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faulty 308 speedometer

Discussion in 'Technical Q&A' started by gary308gtb, Jan 8, 2004.

  1. gary308gtb

    gary308gtb Rookie

    Oct 9, 2003
    41
    I just bought my first Ferrari, a 1978 U.S. Version 308GTB, just last March 2003. When the car was sold to me, the speedometer was working. Then when the 308 was in my possession, the Speedometer just stopped functioning. That's when I noticed that the odometer was stuck with the same mileage that was on it even before I bought the car.

    Once, when the car was on neutral and left at idle, the speedometer needle just went up slowly by itself as if it was a tachometer. The needle rose to the 80mph mark then slowly went down to Zero. It has not functioned ever since.

    Thinking there was a ground, I had the speedo checked. They didn't find anything wrong with it so they said it might be the speedo sensor. I bought a NEW speedo sensor, to no avail.

    My speedo is still as dead as ever !

    What should I do ? Buy a new speedometer ?
     
  2. Husker

    Husker F1 Veteran

    Dec 31, 2003
    7,215
    western hemisphere
    Get a speedometer sensor before you drive it another mile. It's almost certain that's what the problem is. Takes 10-12 minutes to unscrew the old one,screw on the new one. The longer you take to do it, the more harm to your car's value - prospective buyers won't have a clue as to the "real" mileage and then you'll be discounting the car $10K. That's my 2 cents.
     
  3. jbrosseau

    jbrosseau Karting

    Nov 26, 2003
    182
    kirkland,wa
    Full Name:
    joe brosseau
    it is more than likely to be the speedometer sending unit located behind the rear passenger side tire. it is located in the tranny and can be switched out in 10 minutes. my 79' had the same issue. i was able to rebuild mine, but i would just buy a new one and call it good. DO NOT buy from the dealer. they want 3 times what you can buy it for on the internet.
     
  4. Husker

    Husker F1 Veteran

    Dec 31, 2003
    7,215
    western hemisphere
    Meant to say "speedometer sending unit", not "sensor." Sorry to confuse.
     
  5. BigTex

    BigTex Seven Time F1 World Champ
    Rossa Subscribed Owner

    Dec 6, 2002
    70,447
    Houston, Texas
    Full Name:
    Bubba
    Everyone HOPES it's the sender, but the speedo unit often fails.

    Palto Alto Speedometer in CA.
     
  6. gary308gtb

    gary308gtb Rookie

    Oct 9, 2003
    41

    Okay, thanks guys will check if my "speedometer sending unit" is still in working order, if not, I will just buy a new speedometer.
     
  7. BigTex

    BigTex Seven Time F1 World Champ
    Rossa Subscribed Owner

    Dec 6, 2002
    70,447
    Houston, Texas
    Full Name:
    Bubba
    Palo Alto REPAIRS them, keeping your odo correct. ;)
     
  8. jpl

    jpl Formula Junior

    Dec 4, 2003
    314
    Naples
    Full Name:
    JP Lavigne
    My speedo has also decided to quit. Does anyone have a picture of this unit on the car (308). My assumptions (based on the search I did on this site) is to take it off, clean the connectors put it back on and see if that fixes the problem. If it doesn't what can I expect to pay for a new unit?

    JP
     
  9. Darolls

    Darolls F1 Veteran
    BANNED

    Jul 2, 2003
    6,799
    Full Name:
    Sparky
    No picture, but you can't miss it.

    It's mounted on the right side transcase. It has electrical wires attached to it via a connector and is brass coloured.

    It's a common failure, and most likely cleaning the connectors won't do a thing.

    Expect to pay $100+ for it.
     
  10. Trinacria

    Trinacria Formula Junior

    Aug 7, 2002
    665
    Long Island, NY
    Full Name:
    Baldassare Guzzo
    #10 Trinacria, Jun 7, 2004
    Last edited by a moderator: Sep 7, 2017
    There are a few different versions. One is a little smaller than this one but similar. One is all brass and almost looks like a plug. Also check the wiring coming off and and heading back up towards the front. Thats where I found my problem. A broken wire under one of the retaining clips for the wires.
    Image Unavailable, Please Login
    Image Unavailable, Please Login
     
  11. jpl

    jpl Formula Junior

    Dec 4, 2003
    314
    Naples
    Full Name:
    JP Lavigne
    Thanks for the pictures. I will try to clean things up this week-end and see if that fixes it.
     
  12. PeterS

    PeterS Three Time F1 World Champ
    Silver Subscribed

    Jan 24, 2003
    34,959
    95370
    Full Name:
    PeterS
    Before replacing the sending unit, you may want to do a quick check on the wire from the sending unit to the speedometer just to make sure the wire is not fried. Do an end-to-end test.
     
  13. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    16,555
    USA
    Full Name:
    Hugh G. Rection

    Really? In my previous search for 308's and 328's, it was common to see at least one, and sometimes even two replacement speedo senders on the service history...but never saw any speedometer work. I personally, had to have the sender replaced on my 308 at one point, and my current 328 had it replaced a few years ago, by the previous owner. Never had to have any speedometer work.

    Now clocks go with GREAT regularity (have had both repaired by PAS). :) And in the case of the 3.2l motored cars, the 328/Mondials often have the tach break and start reading low (also fixed by PAS, they were very familiar with this defect).
     
  14. BigTex

    BigTex Seven Time F1 World Champ
    Rossa Subscribed Owner

    Dec 6, 2002
    70,447
    Houston, Texas
    Full Name:
    Bubba
    My PO of 308 #2 had the speedo repaired, $1K! I was impressed!

    Someone took the clock out of one of my cars to put a VDO ammeter in! Thanks buddy!!

    Maybe Ferrari UK has 'em.

    Good tip on broken wire! I'm gonna check that!

    I had that happen in the multi wire cable to an outboard. Drove me crazy 'till we found that. Who'd a thought one wire out of twenty!
     
  15. donaldh2o

    donaldh2o Karting

    Nov 10, 2003
    143
    Irvine CA
    Full Name:
    Don
    Just had my '76 308 speedometer repaired in November 2003. It was not the sensor but a failed circuit board inside the speedometer itself.

    Cost = $250 plus shipping.

    Where:

    MOMA
    1321 Second St. NW
    Abuquerque, NM 87102
    505 766-6661

    This is a place that dealers and some shops use. It took about two weeks.

    Hint:

    Be sure to replace all the dash light bulbs, including those in the speedometer, while you have your dash pulled apart.

    Good Luck
     
  16. BigTex

    BigTex Seven Time F1 World Champ
    Rossa Subscribed Owner

    Dec 6, 2002
    70,447
    Houston, Texas
    Full Name:
    Bubba
    Hey, thanks for that info!
     
  17. PeterS

    PeterS Three Time F1 World Champ
    Silver Subscribed

    Jan 24, 2003
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    PeterS
    $1K for a speedo repair? YIKES! If I spent that on just a speedo repair, Melodie would beat me within an inch of my life, sling a cleaver through my heart, put a bullet in my head and THEN start yelling at me!
     
  18. BigTex

    BigTex Seven Time F1 World Champ
    Rossa Subscribed Owner

    Dec 6, 2002
    70,447
    Houston, Texas
    Full Name:
    Bubba
    I told you this guy was straight up! He put new shocks on it last year and put it back in the garage. Felt great on 121, to 128, into Napa!

    Maybe his tech got to him a little on the labor, or it was "in with other things" on the ticket. It's not easy to R & R! He even told me there's about 20 miles on the car, that didn't show because of this! (the distance to the repair shop).

    His clocks not running but I know he disconnected some things that drained the battery. Get this though, the thread from the factory hang tag was still wrapped around the stem!!!!!!
     
  19. BigTex

    BigTex Seven Time F1 World Champ
    Rossa Subscribed Owner

    Dec 6, 2002
    70,447
    Houston, Texas
    Full Name:
    Bubba
    My speedos bad in car #1.

    I have to tell em: "You're right officer...I have NO IDEA how fast I'm going!"
     
  20. jpl

    jpl Formula Junior

    Dec 4, 2003
    314
    Naples
    Full Name:
    JP Lavigne
    Speedomoter now works. Thanks for pointing things out to me. It was very dirty and oily. One of the cars dropped some oil at the track when it quit and that along with all of the dust on the track got into the cable. If it continues to work, then all is well and done.

    searching through Ferrarichat for details on how to fix sending unit 4 hours
    jacking up the rear and taking off the rear wheel of your Ferrari 10 minutes
    removing rear wheel panel 10 minutes
    locating and cleaning wires to speedo sending unit 10 minutes
    Not having to pay your dealer $100/hr to fix sending unit priceless

    Thanks for the help
    JP
     
  21. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    16,555
    USA
    Full Name:
    Hugh G. Rection
    Great news. So what exactly was the problem? Dirty connection where the electrical plug is?
     
  22. jpl

    jpl Formula Junior

    Dec 4, 2003
    314
    Naples
    Full Name:
    JP Lavigne
    yes, dust and oil inside the white plasic connectors. At least I hope so as it now is clean and it now works.
     

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