Re: [Chrysler300] Tach rpm
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Re: [Chrysler300] Tach rpm

Yes that is what I am talking about . Easy to fix on the dash gauges . Lots of room there and they move slowly . Almost impossible on tach. Best thing is not break it on tach in first place . Needle there pulls off like a second hand on clock, which you have to do to get under at the hairspring ( often mangled before you got it ) . If you just pull not knowing ( as normal clock) the wire breaks often right at the needle . It is some kind of spring temper thin wire , maybe steel , solder does not readily take to it and cannot solder the pointer end .. Wrapped around needle outer coating and welded or something . Or embedded in the red coating . 
I would try to fix all intact , do not disturb pointer . Hard as anything to do . 
Have an idea , on that , have not tried yet . But has to wait for next one . 

Tach glass is plastic , usually bad shape ,scratched ,  a guy on e bay sells round real glass discs cut to size for about 4$ . Good deal ,have to glue to chrome ring . 3m sealant ? 
The connection tang to the el dial is also extremely fragile , breaks off if you wiggle it at all , accidentally . Have seen that white wire cut and spliced inside tach body , ball of tape etc bad idea as that wiggles it . It will pull through the grommet ( often stuck)?or take grommet out too. Cut off red plastic end . These things very frustrating to work on . Maybe best to send to JC etc, but all this by way of sharing my trip . 3-4 of them . 
Every one had been opened and mangled before I got car . Chronic problem ? 

Sent from my iPhone

On Aug 14, 2016, at 2:38 AM, Dieter Isler 8496 dieter8496@xxxxxxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:

About the needle not lighting up... I have a friend living in Sweden with a 1960 Saratoga and managed to light the needle again, not only related to the tach, but the clock and all instruments in the Astro Dome cluster as well. According to his description there is a hair like thin wire from the print (e.g. fuel gauge) to the needle that could break or is heavily oxidated.

Good luck!


BTW: your advice about the of the length of the square cable end. I'll observe it. Thank you John

On 13.08.2016 22:49, John Grady jkg@xxxxxxxxxxxxxxxxx [Chrysler300] wrote:

Anyone know the calibration of drive cable rpm to f g h tach reading ? It appears to be 1:2 which would make sense if distributor drive into cable at distributor shaft is 1:1 ( half crank speed is at distributor) . I have one near that , another one reads about half , both have been badly attacked by the golden screwdriver . So tach reads 1000 rpm when cable is at 500 ?
By the way learned something new ; the bushing locating the spinning magnet wears axially , allowing the spinning magnet to physically move in toward tach face and hit the little aluminum cup driving the needle . This makes it jump up , go crazy . I thought it was centering in past causing that ( it can) and have chased that . It works great on bench, jumps in car!! So if cable end is at all long it can press in on shaft causes the wear and the jump . Fixed one by spacer between spinning part and housing to hold it out . Was like a cut washer . Construction of these vary , not sure if by year or whatever . I would think shortening square cable end a bit if at all too long is smart too . The tiny lighting wire to needle is always broken off it seems. Very easy to do if not in there before . You do not see it . Often broken already ( pointer does not light ) seems almost impossible to fix that . Heads up , do not pull needle off shaft . I cannot figure out how they connected that wire under the dial after putting it on . Black magic or special tool ?
If you have a good tach with lit needle , leave it alone !!
Sent from my iPhone



Posted by: John Grady <jkg@xxxxxxxxxxxxxxxxx>

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