Speedometer stuck on 70mph

[bob8619]

My new project 68 came without a speedometer cable. Should the speedo needle fall on zero mph when nothing is connected to it? I installed the new cable and the speedo just spins randomly around, I don't know if I damaged it by hooking it up before it was on zero or if it was already shot.

[demian5]

Originally Posted by bob8619

the speedo just spins randomly around

Id like to see video of that!

[Stocker]

Originally Posted by bob8619

Should the speedo needle fall on zero mph when nothing is connected to it?

Yes. Dunno what else is wrong with it though....

[AussieinNC]

You will find oil has found its way into the speedo head mechanism,,,

the speedo head needs to be cleaned or replaced...

[bill3rail]

Step on the brakes? J/K

Should drop to zero with no cable attached.

I don't think you can damage it unless you hook up the cable while driving!

[toolboxchev]

If its going that fast, don't fix what aint broke!

[bob8619]

I solved the issues that I described but now a new one has appeared. It seems to be accurate (compared to gps speedometer) up until 25+mph. Once I reach 25mph actual speed the truck speedometer says 50mph and it just gets crazier the faster I go. I figure its shot but figured I'd see if anyone here knows for sure.

[Grumpy old man]

Sounds like your problem is in the cable and not the speedometer ...

[TBONE1964]

Originally Posted by bob8619

I solved the issues that I described but now a new one has appeared. It seems to be accurate (compared to gps speedometer) up until 25+mph. Once I reach 25mph actual speed the truck speedometer says 50mph and it just gets crazier the faster I go. I figure its shot but figured I'd see if anyone here knows for sure.

If you want to send it to me, I can go through it and make it work correctly or just send you a good working one.

I have a certified speedometer calibration tester and tools to make your speedometer work like new.

Let me know if interested,
Tom

[bob8619]

Originally Posted by TBONE1964

If you want to send it to me, I can go through it and make it work correctly or just send you a good working one.

I have a certified speedometer calibration tester and tools to make your speedometer work like new.

Let me know if interested,
Tom

Thanks Tom, I'll mess around with it a bit more and if no luck, I'll take you up on that offer.

Grumpy, I know that the the cable can stick if not lubed well enough and causes a jumping needle, but it can also just cause it to read faster than actual? And just in case it sounds like I'm challenging your thought, I assure you I'm not.

[TBONE1964]

Originally Posted by bob8619

Thanks Tom, I'll mess around with it a bit more and if no luck, I'll take you up on that offer.

Grumpy, I know that the the cable can stick if not lubed well enough and causes a jumping needle, but it can also just cause it to read faster than actual? And just in case it sounds like I'm challenging your thought, I assure you I'm not.

Here is the test to know if your trans gears are the issue or the speedometer.

Drive on a portion of road where you can go a measured mile, like on a freeway. Don't worry about your actual speed but drive the mile and see what the odometer does. If it matches and rolls one mile for the measured mile driven, then the trans gearing is good. If it does not and goes over or under a mile in the same driven mile, then you look at different trans gears based off tire size and rear gear ratio.

If the measured mile tile passes, then your probelm is speedometer calibration.

Hope this helps everyone understand how it works.

Thank you,
Tom

[bob8619]

But its within a few mph of the gps reading when under 25 and then once I go over that it jumps to being off my 25mph give or take a few. I wouldn't expect a big jump in inaccuracy if it was just related to trans gear. Sounds more like calibration to me wouldn't you agree?

[TBONE1964]

Originally Posted by bob8619

But its within a few mph of the gps reading when under 25 and then once I go over that it jumps to being off my 25mph give or take a few. I wouldn't expect a big jump in inaccuracy if it was just related to trans gear. Sounds more like calibration to me wouldn't you agree?

Yes it sure does sound like speedometer calibration. I wanted to explain how you can eliminate the trans gearing as the issue.