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Engineer
2003 Chevrolet S10 4.3L Vortec 4x4 LS Crew Cab
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26 Posts
Discussion Starter #1
So first a brief description of the state of things then the questions:
I have a 2003 s10 4.3 4x4. It rides on 5.13 ratio axles and 37" tires. A while back I sent my ECU in for a wait4me tune and after getting it back, it read the speedometer dead on. Recently, I had to pull transmission, tcase, etc because I burnt up my 3-4 clutches. My truck sat in the garage for about 2 months with the battery disconnected. The guy who rebuilt my transmission put many HD upgrades in it (HD sunshell, kevlar bands, HD torque converter, transgo shift kit, etc). After throwing it all back together, it drives perfect except the speedometer is screwing with shift points. The speedometer reads about 20% higher than my actual speed. I checked my VSS and cleaned it with a rag, no changes. I have a scangauge and it reads the exact same speed as my dash, so isn't the cluster. Only real changes that were made was I made a crossmember that holds the rear part of the transfer case in place, I run 5W-30 oil in my transfer case now, and I have a rebuild HD 4L60E.

Now for the questions:
Could something be throwing the VSS off? Bad sensor or the new oil maybe?
Could a new part in the transmission be throwing off my speedometer? I don't know what else factors in the speed for these trucks besides the VSS on the transfer case.
Could leaving my ECU sitting for a couple of months somehow reset my speed calibration? I don't think this is something that can happen but it's worth asking anyways because I am stumped on this and can't figure it out.

Some pics I had that may or may not help

Transfer case gear where VSS reads off:
342205


Transfer case setup:
342206


Any advise is welcome and appreciated.
 

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B4U Task Force Admin
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25,683 Posts
Moved to Transmission/Rearend.
 

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Been there Done it
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9,214 Posts
In the pics it appears you had to make some mods to the TC tail housing for that additional cross member. What all was changed?
 

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Engineer
2003 Chevrolet S10 4.3L Vortec 4x4 LS Crew Cab
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26 Posts
Discussion Starter #4
The transfer case has a slip yoke eliminator kit from JBconversions. I'm using a plate that bolts around the output shaft to support the rear of the transfer case on a poly bushing on the crossmember. The actual part where the vss screws into is still factory. I had the SYE kit before pulling everything and the speedometer was accurate then. Only change made recently was that plate that goes around the output shaft. See pic.

342212
 

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Engineer
2003 Chevrolet S10 4.3L Vortec 4x4 LS Crew Cab
Joined
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26 Posts
Discussion Starter #5
Alright, I narrowed it down more and found a temporary fix. I still had my old ecu from before I sent a junkyard one into wait4me. I used a handheld JET programmer to calibrate tire size and axle ratio years ago. After tossing this one in and firing it up, speedometer ran right on the money with what I was seeing with Waze. Now, I'm wondering why my wait4me tuned ecu lost it's memory. I'll have to send Jesse an email and figure it out.
 
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