Driving the car today and noticed the rpm gauge was running around 900rpm when i should have been around 2100rpm. Then when i excellerated it jumped up to 5500rpm and slowly came back down. By the end of the drive the rpm was reading correct. Is this a ground problem or should i start looking else where. :crazy:

 

IF you have a '75 up car, the tach filter under the hood in the tach circuit is bad....look here in forum search for a wiring diagram to make a new one, they are not available...cheaply....

IF you have an earlier shark, the tach is mechanical, and you have major problems as the distributor gears are most likely trash, and maybe the tach too, and maybe the distributor shaft, and so on.....they get silly to fix....

GENE

 

Reilly,

Had a similar problem with my '80. After driving awhile, RPM's would show about 500 high. After checking clutch (no slip), and speedometer (checked it against GPS), ended up changing the Tach Circuit board on the back of the tach itself. These boards are about $45.00 (that's good ol' greenbacks) from any of the magazine vendors. Swapping the board out was easy and fixed the problem. While you're in there, may as well change all the speedo/tach light bulbs too.

. . . hey, also a good opportunity to upgrade to that 140 MPH speedo.
. . . and change out that faulty wiper switch
. . . and fix that headlight switch
. . . and finally replace that wiring for the left speaker

As you can see, "while-I'm-at-it-itis" took hold of me.

Good Luck

 

thanks av8vito mine is also an 80 and i will tackle the dash in a month when i finish moving into my new home and change it out . I also have allot of things to change out while the dash is apart, this may turn into a bigger project then exspected. May have to save it for a rainy day. Have to cruise as much as i can seeing that the summers are so short up here in Northern British Columbia. thanks again.

 

Riley,

Don't be too daunted by going into the dash. I read a lot of posts about how hard it was to work in the dash and center console area. It really wasn't that tough. Just remember that you're working with 23 year old plastic when you're in there, and it's VERY easy to break things. Some you can fix with glue, some you can't. I ended up having to glue a bunch of cracks in the actual speedo/tach housing. From my experience, some tips:

1) Yes, you'll have to drop the steering column to get the entire gauge housing out. Not too difficult, there's two big bolts on the bottom side of the column that hold it in place.

2) While you're in there, I wasn't kidding about the wiper and headlight switch. To replace both, if necessary, will only take an extra 30 minutes or so once the speedo/tach housing is removed. Sameo-sameo with the bulbs.

3) CAREFUL when removing the electrical connector plug on the backside of the speedo/tach housing. It's a big plug, and pretty rugged, but the wires attached to it may be brittle. Also, the speedo/tach printed circuit is fairly delicate. Don't want to tear it.

4) Up for refurbishing your steering wheel? Chuck Pelton did a great job on mine. If so, pulling the steering wheel to have it redone will eliminate the need to drop the steering column. Just a thought.

5) Redline Gauge & Clock Repair did my speedo upgrade. Excellent job for minimal dollars (around $60 if I remember right). Also, since he retains your original odometer, you get a 140 MPH speedometer but still retain your original mileage (Oops, you're up north. Disregard)

Have fun!!!

 

4) Up for refurbishing your steering wheel? Chuck Pelton did a great job on mine. If so, pulling the steering wheel to have it redone will eliminate the need to drop the steering column. Just a thought.

5) Redline Gauge & Clock Repair did my speedo upgrade. Excellent job for minimal dollars (around $60 if I remember right). Also, since he retains your original odometer, you get a 140 MPH speedometer but still retain your original mileage (Oops, you're up north. Disregard)

I'm thinking about doing both of these while I have my dash out, have a way to contact them or an address??? :cheers:
Thanks,
YBNormal...drive a vette

 

mine was bouncing pretty bad one day after i changed the cap.... come to find out , the tach clip was cracked and i changed it out... needle is dead solid now..

 

Ybnormal,

1) Speedo upgrade is from Red Line Gauge & Clock Repair (800-375-2310 pt 731-661-0239). They'll take your current speedo and upgrade the gears inside, as well as putting the 1979 face on it. Thus you still have "your" speedo, but it now looks much more sporty. Strange thing though, didn't make the car go any faster. Maybe a bigger muffler huh? Cost was $56.50 with shipping.

2) Chuck Pelton does a nice job refurbishing your current steeering wheel. Color matched nicely. His number is 248-681-4336. Cost was $185.00 including shipping. You can either send him your current steering wheel, or he'll send you one that's ready to go, and there'll be a refundable $75.00 core charge.

I was happy with the service of both these places, and would recommend their products.

Good Luck

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