View Full Version : Speedo weirdness


JimM
Apr 29th, 06, 06:49 AM
This season, I've come up with 2 weirdnesses, possibly related.

#1, my speedo seems to read whatever it wants to. Sometimes it don't move at all, sometimes it sticks at 10, 20 or 30 even when I'm stopped. It's read 55, 68, and 72 @ 2100 rpm on the highway (72 is correct) and will stick there even if I speed up or slow down.

At first I thought it might be something to do with the speedo drive on the new TKO, but I've checked the odometer against highway markers 3 times. It's accurate. Thursday, it gained 2/10's over 25 MILES, good enuf.

#2 is I got some sorta oil dripping from under the dash. It lands on the clutch pedal pad (directly under the speedo) on the floor under the clutch, and on my shoe. The clutch pedal lever is clean, as is the brake and everywhere else.

Is it possible for lubricant to migrate up the speedo cable?
Could this be gumming up my speedo?
Can I fix it?

dawg
Apr 29th, 06, 07:17 AM
the dripping is caused by a bad oring seal at the trans.
speedo cable seal that is.
You could also have a bad (broken) speedo cable or the speedo gears are not meshing properly in the trans .

blue ss
Apr 29th, 06, 10:10 AM
Jim
My speedo acted simalar (but no oil dripping) when I put in the 5peed the kit included a cable I belive it was the cable that was worn causing it to act that way. I have herd of the trans oil following up the cable . ( want to think an overfill cased the one I am thinking of) I wounder mabe could your releif vent on the top of the trans be touching the tunnel keeping it from venting properly, and building preasure as it heats up? It is a tight fit with the 5 speeds up there. Brian

JimM
Apr 29th, 06, 11:17 AM
my kit included a machined alluminum insert that sticks in the trans, the gear, and a 3" or less peice of "cable" one end of which sticks into the gear, other other end sticks into the stock speedo cable, which screws directly onto the alluminum adapter. Guess I'll hafta crwal under and pull it out again and give it a looksie.

It is possible or likely that my cable was "heavily lubed" to begin with, but it didn't drip last year, and hasn't been touched in that time.

I don't "think" any part of the trans is touching the floor. I did have issues getting it high enough to get the mount in, particularly with the first crossmember I tried.

When I put it together the last time, I put 2 large peices of "shoebox" cardboard on top of the trans, overlapping in the middle, when everything was tight I was able to pull them out. The vent is VERY close to the floor but shouldn't be touching.

blue ss
Apr 29th, 06, 12:36 PM
If you want to stop by after your looksee, Im not useing my speedo for a few weeks you can swap them for an experiment. Brian

JimM
Apr 29th, 06, 02:17 PM
hmmm, interesting offer, Brian, now if only it would stop raining!

MrDanB
Apr 29th, 06, 03:41 PM
Jim, Did the speedo act up before you installed the 5-speed? If so, I would bet it is cable/trans related. If it has been doing it all along, it may be the needle mechanism itself. I think it is rare to have the needle "go bad". I am chasing down the exact same problem in my 77 Camaro car right now. it has all original drivetrain. When I removed, cleaned and re-installed the speedo cable into the trans, it worked pretty good for a few days, then back to sticking and acting goofy. I hate not knowing how fast (or slow) I'm driving :(
Keep me posted on what you find out.
BTW, the cable swap idea sounds like a good plan to me...
Dano:beers:

JimM
Apr 29th, 06, 04:03 PM
I had no problem with the speedo last year or any time before this spring, well, 2 years ago the needle was jumpy, but lubing the cable real good fixed that.

Still, it's pretty hard to blame a trans for a speedo that sometimes indicates 35 miles per hour while sitting still.

Regardless, it started after I swapped the "wine colored gear" for a white one, so I'll start there. Wife's goint out tonight and my chores are done, so I'll get some garage time.

JimM
Apr 29th, 06, 10:17 PM
spent some time in and under the car tonight. oil and filter change, and pulled the speedo adapter out of the tko.

Everything is good underneath.

I pulled the dash carrier, cleaned the speedo guts by spraying into it with mineral spirits, then dried with low pressure air. Speedo seems fine. Needle moves free and alays returns to zero, moves when I spin the brass drive peice on the back.

I pulled the inner cable and cleaned it and blew it off, looks like new, no rust or nuttin. Cleaned the outer cable by repeatedly spraying amsoil mp in it and then blowing it with air, put the inner cable back in and put the trans adapter on it and left it hang.

Turned the gear and it feels fine. Stuck the speedo on the cable and tightened it down. Now the cable's bound up, won't turn at all. loosened it a bit at the speedo, now i can turn it.

Fired the motor, put it in fifth, and played with the speedo connection... if I leave it unscrewed and push the speedo onto the cable, it reads fine. If I screw it on, it gets funky, depending on how tight and what angle i hold it. never perfect and consistent...

Pulled the inner cable out and verifed it's going into the back of the speedo nice, it is.

Any idea what gives?

I don't see nuttin wrong, but it don't work.

secondtime z
Apr 30th, 06, 08:25 AM
Have you tried connecting the cable at the tranny to a cordless drill and spinning with that,may narrow it down to cable or trans gear.Also I have found the little crimped end on the cable loose

JimM
Apr 30th, 06, 10:12 AM
the trans gear is fine. The trans end oif the cable is fine. When I "make 'er move" (back tires in the air) the inner cable at the dash end spins just fine.

It seems it's binding up somehow when I attach the cable to the speedo.

Success!!!
As I was taking some pics to add here, I n oticed that the inner cable was not centered as it came out of the outer. Pulling the inner out revealed SOMETHING WAS IN THERE! It seems to be a bushing that the inner cable should pass thru.
Some how, somewhere, it got flipped sideways! Wonder it worked at all.

After a certain amount of messing around, it seemed it works just fine if I leave whats left of that bushing on the workbench.

Here's a couple pics. You can see how the speedo cable almost ground thu it. It's probably been like that for who knows how long.

MrDanB
Apr 30th, 06, 10:42 AM
YAAAH! Good job Jim! :hurray:
Dano

JimM
May 2nd, 06, 06:15 PM
it figures... powered up the car today, and when I turn on the headlights, both turn indicators glow.

Guess I've again fallen victim to the old "68 dash woin't ground" syndrome!

Why the heck didn't they put a ground wire in the dash connector? There's 2 blank pins...

click
May 2nd, 06, 08:07 PM
My speedo dripped hot oil on my bare leg on the trip to Seattle in '03, ouch !! new bullet and o-rings and I was good to go but no binding. I leave that to the Chinese food :)

JimM
May 2nd, 06, 08:47 PM
the old ground problem not so bad this time, all I had to do is take all the screws out and pull the unit forward a half inch and everything lit off normal (yes, I have a real ground wire on it, do not rely on the darned top center screw!)

Also talked the right rear window crank into staying on, and ficed the lisence plate light, so all that's left is that door lock.