Hey my name is brian and this is my first post, hopefully someone can
give me a hand. My '80 Z-28 had a ton of engine upgrades on it, and as
a result the previous owner blew the 4 speed T21 right through the bell
housing. I bought the car in this state and had it towed to a shop and
got a rebuilt 4 speed put in it, but now the speedometer does not work.
I dont know whether or not it worked before it went to the shop, but I
cant afford to spend the money right now and im dying to drive the
thing. DOES ANYONE know how I could go about trying to figure out what
the problem is and how to solve it? The tach works fine but the speedo
does not move.
Thank you for any help you can provide,
my email is firstname.lastname@example.org
Im not sure if it is attached to the transmission-where would it be
connected to? i can see from under the dash that it is connected to the
speedometer...so you're right, the problem has to be somewhere else, im
just not sure where else the cable goes and where it could be broken or
disconnected b/c its the first Z ive worked on and the first car ive
had with this problem....any advice would be a big help
p.s. i prefer sincere, im a no bs git r done kinda kid haha-and it
doesnt stop me from driving it it just stops me from getting a sticker
My '78 Camaro had cruise when it was a 6 pot. The speedo cable comes out of
the transmission and into a fist sized unit on the drivers side rear of the
engine bay, may have been on the inner wing etc. There is another cable
coming out from this to the dash.
First buy a service manual. This will help you locate where parts are.
Next does your car have cruise control?
On the left rear of the transmission Tail housing is a where the
Speedometer drive gear is. There is a gear on the tail shaft, and a gear
under a side cover. The one under the side cover is the one the drive
cable goes in to. The end of the cable fits in to the gear, and the
cable has a nut collar on it that screws on to the gear cover. If it
does not screw in, then it is held in with a horse collar clip that uses
a bolt to retain the cable.
If the cable is not attached, try turning it with a drill, and see if
the Speedometer will register. If it won't, your cable may need
replaced. If it does try installing the cable in to the drive gear.
If the cable is hooked up, remove it from the transmission and test it.
If it works, then the problem is with the drive gears. Call the
transmission shop and ask them if they will fix the issue for you.
Remember to ask them nicely.
As for your transmission, in a 1980 it should be a T-10, not a M-21. It
is possible that someone put a M-21 in the car, it is a weaker
transmission then the T-10 or a Super T-10.
If the transmission you had removed blew the guts threw the bell
housing, that's a indication of a vehicle that was in a rear end
collision. The only transmission parts in the bell housing are: The
Clutch Fork, and the Transmission input shaft. Then you have the Clutch
Disk, Pressure plate, Throw out barring, and Engine flywheel.
Both the T-10 & the M-21 have removable bell housings. If your engine
has a good number of modfactions, and is making a vast amount of power
over stock, you should use a Safety Bell Housing. Clutch Explosions are
nothing to joke about. You should also use a clutch rated for the torque
and horse power of the engine.
Some people are not good are gauging speed based off of RPM's and feel.
I drove a car with no Speedometer for 4 years. Never got a ticket. Then
again I know my gear ratio's, and did the math, knowing roughly how fast
I was going in each gear at a given RPM.
I guess I'm taking for granted that everyone lives in a metropolitan
area. Generally it would seem you could gauge your speed with
Do you want polite or do you want sincere?
I'm not far from rural area's. I do live in the city, yet my shop is in
a rural area. I still occasionally do drive vehicles with out a working
Speedometer. Learning how to gage ones speed is to me, a basic driving
skill. Like learning how to recover from a drift.
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