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Topic: Speedo/Tach Troubles

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Speedo/Tach Troubles (13/23)
5/27/11 9:11pm

Jaws79

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Sykesville, MD - USA

Vette(s):
1979 Corvette Coupe Corvette Light Blue Midnight Blue interior Mirrored Glass T-tops

Joined: 4/27/2008
Posts: 4238

Yeah, but 79s have a push button reset on the trip odometer! Mine actually resets to just below 0 ( sounds wierd, I know ). But it works!

Barry

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Speedo/Tach Troubles (14/23)
5/27/11 9:50pm

The Rook

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Pittsburgh, PA - USA

Vette(s):
1979 L-82, 3 spd auto, car was originally Lt. Beige currently painted Sportsman Red, Doeskin leather interior, 103,000 miles......

Joined: 12/4/2002
Posts: 600

[QUOTE=ebo][QUOTE=manget1] Hi Jack! I really had to pull down to get it to go...[/QUOTE]

Hmmmm is this sumthin that should be written in a little book??? LOL

ebo

[/QUOTE]

i didnt seem to make the little book......yet!! Rolling On The Floor Laughing

Marshall..youre gonna need a bigger book......

The Rook2011-05-27 18:51:57

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Speedo/Tach Troubles (15/23)
5/28/11 7:28am

manget1

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Indianapolis, IN - USA

Vette(s):
Silver 1974 Convertible - L82 4 speed Low miles (was only 8,900 when I bought it in March 2006) - Now 54K miles. Original owner bought it as an investment for son's college expenses. 2008 Jetstream Blue Convertible

Joined: 9/3/2006
Posts: 2418

Duly noted!!

The list should make it here to the site this weekend

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I wanted a Corvette my whole life, but I never dreamed of all the wonderful people I would meet because of it!

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target=_blank>Click for another pic!�� And yet another!

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Speedo/Tach Troubles (16/23)
5/30/11 8:04am

manget1

[QUOTE=manget1]Duly noted!!

The list should make it here to the site this weekend

[/QUOTE]

The list is now posted... https://www.c3vr.com/forum/topic82036_post386338.html#386338

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I wanted a Corvette my whole life, but I never dreamed of all the wonderful people I would meet because of it!

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target=_blank>Click for another pic!�� And yet another!

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Speedo/Tach Troubles (17/23)
5/31/11 10:25pm

The Rook

I did indeed realize today that my original rally wheel tires were 225's and my new aluminum rim tires are 255's. Im guessing this is why theres a difference.....so how do I remedy that oh great gods of the C3's? (without changing the tires ebo...)

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Speedo/Tach Troubles (18/23)
5/31/11 10:56pm

Adams' Apple

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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 20129

Change the driven speedo gear....or put a reducer on the cable, if it doesn't already have one. The pic of the gear Albo posted above is incorrect for a 350, but correct for a 400 or 700. Assuming you still have the original trans in yer car, it should be a 400 w/L-82. Take your gear out and count the teeth...then get one with aboot 2-3 teeth LESS to speed the speedo up. Color is really irrelevant anymore, but might be helpful in determining which gear you have. The large gears like is pictured above will also have the tooth count embossed in it. Tongue

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Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

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Speedo/Tach Troubles (19/23)
5/31/11 11:50pm

VetteCountry

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Belvidere, IL - USA

Vette(s):
1977 Black T-Top ZZ4 5Sp 16in Wheels

Joined: 10/24/2004
Posts: 437

One tooth=3mph.

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Speedo/Tach Troubles (20/23)
6/2/11 5:47pm

The Rook

[QUOTE=Adams' Apple]Change the driven speedo gear....or put a reducer on the cable, if it doesn't already have one. The pic of the gear Albo posted above is incorrect for a 350, but correct for a 400 or 700. Assuming you still have the original trans in yer car, it should be a 400 w/L-82. Take your gear out and count the teeth...then get one with aboot 2-3 teeth LESS to speed the speedo up. Color is really irrelevant anymore, but might be helpful in determining which gear you have. The large gears like is pictured above will also have the tooth count embossed in it. Tongue

[/QUOTE]

But I need to slow the speedo down its reading 10 mph faster than Im going...so I want 2 or 3 less teeth...right????

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Speedo/Tach Troubles (21/23)
6/2/11 5:48pm

The Rook

[/QUOTE]

But I need to slow the speedo down its reading 10 mph faster than Im going...so I want 2 or 3 more teeth...right????

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Speedo/Tach Troubles (22/23)
6/2/11 10:24pm

Adams' Apple

Whut?

If you have tires that are taller(255 vs. 225) than original, the speedo would be slower than actual speed. Ermm

Either way...changing the driven gear will get you so far in either direction...more toofers= slow it down, less toofers= speed it up. You can only go so far, however, before you'll need to change the driven gear inside the trans.

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Speedo/Tach Troubles (23/23)
6/3/11 6:19am

lukesvette

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HOWELL, NJ - USA

Vette(s):
1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.

Joined: 5/18/2004
Posts: 6812

[QUOTE=Adams' Apple]Whut?

If you have tires that are taller(255 vs. 225) than original, the speedo would be slower than actual speed. Ermm

[/QUOTE]

Hi Jack!!

Changing the gear on the output shaft is a PITA!! Hopefully you only need to go a couple of teeth on the driven gear. I have a bunch of them - if you let me know which one you need, I'll mail it you ya iffins I got it!!

Paul

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