Help - NP205 to Speedo Canle thingy - The 1947 - Present Chevrolet & GMC Truck Message Board Network

CJ5 Convert · 09-10-2007, 12:16 AM

Hey I posted this in the truck thread cause it has a lot of traffic but I need help on this one. If someone doesn't mind looking. Ok I figured out it's called a ratio adapter. I messed this one upgood.

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http://www.67-72chevytrucks.com/vboa...d.php?t=257679

Thanks Jason

old man jimmy · 09-10-2007, 10:52 PM

Mine came with one of those when new also. But after I went to some bigger tires my spedo was really showing slow. Did away with it, and changed spedo gear. Just put your cable where it was, and check to see if your speedo is off. If not, you don't need it.

CJ5 Convert · 09-11-2007, 01:24 AM

Thanks OldmanJimmy

70gmcjimmy · 09-11-2007, 10:53 PM

Hello CJConvert.
Here is a pic of the one on the 205 in my 70 Jimmy. As you can tell it looks quite different than the one in your pic, and mine has a zerk for greasin' it up.
I'm just gonna clean it up and use it again. OldManJimmy's solution seems like it should work just fine.

Later---DAC

CJ5 Convert · 09-12-2007, 02:27 AM

Quote:

Originally Posted by 70gmcjimmy

Hello CJConvert.
Here is a pic of the one on the 205 in my 70 Jimmy. As you can tell it looks quite different than the one in your pic, and mine has a zerk for greasin' it up.
I'm just gonna clean it up and use it again. OldManJimmy's solution seems like it should work just fine.

Later---DAC

Thanks I need all the help I can get now if I could just figure out how the tire size and rear end ratios affect everything else. I'd be good.

old man jimmy · 09-12-2007, 04:25 AM

It's pretty simple. Taller tires act like taller gears. If you have the size tires on it you plan to run. Just take it on a highway with mile markers, and see what your odometer reads (1/10s that is) and what it read when you get to the next marker. If you loose 1/10th in a mile. your speedo is 10% slow. As an example. If your speedo shows 60mph + 10%, you're really going 66mph. Going back 35 yrs. But I think 1 tooth on speedo gear is about equal to 10%. Only trouble you don't have the nylon (inexpensive) gears. You have a real nice machined steel one, that is probably pretty hight bucks by now.

ericguy320 · 09-12-2007, 07:04 AM

I went from 3.08 to 3.73 with 33" and my speedo was off 15mph at 60, removed that box and now its only off .3mph at 60.

09-10-2007, 12:16 AM	#1
CJ5 Convert Registered User Join Date: May 2007 Location: Las Cruces, NM Posts: 1,079	Help - NP205 Ratio adaper. Hey I posted this in the truck thread cause it has a lot of traffic but I need help on this one. If someone doesn't mind looking. Ok I figured out it's called a ratio adapter. I messed this one upgood. http://www.67-72chevytrucks.com/vboa...d.php?t=257679 Thanks Jason __________________ - Jason *Orange Crush - 1969 K5 Blazer CST 4WD MONEY PIT* 1975 CJ5 Renegade - Levi's Edition - 304 V8 original paint Last edited by CJ5 Convert; 09-10-2007 at 12:44 AM.

09-10-2007, 10:52 PM	#2
old man jimmy Registered User Join Date: May 2007 Location: texas Posts: 329	Re: Help - NP205 to Speedo Canle thingy Mine came with one of those when new also. But after I went to some bigger tires my spedo was really showing slow. Did away with it, and changed spedo gear. Just put your cable where it was, and check to see if your speedo is off. If not, you don't need it.

09-11-2007, 01:24 AM	#3
CJ5 Convert Registered User Join Date: May 2007 Location: Las Cruces, NM Posts: 1,079	Re: Help - NP205 to Speedo Canle thingy Thanks OldmanJimmy __________________ - Jason *Orange Crush - 1969 K5 Blazer CST 4WD MONEY PIT* 1975 CJ5 Renegade - Levi's Edition - 304 V8 original paint

09-11-2007, 10:53 PM	#4
70gmcjimmy GMCDAC Join Date: Apr 2006 Location: Rapid City, SD Posts: 837	Re: Help - NP205 to Speedo Canle thingy Hello CJConvert. Here is a pic of the one on the 205 in my 70 Jimmy. As you can tell it looks quite different than the one in your pic, and mine has a zerk for greasin' it up. I'm just gonna clean it up and use it again. OldManJimmy's solution seems like it should work just fine. Later---DAC Attached Images __________________ 1970 GMC K5 Jimmy Custom 4X4 Mom's driver from 1971 to 2001!! Under rebuild! 1972 GMC C2500 Pickup owned since 1979 Needs a rest and refurbish! 1955 GMC 100 2nd design driven almost daily! Rest In Peace Mom. "Dolly" 7/15/23 - 5/18/09 GMC driver for 30 years!

09-12-2007, 04:25 AM	#6
old man jimmy Registered User Join Date: May 2007 Location: texas Posts: 329	Re: Help - NP205 to Speedo Canle thingy It's pretty simple. Taller tires act like taller gears. If you have the size tires on it you plan to run. Just take it on a highway with mile markers, and see what your odometer reads (1/10s that is) and what it read when you get to the next marker. If you loose 1/10th in a mile. your speedo is 10% slow. As an example. If your speedo shows 60mph + 10%, you're really going 66mph. Going back 35 yrs. But I think 1 tooth on speedo gear is about equal to 10%. Only trouble you don't have the nylon (inexpensive) gears. You have a real nice machined steel one, that is probably pretty hight bucks by now.

09-12-2007, 07:04 AM	#7
ericguy320 Registered User Join Date: Jan 2003 Location: Charlotte, NC Posts: 92	Re: Help - NP205 to Speedo Canle thingy I went from 3.08 to 3.73 with 33" and my speedo was off 15mph at 60, removed that box and now its only off .3mph at 60. __________________ http://community.webshots.com/user/ericguy320 1972 Chevy C10 SOLD 1972 k5 blazer cst 350, sm465, rust 1993 gmc Typhoon for sale $13,900 obo 1980 Ironhead Sportster



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