k5 trans in c10?

[oldcane]

Reading another thread sort of told me what my problem may be. I just bought a 69 c10 with what I'm told is an 87 blazer 350 and most likely transmission. The speedometer isn't working. With the cold and the rain I haven't had time to really look but it seems from reading the speedo cable is connected differently on a 4wd? If this is the case with mine is there any sort of adapter so I can connect it to my cable?

If this question sounds like I don't know much about this you would be on the right track.

[burnin oil]

I am not sure what style speedo GM was using in 87 but I don't think the trans is from a 4x4. Someone would have had to dissasemble the rear and redo the tailshaft to convert it to a 2wd truck. Older 4x4s used the transfer case to drive speedo. Most new stuff uses an ABS sensor for the speedo signal. Sometime in the 80s GM started to use the electronic speedos instead of cable drives. From memory it was 1986.

[oldcane]

Ok, that sounds good to me. So probably not on the trans. I will take a look this weekend and see if its 1) not even there 2) not hooked up or 3) just not working.

It sounds like you're saying I should be able to get this fixed pretty easily. If I find the cable hanging loose I'll try spinning it to see if the gauge is working.

Any other tips? I'm here to learn.

[burnin oil]

The speedo cable should be a metal cable with a ring on the end about the size of a 50 cent piece. The ring should screw onto the tailshaft of the trans on the drivers side. The cable may be black plastic if it has been replaced, and there is a good chance of that. Odds are if the cable is attached to the trans you will need a pair of vice grips to break it loose. Pull the cable of the trans, if it is hooked, and look at the end of the inner piece. It should either be square shaped or have a little metal adapter pin on the end. If it looks like a squirels nest it needs replaced. If all that is good you will need to pull the dash end. You can reach it without pulling the instrument cluster but it is way up there. Drop the cable and look at it. Same deal square or metal pin. If all that is good the speedo should work fine.

Once everything is hooked up and the speedo is working you may need to lube the cable. If the speedo is bouncing a couple mile an hour it needs lubed. To do this you will need to take the cable loose on both ends. The inner cable just slides out. Coat it with light lithium grease.

If it still doesnt work then either the drive gear in the trans is bad or the speedo head is toast. If you pull the piece on the trans that the cable hooks to there are gears on the back. As long as all the teeth are there they will usually work which leaves the speedo head.

****If the tail of the trans has a round adapter sticking out with a wire connector for 2 or 3 pins this is an electric speedo set up. Dont bother to pull that plug out. Even though it is the same size as the mechanical speedo plug the cross shaft for the inner gear is usually missing. The tailshaft will need pulled to fix this. You will need someone that knows autos to help you out on that.

[oldcane]

That should be a sticky.

[oldcane]

One question for you, if I go to a digital dash I'd guess that those come as an electronic speedo? Would that solve that problem?

[burnin oil]

Yes and no. It would work if it was the correct calibration. The systems work on revolution or pulses per mile. Cable drives were 1k or 2k per mile. Some of the early electric are this way but newer ones are 4 or 8k pulses per mile. The change had to do with ABS sensors. Alot of guys buy a convertor box that changes the mechanical cable drive to an electronic pulse count. Alot of places make them but Dakota Digital seems to be the most prevalent.