i just bought a 71 el camino yesterday the speedometer doesnt work the guy i bought it from said the tranny was replaced and the plastic speedo gear was never installed
where is this gear go and how do i instal it? does anyone have some pictures to help me out
thanks alot

You are going to have to find out which trans is in your car, the speedometer gear is located in the tailshaft housing usually on the left side, rear end of trans. To get the right gear you are going to have to know the rear axle ratio and the number of revs your tires make in a mile. Also you will need to find out what drive gear is in the trans., most times you can see it when you take out the cable housing, it will be colored and that determines the number of teeth of that gear. You can't miss the location of the gear, just look for the speedometer cable casing where it enters the trans., undo the casing and remove the bolt that holds adapter into the trans case. Once you have all the info you need about rear etc., a good transmission shop or speedometer place should be able to figure out what driven gear you need. Make sure the cable is free and use a drill to turn the cable and see if the speedo needle moves (reverse drive on the drill). You should have no trouble putting a new gear in.

its a th350 no idea what the ratio of my rear end is how can i find that out?
thanks alot for the info

On the passenger side axle tube near the differential housing there will be some letters and numbers. Clean off the tube with a wire brush and some solvent on a rag to reveal them. Post what you find here and you will receive the axle ratio from a reply.

Doug

ok the number on the tube says 12345 and the rear tire is a 245/60r15

ok the number on the tube says 12345 and the rear tire is a 245/60r15
??? Those numbers don't mean anything to me. Where there not any letters there? May someone else has a clue.

Doug

ok thats number is the foundry casting it was on the backside of the rear ill get the right number tomorrow i know where it is now

alright finally got the stamped number which was really hard to see half of it was gone i dont know if it was a crappy stamp or if i was ground away by someone trying to clean up the rear end
its GAC 245 1

Well I have not found GAC 245 1.

This is what I have found using Google
1971 Chevelle GA Axle code is a 2.56

Doug

thanks

In your original post, you say the gear was left out of the tranny when it was rebuilt. You will need the drive gear (in the tailhousing) and the clip that holds it in place. Might as well get the driven gear to match it, while your at it. They are both easy to replace. Unhook the speedometer cable and pull the driven gear out of the side on the tranny. Then remove the driveshaft. Next remove the four bolts holding the tailshaft housing. Remove the tailshaft housing. There will be a little fluid leak out, but not much, if you have the back of the car higher than the front. Locate the small hole drilled into the side of the tailshaft, this is where the clip goes. Place the clip into the hole, big end toward the rear of the car. Slide the gear over the clip so the clip goes through the notch in the gear, until the end of the clip clears the edge of the gear. It may be a little tight, if you can't slide it on completely by hand, use a large wrench that will fit loosely over the tailshaft and contact the gear at points approximately 180 degrees apart and gently tap it on with a small hammer. If you are sure that you have the original rear end get the gears for that rear and tire combo. If you aren't sure about the rear end ratio, jack up the rear, mark the driveshaft and a tire. Rotate the tire and count how many revolutions the driveshaft makes for each revolution of the tire. I like to spin the tire ten times, so that I get a better reading. If the tire spins around ten times and the driveshaft spins almost 31 that is 3.1 (driveshaft revs divided by tire revs), the closest ratio to that is 3.08.

Here is a calculator for the gears from TCI CLICK HERE (http://tciauto.com/Products/TechInfo/speedo_gears.asp)

The gears are about $10.00 each from TCI and the clip is about $8.00. If your driven gear housing bullet is messed up a new one of those is about $11.00

thanks that really helps