What does this do? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bigblock73 · 07-22-2004, 09:36 PM

This was attached to the end of my old speedo cable. It mounts between the trans and cable itself. What does it do? It was formally attached to the th350 trans that was in my '73.

I purchased a new cable in order to install my Autometer speedometer, do I need to use this or simply screw my new cable to the transmission?

Thanks for the help.

Russell · 07-22-2004, 09:45 PM

I think that has something to do with adjusting the speedo cable ratio...

My SM465 has one just like it attached to it...

**swervin ervin** · 07-22-2004, 10:44 PM

I'm not exactly sure what that is. But to answer your question, no, you don't use this part with a 700R4 and the Autometer speedo.

plumbcut · 07-22-2004, 10:56 PM

it changes the speed of the speedo input cable so your speedometer reads accurate... turn the input of it exact one turn and the output will be slightly different

pc

Lynx · 07-22-2004, 11:05 PM

Hrmm thats interesting, i have the exact same thing on my speedo and it reads wrong.

Maybe it needs adjusting?

bigblock73 · 07-22-2004, 11:07 PM

Quote:

Originally Posted by swervin ervin

I'm not exactly sure what that is. But to answer your question, no, you don't use this part with a 700R4 and the Autometer speedo.

OK, thanks all. I will run the speedo cable from the gauge directly to the transmission.

Thanks again everyone.

ElGracho · 07-22-2004, 11:14 PM

To expand a little...

I don't know why GM didn't just put the right gears in the tranny for the speedo, but three of my six trucks (at least, I don't know that I've looked at them all...) had these factory. They are just two gears in a case to change the speed of the speedo cable compared to the gear in the adapter installed in the transmission.

GM offers enough drive and driven gears to be installed on the transmission output shaft and in the cable adapter to eliminate these external gear boxes, which is what I have been systematically doing on my trucks...

- I do understand that Jeff is going to an electronic speedo and this is all unnecessary for him...

Joe

07-22-2004, 09:36 PM	#1
bigblock73 yeller Join Date: Oct 2001 Location: Twin Cities Posts: 13,824	What does this do? This was attached to the end of my old speedo cable. It mounts between the trans and cable itself. What does it do? It was formally attached to the th350 trans that was in my '73. I purchased a new cable in order to install my Autometer speedometer, do I need to use this or simply screw my new cable to the transmission? Thanks for the help. Attached Images __________________ Jeff 73-87.com 73-87.com Facebook page 73-87 cab corner 6x9 speaker brackets for sale 67-72 cab corner speaker brackets for sale 47-54 cab corner speaker brackets for sale

07-22-2004, 09:45 PM	#2
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	I think that has something to do with adjusting the speedo cable ratio... My SM465 has one just like it attached to it... __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

07-22-2004, 10:44 PM	#3
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	I'm not exactly sure what that is. But to answer your question, no, you don't use this part with a 700R4 and the Autometer speedo. __________________ Mike 1985 Chevy C-10

07-22-2004, 11:05 PM	#5
Lynx Registered User Join Date: Jun 2003 Location: Fort McMurray, Alberta, Canada Posts: 513	Hrmm thats interesting, i have the exact same thing on my speedo and it reads wrong. Maybe it needs adjusting? __________________ Ben 1983 Silverado SWB 305 2002 Silverado Extended Cab 5.3 http://members.shaw.ca/bkennett

07-22-2004, 10:56 PM	#4
plumbcut california fill Join Date: Apr 2004 Location: Sunny So-Cal Posts: 694	it changes the speed of the speedo input cable so your speedometer reads accurate... turn the input of it exact one turn and the output will be slightly different pc

07-22-2004, 11:14 PM	#7
ElGracho Gentleman Jim Driver Join Date: Nov 2002 Location: Poulsbo, WA Posts: 1,553	To expand a little... I don't know why GM didn't just put the right gears in the tranny for the speedo, but three of my six trucks (at least, I don't know that I've looked at them all...) had these factory. They are just two gears in a case to change the speed of the speedo cable compared to the gear in the adapter installed in the transmission. GM offers enough drive and driven gears to be installed on the transmission output shaft and in the cable adapter to eliminate these external gear boxes, which is what I have been systematically doing on my trucks... - I do understand that Jeff is going to an electronic speedo and this is all unnecessary for him... Joe



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