I have a 5.3/4l60 swapped 1990 rcsb, when I did the swap I had 3.08 gears and just changed them out for 4.10's. When the peramiters for the speedo are changed the computer reads out the right speed but the speedo is still off. The speedo was right on with tje old gears but it won't read different on my dash but the laptop reads out the correct speed off the trucks computer? Any ideas could the speedo be on the wrong wire?????
Probably needs a D.R.A.C. calibration. I can't offer any info on it--I am not familiar with it. Do a search on this and other truck sites for D.R.A.C.
Jeff
98 GMC RCSB 2wd, 100% internally stock 305, w/twin T-3 junkyard turbos,Ramjet intake w/42lb inj,12200411 PCM. 4675lbs w/me in it. Best time in 5 passes 13.01@110
It was the drac, thanks for the tip she's all dialed in now :-)
glad you got it working, but why is your drac still in the loop? i wired my speedo ouput from pcm directly to the cluster. is this the wrong way to do it?
mine was in the gauge cluster its self, so i could not figure out a way to bypass. some other trucks had a remote located drac mine did notit was a hassle but it felt great when it worked.
1990 rcsb 5.3 4l60e swap 4.10 gears 3900lbs with a peg leg
14.3 @ 95 1/4 mile
9.1 @ 76 1/8 mile
2.11 60' on street tires open diff
gotcha, guess i caught a break and didnt even know it.
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