1968 GMC Speedometer Cable Help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Willys_MB · 02-07-2020, 08:49 PM

My truck’s speedometer has never worked. A while back I pulled the old cable out and it had broken apart and someone had removed the pieces, so all I had was a portion of it. I ordered a new cable from Rock Auto that was 38” long and it was way too short, so I measured the housing like I should have from the beginning and ordered the next size up, 63” long. That length is too long by roughly 5”. Does anybody know what length speedometer cable I need? Is this something if I go to the old guy at NAPA he can probably help me with? I’m a little confused because LMC (I know they aren’t the best) says it should be one of those two lengths, but nobody seems to have a length in between those two.

It’s a 1968 C20 with an NP435 transmission. I’m guessing the transmission is why I’m having a hard time finding the right length of speedometer cable.

Thanks in advance for any help.

Andy4639 · 02-07-2020, 10:58 PM

I just ordered a cable from O-Reilly's but I got the longest one they showed at 112" because I installed a 700-R4 in it.

RustyPile · 02-08-2020, 12:04 AM

Quote:

Originally Posted by Willys_MB

My truck’s speedometer has never worked. A while back I pulled the old cable out and it had broken apart and someone had removed the pieces, so all I had was a portion of it. I ordered a new cable from Rock Auto that was 38” long and it was way too short, so I measured the housing like I should have from the beginning and ordered the next size up, 63” long. That length is too long by roughly 5”. Does anybody know what length speedometer cable I need? Is this something if I go to the old guy at NAPA he can probably help me with? I’m a little confused because LMC (I know they aren’t the best) says it should be one of those two lengths, but nobody seems to have a length in between those two.

It’s a 1968 C20 with an NP435 transmission. I’m guessing the transmission is why I’m having a hard time finding the right length of speedometer cable.

Thanks in advance for any help.

Five inches too long isn't enough to worry about.. Just reroute the cable in such a way as to take up the access.. No sharp bends, don't allow the cable to come in contact with the hot exhaust parts.. Did the thought ever occur to you that the reason the old cable broke was because it was 5 inches too short?????

Willys_MB · 02-08-2020, 12:27 AM

Quote:

Originally Posted by RustyPile

Five inches too long isn't enough to worry about.. Just reroute the cable in such a way as to take up the access.. No sharp bends, don't allow the cable to come in contact with the hot exhaust parts.. Did the thought ever occur to you that the reason the old cable broke was because it was 5 inches too short?????

I’m looking at trying to reuse the housing that’s in the truck. The way it’s routed doesn’t look like I can remove it and then reinstall a new one. It goes through a small hole in the frame that either end won’t fit through. I’m sure this is making it harder than it should be, but if it gets to that point I can pull the old one and install the new one and route it as you described.

**Sheepdip** · 02-08-2020, 01:10 AM

Quote:

Originally Posted by Willys_MB

I’m looking at trying to reuse the housing that’s in the truck. The way it’s routed doesn’t look like I can remove it and then reinstall a new one. It goes through a small hole in the frame that either end won’t fit through. I’m sure this is making it harder than it should be, but if it gets to that point I can pull the old one and install the new one and route it as you described.

Cut it 5' shorter ….or am I not understanding. Both ends are just raw.

Willys_MB · 02-08-2020, 01:38 AM

Quote:

Originally Posted by Sheepdip

Cut it 5' shorter ….or am I not understanding. Both ends are just raw.

One end is square to fit into the transmission and the other end has a “nock” on it. I’m not sure what purpose the nock serves, I figured it was for the speedometer.

Andy4639 · 02-08-2020, 09:00 AM

The speedometer cable shouldn't go through the frame. I just pulled 2 of them. One out of the LWB frame trans and one out of the SWB and neither one goes through the frame.

The e brake cable does go though the frame right under the drivers floor and it look's a lot like a speedometer cable. The speedometer cable does not go through the frame on any of these model trucks that I have ever seen.

Here is a thread on the speedometer routing.

http://67-72chevytrucks.com/vboard/s...d.php?t=445001

Willys_MB · 02-08-2020, 10:37 AM

Quote:

Originally Posted by Andy4639

The speedometer cable shouldn't go through the frame. I just pulled 2 of them. One out of the LWB frame trans and one out of the SWB and neither one goes through the frame.

The e brake cable does go though the frame right under the drivers floor and it look's a lot like a speedometer cable. The speedometer cable does not go through the frame on any of these model trucks that I have ever seen.

Here is a thread on the speedometer routing.

http://67-72chevytrucks.com/vboard/s...d.php?t=445001

Interesting. I’ll get out there and take a look this week. I might have gotten it confused with the e-brake housing. Thanks for the link. I’ll report back soon!

**Grumpy old man** · 02-08-2020, 11:48 AM

You can measure and cut the longer cable to use as a replacement and buy one of these cheap universal kits to swedge a bead on the speedometer side .

https://www.ebay.com/itm/Universal-S...-/142957131769

https://www.ebay.com/itm/Dorman-9-18...cAAOSwBahU4S3r

Willys_MB · 02-08-2020, 12:38 PM

Quote:

Originally Posted by Grumpy old man

You can measure and cut the longer cable to use as a replacement and buy one of these cheap universal kits to swedge a bead on the speedometer side .

https://www.ebay.com/itm/Universal-S...-/142957131769

https://www.ebay.com/itm/Dorman-9-18...cAAOSwBahU4S3r

Genius! I appreciate all the help, guys. And Grumpy, you always offer sound advice! I’ll report back soon. I had knee surgery on Thursday so once I can get around a little better I’ll go take a look.

Astro-Balls · 02-08-2020, 08:22 PM

I have the same transmission, and just bought a speedo cable a couple weeks ago, Let me go grab the package to see where I bought it,
Dont get a longer than needed cable.

Andy4639 · 02-08-2020, 08:50 PM

Mine came today and I had to take it back. It worked but was way to long by about 30". I took it back out and pulled it to where I needed it. 65" total. I went back to O-Reilly's and we found one at 63", it should work it will be here tomorrow. I'll post once I get it and see how it fit's. If it's 5" to long it should be fine you don't want it to have any sharp bends.

Andy4639 · 02-08-2020, 08:55 PM

Quote:

Originally Posted by Grumpy old man

You can measure and cut the longer cable to use as a replacement and buy one of these cheap universal kits to swedge a bead on the speedometer side .

https://www.ebay.com/itm/Universal-S...-/142957131769

https://www.ebay.com/itm/Dorman-9-18...cAAOSwBahU4S3r

That will only work if the outer cover is in good shape. If the outer cover are the ends are bad it want work. The OP never has said but he said parts where missing. ????

Willys_MB · 02-08-2020, 08:59 PM

Thanks all, I appreciate the help! Astro-Balls, that might be exactly what I need!

Andy4639 · 02-09-2020, 08:23 PM

63" cable with housing worked perfectly. I would have liked a 65" but the 63" is fine. That's a 700-R4 also.

First picture is box from O-Reilly's auto.
Last picture is e brake coming through the frame under the drivers side.

Astro-Balls · 02-10-2020, 03:07 PM

Try here..

https://www.classicindustries.com/pr...SABEgIRo_D_BwE

02-07-2020, 08:49 PM	#1
Willys_MB Registered User Join Date: Apr 2017 Location: Boise, ID Posts: 856	1968 GMC Speedometer Cable Help My truck’s speedometer has never worked. A while back I pulled the old cable out and it had broken apart and someone had removed the pieces, so all I had was a portion of it. I ordered a new cable from Rock Auto that was 38” long and it was way too short, so I measured the housing like I should have from the beginning and ordered the next size up, 63” long. That length is too long by roughly 5”. Does anybody know what length speedometer cable I need? Is this something if I go to the old guy at NAPA he can probably help me with? I’m a little confused because LMC (I know they aren’t the best) says it should be one of those two lengths, but nobody seems to have a length in between those two. It’s a 1968 C20 with an NP435 transmission. I’m guessing the transmission is why I’m having a hard time finding the right length of speedometer cable. Thanks in advance for any help. __________________ 1968 GMC C2500 Long Bed Fleetside

02-07-2020, 10:58 PM	#2
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: 1968 GMC Speedometer Cable Help I just ordered a cable from O-Reilly's but I got the longest one they showed at 112" because I installed a 700-R4 in it. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

02-08-2020, 09:00 AM	#7
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: 1968 GMC Speedometer Cable Help The speedometer cable shouldn't go through the frame. I just pulled 2 of them. One out of the LWB frame trans and one out of the SWB and neither one goes through the frame. The e brake cable does go though the frame right under the drivers floor and it look's a lot like a speedometer cable. The speedometer cable does not go through the frame on any of these model trucks that I have ever seen. Here is a thread on the speedometer routing. http://67-72chevytrucks.com/vboard/s...d.php?t=445001 __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

02-08-2020, 11:48 AM	#9
Grumpy old man Senior Member Join Date: Dec 2013 Location: Gods country East,Tn Posts: 8,545	Re: 1968 GMC Speedometer Cable Help You can measure and cut the longer cable to use as a replacement and buy one of these cheap universal kits to swedge a bead on the speedometer side . https://www.ebay.com/itm/Universal-S...-/142957131769 https://www.ebay.com/itm/Dorman-9-18...cAAOSwBahU4S3r Attached Images __________________ 1967 Factory short bed - Old school '71 - 350 / 4bolt / 487 heads / Edelbrock C3BX Muncie M-22 4 speed / Hurst Comp plus Factory 12 bolt posi 3.73 / 255-70-15 Smoothed firewall / Factory cowl induction Power disc brakes / power steering / 3.5-5" drop Last edited by Grumpy old man; 02-08-2020 at 12:05 PM.

02-08-2020, 08:22 PM	#11
Astro-Balls Registered User Join Date: Feb 2019 Location: Nor Cal Posts: 822	Re: 1968 GMC Speedometer Cable Help I have the same transmission, and just bought a speedo cable a couple weeks ago, Let me go grab the package to see where I bought it, Dont get a longer than needed cable. __________________ 1968 C20 Fleetside 396 4sp PS PB AC CST . https://www.youtube.com/watch?v=RWK8GgWD4uA

02-08-2020, 08:50 PM	#12
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: 1968 GMC Speedometer Cable Help Mine came today and I had to take it back. It worked but was way to long by about 30". I took it back out and pulled it to where I needed it. 65" total. I went back to O-Reilly's and we found one at 63", it should work it will be here tomorrow. I'll post once I get it and see how it fit's. If it's 5" to long it should be fine you don't want it to have any sharp bends. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs. Last edited by Andy4639; 02-08-2020 at 08:56 PM.

02-08-2020, 08:59 PM	#14
Willys_MB Registered User Join Date: Apr 2017 Location: Boise, ID Posts: 856	Re: 1968 GMC Speedometer Cable Help Thanks all, I appreciate the help! Astro-Balls, that might be exactly what I need! __________________ 1968 GMC C2500 Long Bed Fleetside

02-09-2020, 08:23 PM	#15
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: 1968 GMC Speedometer Cable Help 63" cable with housing worked perfectly. I would have liked a 65" but the 63" is fine. That's a 700-R4 also. First picture is box from O-Reilly's auto. Last picture is e brake coming through the frame under the drivers side. Attached Images __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

02-10-2020, 03:07 PM	#16
Astro-Balls Registered User Join Date: Feb 2019 Location: Nor Cal Posts: 822	Re: 1968 GMC Speedometer Cable Help Try here.. https://www.classicindustries.com/pr...SABEgIRo_D_BwE __________________ 1968 C20 Fleetside 396 4sp PS PB AC CST . https://www.youtube.com/watch?v=RWK8GgWD4uA



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