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#1 |
Barrito Loco Diablo
Join Date: May 2008
Location: Cherry Valley, Illinois
Posts: 636
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Speedo Cable Question!!!
72' GMC C/2500.
Speedo didn't work when i got the truck, i looked under and saw i didn't have a speedo cable. There's a bolt and washer plugging the hole in the trans. I'm not really sure why someone would want to eliminate a working speedometer, but who knows. Could there be some sort of issue that would cause someone to block off the hole and not use a cable? I ordered a cable not knowing which size to get. There were 3 choices. I don't remember the sizes, but i went with the longest one thinking better too long than too short. Does anyone know off hand how to tell how long i need? If it matters? |
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#2 |
454 MAKES IT ROAR
Join Date: Jan 2008
Location: Essex, U.K
Posts: 2,701
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Re: Speedo Cable Question!!!
To tell how long your speedo cable should be would usually be determined by measuring your excisting...but since that's not an option i'd say ordering the longest one would be the right way to go. Maybe someone else who knows better will let you know.
__________________
Nigel. An American living in a British body. 1971 Chevy Cheyenne 10 454 "In a time of universal deceit, telling the truth becomes a revolutionary act." - George Orwell "When injustice becomes law, resistance becomes duty" - Thomas Jefferson No more pain. 03.12.60 -- 12.28.10 http://www.youtube.com/Eightbanger Last edited by eightbanger; 03-11-2009 at 07:27 PM. |
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#3 |
Barrito Loco Diablo
Join Date: May 2008
Location: Cherry Valley, Illinois
Posts: 636
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Re: Speedo Cable Question!!!
i am planning on installing the new cable tomorrow (saturday) since the weather is supposed to be 50.
Hope the speedometer works. |
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#4 |
Old member
Join Date: Jan 2002
Location: Liberty, & Garden City S.C. , U.S.
Posts: 19,936
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Re: Speedo Cable Question!!!
The length want matter except you will have to keep it out of the drive shaft and anything hot.
If there is a bolt into the side of the transmission I would bet there is going to be more to it than a cable. The plastic gear is right inside the cap and if that screw or bolt was tightened up to stay put the gear will be of no use.
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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. |
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#5 |
Barrito Loco Diablo
Join Date: May 2008
Location: Cherry Valley, Illinois
Posts: 636
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Re: Speedo Cable Question!!!
So i might need to take off the tail shaft to inspect the gear. The hole isn't big enough to see the gear with a flashlight, is it?
I guess pulling the driveshaft would be a good time to inspect and replace the u-joints as needed. So, it's win win. As long as the bolts co-operate during removal. |
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#6 |
Barrito Loco Diablo
Join Date: May 2008
Location: Cherry Valley, Illinois
Posts: 636
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Re: Speedo Cable Question!!!
well, i tried to install the cable today, no dice.
The bolt was actually just a rubber plug with an adjusting bolt head. After pulling it out, there's nothing to thread the cable into. There's no gear inside either. I know where to get the gear, but what about the threading? |
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#7 |
Registered User
Join Date: Jul 2007
Location: Salina, Kansas
Posts: 1,998
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Re: Speedo Cable Question!!!
tap and die set would be my guess.. im thinking that it leaked tranny fluid and they just plugged it and when they tried plugging it is when they messed up the threads...
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1972 C-10...402/400..flowmaster 40 series 1967 Mustang 347 stroker/C-4 1966 Mustang 289/3-speed 2013 Mustang V6/6speed w/300 ponies I may be 23, but i sure do knows 67-72s are sexy! Its not MPG its smiles per gallon! build started 11/25/08 build thread: http://67-72chevytrucks.com/vboard/s....php?p=2993796 |
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#8 |
Registered User
Join Date: Feb 2009
Location: Crumpler, North Carolina
Posts: 93
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Re: Speedo Cable Question!!!
Sounds like you will need the part that the gear goes in and it is held in by a hold down that looks like a smaller verson of a distributor hold down with a 1/4 bolt then your cable screws to it
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#9 |
Barrito Loco Diablo
Join Date: May 2008
Location: Cherry Valley, Illinois
Posts: 636
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Re: Speedo Cable Question!!!
LMC should carry what i need, right? kinda doubting the parts stores.
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#10 |
Registered User
Join Date: Feb 2009
Location: Crumpler, North Carolina
Posts: 93
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Re: Speedo Cable Question!!!
I looked in LMC and could not find it not sure where you can find it but I will research my books and get back to you
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#11 |
Registered User
Join Date: Sep 2001
Location: Hacienda Heights, California USA
Posts: 474
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Re: Speedo Cable Question!!!
What kind of trans are you using?
These are photos of a tail section from a 700r4. Top is outside and the speedo connection with the hold down tab and screw. Second is inside the tail section, it shows what you need inside. Hope this helps.
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'72 GMC custom camper 350/350 Last edited by spinning wheels; 03-14-2009 at 05:51 PM. |
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#12 |
Barrito Loco Diablo
Join Date: May 2008
Location: Cherry Valley, Illinois
Posts: 636
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Re: Speedo Cable Question!!!
I have a Turbo Hydra-matic trans.
I am wanting to have the trans rebuilt, maybe i should have the shop add what i'm missing while they're in there. |
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#13 |
Registered User
Join Date: Sep 2001
Location: Hacienda Heights, California USA
Posts: 474
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Re: Speedo Cable Question!!!
The tranny shop, would need to know what, the rear axle gear ratios the truck has installed.
That way, they can install the correct gear in the tranny's tail section. Isn't it funny how you start fixing one small thing, and it turns out to be a major overhaul? ![]()
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'72 GMC custom camper 350/350 |
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#14 |
Barrito Loco Diablo
Join Date: May 2008
Location: Cherry Valley, Illinois
Posts: 636
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Re: Speedo Cable Question!!!
Yeah, go figure. I don't know what gears i have in the truck. Any way i can tell without pulling the cover? If not, the chrome cover could use a cleaning anyways.
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#15 |
Registered User
Join Date: Sep 2001
Location: Hacienda Heights, California USA
Posts: 474
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Re: Speedo Cable Question!!!
The way I was taught to tell what gears you have is somewhat simple.
Jack up the rear of the truck/car, so that the rear tires can spin easily. Rotate the tires one full rotation, and count how many times the driveshaft and rear yoke turn. Example: four turns and a little more, you can figure it has 4:10 gears. If it spins less than four turns, calculate if it went past 3 1/2 turns or more. You might have 3:55 or 3:73 or something close to that. By turning the tire, you can also tell if you have a limited slip or an open rear axle. The open rear axle, (the most common), one wheel will spin in the opposite direction. Oh yeah, you will need to have your park brake off and the tranny in neutral ![]() I hope this makes sense. Be sure to use good jackstands. Nothing worse than having a truck smack your melon as you are counting the diff's yoke ![]()
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'72 GMC custom camper 350/350 |
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#16 |
Barrito Loco Diablo
Join Date: May 2008
Location: Cherry Valley, Illinois
Posts: 636
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Re: Speedo Cable Question!!!
I'll have to wait to put it on stands, all my stands are under the Corvair while i fix the floors. I'm working on that today and next weekend to hopefully finish up.
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#17 |
Registered User
Join Date: Feb 2009
Location: Crumpler, North Carolina
Posts: 93
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Re: Speedo Cable Question!!!
got any pics of the Corvair
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#18 |
Senior Member
![]() Join Date: Jul 2004
Location: Estherville, Iowa
Posts: 3,371
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Re: Speedo Cable Question!!!
If you don't have posi, it will be hard to get both wheels to turn together, likely the other side will turn backwards when you side is turned forward. Just leave one tire on the ground and turn the free wheel 2 times and count the drive shaft. If you want to get real precise, turn the wheel 20 times, if the driveshaft turns 41 times even you have a 4.10, 45 1/2 turns would be 4.56 etc. Actually this would be a good time to pull the rear cover and put in new lube, then you can find the tooth count stamped on the ring gear, should see something like 10 41 which would be a 4.10 rear.
__________________
1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0 Last edited by Green Machine; 03-15-2009 at 01:48 PM. |
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#19 |
Barrito Loco Diablo
Join Date: May 2008
Location: Cherry Valley, Illinois
Posts: 636
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Re: Speedo Cable Question!!!
I posted a few pics of the vair here a few months back. I'll have to dig some up.
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