firervfd37 Posted December 1, 2006 Report Share Posted December 1, 2006 will me downshifting my truck manuely hurt it? i like to sometimes at redlights so i can hear the exhaust and leave it in first once in a while if the speed limit is like 25....will this mess the truck up? Quote Link to comment Share on other sites More sharing options...
misterp Posted December 1, 2006 Report Share Posted December 1, 2006 It won't hurt the engine, and within reason won't hurt the tranny either but I wouldn't advise a havit of it; it's a whole lot easier to change brake pads than clutches & bands. Mr. P. Quote Link to comment Share on other sites More sharing options...
perk03z06 Posted December 1, 2006 Report Share Posted December 1, 2006 will me downshifting my truck manuely hurt it? i like to sometimes at redlights so i can hear the exhaust and leave it in first once in a while if the speed limit is like 25....will this mess the truck up? <{POST_SNAPBACK}> If you leave it in 1st long enough (30 MPH), the TCM shifts it out of 1st into 2nd to protect the engine/tranny. Although you might think so, you are never in true manual control of the shifting. Quote Link to comment Share on other sites More sharing options...
Jonmalibuss Posted December 1, 2006 Report Share Posted December 1, 2006 But 2nd sounds so damn good with a nice exhaust comming down a steep hill Quote Link to comment Share on other sites More sharing options...
tonman316 Posted December 1, 2006 Report Share Posted December 1, 2006 I think that using tow/haul mode sounds pretty cool also Quote Link to comment Share on other sites More sharing options...
04silveradoclone07ss Posted December 1, 2006 Report Share Posted December 1, 2006 (edited) wow im so glad this topic came up. because i was doing the same thing yesterday but was thinking if this would hurt my engine? so im glad it doesnt hurt. i love to slow down drop the gear and hear my exhaust get so much louder. can you do the same thing with upshifting without hurting the engine? and how can the tow/haul mode make it sound diffrent???? Edited December 1, 2006 by 04silveradoclone07ss (see edit history) Quote Link to comment Share on other sites More sharing options...
perk03z06 Posted December 1, 2006 Report Share Posted December 1, 2006 wow im so glad this topic came up. because i was doing the same thing yesterday but was thinking if this would hurt my engine? so im glad it doesnt hurt. i love to slow down drop the gear and hear my exhaust get so much louder. can you do the same thing with upshifting without hurting the engine? and how can the tow/haul mode make it sound diffrent???? <{POST_SNAPBACK}> I wouldn't go as far as saying that downshifting will never do any damage to your transmission. I had a '94 Z28 Camaro with an automatic that I used to drive like a stick-shift. I flushed the tranny once a year regardless of mileage, However ... I did find myself in the tranny shop for a $1500 rebuild. Pressure plates, lots of other parts, and a whole lotta labor. And the Z28 Camaro in '94 used the Corvette powertrain ... so it was built to take some abuse ... If I were you, I would stop doing the whole downshifting thing. I know it sounds cool, but in the long run, brakes are way cheaper to replace than getting your tranny rebuilt and/or replaced. Just my $.02 Quote Link to comment Share on other sites More sharing options...
misterp Posted December 1, 2006 Report Share Posted December 1, 2006 I think that using tow/haul mode sounds pretty cool also I'm guilty of this around town - 1st gear + converter = Quote Link to comment Share on other sites More sharing options...
firervfd37 Posted December 1, 2006 Author Report Share Posted December 1, 2006 sounds like i will have to calm down a little i guess...thanks for the info though Quote Link to comment Share on other sites More sharing options...
11H Posted December 1, 2006 Report Share Posted December 1, 2006 I am not going against what anyone is saying, but Mr P put it best ... The same reason I don't down-shift with a manual (unless it's a big rig) ... Brakes are cheaper than driveline friction material as he said, bands and clutches ... Just use some common sense, if the trans upshifts at say 65 mph at wot, don't drop it down at 65 or higher and nail it ... The biggest concern I have with manually shifting (if you are a novice, and if you have to ask a question like this you are a novice) is driveline slack ... Say you drop her in 1st gear at 35 mph, and punch the throttle ... What you're doing, is first, putting the driveline against "backlash", then nailing it and taking up the slack ... all parts get whacked when the slack is taken up ... IMO, this is where you get into unnecessary abuse ... Now if say you are into the gas nice and good in 2nd, and then you drop it into 1st under load, that would be better, but not optimum ... Any time you are shifting manually, you are over-riding the powertrain's sequence of steps taken (mechanically and more-so pcm wise) to make a shift ... There are things that happen in programming during shifts that are there to theoretically lessen driveline abuse ... There are controls however that won't let you over-rev it or drop it down if going too fast rpm wise or speed wise, but those limits are on the high side ... Basically, if you do it, don't do it often, make sure the slack is taken up out of the d-line before you hammer it, and don't drop it down from too high a speed ... Use some common sense; if it feels like it's too harsh on it, it probably is to some degree ... my .02 Quote Link to comment Share on other sites More sharing options...
shakesvho Posted December 1, 2006 Report Share Posted December 1, 2006 I think that using tow/haul mode sounds pretty cool also <{POST_SNAPBACK}> A few people told me this mode is good for racing Quote Link to comment Share on other sites More sharing options...
perk03z06 Posted December 1, 2006 Report Share Posted December 1, 2006 I think that using tow/haul mode sounds pretty cool also <{POST_SNAPBACK}> A few people told me this mode is good for racing <{POST_SNAPBACK}> It is ... if you want the PCM to think that you have a calculated load increase (IE pulling a trailer), and want to keep the tranny in the lower gears longer than normal. Shifts are usually harder in tow mode, so more abuse to the powertrain occurs. Saves the tranny, but not the parts after the tranny. Quote Link to comment Share on other sites More sharing options...
11H Posted December 1, 2006 Report Share Posted December 1, 2006 I think that using tow/haul mode sounds pretty cool also <{POST_SNAPBACK}> A few people told me this mode is good for racing <{POST_SNAPBACK}> It lowers lock-up range in the verter clutch, it lowers shift point RPM at wot, raises it at part throttle, and reduces shift commanded (overlap) times ... However it DOES NOT change timing and fuel ... T/H is trans only I think I got it all Quote Link to comment Share on other sites More sharing options...
misterp Posted December 1, 2006 Report Share Posted December 1, 2006 I think that using tow/haul mode sounds pretty cool also A few people told me this mode is good for racing It lowers lock-up range in the verter clutch, it lowers shift point RPM at wot, raises it at part throttle, and reduces shift commanded (overlap) times ... However it DOES NOT change timing and fuel ... T/H is trans only I think I got it all Pretty much right on; the tow/haul button only changes shift behavior, not engine behavior so engaging the T/H mode will not magically make the motor create more power. The idea behind the T/H button is to make the truck's shift pattern center around torque peak rather than horsepower peak. In T/H mode upshift points are changed so the truck is working in the 2500-4500 RPM range, so you will be much slower in the 1/4-mile because the PCM is 'short-shifting'. The LQ9 in stock trim makes it's peak power at around 5200-5400 RPM, but max torque is 4400-4500 RPM; when towing you will get best performance and parts life if you shift where the motor is making the most grunt (4400-RPM) but when racing you want to put the most power to the ground so you want to be upshifting between 5600-5800 RPM. The nice thing about the factory T/H programming is that the line pressure is raised The bad thing about T/H mode is that it really eats the gas. Mr. P. Quote Link to comment Share on other sites More sharing options...
misterp Posted December 1, 2006 Report Share Posted December 1, 2006 (edited) A few people told me this mode is good for racing The right way to race your 4L60E tranny is to manually drop it all the way into 1st gear - that signals the computer to fully apply the clutches in 1st gear; once you are off the line bump the shifter into 3rd and leave it there until the end of your run. With factory PCM programming, if you leave at WOT in Drive the tranny clutches do not get max pressure, meaning that there is a chance for slippage of the 1st gear clutches. Mr. P. Edited December 1, 2006 by misterp (see edit history) Quote Link to comment Share on other sites More sharing options...
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