Soft shifting: reprogram or shift kit? Tranny guys? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Tim240Z · 06-24-2005, 11:25 AM

I have a 1999 suburban 1500 l31 vortec and 4L60E in my 71. The shifts seem to be very soft and lackluster. The suburban donor vehicle had 62,xxx miles on it, and I do not know the history on the vehicle, except that, apart from the accident damage, it appeared well taken care of.

Can I resolve the sloppy shifting by reprogramming the VCM (I have TunerCat), or would the installation of a shift kit be required, or is this a symptom of greater issues requiring a freshening up of the tranny (don't particularly want to hear that option).

Also, the truck seems to surge a bit right at 40mph. Is that the TC locking and unlocking?

unixadm · 06-24-2005, 11:57 AM

I've had good luck in other 4L60E vehicles by having the shift points raised slightly and the line pressure increased. Nothing too extreme, just enough to get rid of the 'grandpa' shifting. I had the tuner up the pressures by 10% at a time until I was happy.

70 shorty · 06-24-2005, 12:34 PM

I am by no means a tranny expert, but isn't the 4l60 an electronically controlled trans? Therfore you coudn't put a shift kit in it like an old trans? I'm thinking just some reprogramming is in order to get it shifting harder.

**Palf70Step** · 06-24-2005, 12:43 PM

The factory 4l60E are very lackluster from the factory. Shifts are very soft and unprecise. You can do things to fix it, both mechanically and programming wise. I let my tranny guy tell me what is needed, then normally let him do it while I write the check. 62,000 isn't a lot of miles, mine has a 145,000 and mine acts like everyone I have every drive....Just like you described it.

unixadm · 06-24-2005, 01:09 PM

The 4L60E is electronically controlled. You either raise line pressure, or leave the line pressure stock and put in a shift kit, like from Trans-Go. Usually you don't do both.

06-24-2005, 11:25 AM	#1
Tim240Z Senior Member Join Date: Jan 2005 Location: LAX area, So Cal Posts: 499	Soft shifting: reprogram or shift kit? Tranny guys? I have a 1999 suburban 1500 l31 vortec and 4L60E in my 71. The shifts seem to be very soft and lackluster. The suburban donor vehicle had 62,xxx miles on it, and I do not know the history on the vehicle, except that, apart from the accident damage, it appeared well taken care of. Can I resolve the sloppy shifting by reprogramming the VCM (I have TunerCat), or would the installation of a shift kit be required, or is this a symptom of greater issues requiring a freshening up of the tranny (don't particularly want to hear that option). Also, the truck seems to surge a bit right at 40mph. Is that the TC locking and unlocking? __________________ 1972 Suburban C20 454/TH700R4, eaton-corporate 4.10 (looking for 3.7) Sold: 71 Cheyenne 20 Installed a 99 5.7L L31/4L60E from Suburban 1500 (2005)

06-24-2005, 12:34 PM	#3
70 shorty Where's my beer? Join Date: Oct 2004 Location: Glen Allen, VA Posts: 1,772	I am by no means a tranny expert, but isn't the 4l60 an electronically controlled trans? Therfore you coudn't put a shift kit in it like an old trans? I'm thinking just some reprogramming is in order to get it shifting harder. __________________ 70 C10, shortstep, .30 over 250,Hurst shifted 3 spd parts hauler. Holley 390, Clifford Intake, Header, ported cylinder head, unknown bigger cam. 79 Corvette L82, 4 spd, black, red interior, headers, flowmasters, and unkown bigger cam. '03 Grand Cherokee Laredo, 4.0 4x4 daily driver. 165K miles, and runs great '08 Tahoe LTZ 4x4 155K

06-24-2005, 12:43 PM	#4
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 47,083	The factory 4l60E are very lackluster from the factory. Shifts are very soft and unprecise. You can do things to fix it, both mechanically and programming wise. I let my tranny guy tell me what is needed, then normally let him do it while I write the check. 62,000 isn't a lot of miles, mine has a 145,000 and mine acts like everyone I have every drive....Just like you described it. __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

06-24-2005, 11:57 AM	#2
unixadm Registered User Join Date: Jun 2005 Location: Sacramento, CA Posts: 61	I've had good luck in other 4L60E vehicles by having the shift points raised slightly and the line pressure increased. Nothing too extreme, just enough to get rid of the 'grandpa' shifting. I had the tuner up the pressures by 10% at a time until I was happy.

06-24-2005, 01:09 PM	#5
unixadm Registered User Join Date: Jun 2005 Location: Sacramento, CA Posts: 61	The 4L60E is electronically controlled. You either raise line pressure, or leave the line pressure stock and put in a shift kit, like from Trans-Go. Usually you don't do both.



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