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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Red 83 on December 24, 2011, 03:17:13 pm
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Hello, I am new to the forum. I have a 1983 C10 Scottsdale. I was told it has a '76 350 4bbl and a TH350 transmission. When I'm driving down the road, I can barely feel the transmission shifting from 2nd to 3rd. The truck also seems to have a fairly high RPM while cruising at 55-65 MPH. Is it normal for the 2nd to 3rd shift to be very smooth? Is it not shifting, and can this truck even go 65 MPH in 2nd gear? I really like this truck, and I rely on it every day to get to/from work. Thank you!
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a truck can do 65 in 2nd gear.
Sometimes, depending on the modulator, it is difficult to feel it shift. You should be able to tell when it changes though. Have tach? best way to tell.
Start off in L2 and drive it. Put it in 3rd once you get over 50 mph and see if rpms drop, or do the opposite. When you are doing 50 mph, drop it in L2 and see if there is a difference.
welcome, by the way.
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Welcome from California, unless it has a shift kit, the other way to tell if it is shifting without a tach, is drive slowly and let the truck build up before the shifts, this requires lots of road with no one behind you, and you can not get into the gas too much or else it will shift and you wont be able to feel it.
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Thanks, guys!
I'm driving the truck to work all this week, so it will give me plenty of time to try these things out.
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also can you feel any shift? if so when
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I have noticed that if I drive slowly like bake74 said, it will shift into 3rd gear. However, both shifts happen early on, around 20-25mph (2nd) to 30-35 mph (3rd). Is this in the torque converter, or something in the tranny itself?
Plus, I noticed on the sticker/build sheet on the left inside fender that my truck has a heavy duty rearend, so that might explain why the RPMs are higher at highway speeds.
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I have noticed that if I drive slowly like bake74 said, it will shift into 3rd gear. However, both shifts happen early on, around 20-25mph (2nd) to 30-35 mph (3rd). Is this in the torque converter, or something in the tranny itself?
Plus, I noticed on the sticker/build sheet on the left inside fender that my truck has a heavy duty rearend, so that might explain why the RPMs are higher at highway speeds.
My trans shifts a little sooner than that with the 4.56 gear in my C30. What is the code #?
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you can adjust your modulator with a tiny screwdriver to adjust shift points to an extent.
follow your vacuum line from the intake behind the carb...it will go down the firewall towards the trans. Follow it the passendger side of trans where the line goes into the modulator. Take a 3/8" wrench and remove your modulator. Keep the o ring in place. Look down into it where the line connected and you see a little screw head. Adjust it and trial and error until you like it. You may need to replace it, they are pretty cheap.
If you have a low gear rear, then it may well switch into high kind of early.
anyway, hope this helps.
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Yah it does, thanks!