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Discussion Starter #1
Hi All,
A couple weeks ago I took my truck in to have an Eaton posi unit installed and since this would not work with my stock 3.08 I had 3.73 gears installed. My speedometer now read about 10 mph off...reads faster then actually going. I asked the place that installed it and they said go to Chevy and they will give you a new gear or something to put in the Transmission.

Well today I went to the chevy dealer and told him about it and he could not find a gear or anything for the transmission that would correct this...he said talk to service and maybe they can recalibrate the preexisting sensor. I did not have time to talk to service today had to go to class.

My question is though is this right? Do they have to recalibrate the sensor that is already in my truck? What do you guys do...I am sure some of you have changes rear gears in a 1990 or so s-10.

Thanks,
Scott
 

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I'd Rather be Blown than Injected
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251 Posts
Not sure about a 1990 but all newer ones are controlled by the
computer. Its programed in what rear you have. When i put in
the 3.73 in my 96 i went to the dealer to have the change put
in the computer and they said no they would not do it. said
that the truck was not offered with that rear. Soooo i bought
a Hyper Tech unit and did it myself. You also get all the other good stuff thats in it.
 

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Mud Dummy
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46 Posts
You can make your own adjustable VSSB/DRAC here's the link: ftp://ftp.diy-efi.org/incoming/DRAC2.pdf You can order a 7 pin dip switch from radio schack Cat.#: 900-8578 and install it in place of the Jumpers it should be about $1.59 for the part. I did this but was to impatient to wait for themto order the 7 pin so I used the 8 pin Cat.#: 275-1301 it was in stock and I just cut off the legs for #8 then as long as you know your tire diameter and your gear ratio you just set the switches to that combo. This is how superlift makes theirs and sells for $200. If you need more info let me know.

Kurt
 

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I'd Rather be Blown than Injected
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251 Posts
What years will this setup work on?
 

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Mud Dummy
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46 Posts
89-95 After that it is done through flash programing which needs to be done at the dealer, most dealers charge around $25 so it's not outragous. for the guys with 4x4's that seem to change gears and tire sizes like some people change underware

Kurt
 

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Discussion Starter #6
Boghog -

I was reading through and calculating what I need to do with my DRAC unit and I found something that confuses me. Using method 1 it says on one of the divisor charts that a 0 says leave pin and a 1 says remove pin. On the page following the first set of charts is a paragraph saying a 1 on the chart says a jumper should be installed in that position and a 0 means the position should remain open. This seems confusing...which is right? does a 1 indicate leave it or remove it?

Now do these jumpers get removed totally? Or do they just unhook?

Thanks,
Scott
 

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Mud Dummy
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46 Posts
If I recall correctly 1 means there is a connection and 0 means to leave it open. What I did was unsoldered all the jumpers and installed a dip switch. I cut them straight down the middle and then heated up the solder connection. I originally tried to put in new jumpers but it was a major pain.

Kurt
 

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Mud Dummy
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46 Posts
This only corrects your speedo reading.:( to remove the top speed limiter you need to go into the eprom. if you have access to an eprom burner you can get software from www.tunercat.com (they were working on something for OBD2 also), for most of you that have the 7747 ecm (88-89 4.3 autos had 8062 ecm) you only need to get the base software. if anyone out there has an eprom burner for sale I would be interested.

Kurt:D
 

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damn what ever happened to just getting under the truck and changing out the speedo gear witht he right color,,
I installed a Jet SCU 2000 the other day,, works good. Far as calibrating the speed O,, but the cruise control surges, very annoying..:rant: wasting gas,,
 
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