wierd TH400 activity - The 1947 - Present Chevrolet & GMC Truck Message Board Network

magnethead · 09-14-2006, 07:31 PM

should an automatic ever shift out of first gear at 10 MPH with 4.10 axle gears?

when i kick my truck off high idle, it idles in park at 1400, I put it in gear, and it shifts to second gear before the end of the driveway without my foot on the pedal, and when manually downshifting, it won't go into first unless i'm under 10 MPH.

Also, it seems to spool up way high (like the 2500+ range) in first gear under launch if i make it hold the gear yet it barely makes it to 15 MPH. By my math, that would have to be a ton of slippage in the convertor or a 5 something first gear (TH400).

BTW, it does have a RV shift kit.

09-14-2006, 07:31 PM	#1
magnethead 7000 #'s of american IRON Join Date: Dec 2004 Location: north tx Posts: 883	wierd TH400 activity should an automatic ever shift out of first gear at 10 MPH with 4.10 axle gears? when i kick my truck off high idle, it idles in park at 1400, I put it in gear, and it shifts to second gear before the end of the driveway without my foot on the pedal, and when manually downshifting, it won't go into first unless i'm under 10 MPH. Also, it seems to spool up way high (like the 2500+ range) in first gear under launch if i make it hold the gear yet it barely makes it to 15 MPH. By my math, that would have to be a ton of slippage in the convertor or a 5 something first gear (TH400). BTW, it does have a RV shift kit. Last edited by magnethead; 09-14-2006 at 07:32 PM.



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