9C1 speedo swap - Chevy Impala SS Forum
 
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post #1 of 9 (permalink) Old 02-21-2003, 10:46 AM
bigreencar
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I was wondering what I need to do to swap a 9C1 cluster into my 87' civi. See I'm going to be changing the rearend to the 8.5 w/3.08 or 3.42 whatever I can find at pick n pull. My stock speedo only reads 85 while the 9C1 reads 115mph, so will this be a simple r/r or is there alot of work invlovled. Will it have to do anything with the tranny? TIA
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post #2 of 9 (permalink) Old 02-25-2003, 11:37 AM
booth9c1ss
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I don't know about the 80's 9c1s, but I know the 92 civi and the 92 9C1 were different (same shape but different pin assignments). The same is probably true with yours. Try to locate a FSM (if they are still around for your year) to check. If you can find one, remove the back cover and follow the circuit board traces to comare both boards.
post #3 of 9 (permalink) Old 03-05-2003, 11:35 AM
95DGGMWGN
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The 87 has a purely mechanical speedo.If your original speedo is the rectangular one, it is a simple R&R.If your civi has the square speedo, you will need to swap the whole cluster. On my 86 civi I originally had the square speedo. I swapped mine for a Canadian export square model that shows the 0-140 KPH scale on the top ( larger font). I then used a reducer/adapter box on the speedo cable to calibrate correctly. Another option is to use the Canadian 9C1 rectangular speedo whi has the 200 KPH scale. It would use the same adapter as i used. This way you could have a 200 MPH speedo!! The adapter works by reducing the output speed of the speedo cable by approx .62, so that not only is your speed correct your odometer is correct also. The adapter i used was listed as a medium duty truck part. The swap is much easier than i think made it sound. I used be a dealership parts manager so I used to have a lot of time to figure these things out. BTW , I had put in a ZZ3 crate motor in my 86 and it would bury the140 MPH speedo.
 
post #4 of 9 (permalink) Old 03-05-2003, 11:56 AM
95DGGMWGN
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If you only need to calibrate your speedo, it is simply a matter of changing your speedo gears at the transmission. To get the calibration correct, you will need to know your tire size and rear end ratio. The speedo gears stay the same no matter which speedo you are using.
post #5 of 9 (permalink) Old 03-05-2003, 01:53 PM
95DGGMWGN
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To add a little more confusion, the 85-90 square bodies actually had six speedo options. I will try to sum this up as simply as I can.
US base - rectangular 0-85 MPH on top,0-140 KPH on bottom.
US w/gages - square 0-85 MPH on top, 0-140 KPH on bottom.
US 9C1 - rectangular 0-115 MPH on top, 0-200 KPH on bottom.
Export base - rectangular 0-140KPH on top, 0-85 MPH on bottom.
Export w/gages -square 0-140 KPH on top, 0-85 MPH on bottom.
Export 9C1- rectangular 0-200 KPH on top, 0-115 MPH on bottom.
"Gages" means you got a temp gage and either a "Fuel Economy" (vacuum)or volt gage, depending on year.85-90's never got a factory tach.
Some 9C1's had an auxillary gage pkg that included a temp gage, a oil pressure gage and a volt meter. It was about 2"x5" and mounted in the dash to the right of the steering column opening. The right side rear view mirror control was moved down a couple of inches to the sloped part of the dash and the mini cluster covered the opening that was left.
post #6 of 9 (permalink) Old 03-05-2003, 03:50 PM
bigreencar
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The one I have is a rectangle speedo 0-85 with the fuel gauge on the left and idiot lights on the right. 96wgn so your saying all I can do is replace the 0-115 (overlay) with my 85 style and change the speedo gears. Is it simple to change the gears or is this something a transmission shop should do. I might have it rebuilt soon.

tires- 225/ 70 15 26in.?
3.42 gear ratio
post #7 of 9 (permalink) Old 03-06-2003, 12:06 PM
95DGGMWGN
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The speedo replacement and the rear end swap are two different issues.
In your case the speedo replacement is simply a matter of swapping "head" assemblies. You have to reach up under the dash to disconnect the cable, remove the bezel and lens,pull out speedo and transfer the VSS (vehicle speed sensor) to the 115 MPH head and reassemble. There is nothing to calibrate if you haven't changed rear ends yet.
When you do change the rear end , you wil have to swap speedo gears. There were two transmissions offered in 1987,
the 200-4R (MW9) and the 700-R4 (MD8).
On the 200-4R you have to drop the trans pan and pull out the governor assy. On the 700-R4 you have to pull the driveshaft and trans extension to get to the drive gear. Let me know which trans you have and I will tell you which speedo gears you need.
post #8 of 9 (permalink) Old 03-06-2003, 07:25 PM
bigreencar
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I've got the 700R4.
post #9 of 9 (permalink) Old 03-12-2003, 11:34 AM
95DGGMWGN
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Sorry it took so long to get back to you.
The gears you need are:
Drive gear (inside trans, on output shaft)
Part# 8640517 (17 teeth red)list $5.26
Driven gear w/sleeve (cable screws to this)
Part#25522495 (44 teeth Dk gray) list $35.33
Both gears are still available new, or you could try your trans shop for used ones.
Good luck, Barry
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