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| | | | Joined: Jan 2015 Posts: 22 'Bolter | | 'Bolter Joined: Jan 2015 Posts: 22 | So I've got fully rebuilt original in my 49 Suburban and have just fitted to the cable from the 700r4 box (with mechanical adaptor)
The problem I have is the speed will climb but not reduce, any idea's?
49 Suburban Project
| | | | | Joined: Oct 2021 Posts: 6,734 'Bolter | | 'Bolter Joined: Oct 2021 Posts: 6,734 | A fully rebuilt what? Transmission? Speedometer gauge?
Cable is probably hanging up in the sleeve. Pull out the cable and lubricate it with lithium grease.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
| | | | | Joined: Sep 2009 Posts: 5,809 Gearhead, Stovebolt Tech and Parts Tracker, Mod for Swap Meet and GTT | | Gearhead, Stovebolt Tech and Parts Tracker, Mod for Swap Meet and GTT Joined: Sep 2009 Posts: 5,809 | Mike,
I would emphasize Otto's 2nd question above.
Did you rebuild/replace the speedometer itself? An original unrestored speedometer is going to have decades old lube that is more like a gummy/sticky consistency which could cause the results your are describing.
More thoughts and ideas once you can let us know some answers to these questions.
Dan
~ Dan 1951 Chevy 3 window 3100Follow this story in the DITY Gallery"My Grandpa Carl's Truck and How it Became Mine"1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
| | | | | Joined: Jan 2015 Posts: 22 'Bolter | | 'Bolter Joined: Jan 2015 Posts: 22 | Sorry yes it’s an Original speedo that’s been rebuilt with a new cable
The cable getting stuck would make sense, it’s lubed but it’s running through a tight angle off the box so will see if it can be rerouted
49 Suburban Project
| | | | | Joined: Aug 2018 Posts: 1,004 'Bolter | | 'Bolter Joined: Aug 2018 Posts: 1,004 | The cable cannot hold the needle from returning to 0
The cable only drives the magnet
When the cable stops the needle drops to 0 with the clock spring
The spring might have some oil/dust on it or the needle is rubbing the glass or the tiny bearings that the needle cup rides on are too stiff
But the speedometer will have to come apart either way because it should be impossible to hold the needle from the outside of the unit, there is a problem inside the speedometer.
-s | | | | | Joined: Feb 2016 Posts: 1,982 'Bolter | | 'Bolter Joined: Feb 2016 Posts: 1,982 | As 2ManyTrucks stated, it's not the fault of the cable, the speedo head needs cleaning and new lube.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
| | | | | Joined: May 2001 Posts: 1,904 'Bolter | | 'Bolter Joined: May 2001 Posts: 1,904 | Mine does something like that if I have the cable connection on the speedo is too tight. Try loosening it a bit.
1948 3/4-Ton 5-Window Flatbed Chevrolet 34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.
| | | | | Joined: Aug 2018 Posts: 1,004 'Bolter | | 'Bolter Joined: Aug 2018 Posts: 1,004 | Sounds like maybe the tight cable is causing stress that makes the needle touch the glass
The clearance is unfortunate over sensitive for that particular failure mode
Gm should have allowed an extra 1/32 or even 1/16 spacing for the needle because it seems to touch as soon as anything isn’t perfect like the needle aging and bending on its own even
Sometimes the speedo works on the bench and then installing it in dash also warps the whole assembly just enough to bind the needle as well
-s | | | | | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | The core in the cable may be a little to long making it bind.
George
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | | | | Joined: Aug 2018 Posts: 1,004 'Bolter | | 'Bolter Joined: Aug 2018 Posts: 1,004 | Binding the cable won’t make the needle stick tho
There is a gap between the magnet and the needle cup
Maybe the magnet pushes so far out it contacts the needle cup?
I haven’t investigated that possibility
I should write this down for my next speedo rebuild to take more measurements and see what tolerances are involved
I could see how it might happen now
Interesting
-s | | | | | Joined: Dec 2018 Posts: 2,450 'Bolter | | 'Bolter Joined: Dec 2018 Posts: 2,450 | Mike Attewell Is your speedometer hand warped and rubbing on the glass face ?? Mine is in a 51 6400 Everything is working and I just hate to disturb all the original wiring and stuff for that one problem. 2 speed axle controls too. | | |
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