dkb1@hou2h.UUCP (D.BURGESS) (03/04/85)
Z28:: Is there anyone who really knows about the 84 Z28? I have an 84 Z28 with the L69 5.0 HO motor, 4 speed automatic tranny, 323:1 limited slip rear, four wheel disc's, and standard p215 65R15 tires. I am a relatively good 'HOME MECHANIC'. I have built up a few cars for the 1/4 mile(i.e. 69 GTO 76 CAMARO) and have had mostly accelerating results. Those older cars were a breeze to modify because of their basic mechanical structure. My Z28 is a whole different story. With the GM design criterion these days, the mechanicals are designed so tightly that a simple modification such as a better flowing exhaust system, which would guarantee an increase in horsepower and tourque in the older motors, may now cause decreases in the newer motors. If a freer flowing exhaust system would help my L69 motor breath better, FINE , I'll start by removing the catalytic converter. BUT, what do I do with the oxygen sensor that is connected to it which the onboard computer uses? In fact, I have some other questions pertaining to modifications: TWIN TURBO CHARGERS -=> [ How much power increase?; Any overheating problems?; Are they made for my car?; How much? , Would I need a new hood?, What type of exhaust modific- cations?; Would I need a different computer module?; Who makes it??????????] TIRES -=> [ Can I mount something like p255 60R15's on the existing aluminum spoked wheels?; Would I need an offsetted wheel?; Should I bother with a wider tire?( the car already handles like a bear now)????????] TRANSMISSION -=> [ I like this 4 speed automatic but it seems to have a few problems. I like the way it is geared, but i dont think it is shifting correctly. It shifts hard when I don't want it to and not hard enough when I want it to. It's like this: If I punch it from a stand still, it smokes the the tires and winds right up to a mild 5500RPM. Then it hangs for a second and then BANG my back tires start spinning again. It is the same with the second to third shift except I only get a slight chirp from the tires. Now if I keep it floored, it will wind up to 5500 where I would expect another upshift, BUT NOOOOOOOO!! , it just keeps climbing(in RPM). Now I still have that useless 85 MPH speedo, but I would estimate that at this point in third gear I'm somewhere around 105 MPH. If I want to reach the acclaimmed 138 MPH, then I need my 4th gear. [WHERE IS IT?] If I let off the gas, say to about 2/3, it will shift into 4th and start climbing[in speed]. That takes my to somewhere around 125 MPH. Now if I give it anymore throttle, the dang thing DOWNSHIFTS into third and the tach pops up to over 6500 RPM [[ OUCH!!]]. Now back to the shifting problem of the first three gears, what can be done to make it change [when it shifts]? I don't want a harder shift. [DOES ANYONE ELSE HAVE THESE PROBLEMS?] I've got more questions and observations, but I'll wait to see if I get any responses before I speak again. If you can answer any of these problems or you have any of your own, please send me mail as well as putting it on the net, for I don't get much opportunity to READNEWS. Dave Burgess AT&T Consumer Products ihnp4!hou2h!dkb1