speedo cable

[truck847]

I recently swaped out a 2 speed powerglide to a 350 turbo and now the speedo cable screws in but does not work on the dash, does anybody know the length of cable i need to install? and can i just slide the new cable into the original sheath? thanks in advance..

[raycow]

If the speedo worked before you swapped transmissions, there is no reason to automatically assume the cable is at fault. You need to troubleshoot this problem from the bottom.

Get one rear wheel off the ground and chock the fronts so the car doesn't roll away with you under it. Shift the transmission to neutral and release the parking brake. Crawl under and disconnect the cable from the transmission.

First, make sure there is a driven gear inside the fitting that the cable was screwed onto. It will have a small square hole that accepts the cable end. Turn the driveshaft by hand and see if the gear turns. If it does, put a load on the gear by sticking the point of a pencil into the square hole and applying moderate pressure. If the gear continues to turn, now you can suspect the cable and/or the speedo head.

If the gear doesn't turn, remove the gear fitting and look for damage to both the driven gear and the drive gear on the transmission output shaft. You might need to shine a flashlight into the hole so you see the drive gear.

Please post back and tell us what you found.

Ray

[truck847]

I recently swaped out a 2 speed powerglide to a 350 turbo and now the speedo cable screws in but does not work on the dash, does anybody know the length of cable i need to install? and can i just slide the new cable into the original sheath? thanks in advance..

Thanks Ray i'll give that a try, (the pencil) i did check the speedo at the dash with the cable out and it works, seems the cable is too short by about 3" at the transmission, so i ordered a kit with a 127" cable and i'll cut/grimp and try that.

[raycow]

Thanks Ray i'll give that a try, (the pencil) i did check the speedo at the dash with the cable out and it works, seems the cable is too short by about 3" at the transmission, so i ordered a kit with a 127" cable and i'll cut/grimp and try that.

Sorry, I must have misunderstood your original post. If your inner cable is too short for the casing, then you need to deal with that first. Don't even bother with the pencil untill you get the cable problem sorted out.

Now here is the part I don't understand. If all you did was swap transmissions, how did the inner cable suddenly become too short? You didn't say anythng about the speedo not working with your old transmission, so there might be some important information missing here.

Ray