Tranny selection for the Z

[HarrisonTX]

Ok guys, heres my delima.

I am building a 302(yes chevy)

And i have come to the tranny selection.

Now, im buildin this 302 to turns some rpms, i want to spin to 7,500 and still be in the power band. Now to do this, im going to sacrific my lower RPM driveability.

I have a 79 malibu, with a 4speed and 3.42 rear so i know how 4 speeds can be on the highway, so i wanted a nice stronge 5 or 6 speed, so i could get somewhere above 7 MPG, In the 6 speeds i have been in, they usually sit at about 1,200 RPM around 70mph (of coarse depending on the gearin). I assume my motor will not run for anything at 1,200 RPM. So should i just use a 4 speed at cruise around at 3,500 RPM all the time, and say screw gas milage and insane gas prices? or do i scratch my high rpm idea so i can run a overdrive trans?

OR, i could just put some insane low gears in it, and stick it in 6th gear and drive around at 3 or 4 grand? i would get some speeding tickets for sure onthat one?

 

whats some suggestions guys?

[Pop N Wood]

Maybe you should post your cam specs. Might help guys give you better advice about how well that engine will run down around 1200 RPM. Also fuel injection or carb?

 

3500 RPM cruising sounds miserable to me. Can't imagine your engine will have less torque at say 2200 RPM than my 4 cylinder pick up. That what my totally stock truck turns at 70 mph.

[HarrisonTX]

A 3,500 Rpm crusie does sound bad, but thats what i keep the z at now, it about 70 mph, stock inline and a 4speed, i drive 2 hours everyweekend to come home from fort hood, im surprised it makes it everytime.

 

if the motor dosnt run good at 2,000 then i really dont wanna keep it in that range, i wanna keep it where its running decent.

I havnt picked a cam yet.

Its gonna be a carbed motor.

[wheelman]

Sounds to me like you've got some mixed up goals. A high reving 302 sounds like a fun motor but to expect it to get decent mileage, be in the powerband all the time and run a carb is not gonna happen.

 

Here's an idea, put a 5-speed in it, cruise in 5th at about 1700 - 2000 rpm and then when you want to blow someone away shift down and punch it. Even a high rev motor should have enough torque at around 2000 rpm to handle the light weight Z.

 

I'd also look real hard at using some type of EFI system if you're worried about fuel mileage. You can tune the air fuel ratio much better with fuel injection than a carb and if you went with something like Mega-Squirt it doesn't cost a fortune either.

 

Wheelman

[HarrisonTX]

Im not worried a whole lot about MPG, i just know overdrive would help queit a bit, and wouldnt mind having it. maybe yall are right about it having enough power in lower rpms to get it going, if it dosnt i guess i could just down shift to another gear. the more i think about it the more i remember. The DZ 302's were drivin on the street all the time, and they could still rap up to high rpm's maybe im too worried about nothing.

now i need to find a 5 speed that will handle some power

Anyone have a reccomendation for a 400hp (give or take) 5 speed?

[9kredline]

Anyone have a reccomendation for a 400hp (give or take) 5 speed?

 

T5, install a stouter clutch and you're good to go. Though, honestly, I'd go with the T56. I don't see 6th causing any issues with any gearing you're going to have in a Z.

[Phantom]

With your tires at a stock diameter and a 3.42 rear end and LS1 style T56 (.5:1 OD) will have you turning 1385 RPM in 6th at 60 mph. However, if you use the LT1 style T56 (.62:1 OD), you'll be turning 1,720 RPM in 6th. Both trannies have about a .75:1 5th gear so you could run it in 5th at 60 (2,075 rpm) and then shift to 6th when you're at higher speeds. Any tranny with a .75:1 OD 5th gear will allow you a top speed of 216 MPH at 7,500 rpm with your given differential and stock diameter tires. A world class T-5 should handle your torque & Hp and satisfy your cruise rpm requirements plus be less expensive than the T56.

[Dan Juday]

The T5 is sweet, and lighter than the T56 by a good bit. But if you plan to abuse it have it built before you bolt it up. Any good tranny builder can make it stout enough with the variety of aftermarket goodies out there for T5.

 

The T56 is tough enough right out of the box, and a tight shifter for a top loader. But having built and driven a LT1/T56 Z, all that torque in such a light weight package makes six gears superfluous IMHO.

[HarrisonTX]

The T5 is sweet' date=' and lighter than the T56 by a good bit. But if you plan to abuse it have it built before you bolt it up. Any good tranny builder can make it stout enough with the variety of aftermarket goodies out there for T5.

 

The T56 is tough enough right out of the box, and a tight shifter for a top loader. But having built and driven a LT1/T56 Z, all that torque in such a light weight package makes six gears superfluous IMHO.[/quote']

 

So, there is i think 3 different kinds of t5's right? yall said get the world class, and i would be good. I do like extra sercurity so i would get some aftermarket parts for it. If i am gonna do that then could i go ahead and buy the cheapest one? if im gonna put tougher parts in it, then why by an expensive one? sound good?

[peej410]

the only issue with that suggestion is that the weaker of the T5 trannys is weaker because of its internal design the WC T5 is actually a better designed tranny, so in this case its better to start with the more expensive WC T5

[Dan Juday]

the only issue with that suggestion is that the weaker of the T5 trannys is weaker because of its internal design the WC T5 is actually a better designed tranny, so in this case its better to start with the more expensive WC T5

 

2nd that.

[Guest the_dj]

I'm not sure they even make a set of gears for a diff that would leave you turning 3-4K in 6th. I have 3.70's in mine and I can't even use 6th at all before 80 (cam).

[Phantom]

Assuming stock diameter for the tires and a .50:1 ratio 6-spd the differential would have to be a 7.4:1 to turn 3,500 at 70 mph. No use for 1st and little for 2nd if that ratio existed & were used. Obviously a 1:1 fourth gear would turn those RPM's with a 3.70:1 differential gearing. That's why a 5-spd is probably fine as it would drop the RPM down to about 2,600. Still a pretty busy/noisy speed for a V8. I wouldn't want to cruise all day at that RPM as the drone would get to me.

[Guest the_dj]

Get the T56. You knooow you want it and the prices are really coming down these days.

[John Scott]

After seeing a good friend's WC T5 fail for the third time in his mostly stock TA with a wimpy 305, and a lecture from the local transmission repair shop where I was shown a pile of failed T5s many WC,... go for the T56. You always hear the T5 works...if you don't abuse it. Sweet shift the family car. Who doesn't want to abuse their hot rod? Its a royal PITA to change transmissions just because you banged a couple of gears. I opted for the aftermarket T56 with the .62 6th, lower torque rating than the .5 T56, but with the Zs light weight, no issues to date... I have a 383, 244 @ .050 cam, carbureted, 3.55 rear, 225 50 16 tires, I often cruise in 6th at 65mph, with no surging. Don't worry about redundant gearing with the torque of the V8 in a light chassis. Just because you can roll on and smoke the tires in the first two, sometimes three gears doesn't mean you should opt for a two speed. Heck I'd have fun with a 10 speed! Most of our local highway speed limits are 75 where the 6th is welcome on the highway. Yes it is more expensive, but as the saying goes....

John

[peej410]

After seeing a good friend's WC T5 fail for the third time in his mostly stock TA with a wimpy 305' date=' and a lecture from the local transmission repair shop where I was shown a pile of failed T5s many WC,... go for the T56. You always hear the T5 works...if you don't abuse it. Sweet shift the family car. Who doesn't want to abuse their hot rod? Its a royal PITA to change transmissions just because you banged a couple of gears. I opted for the aftermarket T56 with the .62 6th, lower torque rating than the .5 T56, but with the Zs light weight, no issues to date... I have a 383, 244 @ .050 cam, carbureted, 3.55 rear, 225 50 16 tires, I often cruise in 6th at 65mph, with no surging. Don't worry about redundant gearing with the torque of the V8 in a light chassis. Just because you can roll on and smoke the tires in the first two, sometimes three gears doesn't mean you should opt for a two speed. Heck I'd have fun with a 10 speed! Most of our local highway speed limits are 75 where the 6th is welcome on the highway. Yes it is more expensive, but as the saying goes....

John[/quote']

 

i know someone with 175k worth of holeshots and donuts on his 91 mustang gt on the stock transmission, its even got an aftermarket clutch in it, 2nd gear syncro is finally starting to go on it. theres guys running volvo wagons with turbos on top of v8s well into the 10s aswell as quite a few hybridz members doing the same on t5s, i whipped the snot out of my BW t5 when my Z was on the road and it actually shifted better as time went on. maintenance and driving style effect the t5 more than people seem to understand, and the shifters with integrated adjustable stops are invaluable, most t5s blow up because they are overshifted (shift forks actually start to bend overtime) i think youll be happy with a properly built gforce t5 or similar tranny. if your going to abuse it incessantly. you have to spend the money and overbuild your car. in that case i suggest ponying up for a tko600 or whatever its called, its probably lighter than the t56 by a whole lot. also dont forget that everyone that mentions t5s blowing up... most of those came out of 3200-3400 lb cars with v8s in them with people who abused them. not 2400-2800 lb cars with actually car enthusiasts driving them. just food for thought

[John Scott]

i know someone with 175k worth of holeshots and donuts on his 91 mustang gt on the stock transmission, its even got an aftermarket clutch in it, 2nd gear syncro is finally starting to go on it. theres guys running volvo wagons with turbos on top of v8s well into the 10s aswell as quite a few hybridz members doing the same on t5s, i whipped the snot out of my BW t5 when my Z was on the road and it actually shifted better as time went on. maintenance and driving style effect the t5 more than people seem to understand...,

Too often we , myself included, base our opinions on what was current the last time we researched (sometimes many years ago.) When I was shopping for transmissions the T5 wasn't holding a good reputation, even aftermarket builders usually blowing out with sticky tires and hard shifting. The JTR manual summed up the T5s reputation pretty well. "The five speed is great if you are not running a lot of horsepower." Your typical 383 will have no less than 400 lb/ft average from 2000-6000 rpm. Then I just read about the aftermarket G-Force T5 using the stock case and pretty much nothing else. Good for 500+ lb torque in a 3300 lb vehicle. Impressive and light weight to boot. $1700 doesnt sound bad for price either. Nice!

[peej410]

Too often we , myself included, base our opinions on what was current the last time we researched (sometimes many years ago.) When I was shopping for transmissions the T5 wasn't holding a good reputation, even aftermarket builders usually blowing out with sticky tires and hard shifting. The JTR manual summed up the T5s reputation pretty well. "The five speed is great if you are not running a lot of horsepower." Your typical 383 will have no less than 400 lb/ft average from 2000-6000 rpm. Then I just read about the aftermarket G-Force T5 using the stock case and pretty much nothing else. Good for 500+ lb torque in a 3300 lb vehicle. Impressive and light weight to boot. $1700 doesnt sound bad for price either. Nice!

 

agreed, i was looking for a tko untill i personally saw my friends mustang with that many miles on it haha. i need to rebuild mine (output shaft wobble) but i made my own shifter and the transmission is great, factor in that i paid 100 bucks for it and for me i just cant go wrong

[Guest tex]

hello all, first post here, i had buddies back home that blew up t5's left and right. All these trannys were in fox-bodied 5.0's, i knew one guy that destroyed probably 10, one of those being a WC, we had a saying "you're not a real man 'till you blow up your first t5" for what it's worth i'd go with a Tremec or a t56.

 

regards,

steve