The Stovebolt Site Forums The Shop Area Interiors Speedometer: Rebuild or Replace?

Just when I thought I could get down to fixing something useful like the horn, this happened. While driving, the speedo started making horrible noises and the needle started jumping forward, backward, around the clock, etc. It was screaming like a banshee when the needle popped off. The rest of it self destructed shortly after and the Odo even turned backwards.

Should I call a priest to exorcise the demons within? Is it repairable? Are new ones available? Is there a rebuilder that's recommended?

I installed a new cable a couple years back and lubed it the full length with white lithium grease. it worked fine until it didn't.

Otto, Your question will probably get more answers in the Interiors forum so it's been moved there for further discussion and help.

Your truck is hainted (southern derivative of haunted, but somehow way worse).
Shove it into a ditch and forget about it.
You may want to first try just trowing the speedometer as far as you can and replace it with a new one. If you do that, drive cautiously in case it doesn't result in exorcism of the haint.
I have bought aftermarket speedometers and they work just like the originals (somewhat inaccurately).
The only difference that I can see is that the bezel of the reproduction ones are rounded in cross section. The originals are bevelled in cross section. Very minor and hardly noticeable.

Hard to tell, but it looks like the screws loosened in the center, fell out releasing the center cap. I just rebuilt mine with a 90mph face and new gears and needle. I replicated approximate mileage from old, but this came from a completely different truck than the cab I have. Easy to open and repair. I color matched and repainted the tan center. it was scratched up.
Take a screwdriver to the back of the chrome trim ring bending it to slide it off exposing the glass and inside ring. Then from the back, remove the 2 screws on either side of the cable input. Everything inside should fall out. Save the tiny face screws if you find them. They look better IMHO than what comes in the face kit.Then order The proper face, needle and works. I can't tell from the pic how bad the center cover is damaged. It may be reused if the screw holes aren't enlarged, but the replacement dial face I got had one with it. You may be able to reuse the needle and face, just replace the posessed gears.

The two screws that hold the speed face on are not common sizes
They are between 4-40 and 6-32
It’s a 5-40 screw I think but I don’t recall exactly all I know is it’s the only location in the whole truck that uses that size
That includes screws in the radio like RF tuning coils and such
That odd ball screw is only in the Speedo face plate
-s

There's a speedo rebuilder on Facebook by the name of Sam Simone. Stellar reputation, always great reviews. In a world of FB scammers, he's apparently one you can trust. Speaking for myself, I would not hesitate to use his services. YMMV.

Otto local to atlanta area but not local as in just drive on over.

Hamps Speedometer
Contact
5725 N Commerce Ct., Suite 200
Alpharetta, GA 30004
(770) 777-1919

http://www.hampspeedometer.com/

guy has been doing all types for years.

A couple of years ago I started making a GPS speedometer for the years of the AD trucks that used this same type. It works fine. I later asked if there were people around here that might be interested (to allow me to have some idea when negotiating with the folks in China who made the guts of it) but I never got a good idea. Maybe I need to resurrect the project? There is no way to have an analog odometer however people who have seen mine tell me they like the electronic odometer just as well and the trip portion is re-settable. The new version will be made so it can be dropped into the AD housing and mounted more easily.

https://www.stovebolt.com/ubbthread...ometer-for-the-ad-truck.html#Post1453840

Thanks HCB. I'm in Alpharetta at least once a week. I'll be up that way tomorrow. Maybe I'll drive the truck and pop in.

Otto, There is an existing Tech Tip: Speedometer Rebuild for GM Art Deco Truck (1941-1947 1st series Chevy/GMC), by Jeff Erickson, that might give a little insight on your speedo internals. If you want to try and really get down in the dirt and work on yours to see if it can be repaired, check out this 1952 United Motors AC Bulletin covering speedometers and tachometers. Although the scan quality is a little fuzzy, it's clear enough for me with my tri-focals to read and see how everything goes together and what needs what when repairing a speedo.

I found this resource in a long ago thread on your topic that also has some other useful tidbits you may want to read. Thanks to the fellow Bolters that previously posted this info!

HCB, the guy at the place in Alpharetta ballparked around $300 for a rebuild.

Once I get it out of the dash , I'll see if it's something I can fix myself. I'll also look at new ones for sale. I'm not interested in GPS or anything like that.

Classic Industries, LMC, NPD lists a new speedo for $160 but they show 1947-49 0-80mph and 1950-53 0-90mph.

LMC is the only one that list 0-80 as 1947-1951.

My truck is 1950 and has 80mph speedo. What gives?

For that kind of dough, it probably makes sense to buy new if I can't fix it myself.

Time is money to folks that make it their business. Just a matter of how you want to spend your money on someone else time or new parts.
Kind of how I look at all my repairs on vehicles now days. Unless that thing has to be its "all original parts" kind of truck then I would go with the repair yourself of by new option.
Don't even have to buy new. I am sure plenty of guys have used ones on this site.

Oh ya, good point.

I should put the word out. Plenty of people are hot rodding these trucks and putting electronic instruments in them. I should probably do that first and worry about fixing the old one later, if its even repairable.

1950 seems to be the oddball year. I've seen some with 0 to 90 with the high beam dot in the top center and I have seen most with 0 to 80 with the high beam dot down low. It depends on which frame you have...if the high beam indicator dot in yours is up top, then use the 0 to 90 speedometer if you want a working indicator. If your high beam indicator is at the bottom, you have to use the 0 to 80 if you want a working indicator. If you're going with an electronic speedometer, your only choice is GPS unless you have a T5 or other transmission that outputs a pulse signal and most manufacturers ceased making those 3 or 4 years ago. Only one electronic speedometer had an analog odometer...one used in an S10 and it has some oddities that make using it in the AD truck a true challenge.

A couple of years ago (possibly 3 or more) I showed how to repair a broken shaft (often happens when somebody is trying to remove the needle). Those instructions are here somewhere. I also gave a printable decal sheet for free and that is still here. If the gear train or the hair spring are the problem, your only option is to find another as yours may be finished. I've repaired several of these, but today it is impossible to find parts. I'd remove it, take a good close look and see what has happened.

Thanks Jon for that information about the 0-80 / 0-90 question. Mine is 0-80 with the high beam light at the bottom. It works.

I plan to do as you say and get it out and see what exactly is going on.

I haven't looked at the attachment method yet. Are there any secrets I need to be aware of? I assume there are a couple screws or nuts on the back side that , when removed, will allow the entire gauge assembly to be removed from behind the instrument panel?

There are 4 nuts holding the assembly in place. Also remove two general lights and the high beam light (all are typical 50s GM light sockets). Then carefully remove the glass trim piece (usually it will be crimped in three or four places). Set the trim piece, glass and rubber piece aside safely. The needle must (emphasize must) be removed carefully. I think you said yours fell off. That is pretty rare and might indicate another problem. Usually the needle hub is bonded to the shaft fast. Then there will be 2 screws holding on the face plate. Please do not lose those. They are not a common size. Two more screws hold the movement in the case and there will be a rubber piece for sound deadening. Or there should be. Once you get it removed, please let us know what you find. Occasionally lack of lubrication will cause problems but rarely does it create the sort of action you described. I have some images (including how to refresh odometer numerals). First we need to see what is happening.

Here's the situation. Hopefully the screws and everything are still inside there.

If I have to buy new, I'd rather just have to get the odometer part itself and not the whole assembly, lens, etc.

Well...in the roughly 60 years I've been messing with these I have never seen one come apart quite like that. I could take a long shot and guess what happened, but unscrambling the egg may not be possible. Go ahead and pick a cool morning. Remove it and then we can disassemble and see what our options are. Thanks for the image.

It looks like the screws holding the assembly into the casing from the back fell out, allowing the speedo assembly to fall into the lower part of the casing. But the screws holding that small center piece around the needle must have also fell out.
Have you been driving down washboard roads at high speeds Otto? You might want to check other screws for tightness as well.

The needle starting hopping all over the place and the speedo was making a loud racket. The needle then just fell off. Shortly after, (still making a horrible racket, the rest of it fell off.

I was on the highway so couldn't disconnect the speedo until I got off the road.

When I remove the 4 screws holding the speedo behind the dash, will the chrome bezel and lens remain attached or are they just held in place against the dash by the back half of the assembly?

In other words, is all that stuff going to fall out when I pull the body out from the back?

No. The chrome ring and glass are crimped to the entire assembly. Once out, turn upside down on a towel and take a flat screwdriver and carefully bend the chrome ring so it separates from the base.

Tanks s lot.