Speedo Guage Dances

[CarFreak146]

Hey all, at about 75 mph, my speedo guage starts to "dance". It will jump from 70 to about 83 mphon its own, and it makes it very hard for me to tell how fast I'm going. If anybody has an idea of what could be causing this, please let me know. I don't wanna get a ticket, for I do a lot of highway driving.

Thanks in advance.
--Ryan

(btw, its got a 16 tooth speedo gear in it already to accomodate for the 32's)

 

[88vert]

Cable could be getting loose

 

[CarFreak146]

how would I go about checking that?

(Thanks for the quick response too!)

 

[snocross1985]

Mine does the same thing but only does it if it cold (less than 25 degrees out) and I am driving over 50 mph and keeps doing it until it warms up inside the vehicle. If it's not cold out it never does it. Anyone know what is causing this?

 

[RFR2212]

Originally posted by snocross1985
Mine does the same thing but only does it if it cold (less than 25 degrees out) and I am driving over 50 mph and keeps doing it until it warms up inside the vehicle. If it's not cold out it never does it. Anyone know what is causing this?

Yup, mine is the same way...

 

[410Fortune]

Check the speedometercable as mentioned above.

It goes from the t case (4x4) or trans (2wd) through thge firewall above the brake pedal and up to the back of the speedo

It is held in place with a plastic clip, you squeeze it together and the cablr will come free. It takes a while the first time but after you do it a couple times they are a snap.

You can reach up there from under the dash, a flashlight is handy too,

Cables from the dealer are about $90 (IMExperience)

 

[CarFreak146]

so then, you're saying that it could be loose where it connects to the back of the gauge cluster then??

 

[AlaskanJack]

I have the same problem and my experience is that once you pull the speedo cable out of the t-case it bounces. this has happened on two of my Ex's after I swapped a t-case and/or speedo gear for larger tires.

 

[CarFreak146]

it there any way to secure it so it doesn't bounce, like, with epoxy or something??

 

[Maniak]

Another posibility is the drive gear for the speedo (the one in the xfer case)..

If the cruise control speeds up/slows down when it bounces then the cable is changing speeds at the speed sensor. A very bad cable (one that barely spins) could do this, but it would have to be pretty bad.

the easy way to check if the drive gear is worn is to pull the speedo cable/gear out of the side of the xfer case. Now put your finger in the hole (you won't get your head up there to see in there). If the gear feels flat across, then it is still good. If it has a concave shape to it, then its bad. Ours was bad enough that the speedo worked correctly up to about 35mph.. Then It started to bounce. Eventually, it stopped bouncing and just read 20% off.

~Mark

 

[CarFreak146]

I doubt its the gear itself that is worn, b/c I just put in a new speedo gear about 3 months ago after stepping up to 32" tires.

 

[88vert]

How long has it been doing it?

 

[CarFreak146]

for about a week now.

 

[AlaskanJack]

See I think there is something with putting a new speedo gear in the t-case that somehow doesn't get the cable secured back in.

I have found that I can just pull the cable out of the speedo housing on the t-case. Is there something that lets you know you have the cable re-inserted the right way? Also I noticed that some lubricant comes out of the cable and does this have some affect on the dancing speedometer?

 

[CarFreak146]

not sure, good point though.

 

[sbbloom69]

Both Speedo AND Cruise Bounce

Hi,
I have a 93 XLT 4wd. My speedo AND my cruise control oscillate. The cruise is so bad, that it's useless.

Where does the cruise control get the speed data from? I was under the impression that later Explorers just use the VSS sensor mounted on the rear diff for ABS, Speedo (cluster has an electronic gauge) and the cruise. This same guy told me that older Explorers had the cable and mechanical speedo (I can see the cable coming out of my xfer case), but still use the VSS sensor for ABS and cruise.

So, my question, where does the cruise control really get the electronic signal for speed on the 93? It's got to be converted to electronic somewhere.

Autozone wants $30 for the rear sensor, and I don't know how much a cable costs (do you have to get it at Ford??), so I'd like to know how much I'm going to have to spend. I can live with the speedo for a while, but I'd really like to get the cruise to work.

Stu

 

[Maniak]

On the first Generation X's the cruise control gets the speed from a speed sensor on the speedo cable, near the xfer case (or tranny if 2 wheel drive).

If both the speedo AND cruise control are bouncing either the cable is in really bad shape or the driven/drive gear on the speedo cable are bad.

You can check the drive/driven gear easily. To check the driven gear (the one on the end of the cable).. Take the speedo cable out of the transfer case (tranny) and look at the gear on the end. If the gear is not flat (e.g. looks worn) that can cause the problem. While you have the cable out, stick your finger in the xfercase (tranny) where the cable was and feel the gear that is in there. It is a spiral cut gear BUT the gear should feel flat across. If it feels worn (sort of cresent moon shaped) then the drive gear is bad.

The driven gear (the one on the cable) is pretty cheap and easy to replace.. There is just 1 clip holding it on. If the drive gear is bad you need to take the rear drive shaft down, take the big nut off the yoke (end of the tranny). Now that the yoke is out, take out the oil seal. Now you can see and reach in there and just pull out the old drive gear. There is nothing holding it in there other than a magnetic field (it is magnatized). You can put your finger in the speedo gear hole to move the drive gear (its easier to push it out than pull it out).

Now put the new drive gear in, install a new rear output shaft seal, put on the yoke (with the big nut) and put the drive shaft back up. Now put the speedo cable back into the xfercase/tranny. You may have to top off the transfer case as you will lose a little fluid when you do the work.

If the gears feel fine you need to then check/replace/lube the speedo cable. To do this you need to pull the instrument cluster out and pull the cable out of the back of the speedo so you can pull it out. If it is dry you can lube it.. (I use bearing grease, but I've seen people use ATF). If it is frayed, take it to a speedo shop and have them make you a new one. Since the cruise control is bouncing you know the cable (down by the speed sensor) is speeding up/slowing down. This normally won't be caused by a dry cable. A dry cable can cause the speedo to bounce, but not normally the cruise control.

I still have my old drive gear at home if you need a picture of what a bad one looks like (I might even have an old driven gear)

I hope that helps...

~Mark

 

[sbbloom69]

Speedo Bounce

Thanks Maniak,
I know exactly where your talking about. I bought this XLT last March, knowing that the xfer case motor didn't work. I did the "clean the motor and replace the limit switch plastic" repair the weekend I got it. I shaved $500 off the asking price, from the original owner knowing I could probably fix the xfer case motor problem (it had not worked for 2 years).

Another question. Do you HAVE to pull that part of the case apart to push the gear out? I have lots of precision tools, long and very thin pliers, etc. Can the drive gear be pulled? Or, does the case hold the gear in in some manner requiring the case to be split?

I may have to pull the tranny anyway, since I have a leak somewhere around the slave cylinder (I think its just a bad o-ring in the quick disconnect fitting since the fluid seems to be coming only from there). Anyway, if I have to pull the tranny, I'll do it right and split the case, do the clutch, flywheel, slave cylinder, bearing, etc.

Thanks,

Stuart

 

[Maniak]

The driven gear (the one on the end of the cable) will pull out by pulling the 1 bolt that holds the clip on.. (The

The drive gear comes out the back of the xfer case (pull the yoke).. If you pull the driven gear also, you can just put your finger in there to push the drive gear out... I couldn't get a grip on the drive gear when I tried to pull it (instead of push it) out.

Its almost way to simple....

Remember, the driven gear is the small plastic one people change when they change their gear ratio (on the end of the speedo cable). The drive gear is the 1 size gear that is in the xfer case (on the output shaft) that turns the little plastic (driven) gear on the speedo cable.

~Mark