Register or Log In To remove these advertisements. |
|
|
|
Thread Tools | Display Modes |
|
08-29-2010, 06:36 PM | #1 |
Registered User
Join Date: Aug 2007
Location: Laval, Québec, Canada
Posts: 175
|
Identification and function of this part!
Anybody know what is the function of this part placed between tranny and speedo cable on my 1971 C30 TH400. Both end (male and female fitting) look to be the same size, is it possible to cancel this part and hook speedo cable directly on tranny speedo fitting. Thanks
__________________
'71 Custom/10 Deluxe LWB '71 Custom/30 Deluxe Dually |
08-29-2010, 06:44 PM | #2 |
Registered User
Join Date: Oct 2005
Location: Overland Park, Ks.
Posts: 5,229
|
Re: Identification and function of this part!
That is called a ratio adapter. It is used to calibrate the speedo. There are little gears in it that can be changed to get the speedo acurate. You can remove it but it will change the speedo reading. Sometimes it makes it more acurate without it, as so many changes have usually been made since the truck was new. Match the odometer reading with the mile markers on the freeway to check the accuracy. If it turns hard you can take it apart & grease it. If the gears are stripped you may have to get it rebuilt to get the speedo accurate.
|
08-29-2010, 06:52 PM | #3 |
Registered User
Join Date: Aug 2007
Location: Laval, Québec, Canada
Posts: 175
|
Re: Identification and function of this part!
Is it possible to buy new one? Where it's possible to buy part to rebuild it or where you ship it for a rebuild? Is it C30 specific part to compensate for big tire size compare to a C10 tire size?
__________________
'71 Custom/10 Deluxe LWB '71 Custom/30 Deluxe Dually |
08-30-2010, 07:40 AM | #4 | |
Registered User
Join Date: Feb 2000
Location: Center City, MN, USA
Posts: 3,254
|
Re: Identification and function of this part!
Quote:
As near as I can tell, NP205 speedo outputs are geared to make a stock speedo work with 3.73 gears and 28" (stock) tires. I come to this conclusion because the 205 I removed (manual trans version) worked equally as well as my th350 version of the transfer case without that adapter in there. Taller tires would have the same effect as changing to a numerically lower gear ratio in the axel. So yes, it may have been installed to compensate for taller tires. Chevrolet used this transfer case well into the 80s so if you're looking for a used replacement, check under 4x4s in the bone yards. I've never seen or heard of one of these on a 2wd truck before. I'm hanging on to my adapter incase I deside to run bigger tires in the future.
__________________
'70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN |
|
08-30-2010, 01:48 PM | #5 |
Registered User
Join Date: Dec 2001
Location: Manteca, Ca USA
Posts: 305
|
Re: Identification and function of this part!
I have one of those adapters on my 71 c-20. Factory original. Mine was leaking fluid- local tranny shop was able to replace the gasket in it and now all is well again.
__________________
'71 Chevy 3/4 Ton Longbed '22 Chevy Tahoe RST '67 Firebird- 8 sec street car '24 GMC CC 4x4 Duramax Dually |
08-29-2010, 09:28 PM | #6 |
Hollister Road Co.
Join Date: Apr 2005
Location: Houston
Posts: 6,131
|
Re: Identification and function of this part!
Try these guys
http://www.ddspeedometer.com/products.html#RATIOADAPT |
Bookmarks |
Thread Tools | |
Display Modes | |
|
|