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  1. #1
    Venomous Moderator Hissing Cobra's Avatar
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    Default Build your own 140 mph speedometer

    Hey guys/gals, I wanted to share with you a great project to do on your '79-'86 Mustang/Capri. I learned it from my twin brother Paul Slaney (306gt on this site), who's done it on his '85 Mustang GT and on his son's '86 Mustang GT.

    If you've ever wanted to have a 140 mph speedometer in your Mustang/Capri but cannot find those elusive Ford Motorsport or Certified Calibrated SSP speedometers, you're in luck. How? You can now convert your current 85 mph speedometer into a 140 mph unit pretty easily. I just finished this project for my '79 Cobra and it's 100% accurate, as I compared it to my I-Phone's GPS based speedometer app called Speed Box.

    To do this, you must find an '89 - '93 Mustang 140 mph speedometer. I was lucky, as I had one that I took out of my '89 LX 5.0/5-speed when I stripped it last year. It's now been re-purposed into my early foureye with great success!

    Step by step instructions are listed below.

    1. Remove cluster from dash and remove original 85 mph speedometer from cluster

    2. Remove the speedometer needle by pulling up on it. Be careful or it will break (Pull it upwards from center section and not the needle pointer). Once done, drill out the four small rivets from the face of the speedometer that hold it to the frame and remove the face

    3. Now that you're down to the frame that contains the "guts", remove the two small screws from the front of frame that hold the "guts" of the speedometer. You can then remove the "guts." Once removed, you will see a round "brake drum" type thingy with a needle that's still attached to the frame (this needle goes through the frame and is held in place by a small spring on the front of the frame). Pull this out from the backside. Once done, you can carefully remove the spring on the front by gently moving it aside and by loosening the nut that holds it to the frame. BE CAREFUL with this spring because if it breaks the speedometer will not work.

    4. Disassemble the 140 mph speedometer in the same exact fashion and reinstall everything from the 140mph unit onto the '79-'86 frame (the '87-'93 frames are different). Again, be careful with that spring! If you break it, you cannot use the spring from the 85 mph speedometer, because they're different. I know that because I tried to use it and the speedometer was only accurate up to 40 mph. At 80 mph it showed me doing 140! I then relented and made the swap to the correct spring and it became 100% accurate.

    5. Now you can reinstall the 85mph speedometer face by using small screws in the previously drilled out rivet holes. Once done, install your 140 mph gauge overlay decal and reinstall the needle by pushing it into place with it pointing to zero.

    6. Reinstall your "new" 140mph speedometer back into your cluster, reinstall the entire cluster back into the dash, and reinstall your dash bezel. You're now done!

    Tom Clark (69clark on this site) made me this set of gauge decal overlays and they came out great! He decal kits are very reasonable as far as pricing is concerned and he can customize them as well. If anyone is interested, send him a private message.

    Anyway, here's some pic's.

    Stock '89 LX 5.0/5-speed 140 mph speedometer

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    Tom made me these overlays out of Carbon Fiber Paper and I asked him to make a few custom touches. First, he changed the "Redline from 4,800 - 5,800rpms to 6,000 - 7,000 rpms, as my 347 makes peak power at 6,000 rpms and I shift it at 6,500 rpms. Also, instead of the "Redline", he was able to change it to an "Orangeline" to match the colors on my Cobra door decals. He was also able to add the Cobra logo to the speedometer in the same font.

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    Now, my original tachometer was the Turbo 4-cylinder unit that showed 8,000 rpms. The problem is that it wouldn't work with the V8 and the original 6,000 rpm tachometer for the V8 cars would have been useless, as I shift at 6,500 rpms. For that reason, I installed an '83 Mustang GT 7,000 rpm tach and that will work for me. I will need to add the MSD tach adapter (MSD part # 8920) to my ignition in order to make it work with my MSD 6AL ignition box but that won't be a big deal at all. Here they are with the overlays installed. I also painted the needles Fluorescent Orange to match.

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    Pic of them installed. I had to take it back out again and position the needle on zero. DOH!

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    Pic of them at night with lights lit. I chose to remove the Blue covers on my lightbulbs to get rid of that Green hue and it worked out well. These are the stock lights at full brightness but they can be dimmed like normal with the headlight switch.

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    I hope you all like this info!
    Last edited by Hissing Cobra; 03-26-2020 at 08:17 PM.
    Pete

    1979 Mustang Cobra
    347/T-5/4.30's
    420 rwhp/380 rwt (New Motor)
    11.49 @ 121.86
    306/T-5/4.30's (Old Motor)
    307 rwhp/278 rwt
    12.38 @ 111.38


    1989 Mustang LX
    302/T-5/3.73's
    Daily Driver
    14.66 @ 95.63

  2. #2
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    Default

    Good info, thanks for posting.
    Kendal

  3. #3
    Venomous Moderator Hissing Cobra's Avatar
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    Quote Originally Posted by KCoker View Post
    Good info, thanks for posting.
    You're welcome. I've been in the Fox game since 2000 and I wasn't aware of that until now. I figured I'd pass it along.
    Last edited by Hissing Cobra; 03-24-2020 at 02:37 PM.
    Pete

    1979 Mustang Cobra
    347/T-5/4.30's
    420 rwhp/380 rwt (New Motor)
    11.49 @ 121.86
    306/T-5/4.30's (Old Motor)
    307 rwhp/278 rwt
    12.38 @ 111.38


    1989 Mustang LX
    302/T-5/3.73's
    Daily Driver
    14.66 @ 95.63

  4. #4
    FEP Power Member mcb82gt's Avatar
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    Very nice custom work! I think it looks great!!!
    Mike

    Now stang-less.

    88 Cougar 5.0

  5. #5

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    Damn, my crushed and rheumatic fingers don't have the fine motor coordination for that anymore. Great work!

  6. #6

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    Thanks for sharing! this will be useful for years to come.

  7. #7
    FEP Power Member mcb82gt's Avatar
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    Thank you Ford for being cheap and keeping the guts the same! lol
    Mike

    Now stang-less.

    88 Cougar 5.0

  8. #8
    Venomous Moderator Hissing Cobra's Avatar
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    Thanks guys. Without my brother's help, I would have never known that this could be done. I hope it helps anyone on this site. On a side note, you don't have to use the same faces that Tom made me. He can customize faces, fonts, colors, etc....
    Pete

    1979 Mustang Cobra
    347/T-5/4.30's
    420 rwhp/380 rwt (New Motor)
    11.49 @ 121.86
    306/T-5/4.30's (Old Motor)
    307 rwhp/278 rwt
    12.38 @ 111.38


    1989 Mustang LX
    302/T-5/3.73's
    Daily Driver
    14.66 @ 95.63

  9. #9
    FEP Supporter 4-barrel Mike's Avatar
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    Do you suppose he could make stock-appearing voltmeter faces for a reasonable price?

    http://vb.foureyedpride.com/showthre...ash-Volt-Meter

    Mike
    1985 ascMcLaren 5.0 SC Roadster
    My '78 Fairmont build - http://vb.foureyedpride.com/showthre...539-78-Big-Red

  10. #10

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    Looks great Pete.
    Black 1985 GT: 408w, in the 6's in the 1/8 mile
    Color TBD 1988 LX 5.0 Coupe 5-speed: Rear defrost only option
    Grabber Yellow 1973 Mustang Mach 1: 351c, toploader
    Black 2012 5.0 GT, 6-speed, Brembo brakes, 3.73's
    Wimbledon White 1966 F-100 Shortbed Styleside, 390, Tremec 3550, FiTech EFI

  11. #11
    Venomous Moderator Hissing Cobra's Avatar
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    Quote Originally Posted by 4-barrel Mike View Post
    Do you suppose he could make stock-appearing voltmeter faces for a reasonable price?

    http://vb.foureyedpride.com/showthre...ash-Volt-Meter

    Mike
    I'm not sure. You'll have to send him a private message and ask him.
    Pete

    1979 Mustang Cobra
    347/T-5/4.30's
    420 rwhp/380 rwt (New Motor)
    11.49 @ 121.86
    306/T-5/4.30's (Old Motor)
    307 rwhp/278 rwt
    12.38 @ 111.38


    1989 Mustang LX
    302/T-5/3.73's
    Daily Driver
    14.66 @ 95.63

  12. #12
    Venomous Moderator Hissing Cobra's Avatar
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    Quote Originally Posted by Zap's 85 GT View Post
    Looks great Pete.
    Thanks!
    Pete

    1979 Mustang Cobra
    347/T-5/4.30's
    420 rwhp/380 rwt (New Motor)
    11.49 @ 121.86
    306/T-5/4.30's (Old Motor)
    307 rwhp/278 rwt
    12.38 @ 111.38


    1989 Mustang LX
    302/T-5/3.73's
    Daily Driver
    14.66 @ 95.63

  13. #13

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    Very, very, very nice!

  14. #14
    FEP Power Member 306gt's Avatar
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    You can also use the 90-93 5.0L speedometers too. They are alot cheaper to source because Ford used them in all 5.0L H.O. Mustangs right from the factory in those years. Makes them more common. Alot cheaper too.
    85 G.T. All motor
    337 c.i.d 11.44-120 mph

    1984 1/2 G.T. 350 (13.01-106 mph)

    1984 G.T. (Daughters car)

    1986 G.T. (Son's car) (12.99-105 mph)

  15. #15
    FEP Super Member JTurbo's Avatar
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    Great info!!!
    1979 Indy Pace Car Mustang 302 / 5spd
    1982 Mustang GT T-Top 302 / 4spd
    1986 SVO Mustang - 1C

  16. #16

    Default

    That came out great!
    nice job!
    79 Zephyr, 4v/4r70w swap planned, with team z front and rear suspension, 8.8 and upgraded brakes and coil overs.

  17. #17

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    This is AWESOME!!! Thank you Pete! I'll be looking for a 89-93' speedometer now. Being in Canada I'm gonna need to make it a 220 KMH (Kilometers Per Hour)...

  18. #18

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    One thing on the tacho side, if you change the resistor set on the turbo tach for the set from a v8 tach, the 8K tach will work fine. My friend did it for me, back in 1990, on my old 1979.

  19. #19
    Venomous Moderator Hissing Cobra's Avatar
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    Quote Originally Posted by Boomer85gt View Post
    This is AWESOME!!! Thank you Pete! I'll be looking for a 89-93' speedometer now. Being in Canada I'm gonna need to make it a 220 KMH (Kilometers Per Hour)...
    You're welcome. Good luck!
    Pete

    1979 Mustang Cobra
    347/T-5/4.30's
    420 rwhp/380 rwt (New Motor)
    11.49 @ 121.86
    306/T-5/4.30's (Old Motor)
    307 rwhp/278 rwt
    12.38 @ 111.38


    1989 Mustang LX
    302/T-5/3.73's
    Daily Driver
    14.66 @ 95.63

  20. #20

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    Looks great! good info on the 140 MPH speedometers. I had seen it before, but its been a long time.

    The custom faces will look great in an early four eyed car.

    My only thought is if the lighting color you achieved is not what you want, you might try adding colored bulbs. For a deeper tone, buy some tail lap repair or blinker repair tape, etc, and overlay the colored bulbs.

    I did that with red bulbs and red tape in my 86GT and it looks better than it ever did from the factory.

    I have a NOS BBK 170 I'm holding back for my 86 after its redone. I often wish it looked more like the original 85 MPH gauge. Also, why stop the numbering at 3 o-clock..... looks silly IMO. My 85 Saleen is the same way and has the same head behind the face.

    Honestly neither the 140's for the 83-86 or the BBKs look at all right straight out of the box. If you look at the 140 face, its actually a lot more similar to the period Bronco II and Ranger guages. Ah well, picky picky I know....

  21. #21

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    how did you apply the new faces? i would like to do this to my ltd wagon timmy

  22. #22
    Venomous Moderator Hissing Cobra's Avatar
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    Quote Originally Posted by erratic50 View Post
    Looks great! good info on the 140 MPH speedometers. I had seen it before, but its been a long time.

    The custom faces will look great in an early four eyed car.

    My only thought is if the lighting color you achieved is not what you want, you might try adding colored bulbs. For a deeper tone, buy some tail lap repair or blinker repair tape, etc, and overlay the colored bulbs.

    I did that with red bulbs and red tape in my 86GT and it looks better than it ever did from the factory.

    I have a NOS BBK 170 I'm holding back for my 86 after its redone. I often wish it looked more like the original 85 MPH gauge. Also, why stop the numbering at 3 o-clock..... looks silly IMO. My 85 Saleen is the same way and has the same head behind the face.

    Honestly neither the 140's for the 83-86 or the BBKs look at all right straight out of the box. If you look at the 140 face, its actually a lot more similar to the period Bronco II and Ranger guages. Ah well, picky picky I know....
    Nice trick with the colored bulbs/tape. I may look into that in the future.
    Pete

    1979 Mustang Cobra
    347/T-5/4.30's
    420 rwhp/380 rwt (New Motor)
    11.49 @ 121.86
    306/T-5/4.30's (Old Motor)
    307 rwhp/278 rwt
    12.38 @ 111.38


    1989 Mustang LX
    302/T-5/3.73's
    Daily Driver
    14.66 @ 95.63

  23. #23
    Venomous Moderator Hissing Cobra's Avatar
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    Quote Originally Posted by thmpsn70 View Post
    how did you apply the new faces? i would like to do this to my ltd wagon timmy
    Peel and stick! Like any decal, you can peel it off the wax paper, apply Windex glass cleaner to the back of the decal and the face of the gauge, lay the decal on, slide it around to where you need it and squeegee the decal from the middle to the outer edges. Drying it with a soft paper towel in the process. I also used a hair dryer to help form the decals to the bank of the face as they curve outward toward the driver.
    Pete

    1979 Mustang Cobra
    347/T-5/4.30's
    420 rwhp/380 rwt (New Motor)
    11.49 @ 121.86
    306/T-5/4.30's (Old Motor)
    307 rwhp/278 rwt
    12.38 @ 111.38


    1989 Mustang LX
    302/T-5/3.73's
    Daily Driver
    14.66 @ 95.63

  24. #24
    FEP Super Member gr79's Avatar
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    Excellent art work. Interesting what now can be done. 3d replacement parts anyone?
    A mini sized (about 1/3 scale) 79 Cobra sticker looks good on the trunk or spoiler in front of the Mustang emblem.
    I stuck one of my Cobra decals onto magnetic ad backing for the door. Works good during cruises, shows.
    Removed for no advertising what it is when parked unattended.

  25. #25

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    thank you the information you share will help more than me

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