Bouncing speedometer needle after speedometer gear swap help!?!!@#

[95EXP4.0]

Here's the deal, I have a 95 Explorer 4.0 with an auto. I swapped my old 19 tooth speedo gear for a 20 gear because I am currently using 31" tires so it was off 2 miles for every 20 I drove. Now today I installed the gear the shift points seem ok but now the speedometer needle is bouncing like nobodys business! Anywhere from 25mph and lower it will start bouncing or just come to a dead drop. I know it's working because the trip meter is still counting mileage. Is this normal when you switch the speedo gear?

 

[Doug]

Im not sure what does it but my old 96 would do that sometimes. The needles would drop down to zero even though i was cruising 60mph down the highway. It would only last for half a second or so. Im thinking i got mud somewhere it shouldnt be.

 

[JDraper]

Do you have the electronic speedo or do you have a cable running from the gear to the dash?? (I don't remember which year has what ) If you have the cable, it sounds like something is binding, not lubricated properly, or you didn't get the cable installed properly into the housing. Make sure your cable is not kinked or bent too sharply and make sure you lubricated the cable end.

If it's the electronic type, it might be a misaligned sensor.

 

[95EXP4.0]

Originally posted by JDraper
Do you have the electronic speedo or do you have a cable running from the gear to the dash?? (I don't remember which year has what ) If you have the cable, it sounds like something is binding, not lubricated properly, or you didn't get the cable installed properly into the housing. Make sure your cable is not kinked or bent too sharply and make sure you lubricated the cable end.

If it's the electronic type, it might be a misaligned sensor.

I am for certain it's an electric speedo, it's definately not a cable speedo. It had like 3 or 4 wires plugging in the harness right by the yoke of the driveshaft.

 

[Robert]

Are you certain you got the right length gear? Ford has two different lengths. The first 19 tooth gear th Ford Parts guy brought me out was about 1/8" shorter than my original. I sent him back and he brought one out that matched up perfectly with one less tooth. My speedometer does not bounce at all with the new gear.

 

[rpenner54]

Usually they do this when they get tight and they need a bit of oil in the cable itself. My Explorer has done this for some time but I have never really cared since it only bounces a bit...

 

[Alec]

Also, did you reinstall the gear retaining clip with the new gear?

 

[GR899V8]

I put one in my hot rod and it had the same problem. Took it out and the teeth were all chewed up, turns out there are clockwise and counterclockwise gears (this was on a toploader 4 speed). Just a thought...

 

[Mbrooks420]

I had this problem too. On my 1996 a piece of metal got into the gear and chipped it all up. I had to buy 3 different ones to get the right one for my truck. The part # of my truck had a suffix that the part stores(Napa, Advanced)gears didn't have.

 

[95EXP4.0]

Yeah put the retaining clip back in........as a matter fact when it gets to around 30 when the speedo drops it seems like it downshifts and almost feels like neutral this sux.

 

[Byrd91]

I don't have an answer to your question, but I did notice that you went the wrong way in gear teeth. Since you got bigger tires the drivetrain is spinning more slowly at the same ground speed, you need less teeth on your gear to make it spin faster and therefore read higher than before. By the way, mine bounces too, I lubed it and everything but it didn't really help....but now that I think about it...I haven't noticed it bouncing in a while....weird.

 

[95EXP4.0]

Hmm that's strange cause someone told me with 31" tires if I have 18 teeth now all I have to do is go one up. I found out I have 19 teeth so I should go with an 18???

 

[Robert]

They told you wrong. If you get larger tires, you need a gear with less teeth. When I went from 30" tires to 32" tires I went from a 20 tooth gear to a 19 tooth gear.

 

[95EXP4.0]

anyone have an 18 tooth gear for sale?

 

[Okrazie1]

According to this info here, there are different gears for manuals and automatics. For your application, you would need a gray gear.

BTW, I found some info the other day on the odometer accuracy test. According to Ford, when travelling an actual distance of 10.0 miles, an odometer reading of 9.6 miles to 10.4 miles is considered "accurate". My 31's throw mine off to 9.4 indicated at 10.0 actual, but I would need a computer recalibration to correct it, since mine doesn't use a gear.

 

[Robert]

That list is misleading (at least for my '97 Explorer). Mine required a 19 tooth pink gear which according to the chart is for a manual transmission. My transmission is a 5R55E automatic. The service guy brought out the 19 tooth tan one first and it was about 1/8" shorter than my original one.

 

[Okrazie1]

I guess the best bet then is to take your old gear with you, and be aware that there two different gears available.