TKO or T56?

[Steve1968LS2]

Learned today that theres way more than just one type of T56.. there's the f-body one (in newer Camaros for example).. the "viper" T56 and the "aftermarket T56"

Tremec sent me the aftermarket version which is great for bolting up to a SBC but not so much for an LS2. The input shaft is longer and as such I have to use a different bell and a host of other issues like no VSS output.

Jeff at Classic Chevy 5-speed saved my bacon by swapping it for a normal T56. Very nice of him to do.

However Im a bit bummed that it will have the .50 6th gear which makes it useless for anything except mileage. If I had know I would have gotten steeper rear gears rather than the 3.70s I got (3.90's ?).. Someday when I have it rebuilt I will change the gearing.

Oh, the T56 is smoother shifting compared to a TKO and it goes into reverse easier.

[Mkelcy]

T56 Gear Ratios

http://www.ttcautomotive.com/English...s/T-56.asp#Car

[BThibodeaux]

Originally Posted by Mkelcy

Viper sixth gear is 0.5:1, not .62, so there is about a 20% difference in top gear and a significant potential fuel economy advantage for the 6 speed. I did not have to modify the transmission tunnel on my '68 for the T56; maybe '69's are different.

My T56 was the aftermarket version which does have a .62 ratio in sixth gear. I did have to modify the tunnel to get it to fit.

[fatlife]

Originally Posted by Steve1968LS2

Learned today that theres way more than just one type of T56.. there's the f-body one (in newer Camaros for example).. the "viper" T56 and the "aftermarket T56"

Tremec sent me the aftermarket version which is great for bolting up to a SBC but not so much for an LS2. The input shaft is longer and as such I have to use a different bell and a host of other issues like no VSS output.

Jeff at Classic Chevy 5-speed saved my bacon by swapping it for a normal T56. Very nice of him to do.

However Im a bit bummed that it will have the .50 6th gear which makes it useless for anything except mileage. If I had know I would have gotten steeper rear gears rather than the 3.70s I got (3.90's ?).. Someday when I have it rebuilt I will change the gearing.

Oh, the T56 is smoother shifting compared to a TKO and it goes into reverse easier.

They actually have 2 differnet T56's from F bodies, the 93-97 LT1's and then the 98-02s, the first gen, have the closer ratio spread, and have the steeper overdrive but are weaker because of this, I think they are rated at 350ilbs of torque while the LS1 is 450. The LS1 tranny is what you got with the more spread out gear ratios. Then you have the viper which is basically just a beefier output shaft and gears and uses the LS1 gear spread. I think the aftermarket version is the same as the first gen of the F body version.

Also I would think a T56 would be harder to put in reverse because they have a solenoid that helps engage reverse, that can only be operated with a PCM, it engages below 5mph. And when you put a T56 into a older car, you know have no help from the solenoid, and have to slam it over to get it into reverse. Probably hard for your old lady, but thats about it.

And your going to hate those gears, I have 3:73's in my 454 and it lugs and pings bad in 6th gear, its not even usable, not sure if your LS2 is stroked or not or what cam you have, so if you don't have a bunch of low end power, your def gonna want to move up to 4:11's. However you do have fuel injection etc, so I'm sure the computer will help out when it senses anything, so maybe your good. Thing about it is that on my car the 3:73's definetly help me launch the car, easier to not spin the tires, which is nice with over 600hp, but it just takes too long to get into the power band and rev out. BTW I do have a pretty huge cam, so that may be the reason of the bad drivability in 6th, changing gears isnt' hard or expensive, unless you need a different carrier so if you don't like them you can just change them out.

[USAZR1]

Originally Posted by Steve1968LS2

However Im a bit bummed that it will have the .50 6th gear which makes it useless for anything except mileage. If I had know I would have gotten steeper rear gears rather than the 3.70s I got (3.90's ?).. Someday when I have it rebuilt I will change the gearing.

Oh, the T56 is smoother shifting compared to a TKO and it goes into reverse easier.

Better mileage is all a .50 6th cog was designed for,Steve. Back in the day,us older guys running 4.56 or 4.88 gears would have killed for a T56.
My 69 has a D&D Viper T56 with 4.11 gears and it works very well.

[Mkelcy]

Originally Posted by fatlife

Also I would think a T56 would be harder to put in reverse because they have a solenoid that helps engage reverse, that can only be operated with a PCM, it engages below 5mph. And when you put a T56 into a older car, you know have no help from the solenoid, and have to slam it over to get it into reverse. Probably hard for your old lady, but thats about it.

You can get a shift knob like the one in the link and wire the switch to the reverse solenoid. Press the button and shift into reverse easily.

http://store.summitracing.com/partde...5&autoview=sku

[Steve1968LS2]

Originally Posted by fatlife

And your going to hate those gears, I have 3:73's in my 454 and it lugs and pings bad in 6th gear, its not even usable, not sure if your LS2 is stroked or not or what cam you have, so if you don't have a bunch of low end power, your def gonna want to move up to 4:11's. However you do have fuel injection etc, so I'm sure the computer will help out when it senses anything, so maybe your good. Thing about it is that on my car the 3:73's definetly help me launch the car, easier to not spin the tires, which is nice with over 600hp, but it just takes too long to get into the power band and rev out. BTW I do have a pretty huge cam, so that may be the reason of the bad drivability in 6th, changing gears isnt' hard or expensive, unless you need a different carrier so if you don't like them you can just change them out.

I don't know.. I had 3:73's in my 2000 SS and 6th was usable, although the think was such a low RPM that it was an MPG deal only.

Like I said, if I had known I was going to end up with a .50 T56 I would have got to 3.90s.. eventually I will rebuild the trans to the gearing I want. Right now I just want it DONE!! lol - Will see how this goes and then adjust the gears or the trans from there. It's a process

Must be your cam. stock 4th gen Z28s have a .50 6th and they are quite drivable (although sluggish given the low RPM).

[Steve1968LS2]

Originally Posted by BThibodeaux

My T56 was the aftermarket version which does have a .62 ratio in sixth gear. I did have to modify the tunnel to get it to fit.

What was it hooked up to? My problem was that the clutch, shifter, SFI bell and all that jazz was the same as a new F-body uses.. to run the aftermarket T56 I would of had to swap most of that out. I don't think (the one I had) aftermarket T56 even has the VSS deal and it certainly doesn't plug into the LSx wiring harness.

[Teetoe_Jones]

Originally Posted by fatlife

They actually have 2 differnet T56's from F bodies, the 93-97 LT1's and then the 98-02s, the first gen, have the closer ratio spread, and have the steeper overdrive but are weaker because of this, I think they are rated at 350ilbs of torque while the LS1 is 450.

Not accurate. The 93 T56 from the F body is the only one that was rated lower at 400 ft lbs, and used a different gear ratio. The 94-02 T56 all were rated at 450 ft lbs, and use the 2.66 1st, and .5 6th.

Originally Posted by fatlife

Also I would think a T56 would be harder to put in reverse because they have a solenoid that helps engage reverse, that can only be operated with a PCM, it engages below 5mph. And when you put a T56 into a older car, you know have no help from the solenoid, and have to slam it over to get it into reverse. Probably hard for your old lady, but thats about it.

All that needs to be done fix this is hook up the pig tail to any 12V switched source. No PCM is needed. We typically wire street cars to the brake light swithc, that way anytime you apply the brakes, you can put it into reverse.

Originally Posted by fatlife

And your going to hate those gears, I have 3:73's in my 454 and it lugs and pings bad in 6th gear, its not even usable, not sure if your LS2 is stroked or not or what cam you have, so if you don't have a bunch of low end power, your def gonna want to move up to 4:11's. However you do have fuel injection etc, so I'm sure the computer will help out when it senses anything, so maybe your good. Thing about it is that on my car the 3:73's definetly help me launch the car, easier to not spin the tires, which is nice with over 600hp, but it just takes too long to get into the power band and rev out. BTW I do have a pretty huge cam, so that may be the reason of the bad drivability in 6th, changing gears isnt' hard or expensive, unless you need a different carrier so if you don't like them you can just change them out.

I'd say your Carb and Cam are the main reason for these 6th gear issues. The LSX engine with EFI will have none of these problems.

Tyler

[fatlife]

Originally Posted by Teetoe_Jones

Not accurate. The 93 T56 from the F body is the only one that was rated lower at 400 ft lbs, and used a different gear ratio. The 94-02 T56 all were rated at 450 ft lbs, and use the 2.66 1st, and .5 6th.


I'd say your Carb and Cam are the main reason for these 6th gear issues. The LSX engine with EFI will have none of these problems.

Tyler

That info on the trannies goes against everything i've seen and read, but you know more about this than I do, so I suppose I am wrong on that, and you are right about cam and carb, but I thought I recalled that steves motor had a fairly big cam and heads? Even if it didn't I figured the FI would take care of it. IF not he should have no problem with the overdrive, but a steeper gear ration would still be better for performance