ajwoodtransport

Bought a 2000 Z28 automatic with 110,000 miles on it a few months ago. It's all factory even down to the cassette player. Aside from my two concerns...everything else works like it should. Runs smooth, idles smooth, handles good, rides good, etc, etc. I'm getting around 25mpg when just cruising around. My two concerns are,

Transmission feels lazy when you push the peddle down halfway. It's like it's not sure which gear to go into..but normal ends up in the higher gear. Once in a gear it's fine and upshifts and downshifts firm and doesn't appear to be slipping. I checked the fluid and it's pretty clean, doesn't smell, and it's at the proper level. Likewise no leaking or even weeping down below. Do they make the shfit points in Auto lazy like that for fuel savings or longevity sake? Before I get slammed for buying an auto, I drive semi-trucks and shift all day...so despite the lazy feeling transmission...I kinda like the auto for just cruising around with the kid and enjoying a milkshake.

My 10 year old son wanted to know how fast the car was...I said I didn't know but I thought it should be in the high 5's. We live at 1200' and when we did a couple runs the tempature was around 50-60F. First time I stalled up and the tires darn near spun thoughout all of first gear...we got 7.3 seconds 0-60. Second time I just punched from a standstill and we got 6.5 seconds with moderate tire spin...maybe something like 15-25' worth of spinning. Also it seems a little flat at higher rpms, but maybe I'm just used to sportbikes.

Overall I'm happy with the car, whether taking a brisk jaunt by myself through the twisties on a Sunday useing 2nd and 3rd gear or cruising with my son on a Saturday night for ice-cream....but not sure if it's running properly. Can tire spin affect the 0-60 times that much?

RedRocketZ28

iTrader: (19)

Sounds like a typical stock Fbody. High 5's in what though? No way in hell it's that fast in the 1/8th.

Welcome and congrats on the purchase!

RPM WS6

iTrader: (3)

Tire spin can drastically effect 0-60 times, as well as 1/4 mile times in general. When I see people posting something like, "My new LS1 is slow, only ran 14.0!", I always tell them to forget about ET until they have good tires and get solid traction. What you want to look at for a general measurement of power is your trap speed. You might find that you're running 14.30s at 104mph, which shows enough horsepower to get the car into the mid-13s, if you can get traction.

As for the trans, based on your description it's hard to tell if the issue is related directly to the trans or is actually due to something else but appears to effect trans operation. Frankly, I would start with the simple process of cleaning the MAF. I have seen this help with everything from power/driveability issues to some strange auto trans behavior in some applications.

ajwoodtransport

Thanks for the response Redrocketz28. I was talking about 0-60 times.

Nick V.

iTrader: (1)

i believe they are supposed to 0-60 in 5.3 seconds. or 5.1

i dunno.

i also never use my autos 2nd gear. When i do auto cross and drag racing i put it in Drive.

and i use overdrive for normal driving.

with the crappy tires i buy ive spun all the way up to 60 before and my car is just as stock as yours.

MERICA!!!!

ajwoodtransport

RPMWS6, I guess I've never really timed acceleration before so I'm glad to hear opinions from you guys that are experienced with the numbers ....thanks for the info. It's just a matter of time before the snow will come and they will start salting the roads so I'll look into cleaning the MAF sensor and doing a general tune up over the winter. Thanks again.

RedRocketZ28

iTrader: (19)

Ha, yeah I kinda realized that after I posted. I wouldn't worry about 0-60 times man. Take her to the track when you can and see what it does.

ajwoodtransport

Thanks NickV. Your bio at the bottom kinda answered my question...when your are talking about 1/8 mile times depends on how much tire spin you have. Thanks. I tend to use 2nd and 3rd on a couple twisty sections of roads near where I live. However, even when I bring the rpms way down before downshifting it still locks the tires up a little and upsets the balance when downshifting before entering a turn..so I guess there is no replacing a clutch...but I like the power control through the apex and exit of a turn. Most importantly, I like pretending that I'm some awesome racer. "pretend" being the key word.

NC98Z

iTrader: (1)

I believe your lazy transmission feel is caused by the stock 2.73 rear gears. Put a set of 3.73s out back along with a 3200 stall convertor and you will really wakeup the beast.

ajwoodtransport

I might try that someday...unfortunatly they tore down the track that had been around for 30+ years close to my house.

I looked up the build codes on the door and it say it has a GU5 for the axle code. When I google GU5 is says 3.23's...does that sound right, or can GU5's be 2.73 also? Although reading up on some of your guy's builds sound fun, I'll probably put mods aside since I really don't have the money to do those kind of things....but when the time comes that the rear or transmission has to be rebuilt...then I will definatly take your guy's advice on what kind of mods to rebuild it with. Thanks for the reply NC98Z.

therealcreeper

iTrader: (37)

GU5 is 3.23, but who knows if it has been replaced before. Do you use 91/93 octane fuel or regular? Back when my car was auto, the attendant (NJ) put regular in it by accident once and the thing would not downshift for anything, it made the it feel awful.

RPM WS6

iTrader: (3)

It's a moot point now that he's confirmed that he has 3.23s, but neither stock gear ratio should cause odd shifting/gear selection hunt at part throttle as described.

Sounds more trans related than gear related to me.

ajwoodtransport

Yeah, I use 91//93 octane because I think I read where the compression is 10.5 to 1 so I thought it might be better for it. Around here they pump in a lot of ethenal to raise the octane rating....at least my brother who hauls fuel tells me....and since ethenal has lower btu rating...maybe it's messing with it. I'll have to ask him later because he's told me before that some stations use something different to raise the octane without lowering the overall btu rating of the fuel (I think I remember him telling me that once).

I'll try tuning it up in the near future including the MAF sensor and see what that does. Couldn't hurt and in nothing else it will get me to know the car better by tooling around it. Thanks again.

Nick V.

iTrader: (1)

no problem dude. you just need drag slicks

jk, practice helps too. when you finally get to the track you'll be able to test different launching techniques

lemons12

iTrader: (71)

6.5 sounds dead on spinning.. I can drive pretty decent and my buddies challenger hooks better than most ls1s.. I have got his car to mid 5s.. Usually a high 5 though.
Traction plays a huge roll in how quick you get there. You may be going to same speed when you get there, but it will take you longer.
Weird how that works..

S8ER95Z

iTrader: (3)

Not really 'fact' but using the ls1tech spreadsheet that's floated around here (where you enter your 1/4 mile numbers) my stock times at the track hit 4.8 0-60. I would love to know how accurate that is if anyone knows?

ajwoodtransport

Thanks lemons.

badformulaLS1

iTrader: (1)

I haven't been able to get my car to hook on the street at all either. Spins way too easily. And if I start with it in anything lower than D it's even worse. Car likes to try to get sideways too. I wish I could find a way to hook on the street on street tires.

lemons12

iTrader: (71)

That is almost dead on.

Suspension or a stickier tire are the only two ways.

garygnu

change the trans fluid if it ain't red.you would benefit from drag radials to prevent wheel spin.also consider some suspension parts like ,lower control arm ,and new shocks.