80 MPH in a stock '30 Coupe.

bobpo

bobpo

Well-known member
Yep,

I did it yesterday. I had just finished re-timing the engine, cleaning 'er up and then decided to go for a drive. Sunny Day and all. I no more than got out on the road when I looked down at the Speedometer and it was reading 80 MPH. I actually wasn't doing more than maybe 20 mph.

What happened was that I had just pulled the dash off and replaced the little round plate that goes in back of the Speedometer/Odometer. The Speedo had been working just great but the Odometer hadn't been working at all, so I ordered the backer plate. Once installed, the Odometer works fine but now the speedo flutters back and forth and then locks in at 80 mph.

What do you all think I did wrong????:(:o:cool:
 
I thought to myself how could that be possible even w/ overdrive...I think they did it @ Bonneville!!
 
Seriously, why is it reading 80 MPH when it worked fine prior to installing the backer plate on it? The odometer works great now, but not the speedometer....:confused:
 
Sounds like the spring is broken or maybe while you had it semi apart you bumped the "cup" and got is slightly out of balance.
 
Speedometer1.jpg


Speedometer2.jpg


Speedometer3.jpg


There is an oval plate on the bottom that covers the bevel gears. Is this the plate you replaced? I don't know of any round plate on the back. If you had the speedometer cable disconnected is it possible that you didn't have the inside cable fully engaged? If so, then the cable may have had some windup from binding and when it suddenly let loose it would spin up the speedometer to show a much faster speed. Is it still stuck on the high speed?
 
speedometers run on magnetism, and must be calibrated after disassembly. This could be at least part of the problem? Calibration must be done with professional equipment.
 
Yes, it still sticks on 80 MPH at all but the lower speeds like 20-30 mph. The make of this speedometer is Nothern something or other. I'm in the house now, but as soon as I get my laptop back today (I hope), I have all that info. I got a worm in my system and had to take the laptop in for a redo.

The back of the speedo is round and there is a thin plate (a little larger than a quarter) with a small pressure spring-like finger sticking off it inside that applies pressure to the gear. If the plate isn't in place, then the gear doesn't engage, thus, No Odometer. So, as suggested by someone on this site, I ordered the plate from Bratton and it seemed to work fine till I drove it.
 
When first seeing this post, I was going to recommend he make sure his life insurance was paid. But seems to be a different problem.
 
Special Coupe Frank,

You hit it on the head, it is a Northeast. Round plate in the back. Disappeared some time of another. It was gone when I got it. At the lower speeds, it bounces back & forth.
 
No, I didn't lay it anywhere. I had pulled the dash out with the wiring still connected, and detached the speedo cable. I took the new round plate and secured it in the back of the speedo and re-installed the dash.

It was then that the odometer worked, but the speedometer didn't.

It's got me bugged, ya know?:confused:
 
azmodela,

Let me "FIX" your speedometer and you'll get 80 MPH like 'right now'.

It looks just like mine...............except for the speed reading..............:D
 
I failed to add that the speedometer was rocking back & forth which caised the O/D speedo cable to break.
 
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