on whichever cable you use. One style is smaller.

Tim

[TJ Hopland]

Last time I had to deal with cables which was a few years back now the store I used still had books and knew how to use them.   The start of the book showed the ends so by looking at the actual size photos we figured out I needed a D and T end or what ever the numbers were.   We then flipped through the book till we got to the page that had the D and T cables and picked the closest slightly longer length to my original.   No idea if there is a similar sort of system online.

[bcroe]

2.   After removing both speedometer cables from the cruise control transducer, I happen to look down and found the copper washer shown in the photo directly underneath the transducer. I am not sure if it happened upon removal of the cables, or came from somewhere else. It will fit the cable connection which goes to the speedometer, but not positive where it belongs. Does it ring a bell with anyone?     

From here the copper washer looks like one used to seal a joint
on a fuel injection rail.  Bruce Roe

[toukow]

From here the copper washer looks like one used to seal a joint
on a fuel injection rail.  Bruce Roe

Thanks Bruce. I certainly did replace those a couple of years ago per comments on the forum as to fires on this year/model, but honestly didn't remember what they looked liked. Glad I asked, and thanks. Toukow.

[Scot Minesinger]

I restored the cruise control and speed operation on a 1972 Edlorado and used the longer cable.  It worked fine.  There was no copper washer either.