The Infamous 85mph To 140mph Swap!!!

tha great one

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Hey guys long time no see. Just started a new project and before I dive to deep into in I was trying to see if there was a sticky somewhere for this issue, that maybe I overlooked. 88 GT 5 - speed SD of course. Purchased a 140mph gauge cluster off Craigslist for $40 bucks. Wondering if it's truly plug and play or if I have to go inside of it to make it work. Any help will be greatly appreciated.

P.S. Came out of a 91 GT l, I've seen where only the early model 89's are a direct for but not certain
 
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tha great one

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Thanks for the speedy response. I've also heard you can just remove the 140 portion from the cluster and install in over the 85 original gauge and there shouldn't be any problems. Any takers? Or anyone that has done the swap? I'll be honest I did bolt it up to see how it would run. And the temp gauge, voltage gauge, rpm tachometer all work. A little off albeit ( speedometer seems to display a faster speed than I'm actually going when 1st installed. And when I pull the e-brake rpm gauge drops to 0 until I release the e-brake.) oil pressure and fuel gauges are completely wrong and not working ( fuel sending unit needs to be replaced as it wasn't working on my 88 guage cluster until I was at the low fuel mark at which time my low fuel light would come on.)
 

jrichker

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Thanks for the speedy response. I've also heard you can just remove the 140 portion from the cluster and install in over the 85 original gauge and there shouldn't be any problems. Any takers? Or anyone that has done the swap? I'll be honest I did bolt it up to see how it would run. And the temp gauge, voltage gauge, rpm tachometer all work. A little off albeit ( speedometer seems to display a faster speed than I'm actually going when 1st installed. And when I pull the e-brake rpm gauge drops to 0 until I release the e-brake.) oil pressure and fuel gauges are completely wrong and not working ( fuel sending unit needs to be replaced as it wasn't working on my 88 guage cluster until I was at the low fuel mark at which time my low fuel light would come on.)
That's because you need to read the cluster interchange document that I posted the link to. There are wires that need to be moved around to make everything work correctly.
 
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Mustang5L5

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Thanks for the speedy response. I've also heard you can just remove the 140 portion from the cluster and install in over the 85 original gauge and there shouldn't be any problems. Any takers? Or anyone that has done the swap?
I did it this way.

I disassembled the 90+ cluster down to the speedo. I removed the needle, and unbolted the mechanism from the plastic frame that the gauge face is glued to. At that point, it's a direct swap into your 87-89 cluster.

hard part now is the gauge face. In my case, I purchased BBK white face gauges, but they suck. Today there are overlays that are might better that I may probably go with. You can also carefully remove and trim the 1990+ face to work by sticking it on the 87-89 clear gauge frame backing. Lighting may not be perfect however.
 

stykthyn

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I've swapped just the speedo on mine. Reads a little off. In town not a big deal. Maybe 10% on hwy.
 
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tha great one

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I found one from a 89 and tossed it in with led's


Yeah this is what I really wanted to do but I couldn't find a good deal on one. So today I guess I will be attempting to remove the 140 mph sticker from the 90-93 cluster. And placing it over my 1988 85mph gauge. And trying it mustang5L5 way. I appreciate all the responses and will post pics and update you guys later on today. Thanks for all the speedy responses!
 

tha great one

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image.jpeg
Used this free heads up display app on my iPhone ( pretty sure it's on android phones too) to check my speed. About 5 miles lower than its suppose to be. Will read 65 when I'm doing 70. And this was after taking the bezel off several times. In the process I ripped the circuit board a little and now have no dash lights. In the process of fixing that now. Will update soon!!!
 

7991LXnSHO

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@jrichker It is even easier to open .PDF files on at least Win 10 and Android devices. Microsoft Edge (Internet Explorer's replacement) already reads .PDF files. Most new office suites and printing apps also do so on android/Kindle.
With some of the sticky links not working and old tech threads gone or hiding on this new site, I am glad someone can still find them. It s till would be great to have an indexed version of all the tech for offline use.
 

Noobz347

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@jrichker It is even easier to open .PDF files on at least Win 10 and Android devices. Microsoft Edge (Internet Explorer's replacement) already reads .PDF files. Most new office suites and printing apps also do so on android/Kindle.
With some of the sticky links not working and old tech threads gone or hiding on this new site, I am glad someone can still find them. It s till would be great to have an indexed version of all the tech for offline use.
Have you seen the Technical Thread Index sticky?
 

7991LXnSHO

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I have not checked in a couple of months, but there were many broken links last time I looked. If they are fixed, Thanks!
PS I saw this was a zombie thread after I posted, but it came up at the top of recent posts when I I read it. Strange.