6066 (1960-1966) GMC Truck Club Bitcoin now accepted here! 
Pay Dues
Pay Dues or become a Site Supporter
 



Go Back   6066 (1960-1966) GMC Truck Club > 6066 GMC Truck Club Forum > Transmissions and Rear Ends


Transmissions and Rear Ends Three on the tree or four in the floor? Shift it all here.

Reply
 
Thread Tools
  #1  
Old December 21st, 2016, 05:35 PM
Sponge Sponge is offline
Member
 
Join Date: Oct 2016
Location: Musson, Musson
Truck: 1962 1500
Age: 36
Posts: 44
Rep Power: 18
Sponge is on a distinguished road
Default SM420 speedometer

Hello,

My speedometer cable was toasted so i replaced it, i also cleaned the speedometer and greased it and it works perfectly on the bench.

Now, having driven the truck, the speedometer does not move so i wanted to understand if the issue was coming from the speedometer or the cable so i removed the speedometer cable from the back of the speedometer and i drove it again and it does not move so i suspect something is wrong in the transmission.

Have you ever faced this issue?

I need to jack the rear end and to put the truck in gear to see if it moves at the transmission itself.

Thanks;


Dylan
Reply With Quote
  #2  
Old December 21st, 2016, 05:44 PM
FetchMeAPepsi's Avatar
FetchMeAPepsi FetchMeAPepsi is offline
-= Dues Paid =-
 
Join Date: Jan 2013
Location: Edmond, Ks
Truck: 1962 4x4 GMC CECILIA
Posts: 1,336
Rep Power: 364
FetchMeAPepsi is on a distinguished road
Default Re: SM420 speedometer

I believe there's a little plastic gear in the transmission that the cable goes into. That thing sometimes cracks (or disintegrates!) and keeps the tranny from turning it.
__________________
Step by steps:

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Some people are like slinkys. Not worth much but funny as heck when pushed down stairs.
__________________
If the women don't find you handsome, they should at least find you handy.
Reply With Quote
  #3  
Old December 21st, 2016, 05:46 PM
Sponge Sponge is offline
Member
 
Join Date: Oct 2016
Location: Musson, Musson
Truck: 1962 1500
Age: 36
Posts: 44
Rep Power: 18
Sponge is on a distinguished road
Default Re: SM420 speedometer

Quote:
Originally Posted by FetchMeAPepsi View Post
I believe there's a little plastic gear in the transmission that the cable goes into. That thing sometimes cracks (or disintegrates!) and keeps the tranny from turning it.
Strang enough, I was also expecting that but the cable end is just inserted in the transmission.

I did not see a drivegear....
Reply With Quote
  #4  
Old December 21st, 2016, 05:49 PM
FetchMeAPepsi's Avatar
FetchMeAPepsi FetchMeAPepsi is offline
-= Dues Paid =-
 
Join Date: Jan 2013
Location: Edmond, Ks
Truck: 1962 4x4 GMC CECILIA
Posts: 1,336
Rep Power: 364
FetchMeAPepsi is on a distinguished road
Default Re: SM420 speedometer

Dang it, I have to go check now...

Gimme about 20 minutes
__________________
Step by steps:

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Some people are like slinkys. Not worth much but funny as heck when pushed down stairs.
__________________
If the women don't find you handsome, they should at least find you handy.
Reply With Quote
  #5  
Old December 21st, 2016, 06:13 PM
FetchMeAPepsi's Avatar
FetchMeAPepsi FetchMeAPepsi is offline
-= Dues Paid =-
 
Join Date: Jan 2013
Location: Edmond, Ks
Truck: 1962 4x4 GMC CECILIA
Posts: 1,336
Rep Power: 364
FetchMeAPepsi is on a distinguished road
Default Re: SM420 speedometer

Well I stink at looking at titles, I guess. I run an SM318, not a 420. But I didn't see that before I went and tore mine apart so here's what that looks like. Surely yours is similar. Heck, this style was used up to the 80's or so in one form or another!

This is probably way more detail than you need, but if someone else needs it at least it's posted. Here's a look up inside the hole where the speedo cable goes. Notice that it's square so it can hold the cable and turn it.












You take off the hold-down bolt on the side and that releases the clip holding the cylinder in.












Once the clip is out of the way the cylinder just pulls out. You might have to twist it back and forth a little if it's rusted or painted on.












This is the cylinder all the way out. That yellowish goopy looking thing sticking out of the cylinder is the plastic piece that busts up sometimes.












That plastic piece just pulls out. It's not screwed in or anything. Here's what it looks like.













And that's it. If yours doesn't have a plastic thingy at all it has probably been tossed by someone that didn't want to put miles on their truck.No plastic, no odometer, truck never drops in value...It was common in the older days. Or it just disintegrated one day and nobody bothered to replace it.
__________________
Step by steps:

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Some people are like slinkys. Not worth much but funny as heck when pushed down stairs.
__________________
If the women don't find you handsome, they should at least find you handy.
Reply With Quote
  #6  
Old December 21st, 2016, 06:27 PM
Sponge Sponge is offline
Member
 
Join Date: Oct 2016
Location: Musson, Musson
Truck: 1962 1500
Age: 36
Posts: 44
Rep Power: 18
Sponge is on a distinguished road
Default Re: SM420 speedometer

I don't recall having seen the hold down bolt but i'll have a look, for sure.

Thanks a lot from Belgium :-)
Reply With Quote
  #7  
Old December 21st, 2016, 06:29 PM
Sponge Sponge is offline
Member
 
Join Date: Oct 2016
Location: Musson, Musson
Truck: 1962 1500
Age: 36
Posts: 44
Rep Power: 18
Sponge is on a distinguished road
Default Re: SM420 speedometer

Oh yes, seen here:

http://6066gmcclub.com/showpost.php?p=65272&postcount=5
Reply With Quote
  #8  
Old December 22nd, 2016, 01:15 PM
Sponge Sponge is offline
Member
 
Join Date: Oct 2016
Location: Musson, Musson
Truck: 1962 1500
Age: 36
Posts: 44
Rep Power: 18
Sponge is on a distinguished road
Default Re: SM420 speedometer

Looks like on the SM420, it is different and of course, I don't have the right socket....
Attached Images
File Type: jpg IMG_7713.JPG (743.8 KB, Multiple views, 8 clicks)
Reply With Quote
  #9  
Old December 22nd, 2016, 01:28 PM
Sponge Sponge is offline
Member
 
Join Date: Oct 2016
Location: Musson, Musson
Truck: 1962 1500
Age: 36
Posts: 44
Rep Power: 18
Sponge is on a distinguished road
Default Re: SM420 speedometer

After some researches, it looks like this.



Does anyone have some in stock?

I've got the 4.11 rear end.
Reply With Quote
  #10  
Old December 23rd, 2016, 12:38 AM
James James is online now
Tinkering on old trucks.
 
Join Date: Jun 2013
Location: Greer, SC
Truck: 1964 GMC 1500 2wd
Age: 62
Posts: 89
Rep Power: 49
James is on a distinguished road
Default Re: SM420 speedometer

How many teeth on your gear? I have a small selection.
Reply With Quote
Reply

Bookmarks

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Speedometer adaptor Archiver Previous Forum Posts 0 October 27th, 2007 01:08 AM
Speedometer cable Archiver Previous Forum Posts 0 February 19th, 2005 11:29 AM
Re: Speedometer cable Archiver Previous Forum Posts 0 February 19th, 2005 12:55 AM
speedometer gear Archiver Previous Forum Posts 0 February 2nd, 2003 12:33 AM
Speedometer Gear Archiver Previous Forum Posts 0 August 15th, 2001 01:29 AM


All times are GMT +1. The time now is 04:47 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2013, Jelsoft Enterprises Ltd 111|0
Feedback Buttons provided by Advanced Post Thanks / Like (Lite) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.