I recently installed a HPP to change gear ratio to 4.56, and the part throttle shifting now sucks. My truck has a stock 1200 rpm stall, so I decided to throw in gears instead of a converter as to not void the trans warentee. The truck feels like it is bogging constantly with the new gears, when it should feel more responsive. Part throttle the trans shifts real quick, and now the thing goes into 4th. gear by 18 mph. in reg mode, and into 4th. by 27 mph in tow-haul mode at part throttle. Has anyone else had a problem like this? Am I missing something? I spoke to Hypertech, and they said they never had this prob. before and would take care of it for me. Thanx...

 

This is just my opinion but 4.56 gears are to low unless you've got some tall *** tires to compensate for. With 4.56's you'll be reaching shift points real fast during normal driving, I'm not surprised your in OD at 18 mph. OR the HPP didn't program your ECM properly and that's why the shift points are all goofed up <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> .
Jim

 

Let me explain it differently. With the programmer installed, it corrects the speedo, but all shifts up to 3/4 throttle occur at about 1200-1300 rpm. This includes OD. When you floor it, it shifts at 5500 rpm. There is no happy medium. With tow haul mode on, it is a little better, like 1500, but without the programmer installed, it used to shift at about 2300-2500 part throttle in tow haul mode. I'll prob. just send it in to Hypertech to tweak it.....

 

this is just me and i could be completely wrong...but i remember hearing somewhere that tow/haul is useless. and when you have programming in the truck such as a hpp3 that turning the tow/haul on is dumb because it over-rides the programming. i could be completely wrong about this though. also, what made you choose the 4.56 gears? that is far to much gear for a basically stock truck with i'm guessing stock wheel and tire sizes. if you were running like a 26" tire i guess it would work ok...but like i said this is all just my opinion and i could be wrong.

 

I chose 4.56 because I run the stock tire size(29.75") The effective ratio is equal to a 4.10 and a 26.5" tall tire. Most guys seem to run the et-streets that is about 26 or 27" tall at the track. I chose 4.56 because I am not going to change any thing from street to track. I mostly drive on the street, and want the quickest ET in street trim, and want to see the full potential of the 5.3 is in stock trim with only a gear change, and minor bolt-ons. I think I can get a low 14 sec. run out of it with minor stuff, like gears, HPP, pulley ect... <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

I think 4.56's ROCK, what do you cruise at RPM wise at highway speeds? 2500rpm at 75-80? That's not too bad IMO.

 

To each his own, but I think 4.56 with a stock tire is WAY too much gear when you consider that these things quit makin' power at around 6000 rpm. I wouldn't have gone over a 4.10, at the most, especially if you drive it mostly on the street. But hey, I'm an old man, and my idea of streetable is probrobally not the same as other peoples idea of streetable. Good luck!

 

And I think it would be completely miserable with a 26" tall tire. Maybe with a 33" or 35" tire on a 4x4 it would be ok, but I think Slowverado went the wrong way on this. A 26" tire with a 4.56 rear would be like runnin' a 5.13 rear with a stock tire! Way, Way too much. I dropped down my tire size from 29.8 to 28.5 and could tell a big difference. A 26" tire and 4.56 gear will never hook on street tires. Never ever ever never.

 

I have a not-really-similar addition to this post I guess... my 99 Z28 had 4.30 gears and 26" tall tires, I loved them. A friend of mine has a stock-ish 99 Z28 with 4.56 gears and 26" tall tires and he loves those too. BUT both of those are 6 speeds.

My 96 Z28 ran 26" tall tires, an A4, and 4.10's and I loved those too, but I just love 'gear' I guess. I plan on doing 4.10's in our Yukon at some point, but the only reason I'm staying small is because we do a lot of triple-digit cruising in it.