Another speedometer cable and gear question

[Kipprc]

I swapped out the original speedometer gear in my transmission for a 32 tooth gear. I had a bouncing needle at all speeds. I originally just replaced the gear and ran the original cable. My needle then went dead so I have ordered a new cable and will be installing it Saturday. I noticed when I removed the original gear there was no small o-ring. Install the new gear with a new small o-ring. Could this have caused my needle to stop working altogether? I also noticed that some sellers of the long nose gear include a snap ring. Does a 904 require a snap ring somewhere? Lastly if this new cable doesn't work, what's the best way to clean the sheath on the old cable? I went through a can of brake fluid cleaner and never got a steady stream to come out of the housing sheath.

 

[Kendog 170]

I believe the gray O-ring and snap ring stay in the tranny. Without it it will leak.

 

[jimjimjimmy]

If you don't have it clocked right for the gear it will not work .

 

[Kipprc]

If you don't have it clocked right for the gear it will not work .

I thought I had it clocked properly. I have a housing that has the 4 hash marks but it only has 1 set of numbers. I clocked based off of a picture I found here of a housing with numbers by each hash mark. I may just have to get a new housing to be sure it's right.

 

[Professor Fate]

Pull the cable off at the tranny. Chuck the cable end up in a hand drill and run it at slow rpms. If the speedo needle registers, then your issue is in the clocking of the adapter. To confirm this, put a small screwdriver into the adapter and try to turn the gear. If it turns, it's not clocked right and the gear is not engaging the output shaft.

I have a housing that has the 4 hash marks but it only has 1 set of numbers.

What numbers are on it?
There are two different housings- one for 21-25 tooth gears, and one for 26-45 tooth gears.
If yours has only one set of numbers and is marked 21/25, you have the wrong adapter.
The correct adapter should have all hashmarks marked with a range- select the one marked with your tooth count.

 

[jos51700]

The bouncing is the binding of the cable in the sheath, and then breaking loose, then binding, then loose.

The dead speedo is the cable breaking inside the housing.

Don't use thin oil on the cable, or it'll pump along the cable to the speedo head. That's bad. The factory used a waxy grease.

Some better member than me will have a diagram where all the seals go, shortly.

 

[Professor Fate]

It's all in the FSM.

 

[Kipprc]

@profeyou were right. I have to swap the housing first. I don't have the right one. I ordered a proper one from Mancini racing. From there I will follow the procedure to check if the speedometer gauge housing is bad.

 

[Dana67Dart]

The speedo gear housing has to be properly clocked for the gear you are using.

If it was installed in the wrong position the gear will not make contact with the gear on the shaft.

IMHO, your speedo head is in need of repair.

My speedo started to bounce at low speeds, then higher and higher, and then you could hear a tick tick tick, I replaced the cable, no change.

There is a bushing (jewel) in the speedo head that fails and allows the cup attached to the speedo needle to move out of place allowing contact with the magnetic part that is rotated with the speedo cable.

 

[Kipprc]

All I can do is install the proper speedometer housing and then install the fresh cable. Then I can run the test to see if the speedometer will work. If it doesn't, then I will get to replacing or repairing it eventually.