Speedo buzzing and tach going limp

SeriousFunk104 · 02-01-2004, 10:16 AM

Hello,

I am hoping to gather a little insight to my immediate woes from this great BBS. On my last outing a month ago in my 73T, Speedo (stock VDO 150 MPH) started to buzz horrendously to the point the needle fell of its shaft!

What I am wondering is the original failure likely to be cable, the gage or both? Other than the needle needing to be put back on, what should I be looking for in worn parts? This was on the drive to my destination......

On the way home, using my Tach (again a stock VDO) to keep an eye on speed I noticed it getting really limp, it had always been a little "washy" since I have bought the car in April, but now it was not even getting up to the correct RPM. By the time I got home the poor tired needle would not leave its resting pin. What type of electrical problem am I looking at here? I think the car was really protesting against being out in the cold weather, grumpy Californian car ;-)

Any bits of wisdom would be greatly appreciated.

Thanks,

Jason

SeriousFunk104 · 02-02-2004, 05:48 PM

Bump...

Norm Faustino · Norm Faustino's Garage

Needle falling off its shaft?
tach going limp?

Man! Get to a doctor, fast!

Jim Sims · 02-02-2004, 08:46 PM

(1)Check your ignition points dwell (gap) first; then look for a loose wire to fix the tach.
(2) Speedo appears to be a badly worn drive cable (real pain to replace - runs through tunnel to front of transmission) but given the vibration level you relate you may also now have some worn bushings in the speedometer head. I do believe you could have just pulled the speedometer head backwards out of the dash (it's retained by a rubber grommet) and undone the drive cable connection nut when the vibration became excessive. Also never reset the trip odometer while the car is moving; such action can strip the plastic drive gear inside or break it's hub's bond the the shaft it is mounted on. Cheers, Jim

SeriousFunk104 · 02-03-2004, 07:17 AM

Hmm never thought about the points, I will check that out. I will ohm out the wire that runs to the Tach, when I pull the speedo out, to make sure the wire is good. At least the connection looks sound on the distributor and on connectors on the left of the engine bay. What type of electrical signal is pulsing thought that wire? I am guessing its not high voltage, maybe a connection to positive voltage?

I am just hoping the Speedo can be repaired, that the vibration did not take it out.

Thanks for the tips Jim!