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Discussion Starter · #1 ·
Hi everyone!
Some time ago I bought caprice 92 9c1 and now I have some questions.
How I can change 9c1 cluster to km/h?
I read this -
http://www.impalaforums.com/chevy-caprice/328166-cluster-mph-to-km-2.html
and made likewise. Now I see on speedometer title "km/h", but its really miles. Gps navigator confirms it.
WTF? May be it neccesary to weld some resistance?
Thank.
 

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Discussion Starter · #3 · (Edited)
Thank!
I figured out the cause. The problem in another thing. Stock rear end 8.5 with 3.42 was replaced and now it's a civil rear end 7.5 with 2.56. I don't know about this at first time.
It look like a rear end on my civil caprice 92 305. I compared them.
And now I don't know what to do? - replace rear end to 8.5 with 3.42 (or another ratio) or simply replace differential ring and pinion? For example, install 3.42 for rear end 7.5 -
http://www.rockauto.com/catalog/moreinfo.php?pk=2988951&cc=1037326
I read about 7.5 rear end that it is "weakly" and 350 engine break it. Also i heard that it's a rumor and no more.
What you think about this?
Thank.
 

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That's odd that someone swapped in the smaller rear. Maybe that's all that was available at the time? I've swapped from the 7.5" to the larger 8.5 when I swapped in my LT1 and the 8.5 is stronger. Just be aware if you swap sizes, that you also need a different length driveshaft. The 7.5" DS is a little longer and will not fit on an 8.5 rear....I learned this on my swap.

Not sure on the pre LT1 engine cars, but a speedo change due to a ratio change on the LT1 and L99 cars is done thru a ECM tune. Just send the computer out or reprogram yourself for the new gears. Not sure if this is the same on the earlier cars burnt suspect it is and. Would be a lot easier cost effective than a rear/gear swap. Personally I would be looking for a larger rear with a little bit steeper gear. Having gone from a 2.92, then to a 3.08 and now a 3.73.....I really prefer the 3.73 for the smile factor.:).
 

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Discussion Starter · #5 ·
Thanks.
I think that's really was available only 7.5, because i'm in Russia. I think you understand the situation.
I know about driveshaft and it's reason to change only gear in 7.5". The vehicle speed sensor on caprice 91-93 with 4l60 (not 4l60E) had a speedo gear for 2.56, 3.08 and 3.42 axle ratio. May be I mistaken. But if it is true, the speedometer will be working incorrect with another axle ratio and it is impossible to fix it.
I want to change gear to 3.08 or 3.42 for this reason. But some people say me that 3.42 or 3.73 is wery hard to use everyday. Gear ratio 3.23 is compromise, but speedometer will be working incorrect.
What you think about 3.42?
 
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