Irratic Speedometer reading - The 1947 - Present Chevrolet & GMC Truck Message Board Network

coach34 · 02-10-2007, 03:41 PM

Hello,
I have a 69 c10. It has a 350 & 400 tranny. Since I purchased it in January, it has never shown a speed. I put a spedo cable on, the other was broken. It now shows speed but is extremely high about 25 -30 mph off, ( also seems irratic not smooth)and it doesn't show any milage. What is the problem? Again, thanks for any help and for having this site.
Steven

low'n slow · 02-10-2007, 05:47 PM

Your erratic speed could be the result of a sticky/dirty cable housing. Did you replace the whole thing or just the inside? Your too high reading could be the result of a couple of issues.
1. Different transmission that was set up for a different rear end gear ratio (I have a similar issue in my GMC).
2. Tires are much smaller than stock.

**CMars45000** · 02-10-2007, 06:27 PM

If the speedo needle seems "bouncy", the first thing to check is the cable routing. If a bend it soo sharp, it can cause the cable to bind in the housing and casue what you have descirbed. Also try some good teflon lube in the cable ends. I used to have a bouncy speedo in my K5 and the only thing that fixed it was a lokar speedo cable...Even a NEW cable form Napa bounced...

good luck

lilpup69chevy · 02-10-2007, 08:32 PM

i'm gonna have to agree and say the speedo gear in the transmission needs to be changed to correct the mph issue

ThatOneBlue67 · 02-10-2007, 09:58 PM

But you said it doesn't count the mileage? It just stays put at whatever number? That sounds like the actual speedometer is broken inside. Like the little gear at the end of the roll is missing.

67ChevyRedneck · 02-10-2007, 10:09 PM

I agree that it sounds like the speedo itself is broken. That may fix your mph problem too, but I doubt it, you probably need to swap the speedo gear in the tranny's tail like the others mentioned.

coach34 · 02-10-2007, 11:16 PM

Thanks for your help I'm going to dig a little deeper on tranny gears.

low'n slow · 02-11-2007, 11:00 AM

Another option would be a reducer that goes between the transmission and the cable. Stewart Warner sells them and you may have a local speedo shop that can make one up for you. Just a little box full of gears. May be easier for you than opening up the transmission.

**Stocker** · 02-11-2007, 11:46 AM

Quote:

Originally Posted by CMars45000

If the speedo needle seems "bouncy", the first thing to check is the cable routing. If a bend it soo sharp, it can cause the cable to bind in the housing and casue what you have descirbed. Also try some good teflon lube in the cable ends.

Also, pull the inner cable out of the cable housing, clean it thoroughly, and lube the entire length of it and re-insert. I use a lightweight white lithium grease, but anything similar should work fine.

cgoodwin · 02-11-2007, 09:26 PM

I checked with Stewart Warner and they told me they are not manufacturing the reducers any longer. I'd have to find a used one. This was within the last 4 weeks I asked them. I'm in the same boat. Doing 100mph plus everywhere I go.

low'n slow · 02-12-2007, 12:23 AM

Check your local wrecking yard. I just picked 2 of them up for $15 each.

02-10-2007, 03:41 PM	#1
coach34 Registered User Join Date: Jan 2007 Location: Georgia Posts: 7	Irratic Speedometer reading Hello, I have a 69 c10. It has a 350 & 400 tranny. Since I purchased it in January, it has never shown a speed. I put a spedo cable on, the other was broken. It now shows speed but is extremely high about 25 -30 mph off, ( also seems irratic not smooth)and it doesn't show any milage. What is the problem? Again, thanks for any help and for having this site. Steven Last edited by coach34; 02-10-2007 at 03:55 PM. Reason: gramatical error

02-10-2007, 05:47 PM	#2
low'n slow Too Dumb To Know Better Join Date: Nov 2005 Location: Texas Posts: 882	Re: Irratic Speedometer reading Your erratic speed could be the result of a sticky/dirty cable housing. Did you replace the whole thing or just the inside? Your too high reading could be the result of a couple of issues. 1. Different transmission that was set up for a different rear end gear ratio (I have a similar issue in my GMC). 2. Tires are much smaller than stock.

02-10-2007, 06:27 PM	#3
CMars45000 Registered User Join Date: Jul 2006 Location: Pittsburgh, PA Posts: 204	Re: Irratic Speedometer reading If the speedo needle seems "bouncy", the first thing to check is the cable routing. If a bend it soo sharp, it can cause the cable to bind in the housing and casue what you have descirbed. Also try some good teflon lube in the cable ends. I used to have a bouncy speedo in my K5 and the only thing that fixed it was a lokar speedo cable...Even a NEW cable form Napa bounced... good luck __________________ Project Family Values Build Thread Vehicles/Projects: -1971 C10 SWB Fleetside! Gathering parts now, will begin frame-off resto soon... Pleasure in the job puts perfection in the work. -Aristotle

02-10-2007, 08:32 PM	#4
lilpup69chevy 67-72 parts finder Join Date: Aug 2006 Location: southeast mo Posts: 788	Re: Irratic Speedometer reading i'm gonna have to agree and say the speedo gear in the transmission needs to be changed to correct the mph issue __________________ 1969 chevy shortstep 2wd (under construction) 1981 chevy scottsdale lwb 2wd (parts chaser) 2004 pontiac gto (daily driver) 2004 pontiac grand prix gt (the ol ladys car) 1985 chevy short wide 1970 chevy c10 lwb (another parts rig) 1969 gmc lwb (rainy day project) 1968 chevy lwb c10 250 I6 3 spd (soon to be swb)

02-10-2007, 09:58 PM	#5
ThatOneBlue67 I survived Dead Man's Curve. Join Date: Apr 2006 Location: The Nine-Five-687 Posts: 389	Re: Irratic Speedometer reading But you said it doesn't count the mileage? It just stays put at whatever number? That sounds like the actual speedometer is broken inside. Like the little gear at the end of the roll is missing. __________________ "The people should not be afraid of their government. The government should be afraid of it's people." "The Hurricane" 1967 Chevrolet C10 350 Eight Cylinder, 700R4 BowtieOverdrive *Cherry Bomb...* Disturbing the Peace Since 1968.

02-10-2007, 10:09 PM	#6
67ChevyRedneck Hittin E-Z Street on Mud Tires Join Date: Nov 2004 Location: Greenville, SC Posts: 23,090	Re: Irratic Speedometer reading I agree that it sounds like the speedo itself is broken. That may fix your mph problem too, but I doubt it, you probably need to swap the speedo gear in the tranny's tail like the others mentioned. __________________ Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride American Born, Country by the Grace of God 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications!

02-10-2007, 11:16 PM	#7
coach34 Registered User Join Date: Jan 2007 Location: Georgia Posts: 7	Re: Irratic Speedometer reading Thanks for your help I'm going to dig a little deeper on tranny gears.

02-11-2007, 11:00 AM	#8
low'n slow Too Dumb To Know Better Join Date: Nov 2005 Location: Texas Posts: 882	Re: Irratic Speedometer reading Another option would be a reducer that goes between the transmission and the cable. Stewart Warner sells them and you may have a local speedo shop that can make one up for you. Just a little box full of gears. May be easier for you than opening up the transmission.

02-11-2007, 09:26 PM	#10
cgoodwin Registered User Join Date: Dec 2006 Location: winter haven, fl Posts: 56	Re: Irratic Speedometer reading I checked with Stewart Warner and they told me they are not manufacturing the reducers any longer. I'd have to find a used one. This was within the last 4 weeks I asked them. I'm in the same boat. Doing 100mph plus everywhere I go.

02-12-2007, 12:23 AM	#11
low'n slow Too Dumb To Know Better Join Date: Nov 2005 Location: Texas Posts: 882	Re: Irratic Speedometer reading Check your local wrecking yard. I just picked 2 of them up for $15 each.



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