ok guys my trucks speedometer doesnt work quite right. first the problem: i drove down to charleston to visit my dad (he works down there at Force Protection) an i found out that my speedometer reads wrong. i gert confused when i try an explain it any other way than when it says 70 MPH im really going 80 MPH. intriguing aint it? probably why i got a ticket a while back. okay now the history: when we bought the truck a couple months ago the speedometer didnt work, the guy told us that up front but he also told us that it just needed a new speedometer cable. i put one on but it didnt work, i new i put it on right, its pretty hard not to, and then something in the transmission popped. it drove fine so i drove it to the shop. they replaced the speedometer drive andspeedometer driven gears the old ones were completely worn down. it worked after that, (dont know if it displayed my speed correctly). then the speedometer cable melted, i laccidentaly let it sit on the exhaust pipe when i put it in. i put in a new one and zip tied. that was all about a month and a half ago. so while we were driving down my mom told me to set my cruise control to 70 MPH (gotta fix that to) i did and she did and i pulled away from her. i asked her on my cell how fast she was going long story short i was going 80 even though i thought i was going 70, i checked this with the Expedition also with the same results. anyone have any ideas? the only thing i can think is that the gears they put in werent the right gears. please help.thanks in advance guys.

 

It appears as though you need to change the speedo DRIVEN gear. They catalog these by the color they are casted in. You need a gear with 3 FEWER teeth than your's has (each tooth willdecrease your indicated speed by 3MPH at highway speed). Since your speedo is @10 MPH slower than your actual speed, a gear with 3 fewer teeth will speed it up 9MPH. You need to know the color of your current driven gear, and use this site http://www.transmissioncenter.net/sp...n_______va.htmto order, or at least determine what color to buy. If you have changed the cable twice, it will be a very quick and easy repair for ya!

 

thank you. question though. they said they had to, and billed me for, pulling the drive shaft and transmission tail shaft to get at the gears. does this mean i have to take it in to the shop?

 

No, to chage the DRIVE gear that is true, You have to remove the tail shaft housing to change the drive gear, but the driven gear is as simple as removing the cable end and then removing the bolt/clamp that holds the gear housing on the transmission tail housing.I should tell you that it MAY be necessary to change your drive gear, you won't know for sure until you know the COLOR of your current DRIVEN gear. Then you can check and see if a driven gear with 3 fewer teeth is available for your current DRIVE gear..Understand? The site above explains this I believe.

 

i have another question. the transmission is leaking about a quart of fluid a week if i drive it every day (like to school). it only leaks at night from what i can see. that confuses me but oh well. i checked with the guy at Advance and he confirmed my suspicion that the transmission pan gasket needed replacing. so i bought the reccomended filter kit. im going to change the filter and gasket at the same time. now to the question: would you reccomend replacing the driven gear at the same time or would it be better to do the 2 operations seperately? i cant think of a reason to keep them seperate but then again a couple weeks ago i couldnt come up with a reason why my speeding wasbad (that got corrected the hard way).
thanks again. also the link helped a lot.

 

Change them both (filter and gear) at the same time, because you will loose a little fluid whan you take the gear housing off. After you get the pan off, change the gear.

 

thanks. i just looked in the Haynes manual i bought last week. i thought it would be harder than that.
it just occured to me that i put this in the wrong section. oops. oh well thanks again.

 

okay i have another completely Blazer unrelated question. my horn doesnt work. neither does the clock but thats not the issue. its not up for inspection until november but why wait until the last minute to fix it. i checked the Haynes manual and didnt see anything about the horn. what could be wrong with it? also im not real good with electronics so should i get this looked at professionally? thanks again.

 

Pull the horn pad off, it literally just pulls off...the wire probably isn't hooked up to the cancelling cam in the wheel....it's kinda hard to explain, but the horn button just grounds the wire to complete the circuit and that wire is probably not hooked up, it's common for the cancelling cam to break off where it retains the horn wire, if that's what happened to your's you will probably be better off having it fixed by a pro..the part won't be expensive, a few bucks, but you have to partially disassemble the colum to replace it, which requires a couple specialty tools (a wheel puller and a lock plate compressor). If the wire is in place....start looking at the horn wiring out by the radiator support.

 

okay. thank you. as far as the cover pulling off thats what i play with at stop lights. ill go have a look tomorrow in the light. im planning on cleaning it up some tomorrow so ill be out there anyways.