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Driveability of LS1 with T56


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Hope everyone had a good holiday. Sitting around all weekend I have been thinking about my Z alot. Too damn cold to do any real work on it.

 

As some of you know, I am installing the LS1 in my 240Z. The motor I have came with an auto trans but I am still thinking about that a true sportscar should have a manual trans(IMHO) and how much I enjoy rowing through the gears.

 

I have a line on a low mileage T56 from a 2001 Trans-Am for a good price.

 

 

I have heard that if using the 6 speed that 6th gear is a waste with the ratio of .50 and that a 5 speed is all you need.

 

So that brings me to my questions. Of those of you with an LS1, LT1, SBC and 6 speed in your 1970-1978 Z car, how is the driveability of the car with the 6 speed? Is 6th a waste of a gear? at 70mph what rpm are you turning in 6th? how about in 5th? Also, is first gear a waste in a 2500 pound Z?

 

Please provide any input you feel might help me decide.

 

Your comments and opinions are welcomed.

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David,

6th gear is definitely NOT a waste. With my 3.70:1 R200 I'm turning right at 1,500 rpm in 6th at 60 mph. The LS1 will 'cruise' at rpms as low as around 1,200 rpm.

I normally start in 2nd gear when just cruising around town because the LS1's torque will start it off ok in 3rd. The big challenge with 1st is to not totally fry the tires when the hammer goes down. It can be controlled pretty consistantly with a little practice. With over 13,000 miles on my LS1 / T56 combo I'm going to claim the "most experienced" title.

I considered going with either a 3.54 or 3.36 ratio in the R200 for more usefulness of 1st but that would make 6th borderline at 60 where it is very happy right now. Since my car is really a daily driver I think I'll stay right where I am and just slowly evolve the suspension so I can eventually run some slightly wider tires - 225/50-16's are the widest I can run now without coil-overs.

Bill

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david, i haven't driven an ls1 z yet...but did drive 2 different trans am ram air ws6's. one had the stock 3.42 diff, the other a 4.11. i was very suprised the 4.11 ta still had a very streetable 1st gear. i'm going to start out using my existing r200 3.9 nismo lsd and see how that feels. if necessary, i'll swap to a 3.54 [fortunately i have one of those as well] since the 3.36 r200 is a very rare diff. i believe it came only in the 79 2+2 zx 4spd manual cars. pig in a poke...

 

david

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OK. So I bit the bullet and bought the T56. I will be running it with my R180 3.54:1 LSD. I hope It will hold up. I don't plan to abuse it. I guess I really wanted to shift the car. I now have a 2002 4L60E auto trans for sale. It is from a camaro and has 20,000 miles on it. It will come with the flywheel and the torque converter too. $600 or best off if you know anyone that wants one.

 

Thanks for the help guys.

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I am using an LT1 with a T56 and my 6th gear ratio is .62:1. I have found that with the 3.54 R200 that 1st is still very useful an so is 6th. I cant remember exactly what RPM Im cruise at with it in 6th at 60mph but it was around 1500rpms. I usually only used 6th for highway use though because my engine likes to run better/smoother at about 1800-2000rpms cruiseing(doesnt bog down as much) Im not sure if that because of the cam or what though(LT4 HC).

 

I too love to shift gears and you cant beat the stock strength of the T56!

 

 

Guy

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OK. So I bit the bullet and bought the T56. I will be running it with my R180 3.54:1 LSD. I hope It will hold up. I don't plan to abuse it. I guess I really wanted to shift the car. I now have a 2002 4L60E auto trans for sale.

 

I'll be running the R180 3.36 LSD in mine, but the auto will be nicer to the diff, I'm sure. However, I don't think you'll need to worry about it. I wouldn't mind getting your trans, just wonder how much shipping would run?

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My 240z has the 4l60e in it so I cant tell you how the t56 would be in the z-car. But my 1993 Ls1 RX7 does have a t56 in it. Right now I have 4.08 or 4.10 gears in it. I still find 1st very usable, I use 6th gear over 60mph. The t56 will not be as fast but it will be alot of fun.

 

Mike

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