steve65

I'm new here and in the market for an LS1 fbody. This will be a daily driver to the tune of ~100 miles/day highway and tollroad. Important consideration for me is mpg and ability to last into high mileage. If I can find a 1 or 2 adult owner car that is stock or almost stock, I have high confidence in the engine, but I'm not sure on the manual or auto. My instinct is to go with the 6 speed for mpg and maybe worse thing I have to do is a clutch. On stock cars that are driven mildly how long does the stock clutch hold up? I've seen threads on clutch master/slave cylinder issues...is that common? Any common problems with the 6 speed tranny? My budget is probably going to put me in a 60-80K miles car and I'd hope the clutch would last awhile. In my '94 T/A the A4 seemed solid vs. the 700r4's I've experienced in 3rd gens. I'd be gving up some mpg's, but in the end would the A4 maybe hold up better in a stock hp car?

Anybody know what the code is, and where to look, for a 2.73 gear car? I think I'd want to look for one if I go auto.

Thanks!

*98TransAm*

if your going for a daily driver and you want good gas mileage go with the six speed, great on the highway and a blast when cruising.Look for the RPO codes on the door or in the glove box for the gear ratio. GU2 = 2.73, GU5 = 3.23 and GU6 = 3.42, all ls1 six speed cars came with 3.42.

eseibel67

iTrader: (10)

Hiway mileage for A4 is good due to locking conveter, especially with 2.73 ratio (RPO GU2).

T56 is great trans, but car with 60k - 80k will need a clutch if it hasn't already.

TireSm0ke

iTrader: (1)

The code for 2.73s is GU2, 3.23 is GU5, and 3.42 (M6) is GU6. All A4 trans am's came with 3.23s, And all M6 F-bodys came with a 3.42. You can find an A4 formula or z28 with a 2.73, not sure what the SS came standard with.

The 700r4 is identical to the 4L60, not to be confused with the 4L60E, which is electronically controlled.

If your looking for good highway MPG the M6 is the way to go. I have a built A4 with a 3.23 and stock stall converter and its not terrible, but with the traffic we have here in Los Angeles a 6 speed would be hell.

The T56 (6 speed) is a very stout transmission. A clutch change is inevitable of course, but compared to the 4L60 which almost always needs a rebuild close to 100k miles, the T56 is pretty strong unless its been really beat on or not maintained. FWIW the Dodge Viper uses a T56 also, although its a little different from ours with some slight modifications.

My advice is drive both, see what your comfortable with, and check to make sure the car has been maintained. If its an A4 check for slippage throughout the gears, especially at higher rpms. The only downside to the A4 is you will most likely need it rebuilt at some point, as opposed to just a clutch change in the T56.

the_merv

iTrader: (88)

I'd go with a T56..I'm switching to a T56 for dependability cause I keep shredding 4L60E's..

ZMONSTER!

iTrader: (9)

turbo 400!
Id say an A3/4 because they are typically faster with a stall than a similarly modded M6.

1996firebirdformula

iTrader: (3)

Get Manual with low miles more fun. Clutch should be good in them. 2.73 Auto wont get better gas milage then a Manual they rev higher at highway speeds. as long as don't beat on it clutch will stay good. But what is fun in that. Just buy performance clutch.

2.73 Auto 1800 rpm @ 72 mph.
3.42 Manual 1600 rpm @ 71 mph. Or 1800 @ 80 mph

http://www.f-body.org/gears/

93LEETZ

He said he is looking for good gas mileage.. I doubt he will get that with an A3 or 4. He also stated he is getting a STOCK car.

To the OP, I'd go with an M6 based on reliability and the clutch being the only thing you would have to replace as long as you don't head to the track every weekend with slicks. lol

AiDRocks

iTrader: (13)

T-56 6 speeds are way more fun and reliable compared to automatic 4L60E

KENS_SS_4

I love my M6. I'm the orignal owner and its low miles ~40k. No issues so far. 21.9mpg average over the life of the car.
NOT FOR SALE!

406malibu

4l60E is a weak transmission. go with a t-56 the only problems they have is if you beat on them, then the shift forks tend to get bent, along with the keys.

chavez885

iTrader: (12)

on a stock car? I don't think so.

406malibu

yea, i have to agree, if it hasn't been beat on it can go further on a stock clutch. mine had 93 before it needed replacing, and i still had about another 10k miles worth of life left in it, but while i had the trans out i thought might as well...

LS1W66

I'm currently at 129K miles on my original clutch.
300+ Street runs 30 track passes (but no High rpm drops) and still going strong.

silverM6TA

iTrader: (5)

i know that if you were looking for a daily driver i would go for the auto because of the gears in it and the fact that fbody dont have the greatest clutches in the world.

406malibu

a clutch is much easier to replace, than to rebuild the 4l60e... and the t-56 will hold up substantially more power than the A4.

S8ER95Z

iTrader: (3)

Here I thought it was the Z06 clutch in the 01+ cars that was just doing well..

94K on the factory clutch with ~50 passes on it... so far so good. Doesn't slip at all.

JosephIV

iTrader: (14)

Like others have said, go drive both and figure it out. If you want to move out quickly and look good at the track, a stalled auto is the way to go.

If you enjoy the driving experience and don't mind learning how to launch, shift etc. then go 6 speed.

The only time my 6m is a PITA is while creeping in stop and go traffic.

steve65

First of all, you guys are great with all the replies...this really helps! My initial instinct and preference for fun as well as mpg is the M6. Another interesting point in one of the last comments, and after some reading on here, I'm starting to get the sense that an '01-'02 car would be the best choice. So is it true they have a different clutch setup? Problem is, finding the newer model that fits in my budget.

the_merv

iTrader: (88)

^^They have a better Slave Cylinder from the Factory, more than likely if one has been replaced, it's a newer style one too.