solution for mecanical speedo wirh 4L80e

[gui67]

Hi,
I am running a 4L80E in my 67 Camaro since around 10 years. I have an Autometer electronic speedometer for the moment.
But I want to go back with the original speedometer. (For stock look)
First i wanter to modify it in order to be compatible with the transmission, but I always have problems with the odometer.

So there are 2 solutions left:
A modified tail housing with a cable outlet.
And speedbox

Both are approximately the same price, around 400$ without the cable.
What are the advantages and drawbacks of borh solutions?
Speedbox would be more versatile if i once change the tire size or rear end ratio.
Is it noisy? (If i remember comments about older cable x, it was rather noisy and not so precise)

Did you have the opportunity to use one of these solutions or maybe both? What are your advices, preference, comments?

How do they compare in term of noise(certainly the engine will be noisier), of precision, reaction, reliability...

Thanks in advance for your help
Guillaume

[Zachalanche]

I have the Dakota Digital speed box: ECD-200BT. Sometimes they have black Friday deals on their stuff, and I got a really good price on it a couple years back. You use a phone app to adjust it by comparing your speedometer to GPS speed, and it works really well. I don't hear any noise.....at least over the other things that make noise. The needle sometimes jumps a little when I go from stopped to moving, or from moving to stopped. This might be due to some tight bends in the cable (despite my best efforts to avoid that). aside from that, my speedometer is dead accurate at all speeds.

Lastly, think about where you want to install it, and how the cable will be routed. Sometimes the space you have under your dash, doesn't allow for large radius bends in the cable.

I highly recommend it if you want to run your original speedometer.

[KiwiStarChief]

I have the Cable-X in my Star Chief, and although I don't think much about it now as it is working fine, I do remember it being a pain to set right. There were multiple little switches to move up and down to set, and it was so noisy that I had to remount it in the engine compartment.

I would go with the Dakota Digital unit or similar, for their ease of setting up.

[Timbers68]

If you can get something to work correctly for $400 you're doing good.

This was the only solution that I was aware of. I know someone else is producing this, you may find it cheaper, but not much: https://bowlertransmissions.com/products/4l80e-4l85e-mechanical-speedometer-conversion?_pos=1&_psq=4l80e+spee&_ss=e&_v=1.0&variant=31473404739647

[JLMounce]

I have the Dakota Digital box as well. It's easy to set with the bluetooth app and it's silent. Stuffed behind the dash, you don't know it's there.

[hp jnkey]

I bought a used DD speed box for my 71 c10. Harness plugs into ODBII , it works pretty good for the most part.
Needle does jump around once in a while and sometimes it does work when it take off, so I pull over , shut off
the engine and usually works the second time. It's a used unit so maybe that's why it glitches.
I mounted the module unit under the hood with short cable to the speedometer.
It's nice and easy to adjust with the phone app.
I recommend it.